Artículos de revistas: "Xantine"

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Suwandi, Deden Winda y Farid Perdana. "AKTIVITAS PENGHAMBATAN XANTIN OKSIDASE EKSTRAK ETANOL DAUN ALPUKAT (Persea americana MILL) SECARA IN VITRO". Jurnal Ilmiah Farmako Bahari 8, n.º 2 (27 de julio de 2017): 40. http://dx.doi.org/10.52434/jfb.v8i2.784.

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Hiperurisemia merupakan keadaan berlebihnya kadar asam urat dalam darah disebabkan oleh ketidak seimbangan antara produksi dan ekskresi asam urat dalam tubuh. Kondisi ini dapat menimbulkan penyakit gout yang ditandai pengendapan kristal monosodium urat. Salah satu obat yang digunakan untuk menurunkan kadar asam urat adalah allopurinol dengan cara menghambat aktivitas xantine oxidase sebagai enzim pembentuk asam urat. Penggunaan obat tradisional seperti tumbuhan alpukat yang mengandung flavonoid diduga memiliki aktivitas antihiperurisemia karena dilaporkan bahwa senyawa flavonoid dapat menurunkan kadar asam urat darah dengan cara menghambat aktivitas xantin oksidase. Telah dilakukan penelitian terhadap ekstrak etanol daun alpukat dalam menghambat aktivitas xantin oksidase sehingga bisa digunakan sebagai obat penyakit gout. Aktivitas penghambatan enzim xantin oksidase oleh ekstrak etanol daun alpukat secara invitro ditentukan melalui penurunan produksi asam urat yang diukur dengan alat spektrofotometer pada (λ) 293 nm dengan xantin sebagai substrat. Ekstrak etanol daun alpukat dapat menghambat enzim xantin oksidase pada pada konsentrasi 40; 60; 80; 100 dan 120 ppm dengan persen penghambatan sebesar 27,97; 51,98; 64,07; 71,15 dan 77,54 %. Aktivitas penghambatan xantin oksidase ekstrak daun alpukat ditentukan dengan nilai IC50, dimana hasilnya menunjukkan ekstrak etanol daun alpukat mampu menghambat aktivitas xantin oksidase dengan IC50 65,55 ppm yang lebih lemah bila dibandingkan dengan IC50 allopurinol yaitu sebesar 0,59 ppm. Kata kunci: Hiperurisemia, daun alpukat, penghambatan xantin oksidase.

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Husein, Sri Gustini, Achmad Zainuddin y Sani Hoeruman. "Synthesis N1-Tersier-Butilteobromin from Teobromin and Tersier-Butylbromides". Indonesian Journal of Pharmaceutical Science and Technology 5, n.º 3 (1 de octubre de 2018): 93. http://dx.doi.org/10.24198/ijpst.v5i3.17931.

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Xantine derivatives are known to have some pharmacological activity, such as a bronchodilator. The substitution on atoms N1 xantine can improve the activity and selectivity as a tracheaspasm. The purpose of this research was to investigate the influence of concentration sodium hydroxide in sodium acetate as solvent used on the production yield of N1-tert-butilteobromin. The result of the synthesis was isolated using chloroform and purified with the preparative thin layer chromatography. The molecule structure of N1-tert-butilteobromin was confirmed using ultraviolet and infrared spectrophotometry. The result showed that sodium hydroxide concentration could effect the results of yield. The yields of 4%, 8%, and 12% sodium hydroxide concentration were 3.7% (0.074 g), 7.2% (0.144 g), and 1.3% (0.026 g), respectively.Keywords: N1-tert-butylteobromin, sodium hydroxide, tert-butylbromide, theobromine

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Kamilov, F. Kh, G. A. Timirkhanova, A. I. Samorodova, A. V. Samorodov, F. A. Khaliullin y D. Z. Murataev. "Antiaggregatory activity of new 1-ethylxanthine cyclohexylammonium salt in vitro". Kazan medical journal 94, n.º 5 (15 de octubre de 2013): 692–95. http://dx.doi.org/10.17816/kmj1921.

