Articoli di riviste: "Methiin"

1

Takada, Noboru, Sayaka Sutoh, Masuru Toyota, Yoshihisa Yamazaki, Nozomi Kitano-Yamashita, Chisato Ushida e Kazuo Yamashita. "Methiin as a nematode attractant in Allium sativum". Canadian Journal of Chemistry 98, n. 3 (marzo 2020): 164–68. http://dx.doi.org/10.1139/cjc-2019-0338.

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Damage to garlic (Allium sativum L.) caused by nematodes (Ditylenchus destructor Thorne) is becoming a serious agricultural hazard, leading to a great loss in garlic production. Once the garlic bulbs are invaded, the pathogenic nematode drastically increases in number along with the rotting of bulbs. It was therefore conceived that nematode attractants are present in the bulbs. Based on this hypothesis, chemical investigations were performed to explore a nematode attractant in A. sativum bulbs, which resulted in the identification of methiin (S-methyl-l-cysteine S-oxide) as an attractant. Bioassay and quantification experiments of methiin in extracts of A. sativum bulb led to the conclusion that methiin possesses sufficient potential to attract D. destructor into A. sativum bulbs. Moreover, an activity comparing study of methiin with its analogs showed that the sulfoxide functionality is essential for attractant activity. Moreover, methiin was revealed to attract Caenorhabditis elegans. Further investigation of methiin will help to elucidate the neuronal system of D. destructor.

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Ovesná, Jaroslava, Ladislav Kučera, Jana Králová, Leona Leišová, Helena Stavělíková e Jan Velíšek. "Genetic Diversity Among Garlic Clones as Revealed by Aflp, Phenotypic Descriptors and S-Amino Acids Level". Vegetable Crops Research Bulletin 66, n. 1 (1 gennaio 2007): 105–16. http://dx.doi.org/10.2478/v10032-007-0013-9.

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Genetic Diversity Among Garlic Clones as Revealed by Aflp, Phenotypic Descriptors andS-Amino Acids LevelGarlic (Allium sativumL.) belongs to well known vegetables. Garlic is considered a valuable source of health benefit compounds.S-amino acids, namelyS-alk(en)yl-L-cysteine sulfoxides, are one of the major garlic constituents. We evaluated a set of garlic genetics resources representing namely valuable germplasm from Czech Republic, Slovakia, Poland and former Soviet Union. We showed that differences exist among analysed genotypes inS-amino acids (alliin/methiin) level and donors of high level of alliin/methiin can be identified. High alliin/methiin level was found within genetic resources and registered cultivars under the use. Level of alliin and isoalliin did not correlate with measured level of methiin. Donors of high methiin level were found within accessions marked as being "wild" in EVIGEZ database. Sufficient variability was found by AFLP analysis as well. Accessions were divided by PCA basically into two categories: hardnecks (Ophioscorodongroup,Longicuspisgroup) and softneck (sativum group). Presented work showes possibility to find suitable donors of biologically active compounds in garlic.

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Horníčková, J., R. Kubec, J. Velíšek, CejpekK, J. Ovesná e H. Stavělíková. "Changes of S-alk(en)ylcysteine sulfoxide levels during the growth of different garlic morphotypes". Czech Journal of Food Sciences 29, No. 4 (10 agosto 2011): 373–81. http://dx.doi.org/10.17221/3/2011-cjfs.

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The contents of three S-alk(en)ylcysteine sulfoxides (alliin, methiin, and isoalliin) were determined in the leaves, pseudostems, and bulbs of six garlic genotypes (two flowering plant morphotypes, two semi bolters, and two scape absent morphotypes) cultivated for five consecutive years at the same location. The average levels of alliin, methiin, and isoalliin were found to be as follows: 1.92, 0.44, and 0.07 mg/g fw in the leaves, 1.57, 0.27, and 0.08 mg/g fw in the pseudostems, and 1.71, 0.20 and 0.13 mg/g fw in the bulbs, respectively. No statistically significant year-to-year differences were observed between the samples. Furthermore, the total contents and relative proportions of S-alk(en)ylcysteine sulfoxides in various parts of the plants (leaves, pseudostems, bulbs and roots) were evaluated in detail during the whole vegetation period. It was observed that the total content of these amino acids gradually decreased in all parts except for the bulbs. In the bulbs, the total content initially decreased after planting but significantly increased in June and culminated before harvest. Analogous trends were also observed for alliin and methiin concentrations. On the other hand, isoalliin levels steadily decreased during the whole vegetation period in all parts of the plants.

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4

Horníčková, J., R. Kubec, K. Cejpek, J. Velíšek, J. Ovesná e H. Stavělíková. "Profiles of S-alk(en)ylcysteine sulfoxides in various garlic genotypes". Czech Journal of Food Sciences 28, No. 4 (6 settembre 2010): 298–308. http://dx.doi.org/10.17221/135/2010-cjfs.

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The contents of major S-alk(en)ylcysteine sulfoxides (namely alliin, methiin and isoalliin) were determined in a set of 58 various garlic genotypes (22 flowering plant morphotypes, 14 semi bolting plants and 22 scape absent morphotype plants), representing the garlic collection of the Allium gene bank in the Czech Republic. The plants were cultivated in four successive years (2005–2008) and analysed immediately after harvest and subsequently after eight weeks of storage at 5°C. The total content of the three cysteine derivatives in fresh samples varied considerably between 3.35 mg/g fresh weigh and 12.77 mg/g fresh weight, with the mean of 7.50 mg/g fresh weight and the average relative proportions of alliin/methiin/isoalliin of 83/16/1. Upon 8-week storage at 5°C, the average total amount of S-alk(en)ylcysteine sulfoxides increased by 30% to 9.75 mg/g fresh weight, with the alliin/methiin/isoalliin ratio changing to 82/14/4. The data obtained were statistically evaluated using linear discrimination analysis to distinguish the differences between the years of harvest, between freshly harvested and stored samples, and between the individual morphotypes. While the year-to-year differences between the samples were statistically not very significant, the fresh and stored samples as well as the individual garlic morphotypes differed considerably in S-alk(en)ylcysteine sulfoxide content. Our results indicate that the content of S-alk(en)ylcysteine sulfoxides primarily depends on various genetic factors and post-harvest storage conditions, whereas the climatic conditions during the growth (e.g. temperature, irrigation) influence their level to a lesser extent. Various implications for the food and pharmaceutical industries are discussed.  

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5

Velíšek, J., e R. Kubec. "S-Substituted cysteine derivatives in production of flavour and colour". Czech Journal of Food Sciences 22, SI - Chem. Reactions in Foods V (1 gennaio 2004): S54—S59. http://dx.doi.org/10.17221/10611-cjfs.

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A brief review of our continuous investigations on S-substituted cysteine derivatives is presented herein. It comprises a summary on nonenzymatic (thermal) decomposition of these amino acids as well as on their role in the formation of blue and pink pigments during processing of garlic and onion, respectively. The emphasis is put on four most common derivatives, namely S-methyl-, S-allyl-, S-1-propenyl- and S-propylcysteine sulfoxides (methiin, alliin, isoalliin and propiin, respectively). Our results demonstrate that these sulfur-containing amino acids are the key primary precursors in the formation of both flavour and colour of alliaceous plants.

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Kolodiazhna, Anastasy О., Аleksei I. Skliarov, Alena A. Slastennikova e Oleg I. Kolodiazhnyi. "Asymmetric synthesis of (S,R)- and (R,R)-methiin stereoisomers". Phosphorus, Sulfur, and Silicon and the Related Elements 195, n. 9 (29 aprile 2020): 713–17. http://dx.doi.org/10.1080/10426507.2020.1755972.

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7

Horie, Hideki, e Ken-ichiro Yamashita. "Non-derivatized analysis of methiin and alliin in vegetables by capillary electrophoresis". Journal of Chromatography A 1132, n. 1-2 (novembre 2006): 337–39. http://dx.doi.org/10.1016/j.chroma.2006.09.018.