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Aim. To study the biochemical effect on hemostasis of a new cyclohexilammonium salt of 2-[1-ethyl-3-methyl-7(dioxotiethanyl-3)xantinyl-8-thio]acetic acid in vitro. Methods. Thromboelastography was performed using the citrate blood samples of healthy male donors. Global hemostatic effect, fibrinogen and platelet function, fibrinolysis and clot strength, and stability were analyzed at thromboelastography. The impact of firstly synthesized xantine derivative and pentoxifylline on the functional activity of platelets in vitro was studied using a laser analyzer of platelet aggregation. Adenosine diphosphate, collagen, epinephrine and ristocetin induced clotting were registered. General clotting characteristics, maximal aggregation values, maximal aggregation speed, mean platelet aggregate size, activity of platelet-derived factor 3, level of platelet-derived factor 4 were measured. Release of platelet-derived factors 3 and 4 at platelet aggregation were assessed after adenosinediphosphate-induced aggregation and centrifugation. Results. Cyclohexylammonium salt of 2-[1-ethyl-3-methyl-7-(dioxotiethanyl-3)xantinyl-8-thio]acetic acid in vitro showed antiaggregatory activity that exceeds such of pentoxifylline. It has been revealed that the second platelet aggregation wave, that is induced by small dose of adenosinediphosphate, is absent in the presence of the new cyclohexylammonium salt, lag-period in collagen-induced platelet aggregation elongates, and availability and release of platelet-derived factors 3 and 4 decreases. Conclusion. The research findings show potentially high antiaggregatory activity of 2-[1-ethyl-3-methyl-7-(dioxotiethanyl-3)xantinyl-8-thio]acetic acid cyclohexylammonium salt as an inhibitor of platelet release reaction.

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Kamilov, F. Kh, G. A. Timirkhanova, A. I. Samorodova, F. A. Khaliullin y R. A. Gubaeva. "Features of hemostatic activity of 2-[3-methyl-1-h-propyl-7-(1,1-dioxothiethanyl-3) xantinyl-8-thio] acetic acid cyclohexilammonium salt". Kazan medical journal 94, n.º 4 (15 de diciembre de 2013): 549–52. http://dx.doi.org/10.17816/kmj1969.

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Aim. To study the systemic hemostatic activity of firstly synthesized 2-[3-methyl-1-h-propyl-7-(1,1-dioxotiethanyl-3) xantinyl-8-thio] acetic acid cyclohexilammonium salt in vitro and in vivo. Methods. Experiments in vitro using the blood samples form healthy male donors, and in vivo on male rats by intraperitoneal injection of the equimolar concentrations of researched substances. The effect of the firstly synthesized xantine and etamsylate derivative on the platelet functional activity in vitro and in vivo was studied using a platelet aggregation laser analyzer «Biola 230 LA» (Russia). 20 mkg/ml of adenosinediphosphate and 5 mg/ml of collagen (produced by «Technologia-Standart» company, Russia) were used as an aggregation inducers. Aggregation was analyzed using the AGGR software. General aggregation parameters, maximal aggregation value, maximal aggregation speed, average size of platelet aggregates were analyzed. Experimental assessment of specific systemic hemostatic activity in vivo was made in accordance with the parenchymal hemorrhage model on mature male rats. Coagulation time and blood loss volume were registered. Results. 2-[3-Methyl-1-h-propyl-7-(1,1-dioxotiethanyl-3) xantinyl-8-thio] acetic acid cyclohexilammonium salt showed a pro-aggregative effect both in vitro and in vivo. 2-[3-Methyl-1-h-propyl-7-(1,1-dioxotiethanyl-3) xantinyl-8-thio] acetic acid cyclohexilammonium salt pro-aggregative effect which was observed both in vitro and in vivo increased the systemic hemostatic activity, exceeding the results of the control group and etamsylate group. Conclusion. The findings reveal potentially high systemic hemostatic activity of 2-[3-methyl-1-h-propyl-7-(1,1-dioxotiethanyl-3) xantinyl-8-thio] acetic acid cyclohexilammonium salt and confirm the need for further studies of this compound and its equivalents in order to create highly effective selective hemostasis correctors on their basis.

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Orhan, Ilkay E. "Natural Products and Extracts as Xantine Oxidase Inhibitors - A Hope for Gout Disease?" Current Pharmaceutical Design 27, n.º 2 (2021): 143–58. http://dx.doi.org/10.2174/18734286mta4lntc95.

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Rohmat, Muhammad Lathiful Hidayatul y Nuniek Herdyastuti. "REVIEW ARTIKEL: ISOLASI DAN PENGUKURAN AKTIVITAS ENZIM XANTIN OKSIDASE". Unesa Journal of Chemistry 10, n.º 1 (25 de enero de 2021): 96–108. http://dx.doi.org/10.26740/ujc.v10n1.p96-108.