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8

Horníčková, J., J. Velíšek, J. Ovesná e H. Stavělíková. "Distribution of S-alk(en)yl-l-cysteine Sulfoxides in Garlic (Allium sativum L.)". Czech Journal of Food Sciences 27, Special Issue 1 (24 giugno 2009): S232—S235. http://dx.doi.org/10.17221/610-cjfs.

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This study was devoted to distribution of S-alk(en)yl-L-cysteine sulfoxides (particularly alliin, methiin, and isoalliin) in plants of Allium sativum L. and to diversity of selected groups of garlic clones representing the three basic garlic morfotypes (i.e. flowering plants, scape absent and semi-bolters – this classification is based on IPGRI descriptors). The content of S-alk(en)yl-L-cysteine sulfoxides, important non-volatile precursors flavour-active compounds, was determined in four parts (roots, bulbs, false stems, and leaves) of six different clones of garlic (Allium sativum L.) plants collected during the whole of vegetation – in March, April, May, June, and July. The contents of target S-alk(en)yl-L-cysteine sulfoxides were dependent not only on part of garlic plants but also on morfotype of garlic plants and vegetation period.

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Jang, Gwang-Ju, Mi Jeong Sung, Haeng Jeon Hur, Miyoung Yoo, Jung Hoon Choi, In Koo Hwang e Sanghee Lee. "Metabolomics Analysis of the Lipid-Regulating Effect of Allium hookeri in a Hamster Model of High-Fat Diet-Induced Hyperlipidemia by UPLC/ESI-Q-TOF Mass Spectrometry". Evidence-Based Complementary and Alternative Medicine 2018 (27 settembre 2018): 1–8. http://dx.doi.org/10.1155/2018/5659174.

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Hyperlipidemia is a risk factor for atherosclerotic cardiovascular disease and is a major public health concern. Allium hookeri (AH) is an Allium species containing high levels of bioactive organosulfur compounds such as methiin and cycloalliin. AH exerts hypolipidemic effects in animals fed a high-fat diet. However, there exists little information on the mechanisms underlying these effects. To address this issue, we used a metabolomic approach based on ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry to identify factors mediating the lipid-lowering effects of AH. Principal component and partial least-squares discriminant analyses of serum metabolome profiles revealed 25 metabolites as potential biomarkers for the effects of AH on lipid levels. These compounds were predominantly phospholipids, including phosphatidylcholines (PCs), lysoPCs, and lysophosphatidylethanolamines. Glycerophospholipid metabolism was identified as a significantly enriched pathway. These results provide mechanistic insight into the antihyperlipidemic effects of AH and evidence for its efficacy as a therapeutic agent.

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10

Seino, Teruyuki. "Effects of Processing and Preservation Conditions on Methiin and Alliin Contents of Chinese Chive Stems". Nippon Shokuhin Kagaku Kogaku Kaishi 69, n. 7 (15 luglio 2022): 343–52. http://dx.doi.org/10.3136/nskkk.69.352.

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11

Sasi, Minnu, Sandeep Kumar, Manoj Kumar, Sandhya Thapa, Uma Prajapati, Yamini Tak, Sushil Changan et al. "Garlic (Allium sativum L.) Bioactives and Its Role in Alleviating Oral Pathologies". Antioxidants 10, n. 11 (21 novembre 2021): 1847. http://dx.doi.org/10.3390/antiox10111847.

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Garlic (Allium sativa L.) is a bulbous flowering plant belongs to the family of Amaryllidaceae and is a predominant horticultural crop originating from central Asia. Garlic and its products are chiefly used for culinary and therapeutic purposes in many countries. Bulbs of raw garlic have been investigated for their role in oral health, which are ascribed to a myriad of biologically active compounds such as alliin, allicin, methiin, S-allylcysteine (SAC), diallyl sulfide (DAS), S-ally-mercapto cysteine (SAMC), diallyl disulphide (DADS), diallyl trisulfide (DATS) and methyl allyl disulphide. A systematic review was conducted following the PRISMA statement. Scopus, PubMed, Clinicaltrials.gov, and Science direct databases were searched between 12 April 2021 to 4 September 2021. A total of 148 studies were included and the qualitative synthesis phytochemical profile of GE, biological activities, therapeutic applications of garlic extract (GE) in oral health care system, and its mechanism of action in curing various oral pathologies have been discussed. Furthermore, the safety of incorporation of GE as food supplements is also critically discussed. To conclude, GE could conceivably make a treatment recourse for patients suffering from diverse oral diseases.

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Ingallina, Cinzia, Giacomo Di Matteo, Mattia Spano, Erica Acciaro, Enio Campiglia, Luisa Mannina e Anatoly Petrovich Sobolev. "Byproducts of Globe Artichoke and Cauliflower Production as a New Source of Bioactive Compounds in the Green Economy Perspective: An NMR Study". Molecules 28, n. 3 (31 gennaio 2023): 1363. http://dx.doi.org/10.3390/molecules28031363.

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The recovery of bioactive compounds from crop byproducts leads to a new perspective way of waste reutilization as a part of the circular economy. The present study aimed at an exhaustive metabolite profile characterization of globe artichoke and cauliflower byproducts (leaves, stalks, and florets for cauliflower only) as a prerequisite for their valorization and future implementations. The metabolite profile of aqueous and organic extracts of byproducts was analyzed using the NMR-based metabolomics approach. Free amino acids, organic acids, sugars, polyols, polyphenols, amines, glucosinolates, fatty acids, phospho- and galactolipids, sterols, and sesquiterpene lactones were identified and quantified. In particular, globe artichoke byproducts are a source of health-beneficial compounds including chiro-inositol (up to 10.1 mg/g), scyllo-inositol (up to 1.8 mg/g), sesquiterpene lactones (cynaropicrin, grosheimin, dehydrocynaropicrin, up to 45.5 mg/g in total), inulins, and chlorogenic acid (up to 7.5 mg/g), whereas cauliflower byproducts enclose bioactive sulfur-containing compounds S-methyl-L-cysteine S-oxide (methiin, up to 20.7 mg/g) and glucosinolates. A variable content of all metabolites was observed depending on the crop type (globe artichoke vs. cauliflower) and the plant part (leaves vs. stalks). The results here reported can be potentially used in different ways, including the formulation of new plant biostimulants and food supplements.

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Moreno-Ortega, Alicia, Gema Pereira-Caro, Iziar A. Ludwig, María-José Motilva e José Manuel Moreno-Rojas. "Bioavailability of Organosulfur Compounds after the Ingestion of Black Garlic by Healthy Humans". Antioxidants 12, n. 4 (13 aprile 2023): 925. http://dx.doi.org/10.3390/antiox12040925.

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The consumption of black garlic has been related to a decreased risk of many human diseases due to the presence of phytochemicals such as organosulfur compounds (OSCs). However, information on the metabolization of these compounds in humans is limited. By means of ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS), this study aims to determine the OSCs and their metabolites excreted in urine 24 h after an acute intake of 20 g of black garlic by healthy humans. Thirty-three OSCs were identified and quantified, methiin (17,954 ± 6040 nmol), isoalliin (15,001 ± 9241 nmol), S-(2-carboxypropyl)-L-cysteine (8804 ± 7220 nmol) and S-propyl-L-cysteine (deoxypropiin) (7035 ± 1392 nmol) being the main ones. Also detected were the metabolites N-acetyl-S-allyl-L-cysteine (NASAC), N-acetyl-S-allyl-L-cysteine sulfoxide (NASACS) and N-acetyl-S-(2-carboxypropyl)-L-cysteine (NACPC), derived from S-allyl-L-cysteine (SAC), alliin and S-(2-carboxypropyl)-L-cysteine, respectively. These compounds are potentially N-acetylated in the liver and kidney. The total excretion of OSCs 24 h after the ingestion of black garlic was 64,312 ± 26,584 nmol. A tentative metabolic pathway has been proposed for OSCs in humans.