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Abstrak. Xantin oksidase adalah enzim yang mengkatalisis oksidasi hipoxantin menjadi xantin dan kemudian xantin menjadi asam urat yang memerankan peran penting dalam katabolisme purin. Xantin oksidase dapat diisolasi dari berbagai sumber susu, jaringan hewan, dan mikroorganisme baik mesofilik maupun termofilik. Pemurnian enzim xantin oksidase untuk mendapatkan aktivitas enzim yang tinggi telah dilakukan dengan berbagai metode antara lain, presipitasi amonium sulfat, dialisis, dan berbagai macam metode kromatografi. Pengukuran aktivitas enzim xantin oksidase dapat dilakukan secara in vintro dengan mengukur kadar produk ataupun kadar substrat yang beraksi. xantin oksidae berpotensi diaplikasikan dalam bidang medis sebagai kit, bidang industri sebagai biosensor dan penyiapan makanan sehat rendah purin, serta dalam bidang lingkungan hidup sebagai bioremediasi senyawa heterogen siklik yang berbahaya. Kata kunci: Xantin oksidase, isolasi, pengukuran aktivitas, aplikasi Abstract. Xanthine oxidase is an enzyme that catalyzes the oxidation of hypoxanthine to xanthine and then xanthine to uric acid which be an important role in purine catabolism. Xanthine oxidase can be isolated from various sources of milk, animal tissue, and mesophilic and thermophilic microorganisms. Purification of xanthine oxidase to obtain high enzyme activity has been carried out by various methods include ammonium sulfate precipitation, dialysis, and various chromatographic methods. Measurement of xanthine oxidase enzyme activity can be doing by in vitro with measuring product levels or substrate levels in action. xanthine oxide has the potential to be applied in the medical field as a kit, in the industrial field as a biosensor and preparation of low purine healthy foods, as well as in the environmental field as a bioremediation of dangerous cyclic heterogeneous compounds. Keywords: Xanthine oxidase, isolation, activity measurement, application

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Borghi, Claudio, Krzysztof Narkiewicz y Giuseppe Mancia. "Uric acid and xantine-oxidase inhibitors in patients with gout: A re-assessment and an update". Cardiology Journal 26, n.º 1 (14 de marzo de 2019): 99–101. http://dx.doi.org/10.5603/cj.2019.0015.

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Aleksandrova, K. V., Ye S. Pruhlo, Ye K. Mykhalchenko, O. S. Shkoda y O. Yu Cherchesova. "Search for potential hypoglycemic agents among potassium salts of 3-benzyl-8-substituted xanthines". Current issues in pharmacy and medicine: science and practice 15, n.º 3 (15 de noviembre de 2022): 266–70. http://dx.doi.org/10.14739/2409-2932.2022.3.253385.

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Nowadays, the prevalence of metabolic syndrome (MS) is a serious problem among the world’s population. Metabolic syndrome includes the so-called “deadly” quartet – hypertension, type 2 diabetes mellitus (diabetes mellitus), dyslipidemia and alimentary obesity. After all, type 2 diabetes is included in the list of pathologies of the metabolic syndrome, it is important to find ways to alleviate the disease. Derivatives of such a heterocyclic system as xanthine are of great interest in this aspect. The aim of the study was to explore the hypoglycemic activity of newly synthesized water-soluble derivatives of 3-benzyl-8-substituted xanthines. Materials and methods. We obtained water-soluble potassium 3-benzyl-8-R-xanthin-7-ides, the structure and individuality of which were confirmed by a set of physical-chemical studies. Results. The hypoglycemic effect of the newly synthesized compounds was assessed by an oral glucose tolerance test. The obtained data were processed using modern statistical in silico-methods. Conclusions. The results of the hypoglycemic activity study among the potassium salts of 3-benzyl-8-substituted xanthine derivatives showed, that some new compounds are in close vicinity to the reference drug’s hypoglycemic action.

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Lemos, Agostinho, Ana Sara Gomes, Joana B. Loureiro, Pedro Brandão, Andreia Palmeira, Madalena M. M. Pinto, Lucília Saraiva y Maria Emília Sousa. "Synthesis, Biological Evaluation, and In Silico Studies of Novel Aminated Xanthones as Potential p53-Activating Agents". Molecules 24, n.º 10 (22 de mayo de 2019): 1975. http://dx.doi.org/10.3390/molecules24101975.