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Bernaert, Nathalie, Lien Goetghebeur, Hervé De Clercq, Marc De Loose, Els Daeseleire, Els Van Pamel, Erik Van Bockstaele e Bart Van Droogenbroeck. "Influence of Cultivar and Harvest Time on the Amounts of Isoalliin and Methiin in Leek (Allium ampeloprasum var.porrum)". Journal of Agricultural and Food Chemistry 60, n. 44 (29 ottobre 2012): 10910–19. http://dx.doi.org/10.1021/jf302132a.

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Xia, Shi-Wei, Lin-Feng Hang, Siyad Ali, Xiao-Yu Xu, Yan-Jun Liu, Qian-Qian Yan, Qiu-Yu Luo et al. "Biosynthesis and Metabolism of Garlic Odor Compounds in Cultivated Chinese Chives (Allium tuberosum) and Wild Chinese Chives (Allium hookeri)". International Journal of Molecular Sciences 23, n. 13 (24 giugno 2022): 7013. http://dx.doi.org/10.3390/ijms23137013.

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Chinese chives is a popular herb vegetable and medicine in Asian countries. Southwest China is one of the centers of origin, and the mountainous areas in this region are rich in wild germplasm. In this study, we collected four samples of germplasm from different altitudes: a land race of cultivated Chinese chives (Allium tuberosum), wide-leaf chives and extra-wide-leaf chives (Allium hookeri), and ovoid-leaf chives (Allium funckiaefolium). Leaf metabolites were detected and compared between A. tuberosum and A. hookeri. A total of 158 differentially accumulated metabolites (DAM) were identified by Gas Chromatography—Mass Spectrometry (GC-MS) and Liquid Chromatography—Mass Spectrometry (LC-MS), among which there was a wide range of garlic odor compounds, free amino acids, and sugars. A. hookeri contains a higher content of fructose, garlic odor compounds, and amino acids than A. tuberosum, which is supported by the higher expression level of biosynthetic genes revealed by transcriptome analysis. A. hookeri accumulates the same garlic odor compound precursors that A. tuberosum does (mainly methiin and alliin). We isolated full-length gene sequences of phytochelatin synthase (PCS), γ-glutamyltranspeptidases (GGT), flavin-containing monooxygenase (FMO), and alliinase (ALN). These sequences showed closer relations in phylogenetic analysis between A. hookeri and A. tuberosum (with sequence identities ranging from 86% to 90%) than with Allium cepa or Allium sativum (which had a lower sequence identity ranging from 76% to 88%). Among these assayed genes, ALN, the critical gene controlling the conversion of odorless precursors into odor compounds, was undetected in leaves, bulbs, and roots of A. tuberosum, which could account for its weaker garlic smell. Moreover, we identified a distinct FMO1 gene in extra-wide-leaf A. hookeri that is due to a CDS-deletion and frameshift mutation. These results above reveal the molecular and metabolomic basis of impressive strong odor in wild Chinese chives.

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Abdelrahman, Mostafa, Sho Hirata, Takuya Mukae, Tomohiro Yamada, Yuji Sawada, Magdi El-Syaed, Yutaka Yamada, Muneo Sato, Masami Yokota Hirai e Masayoshi Shigyo. "Comprehensive Metabolite Profiling in Genetic Resources of Garlic (Allium sativum L.) Collected from Different Geographical Regions". Molecules 26, n. 5 (5 marzo 2021): 1415. http://dx.doi.org/10.3390/molecules26051415.

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Garlic (Allium sativum) is the second most important Allium crop that has been used as a vegetable and condiment from ancient times due to its characteristic flavor and taste. Although garlic is a sterile plant that reproduces vegetatively through cloves, garlic shows high biodiversity, as well as phenotypic plasticity and environmental adaptation capacity. To determine the possible mechanism underlying this phenomenon and to provide new genetic materials for the development of a novel garlic cultivar with useful agronomic traits, the metabolic profiles in the leaf tissue of 30 garlic accessions collected from different geographical regions, with a special focus on the Asian region, were investigated using LC/MS. In addition, the total saponin and fructan contents in the roots and cloves of the investigated garlic accessions were also evaluated. Total saponin and fructan contents did not separate the garlic accessions based on their geographical origin, implying that saponin and fructan contents were clone-specific and agroclimatic changes have affected the quantitative and qualitative levels of saponins in garlic over a long history of cultivation. Principal component analysis (PCA) and dendrogram clustering of the LC/MS-based metabolite profiling showed two major clusters. Specifically, many Japanese and Central Asia accessions were grouped in cluster I and showed high accumulations of flavonol glucosides, alliin, and methiin. On the other hand, garlic accessions grouped in cluster II exhibited a high accumulation of anthocyanin glucosides and amino acids. Although most of the accessions were not separated based on country of origin, the Central Asia accessions were clustered in one group, implying that these accessions exhibited distinct metabolic profiles. The present study provides useful information that can be used for germplasm selection and the development of new garlic varieties with beneficial biotic and abiotic stress-adaptive traits.

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Lyon, S. B., L. Buonocore e M. Miller. "Naturally occurring methylation inhibitor: DNA hypomethylation and hemoglobin synthesis in human K562 cells". Molecular and Cellular Biology 7, n. 5 (maggio 1987): 1759–63. http://dx.doi.org/10.1128/mcb.7.5.1759-1763.1987.

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A naturally occurring methylation inhibitor isolated from rabbit liver and named methinin inhibits a number of methyltransferases. Methinin is a low-molecular-weight compound (1,400) that has an active amine group. This compound inhibits the DNA methyltransferase of human erythroleukemia cells (K562) in vitro. When the K562 cells were grown in medium containing methinin, fetal hemoglobin was produced. Small but detectable amounts of adult hemoglobin were also produced. Methinin was not toxic to these cells. The overall rate of genomic DNA methylation was reduced by 60% in cells grown in medium containing methinin. Southern blots of genomic DNA from methinin-treated cells and untreated cells hybridized to a 32P-labeled globin gene probe showed that one site in the globin gene region was hypomethylated. Methinin is a naturally occurring compound which inhibits DNA methylation both in vitro and in vivo.

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Lyon, S. B., L. Buonocore e M. Miller. "Naturally occurring methylation inhibitor: DNA hypomethylation and hemoglobin synthesis in human K562 cells." Molecular and Cellular Biology 7, n. 5 (maggio 1987): 1759–63. http://dx.doi.org/10.1128/mcb.7.5.1759.

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Abstract (sommario):

A naturally occurring methylation inhibitor isolated from rabbit liver and named methinin inhibits a number of methyltransferases. Methinin is a low-molecular-weight compound (1,400) that has an active amine group. This compound inhibits the DNA methyltransferase of human erythroleukemia cells (K562) in vitro. When the K562 cells were grown in medium containing methinin, fetal hemoglobin was produced. Small but detectable amounts of adult hemoglobin were also produced. Methinin was not toxic to these cells. The overall rate of genomic DNA methylation was reduced by 60% in cells grown in medium containing methinin. Southern blots of genomic DNA from methinin-treated cells and untreated cells hybridized to a 32P-labeled globin gene probe showed that one site in the globin gene region was hypomethylated. Methinin is a naturally occurring compound which inhibits DNA methylation both in vitro and in vivo.

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Keith Philips, T., e Michael A. Ivie. "The Methiini of the West Indies (Coleoptera: Cerambycidae) with notes on the circum-Caribbean species". Insect Systematics & Evolution 29, n. 1 (1998): 57–87. http://dx.doi.org/10.1163/187631298x00203.

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AbstractThe Methiini of the West Indies are revised. Cyanomethia pseudothonalmus, new genus, new species and Methia jamaicensis new species are described. Methia pusilla, M. constricticollis, M. impressicollis, M. insularum, M. pallida, M. pulchra, M. punctata, and M. rhizophorae are new synonyms of M. necydalea. Keys to genera of Methiini and species of Methia in the West Indies are given and the biology and morphological variation of the genus Methia discussed. A phylogenetic analysis of the Methiini is conducted to determine relationships among the genera, and the zoogeographic patterns of species found in the West Indies is included.

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Barrangou-Poueys-Darlas, Malcolm, Marie Gerardin, Sylvie Deheul, Marion Istvan, Marylène Guerlais, Pascale Jolliet, Thomas Dejoie e Caroline Victorri-Vigneau. "Poppers Use and High Methaemoglobinaemia: ‘Dangerous Liaisons’". Pharmaceuticals 14, n. 10 (19 ottobre 2021): 1061. http://dx.doi.org/10.3390/ph14101061.

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Poppers are legal and largely used in France despite severe side effects, such as methaemoglobinaemia (MetHbia). Our work aimed to assess the prevalence of poppers consumers among patients with a MetHbia higher than or equal to 5% in French university hospitals and its evolution before and after the legalization of poppers in France. We conducted a national multicentre observational retrospective study. All patients for whom at least one MetHbia measurement was performed from 2012 to 2017 in university hospitals where the French addictovigilance network (FAN) is implanted were included. For each MetHbia measurement exceeding or equal to 5%, a return to the clinical file was made by the FAN to assess poppers consumption. We calculated the prevalence of MetHbia exceeding or equal to 5% and 25% and the prevalence of poppers consumption before and after the legalization. A total of 239 (0.14%) patients had a MetHbia level exceeding or equal to 5% with 25 (10.46%) cases of poppers consumption. Poppers consumption represented 68.4% (13 out of 19) of cases with MetHbia greater than or equal to 25%. Poppers consumption among patients with MetHbia exceeding or equal to 5% increased after the legalization from 4.76% to 11.67% (prevalence ratio PR = 2.45, 95% CI = [0.98–8.37], p-value = 0.190). The proportion of patients with a MetHbia level of 25% or more increased after the legalization from 4.76% to 8.63% (PR = 1.81, 95% CI = [0.68–6.82], p-value = 0.374). The use of poppers is very frequently reported by patients with MetHbia greater than or equal to 25%.

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Michat, Mariano C., Yves Alarie, Patricia L. M. Torres e Yoandri S. Megna. "Larval morphology of the diving beetle Celina and the phylogeny of ancestral hydroporines (Coleoptera:Dytiscidae:Hydroporinae)". Invertebrate Systematics 21, n. 3 (2007): 239. http://dx.doi.org/10.1071/is06037.

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Phylogenetic relationships within diving beetles (Dytiscidae) are imperfectly known. In particular, some authors have considered that the tribe Methlini is included in the subfamily Hydroporinae (a large group including about half of the dytiscid species worldwide), whereas others have argued in favour of excluding Methlini from the Hydroporinae and giving it subfamilial rank. Larval characters have been underutilised in phylogenetic studies, mainly because the larvae of many taxa within the family are still unknown. The larval morphology of the dytiscid tribe Methlini, in particular, remains poorly known. In this study, the phylogenetic relationships among ancestral lineages of the Hydroporinae are investigated based on a cladistic analysis of 34 taxa and 127 morphological larval characters. For this purpose, larvae of the Methlini (Celina parallela (Babington, 1841)) and C. imitatrix Young, 1979) are described and illustrated in detail for the first time, with particular emphasis on morphometry and chaetotaxy. The results show high support for a monophyletic origin of the Hydroporinae, including Methlini, based on eight unique character states. Giving Methlini subfamily rank would leave Hydroporinae with a single unique larval apomorphy. This supports the inclusion of Methlini as a tribe of Hydroporinae. Other interesting but less well supported results include: 1, the clade Laccornini + Hydrovatini + Canthyporus Zimmermann, 1919 (Hydroporini) resolved as the sister-group to the other Hydroporinae minus Methlini; and 2, Hydrovatini and Canthyporus resolved as sister-groups. The presence of a galea, albeit in a reduced form, in larvae of Methlini, Laccornini and Hydrovatini is of the utmost interest. The putative hypothesis of an ancestral position for these genera within Hydroporinae suggests that hydroporines lost the galea secondarily.

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Wan, Peter, Beverly Barker, Li Diao, Maike Fischer, Yijian Shi e Cheng Yang. "1995 Merck Frosst Award Lecture Quinone methides: relevant intermediates in organic chemistry". Canadian Journal of Chemistry 74, n. 4 (1 aprile 1996): 465–75. http://dx.doi.org/10.1139/v96-051.

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ortho and para-Quinone methides (2-methylene-3,5-cyclohexadien-1-one and 4-methylene-2,5-cyclohexadien-1-one, respectively) are intermediates in a variety of important chemical systems. In particular, o-quinone methides are useful in synthesis for the construction of chroman ring systems. A brief account of the relevance of quinone methide chemistry will be provided. This is followed by a review of recent studies from our laboratory on efficient methods for the photogeneration of quinone methides, concentrating on the use of hydroxy-substituted benzyl alcohols in aqueous media. It is shown that this method is general since it provides access to o-, m-, and p-quinone methide isomers. When appropriately substituted, all of these quinone methide isomers have been spectroscopically characterized by laser flash photolysis, making this technique the one of choice for studying the dynamics of these reactive intermediates. The mechanism of photochemical generation from hydroxybenzyl alcohols and extensions of the reaction to photogeneration of fluorenyl and biphenyl quinone methides will also be presented. Key words: quinone methide, biphenyl quinone methide, carbocation, photosolvolysis, photodehydroxylation, hetero-Diels–Alder reaction.

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23

LeBel, CP, L. Langlois, DP Bell, JD Young, WC Kenney, BJ Payne, LE Sendelbach e Lck Wong. "Pharmacokinetic, pharmacodynamic, and pharmacotoxic profiles of recombinant- methionyl human interleukin-2 [alanine- 125] (r-metHuIL-2[ala-125]) following intravenous and subcutaneous administration in rats". Human & Experimental Toxicology 14, n. 11 (novembre 1995): 909–15. http://dx.doi.org/10.1177/096032719501401109.

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Abstract (sommario):

Comparative pharmacotoxicity studies in rats were per formed to evaluate the response to r-metHuIL-2[ala-125] following 2 or 4 weeks of daily intravenous or sub cutaneous administration, as well as to evaluate pharmacokinetic and pharmacodynamic responses. Pharmacokinetic analysis indicated that r-metHuIL-2[ala- 125] showed high bioavailability and nonlinear concentra tion profiles. Pharmacodynamic responses to intravenous or subcutaneous dosing with r-metHuIL-2[ala-125], as measured by white blood cell counts, were comparable. Preclinical safety studies (6, 30, and 150 μg kg-1 day -1) indi cated that r-metHuIL-2[ala-125], whether given intra venously or subcutaneously, was associated with increased circulating and infiltrating levels of lympho cytes and eosinophils. Bone marrow lymphoid hyperpla sia and splenic extramedullary hematopoiesis were simi larly observed in each study. This pattern of effects was considered an exaggerated pharmacodynamic response to r-metHuIL-2[ala-125]. Of further note was a histopatholog ic finding described as hepatocyte single cell necrosis which was observed following both intravenous and sub cutaneous administration and was considered to be a toxic response to high doses of r-metHuIL-2[ala-125]. The no observable adverse effect level (NOAEL) for r-metHuIL- 2[ala-125] via intravenous administration was 6 μg kg -1 day-1, while that for subcutaneous administration was 30 μg kg-1 day-1. Data herein present a form of rHuIL-2 with pharmacokinetic and pharmacodynamic profiles that are similar when given by these two systemic routes. Pharmacotoxic data, based on NOAELs, suggest that sub cutaneous administration may be a preferred clinical route of administration.

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24

Lukeman, Matthew, Duane Veale, Peter Wan, V. Ranjit N. Munasinghe e John ET Corrie. "Photogeneration of 1,5-naphthoquinone methides via excited-state (formal) intramolecular proton transfer (ESIPT) and photodehydration of 1-naphthol derivatives in aqueous solution". Canadian Journal of Chemistry 82, n. 2 (1 febbraio 2004): 240–53. http://dx.doi.org/10.1139/v03-184.

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Abstract (sommario):

The photochemistry of naphthols 1, 2, 4, 5 and 9, and phenol 10 has been studied in aqueous solution with the primary aim of exploring the viability of such compounds for naphthoquinone and quinone methide photogeneration, along the lines already demonstrated by our group for phenol derivatives. 1-Naphthol (1) is known to be substantially more acidic than 2-naphthol (2) in the singlet excited state (pKa* = 0.4 and 2.8, respectively) and it was expected that this difference in excited-state acidity might be manifested in higher reactivity of 1-naphthol derivatives for photochemical reactions requiring excited-state naphtholate ions, such as quinone methide formation. Our results show that three types of naphthoquinone methides (26a, 26b, and 27) are readily photogenerated in aqueous solution by irradiation of 1-naphthols. Photolysis of the parent 1-naphthol (1) in neutral aqueous solution gave 1,5-naphthoquinone methide 26a as well as the non-Kekulé 1,8-naphthoquinone methide 26b, both via the process of excited-state (formal) intramolecular proton transfer (ESIPT), based on the observation of deuterium exchange at the 5- and 8-positions, respectively, on photolysis in D2OCH3CN. A transient assignable to the 1,5-naphthoquinone methide 26a was observed in laser flash photolysis experiments. The isomeric 2-naphthol (2) was unreactive under similar conditions. The more conjugated 1,5-naphthoquinone methide 27 was formed efficiently via photodehydroxylation of 4; isomeric 5 was unreactive. The efficient photosolvolytic reaction observed for 4 opens the way to design related naphthol systems for application as photoreleasable protecting groups by virtue of the long-wavelength absorption of the naphthalene chromophore.Key words: photosolvolysis, excited-state intramolecular proton transfer, quinone methide, photorelease, photoprotonation.

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25

NASCIMENTO, FRANCISCO E. DE L., e FREDDY BRAVO. "Review of Acangassuini Galileo & Martins, 2001 (Insecta, Coleoptera, Cerambycidae), with description of a new genus and species, and description of two new species in the tribes Methiini Thomson, 1860 and Oemini Lacordaire, 1868". Zootaxa 4379, n. 4 (15 febbraio 2018): 576. http://dx.doi.org/10.11646/zootaxa.4379.4.9.

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Abstract (sommario):

Acangassuini is reviewed. Acangarana gen. nov. is described for A. santossilvai sp. nov. from Brazil. In addition, two species are newly described from Brazil: Methia flavomera sp. nov. (Methiini) and Stenoeme furca sp. nov. (Oemini).

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26

Beghidja, Noureddine, Samir Benayache, Fadila Benayache, David W. Knight e Benson M. Kariuki. "Crystal structure of pseudoguainolide". Acta Crystallographica Section E Crystallographic Communications 71, n. 3 (11 febbraio 2015): o162. http://dx.doi.org/10.1107/s2056989015002510.

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Abstract (sommario):

The lactone ring in the title molecule, C15H22O3(systematic name: 3,4a,8-trimethyldodecahydroazuleno[6,5-b]furan-2,5-dione), assumes an envelope conformation with the methine C atom adjacent to the the methine C atom carrying the methyl substituent being the flap atom. The other five-membered ring adopts a twisted conformation with the twist being about the methine–methylene C—C bond. The seven-membered ring is based on a twisted boat conformation. No specific interactions are noted in the the crystal packing.

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27

Caracelli, Ignez, Julio Zukerman-Schpector, Henrique J. Traesel, Paulo R. Olivato, Mukesh M. Jotani e Edward R. T. Tiekink. "2-[(4-Chlorophenyl)sulfanyl]-2-methoxy-1-phenylethan-1-one: crystal structure and Hirshfeld surface analysis". Acta Crystallographica Section E Crystallographic Communications 74, n. 5 (27 aprile 2018): 703–8. http://dx.doi.org/10.1107/s2056989018006072.

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Abstract (sommario):

The title compound, C15H13ClO2S, comprises (4-chlorophenyl)sulfanyl, benzaldehyde and methoxy residues linked at a chiral methine-C atom (the crystal is racemic). A twist in the methine-C—C(carbonyl) bond [O—C—C—O torsion angle = 19.3 (7)°] leads to a dihedral angle of 22.2 (5)° between the benzaldehyde and methine+methoxy residues. The chlorobenzene ring is folded to lie over the O atoms, with the dihedral angle between the benzene rings being 42.9 (2)°. In the crystal, the carbonyl-O atom accepts two C—H...O interactions with methyl- and methine-C—H atoms being the donors. The result is an helical supramolecular chain aligned along the c axis; chains pack with no directional interactions between them. An analysis of the Hirshfeld surface points to the important contributions of weak H...H and C...C contacts to the molecular packing.

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28

Benzecry, Gabriel Frank. "Friedrich List’s Critique of the Methuen Treaty". Iberian Journal of the History of Economic Thought 9, n. 2 (9 dicembre 2022): 059–68. http://dx.doi.org/10.5209/ijhe.83356.

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Abstract (sommario):

This article examines Friedrich List’s critique of the Methuen Treaty. The Methuen Treaty removed all restrictions on English wool entering Portugal and reaffirmed England’s commitment to import Portuguese wines at two-thirds the tariffs of French wines. Friedrich List argues that the agreement hurt Portugal’s textile industry and slowed Portugal’s economic growth. List’s critique of the Methuen Treaty is a strong representation of his resistance to Adam Smith and Jean-Baptiste Say, but it is isolated from his robust theoretical framework. One possible explanation for the discontinuity is that the knowledge problem undermines List’s theory. The lack of local data makes it difficult to conduct an accurate and straightforward policy analysis of the Methuen Treaty, making the analysis vulnerable to normative interpretations. Specifically, List’s disagreement with Adam Smith’s cosmopolitanism pushed him further away from a straightforward application of his theory.

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29

Bicalho, Keylla U., Mariana M. Santoni, Philipp Arendt, Cleslei F. Zanelli, Maysa Furlan, Alain Goossens e Jacob Pollier. "CYP712K4 Catalyzes the C-29 Oxidation of Friedelin in the Maytenus ilicifolia Quinone Methide Triterpenoid Biosynthesis Pathway". Plant and Cell Physiology 60, n. 11 (26 luglio 2019): 2510–22. http://dx.doi.org/10.1093/pcp/pcz144.

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Abstract (sommario):

Abstract The native Brazilian plant Maytenus ilicifolia accumulates a set of quinone methide triterpenoids with important pharmacological properties, of which maytenin, pristimerin and celastrol accumulate exclusively in the root bark of this medicinal plant. The first committed step in the quinone methide triterpenoid biosynthesis is the cyclization of 2,3-oxidosqualene to friedelin, catalyzed by the oxidosqualene cyclase friedelin synthase (FRS). In this study, we produced heterologous friedelin by the expression of M. ilicifolia FRS in Nicotiana benthamiana leaves and in a Saccharomyces cerevisiae strain engineered using CRISPR/Cas9. Furthermore, friedelin-producing N. benthamiana leaves and S. cerevisiae cells were used for the characterization of CYP712K4, a cytochrome P450 from M. ilicifolia that catalyzes the oxidation of friedelin at the C-29 position, leading to maytenoic acid, an intermediate of the quinone methide triterpenoid biosynthesis pathway. Maytenoic acid produced in N. benthamiana leaves was purified and its structure was confirmed using high-resolution mass spectrometry and nuclear magnetic resonance analysis. The three-step oxidation of friedelin to maytenoic acid by CYP712K4 can be considered as the second step of the quinone methide triterpenoid biosynthesis pathway, and may form the basis for further discovery of the pathway and heterologous production of friedelanes and ultimately quinone methide triterpenoids.

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30

BEZARK, LARRY G., e ANTONIO SANTOS-SILVA. "Notes, synonymy and description in American Methiini (Coleoptera, Cerambycidae, Cerambycinae)". Zootaxa 4565, n. 1 (7 marzo 2019): 71. http://dx.doi.org/10.11646/zootaxa.4565.1.5.

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Abstract (sommario):

Tessaropa Haldeman, 1847 is considered a junior synonym of Methia Newman, 1842. Notes on Methia carioca (Martins, 1981) and M. elongata (Galileo & Martins, 2009) are provided. A new species, M. similis sp. nov., is described from Ecuador, becoming the second species of Methiini known in the country.

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31

BEZARK, LARRY G., e ANTONIO SANTOS-SILVA. "A new genus and new species of Neotropical Cerambycinae (Coleoptera, Cerambycidae)". Zootaxa 5194, n. 4 (7 ottobre 2022): 585–94. http://dx.doi.org/10.11646/zootaxa.5194.4.7.

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Abstract (sommario):

One new genus and three species are described and illustrated: Sulcogracilia mexicana new genus and species from Nuevo León, Mexico (Graciliini); Methia nigra sp. nov. from Quetzaltenango, Guatemala (Methiini) and Euderces lineatus from the State of Mexico, in Mexico (Tillomorphini). The new species of Euderces is included in a previous key.

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32

Sugumaran, M., H. Dali e V. Semensi. "The mechanism of tyrosinase-catalysed oxidative decarboxylation of α-(3,4-dihydroxyphenyl)-lactic acid". Biochemical Journal 277, n. 3 (1 agosto 1991): 849–53. http://dx.doi.org/10.1042/bj2770849.

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Abstract (sommario):

Mushroom tyrosinase, which is known to catalyse the conversion of o-diphenols into o-benzoquinones, has been shown to catalyse the oxidative decarboxylation of 3,4-dihydroxymandelic acid [Sugumaran (1986) Biochemistry 25, 4489-4492]. To account for this unusual reaction, a quinone methide intermediate has been proposed. Since all attempts to trap this intermediate ended in vain, mechanistic studies were designed to support the formation of this transient product. Replacement of the alpha-proton in 3,4-dihydroxymandelic acid with a methyl group generates alpha-(3,4-dihydroxyphenyl)-lactic acid, the enzymic oxidation of which should produce 3,4-dihydroxyacetophenone as the end product if the oxidative decarboxylation proceeds through the quinone methide intermediate. Accordingly, chemically synthesized alpha-(3,4-dihydroxyphenyl)-lactic acid on enzymic oxidation produced 3,4-dihydroxyacetophenone as the major isolatable product. Non-steady-state kinetic analysis of the enzyme reaction attested to the transient formation of the conventional quinone product. Thus the enzymic oxidation of alpha-(3,4-dihydroxyphenyl)-lactic acid seems to generate the conventional quinone, which, owing to its instability, is rapidly decarboxylated to yield the transient quinone methide. The coupled dieneonephenol re-arrangement and ketol-enol tautomerism transforms the quinone methide into 3,4-dihydroxyacetophenone.

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33

Zhong, Jia-liang, Jia-wei Hou, Li-hong Liu e He Liu. "Crystal structure of 1,7,8,9-tetrachloro-4-(2-fluorobenzyl)-10,10-dimethoxy-4-azatricyclo[5.2.1.02,6]dec-8-ene-3,5-dione". Acta Crystallographica Section E Crystallographic Communications 71, n. 1 (1 gennaio 2015): o32. http://dx.doi.org/10.1107/s2056989014026279.

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Abstract (sommario):

In the title compound, C17H12Cl4FNO4, the configuration of the cycloalkene skeleton isendo,cis. The benzene ring is twisted by 71.01 (11)° from the attached pyrrolidine ring. In the crystal, one of the methine groups of the fused-ring system forms a weak C—H...O hydrogen bond. The other methine groups participates in a C—H...F interaction to the same adjacent molecule. Together, these generate [010] chains.

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34

ZHU, Jianjun, Stephen G. WITHERS, Paul B. REICHARDT, Edward TREADWELL e Thomas P. CLAUSEN. "Salicortin: a repeat-attack new-mechanism-based Agrobacterium faecalis β-glucosidase inhibitor". Biochemical Journal 332, n. 2 (1 giugno 1998): 367–71. http://dx.doi.org/10.1042/bj3320367.

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Abstract (sommario):

Salicortin, a natural product abundant in most members of the Salicaceae family, is a mechanism-based inactivator of Agrobacterium faecalis β-glucosidase. Inactivation is delayed in the presence of competitive inhibitors, thereby demonstrating the requirement for an enzyme-bound salicortin before inactivation. Product studies suggest that inactivation proceeds via a quinone methide intermediate formed by the fragmentation of the aglycone of salicortin while it is bound to the enzyme. Tryptic digest and HPLC/MS studies confirm the role of quinone methide attack and also show that the enzyme undergoes multiple modifications. In addition, when the inactivation was run in the presence of a mutant inactive form of the enzyme, HPLC/MS analyses clearly showed no modification of the mutant enzyme, demonstrating that the quinone methide does not exist in free solution and suggesting that inactivation is active-site directed.

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35

Kolmakov, Kirill A., e A. Jerry Kresge. "Synthesis of possible o-thioquinone methide precursors". Canadian Journal of Chemistry 86, n. 2 (1 febbraio 2008): 119–23. http://dx.doi.org/10.1139/v07-142.

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Abstract (sommario):

Investigating the synthetic accessibility of o-thioquinone methide precursors containing electron donating groups, we prepared four methyl- and methoxy-substituted 2H-benzo[b]thiete derivatives by means of flash vacuum pyrolysis of the corresponding benzooxathiinone species. Methyl- and methoxy-substituted substrates proved to be compatible with the pyrolysis protocol. The pyrolysis can be performed at considerably lower temperatures and with higher yields than in previously reported syntheses of nonsubstituted 2H-benzo[b]thiete. Under proper conditions the reaction products can be isolated in excellent yields and with 100% purity, so the troublesome purification of temperature sensitive and volatile 2H-benzo[b]thiete derivatives becomes unnecessary. The sulfur-containing compounds so obtained are efficient o-thioquinone methide precursors and possible synthones for heterocyclic chemistry.Key words: 2H-benzo[b]thietes, flash vacuum pyrolysis, methyl-substituted, methoxy-substituted, o-thioquinone methide precursors.

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36

Thierbach, Michael, e Anja Vomberg. "Permethrin in Schutzkleidung – Nutzen versus Gefährdung im europäischen Normentwurf/Permethrin in protective clothing – benefits versus hazards in the European draft standard". Gefahrstoffe 82, n. 03-04 (2022): 63–66. http://dx.doi.org/10.37544/0949-8036-2022-03-04-17.

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Abstract (sommario):

Ein Normentwurf zu mit Per- methrin behandelter Schutzkleidung zum Schutz gegen Zeckenstiche legte für den Wirkstoffgehalt Werte fest, die über die von der World Health Organization (WHO) empfohlenen Grenzwerte hinausgingen. Die Kommission Arbeitsschutz und Normung (KAN) hat sich auf Initiative der Sozialversicherung für Landwirtschaft, Forsten und Gartenbau (SVLFG) für eine Verbesserung des Normentwurfs eingesetzt und regt weitere Forschung zu dem Thema an.

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37

Nellaiappan, K., R. Ramakrishnan e M. Jameela Banu. "Evidence for the presence of quinone methide isomerase in the metacercarial cyst of Microphallus sp. (Trematoda: Microphallidae)". Parasitology 103, n. 2 (ottobre 1991): 299–303. http://dx.doi.org/10.1017/s0031182000059576.

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Abstract (sommario):

The white colour of the cyst wall of the metacercaria of Microphallus sp., even in the presence of dihydroxy phenol and phenoloxidase, is due to proteins generated through a possible quinone methide interaction. The quinone methide isomerase converts the phenoloxidase mediated quinone into β-hydroxy catechol. Formation of catechol from quinone by cyst extracts was observed spectrophotometrically and chromatographically. This enzyme is involved in detoxification of excess quinone and β-sclerotization of the cyst wall.

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38

Sugumaran, M., H. Dali e V. Semensi. "Mechanistic studies on tyrosinase-catalysed oxidative decarboxylation of 3,4-dihydroxymandelic acid". Biochemical Journal 281, n. 2 (15 gennaio 1992): 353–57. http://dx.doi.org/10.1042/bj2810353.

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Abstract (sommario):

Mushroom tyrosinase, which is known to convert a variety of o-diphenols into o-benzoquinones, has been shown to catalyse an unusual oxidative decarboxylation of 3,4-dihydroxymandelic acid to 3,4-dihydroxybenzaldehyde [Sugumaran (1986) Biochemistry 25, 4489-4492]. The mechanism of this reaction was re-investigated. Although visible-region spectral studies of the reaction mixture containing 3,4-dihydroxymandelic acid and tyrosinase failed to generate the spectrum of a quinone product during the steady state of the reaction, both trapping experiments and non-steady-state kinetic experiments provided evidence for the transient formation of unstable 3,4-mandeloquinone in the reaction mixture. The visible-region spectrum of mandeloquinone resembled related quinones and exhibited an absorbance maximum at 394 nm. Since attempts to trap the second intermediate, namely alpha,2-dihydroxy-p-quinone methide, were in vain, mechanistic studies were undertaken to provide evidence for its participation. The decarboxylative quinone methide formation from 3,4-mandeloquinone dictates the retention of a proton on the alpha-carbon atom. Hence, if we replace this proton with deuterium, the resultant 3,4-dihydroxybenzaldehyde should retain the deuterium present in the original substrate. To test this hypothesis, we chemoenzymically synthesized alpha-deuterated 3,4-dihydroxymandelic acid and examined its enzymic oxidation. Our studies reveal that the resultant 3,4-dihydroxybenzaldehyde retained nearly 90% of the deuterium, strongly indicating the transient formation of quinone methide. On the basis of these findings it is concluded that the enzymic oxidation of 3,4-dihydroxymandelic acid generates the conventional quinone product, which, owing to its unstability, is rapidly decarboxylated to generate transient alpha,2-dihydroxy-p-quinone methide. The coupled dienone-phenol re-arrangement and keto-enol tautomerism of this quinone methide produce the observed 3,4-dihydroxybenzaldehyde.

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39

Ketuly, Kamal Aziz, A. Hamid A. Hadi e Seik Weng Ng. "3-Iodo-8β,9α,14α-estra-1,3,5(10)-trien-17-one". Acta Crystallographica Section E Structure Reports Online 65, n. 6 (7 maggio 2009): o1195. http://dx.doi.org/10.1107/s1600536809014603.

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Abstract (sommario):

In the title compound, C18H21IO, the cyclohexane ring adopts a chair conformation, whereas the cyclopentane ring and the ten-membered tetraline portions each adopt an envelope conformation. For the five-membered ring, the methine C atom deviates by 0.638 (4) Å (r.m.s. of the four other atoms is 0.005 Å) and for the ten-membered ring, the methine C atom constituting the flap deviates by 0.671 (3) Å (r.m.s. of the other nine atoms is 0.066 Å).

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40

Caracelli, Ignez, Julio Zukerman-Schpector, Henrique J. Traesel, Paulo R. Olivato, Mukesh M. Jotani e Edward R. T. Tiekink. "2-[(4-Bromophenyl)sulfanyl]-2-methoxy-1-phenylethan-1-one: crystal structure, Hirshfeld surface analysis and computational chemistry". Acta Crystallographica Section E Crystallographic Communications 75, n. 6 (17 maggio 2019): 816–22. http://dx.doi.org/10.1107/s2056989019006765.

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Abstract (sommario):

The title compound, C15H13BrO2S, comprises three different substituents bound to a central (and chiral) methine-C atom, i.e. (4-bromophenyl)sulfanyl, benzaldehyde and methoxy residues: crystal symmetry generates a racemic mixture. A twist in the molecule is evident about the methine-C—C(carbonyl) bond as evidenced by the O—C—C—O torsion angle of −20.8 (7)°. The dihedral angle between the bromobenzene and phenyl rings is 43.2 (2)°, with the former disposed to lie over the oxygen atoms. The most prominent feature of the packing is the formation of helical supramolecular chains as a result of methyl- and methine-C—H...O(carbonyl) interactions. The chains assemble into a three-dimensional architecture without directional interactions between them. The nature of the weak points of contacts has been probed by a combination of Hirshfeld surface analysis, non-covalent interaction plots and interaction energy calculations. These point to the importance of weaker H...H and C—H...C interactions in the consolidation of the structure.

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41

Pettigrew, Jeremy D., Rebecca P. Freeman e Peter D. Wilson. "Total synthesis of ()-xyloketal D and its enantiomer Confirmation of absolute stereochemistry". Canadian Journal of Chemistry 82, n. 11 (1 novembre 2004): 1640–48. http://dx.doi.org/10.1139/v04-138.

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Abstract (sommario):

The total synthesis of ()-xyloketal D and its enantiomer have been achieved by the reaction of an ortho-quinone methide with (4R)- and (4S)-4,5-dihydro-2,4-dimethylfuran via a diastereoselective inverse electron demand DielsAlder reaction. This total synthesis confirmed the absolute stereochemistry of the natural product. The ortho-quinone methide was generated by reaction of an appropriately functionalized Mannich base with methyl iodide. The Mannich base was prepared in one step from 2,4-dihydroxyacetophenone, formaldehyde, and morpholine. The enantiomeric dihydrofurans were prepared from (2R)- and (2S)-2-methylpent-4-ynoic acid via a three-step reaction sequence. These chiral nonracemic synthetic precursors were prepared from the corresponding (R)-phenylglycinol-derived diastereomeric amides of the readily available racemic carboxylic acid. The absolute stereochemistry of these carboxylic acids was firmly established by conversion to a known compound that had been previously prepared from a chiral pool starting material.Key words: xyloketal D, inverse electron demand DielsAlder reaction, ortho-quinone methide, dihydrofuran.

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42

Patel, Anjan, Francesco Mazzini, Thomas Netscher e Thomas Rosenau. "A Novel Dimer of α-Tocopherol". Research Letters in Organic Chemistry 2008 (21 settembre 2008): 1–4. http://dx.doi.org/10.1155/2008/742590.

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Abstract (sommario):

Decomposition of the complex 4, formed between the α-tocopherol ortho-quinone methide (2) and NMMO, by fast heating from −78∘C to 70∘C in inert solvents produces a novel α-tocopherol dimer with 6H,12H-dibenzo[b,f][1,5]dioxocine structure (5) which—in contrast to the well-known spiro-dimer of α-tocopherol (3)—is symmetrical. This is the first example of a direct reaction of the highly transient zwitterionic, aromatic precursor 2a in the formation of the ortho-quinone methide 2.

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43

BOTERO, JUAN PABLO, LARRY BEZARK e ANTONIO SANTOS-SILVA. "Neoxela: A new replacement name for Xela Botero, Bezark & Santos-Silva, 2020 (Coleoptera, Cerambycidae, Lamiinae)". Zootaxa 5169, n. 6 (3 agosto 2022): 599. http://dx.doi.org/10.11646/zootaxa.5169.6.6.

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Abstract (sommario):

Recently, Botero, Bezark & Santos-Silva (2020) described a new genus of Methiini (Cerambycinae), Xela, for their new species Xela tysoni, from Guatemala. Currently, the genus remains monotypic and the species is known only from their type locality. Unfortunately, the authors did not realize that the name had already been used for a trilobite species (Xela drena Jell, 1990). Herein, we propose a new replacement name for the genus.

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44

Migneault, David, Michael A. Bernstein e Cheuk K. Lau. "Preparation of ortho-hydroxyalkylanilines as ortho-quinone methide imine precursors via an aminoborane complex". Canadian Journal of Chemistry 73, n. 9 (1 settembre 1995): 1506–13. http://dx.doi.org/10.1139/v95-186.

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Abstract (sommario):

A general process for ortho-specific hydroxyalkylation of secondary anilines has been developed. N-Methylanilinochlorophenylboranes react readily with aryl aldehydes, and with α,β-unsaturated or saturated aliphatic aldehydes to give the corresponding ortho-hydroxyalkylanilines in good yield. Thermolysis of the latter generated the corresponding ortho-quinone methide imine, which can participate in an electrocyclic or intramolecular [4 + 2] cycloaddition reaction to give various dihydro- and tetrahydroquinoline derivatives. Application of the method to the syntheses of 5-aza analogs of hexahydrocannabinol is demonstrated. Keywords: quinone methide imine, ortho-hydroxyalkylaniline, azacannabinoids.

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45

Mastalerz, Harold, Taj Mohammad e Martin S. Gibson. "A 2-methylthio-3,5-diaryl-1,3,4-thiadiazolium cation; its reactions, and further exploration of the chemistry of 2-alkyl-3,5-diaryl-1,3,4-thiadiazolium cations". Canadian Journal of Chemistry 65, n. 12 (1 dicembre 1987): 2713–16. http://dx.doi.org/10.1139/v87-450.

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Abstract (sommario):

Activation of a representative 3,5-diaryl-1,3,4-thiadiazole-2-thione by thione S-methylation gives a cation that is readily susceptible to nucleophilic substitution. Reactions with diethyl malonate, ethyl acetoacetate, acetylacetone, cyclopentan-1,3-dione, or 3-ethylrhodanine under basic conditions lead to β,β-disubstituted methine bases and (or) β-substituted methine bases in cases where deacetylation occurs under the reaction conditions. This cation and the 2-alkyl-3,5-diaryl-1,3,4-thiadiazolium cation are convenient sources of a series of neutral and cationic dyes containing the 1,3,4-thiadiazole ring system.

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46

Gupta, Ajay K., Ali Ben-Mahmud, Lisa J. Kamphuis, Jennifer L. Mueller, Suzie S. Rigby, Martin S. Gibson, Mary Frances Richardson, Linda Humeniuk e Stanley Walker. "Methine bases in the benzothiazole, benzoselenazole, and quinoline series, and geometry and conformational preferences of their acyl derivatives". Canadian Journal of Chemistry 73, n. 8 (1 agosto 1995): 1278–86. http://dx.doi.org/10.1139/v95-157.

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Dimeric structures 2a–c are confirmed for the "methine bases" obtained from 2-methylbenzo-thiazolium and -selenazolium salts and aqueous sodium hydroxide, whereas monomeric structures 3 are confirmed for methine bases similarly derived from 2-methylquinolinium salts. The latter monomers dimerize slowly on standing. Monomeric methine bases 6–9, too hindered to dimerize, are described. 2-Acetonylidene-2,3-dihydro-3-methylbenzothiazole 10a and related compounds are assigned (Z) configurations on the basis of NOE difference spectra. Molecular mechanics calculations predict a slightly higher steric energy for the observed s-cis conformer of 10a than for the s-trans, indicating a stabilizing [Formula: see text] interaction in the s conformer that need only be a few kJ mol−1 in magnitude. For the quinolines 13a and b, the (E) configuration/s-cis conformation is favoured. The dielectric absorption method provides a rotational energy barrier of approximately 60 kJ mol−1 for acetyl group relaxation in 10a. Oxygen–sulfur exchange is observed in the conversion of 10a to 12a by thioacetic acid. Keywords: conformation, configuration, heterocyclic compounds, [Formula: see text] interaction.

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47

ET, Oğuzhan. "BÂKÎ’NİN “SÜNBÜL KASİDESİ”Nİ YÖNELİM METAFORLARI ÜZERİNDEN OKUMAK". Hacettepe Üniversitesi Türkiyat Araştırmaları Dergisi (HÜTAD), n. 38/Özel Sayı (7 luglio 2023): 77–87. http://dx.doi.org/10.20427/turkiyat.1238993.

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Çağdaş metafor teorisinin kurucuları George Lakoff ve Mark Johnson, metafor kavramını bilişsel düzeyde ele almış ve bu kavramı yapı metaforları, yönelim metaforları ve ontolojik metaforlar olmak üzere üç kısma ayırmıştır. Yönelim metaforları; yukarı-aşağı, içeri-dışarı, ön-arka, merkez-çevre gibi uzay/mekân istikametleriyle ilişkili metaforlardır. Bu tür metaforlarda kavramlar, sözü edilen istikametlere göre organize edilmiştir. Bu çalışmada Bâkî’nin, hocası Karamanlı Mehmet Efendi için yazdığı “sünbül” redifli kasidesi, yönelim metaforları açısından ele alınmıştır. Kasidenin nesip bölümünde iki, methiye bölümünde on ve tegazzül bölümünde iki beyitte yönelim metaforları tespit edilmiştir. Bu beyitlerde aşağı-yukarı, iç-dış, merkez-çevre istikametleri kullanılmıştır. Kasidenin nesip bölümünde sümbül, yukarıda konumlandırılarak diğer çiçeklerden güzellik yönünden üstün tutulmuştur. Sümbül sembolü üzerinden öğrenci-hoca hiyerarşisi yansıtılan methiye bölümünde, Karamanlı Mehmet Efendi yukarı, iç ve merkezde konumlandırılarak yüceltilmiştir. Yönelim metaforlarından en yoğun olarak yararlanılan methiye bölümünde memduhun çoğunlukla manevi güzellikleri övülmüştür. Övgünün devam ettiği tegazzülde ise Karamanlı Mehmet Efendi’nin saçı ve yanağı, yönelim metaforlarından yararlanılarak yukarıda konumlandırılarak güzellik yönünden yüceltilmiştir. Kasidenin fahriye ve dua bölümünde ise yönelim metaforları kullanılmamıştır. Anahtar kelimeler: Divan edebiyatı, Bâkî, Sünbül Kasidesi, çağdaş metafor teorisi, yönelim metaforları.

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48

BOTERO, JUAN PABLO, LARRY G. BEZARK e ANTONIO SANTOS-SILVA. "A new genus, new species and taxonomic notes on American Cerambycinae (Coleoptera, Cerambycidae)". Zootaxa 4758, n. 1 (27 marzo 2020): 157–75. http://dx.doi.org/10.11646/zootaxa.4758.1.7.

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Four new species and one new genus are described: Nesanoplium spinosum (Elaphidiini), from Honduras; Psyrassa zacki (Elaphidiini), from Mexico and Guatemala; Euderces ecuadorensis (Tillomorphini), from Ecuador; and Xela tysoni (Methiini), gen. nov., from Guatemala. Pteroplatus suturalis Buquet, 1840 is synonymized with Pteroplatus pulcher Buquet, 1840 (Pteroplatini). Acyphoderes baeri Gounelle, 1913 (= Odontocera baeri) is transferred to Acutiphoderes Clarke, 2015 (Rhinotragini). We question the validity of the lectotype designation for Cyrtomerus puberulus Fleutiaux & Sallé, 1889.

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49

Whitworth, Colin. "Drag in a Changing Scene, Volumes 1 & 2 Volume 1: Contemporary Drag Practices and Performers, Mark Edward and Stephen Farrier (Eds) (2020) Volume 2: Drag Histories, Herstories and Hairstories, Mark Edward and Stephen Farrier (Eds) (2022)". Queer Studies in Media & Popular Culture 8, n. 1 (6 aprile 2023): 119–22. http://dx.doi.org/10.1386/qsmpc_00092_5.

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Review of: Drag in a Changing Scene, Volumes 1 & 2 Volume 1: Contemporary Drag Practices and Performers, Mark Edward and Stephen Farrier (Eds) (2020) London: Methuen Drama, 248 pp., ISBN 978-1-35008-294-6, h/bk, $110.00 ISBN 978-1-35031-919-6, p/bk, $39.95 ISBN 978-1-35008-295-3, e-book, $35.95 Volume 2: Drag Histories, Herstories and Hairstories, Mark Edward and Stephen Farrier (Eds) (2022) London: Methuen Drama, 256 pp., ISBN 978-1-35010-436-5, h/bk, $115.00 ISBN 978-1-35019-851-7, p/bk, $39.95 ISBN 978-1-35010-437-2, e-book, $35.95

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50

Sárik, Julián Robin, Anasztázia Hetényi, Róbert Berkecz, István Szatmári e Bálint Lőrinczi. "Ortho-quinone methide driven synthesis of kynurenic acid lactams". RSC Advances 14, n. 31 (2024): 22123–31. http://dx.doi.org/10.1039/d4ra04341c.

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