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Xanthone scaffold has been regarded as an attractive chemical tool in the search for bioactive molecules with antitumor activity, and in particular two xanthone derivatives, 12-hydroxy-2,2-dimethyl-3,4-dihydro-2H,6H-pyrano [3,2-b]xanthen-6-one (4) and 3,4-dimethoxy-9-oxo-9H-xanthene-1-carbaldehyde (5), were described as a murine double minute 2 (MDM2)-p53 inhibitor and a TAp73 activator, respectively. The xanthone 5 was used as a starting point for the construction of a library of 3,4-dioxygenated xanthones bearing chemical moieties of described MDM2-p53 inhibitors. Eleven aminated xanthones were successfully synthesized and initially screened for their ability to disrupt the MDM2-p53 interaction using a yeast cell-based assay. With this approach, xanthone 37 was identified as a putative p53-activating agent through inhibition of interaction with MDM2. Xanthone 37 inhibited the growth of human colon adenocarcinoma HCT116 cell lines in a p53-dependent manner. The growth inhibitory effect of xanthone 37 was associated with the induction of G1-phase cell cycle arrest and increased protein expression levels of p53 transcriptional targets. These results demonstrated the potential usefulness of coupling amine-containing structural motifs of known MDM2-p53 disruptors into a 3,4-dioxygenated xanthone scaffold in the design of novel and potent p53 activators with antitumor activity and favorable drug-like properties. Moreover, in silico docking studies were performed in order to predict the binding poses and residues involved in the potential MDM2-p53 interaction.

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Ferrari, Fernanda Cristina, Rita de Cássia Lemos Lima, Zilma Schimith Ferraz Filha, Camila Helena Barros, Marcela Carolina de Paula Michel Araújo y Dênia Antunes Saúde-Guimarães. "Effects of Pimenta pseudocaryophyllus extracts on gout: Anti-inflammatory activity and anti-hyperuricemic effect through xantine oxidase and uricosuric action". Journal of Ethnopharmacology 180 (marzo de 2016): 37–42. http://dx.doi.org/10.1016/j.jep.2016.01.007.

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Kostadinović, Ljiljana M., Sava T. Pavkov, Jovanka D. Lević, Tamara A. Galonja-Coghill, Gordana K. Dozet y Nenad Č. Bojat. "Effect of sulphachloropyrazine on antioxidative systems in blood and liver of broilers". Acta Veterinaria Brno 80, n.º 2 (2011): 165–70. http://dx.doi.org/10.2754/avb201180020165.

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This report describes the effects of therapeutic doses of coccidiocid sulphachloropyrazine on enzymatic and non-enzymatic antioxidative systems in haemolysed blood and liver homogenate from broilers (glutathione, glutathione-reductase, glutathione-peroxidase, peroxidase, superoxide-dismutase, xantine-oxidase and lipid peroxidation). The in vivo investigation was carried out on 120 heavy-line broilers (Arbor acres) of both sexes. One-day-old broilers were randomly distributed into 2 groups, each numbering 60 individuals of both sexes: Group 1 - control group; Group 2 - group of broilers inoculated with laboratory derived coccidia species on the 21st day-of-age. When symptoms of coccidiosis appeared (30th day-of-age), blood sampling and decapitation of 20 chickens were carried out (Group 2a). The remaining broilers were treated with therapeutic doses of sulphachloropyrazine (60 ppm). Decapitation of 20 chickens was carried out after the therapy was concluded (38th day-of-age – Group 2b). Infection of broilers with coccidia intensified free radical processing in haemolysed blood and liver homogenate. This was evident from the increased levels of lipid peroxidation and the catalytic activity of almost all examined enzymes (SOD, GSHPx and Px). Therapeutic doses of sulphachloropyrazine inhibited free-radical activity induced by disease and establishing of physiological values of lipid peroxidation and catalase activity of examined enzymes.

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Ningsih, Sri y Churiyah. "EVALUASI AKTIVITAS INHIBISI XANTIN OKSIDASE DAN KANDUNGAN SENYAWA POLIFENOL DARI EKSTRAK SAPPAN". Jurnal Bioteknologi & Biosains Indonesia (JBBI) 5, n.º 2 (26 de diciembre de 2018): 157. http://dx.doi.org/10.29122/jbbi.v5i2.2880.

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Evaluation of xanthine oxidase inhibitory activity and polyphenolic content of sappan extractABSTRACTHyperuricemia is a disease that is characterized by a high uric acid level, in which the number of patients tends to increase every year. This research was intended to evaluate the xanthine oxidase (XO) inhibitory activity and determinate the total polyphenol content of heartwood sappan (Caesalpinia sappan L.) extract. The extract was prepared by macerating the dry powder wood using 70% ethanol at room temperature. The quality of ethanolic extract obtained was evaluated based on BPOM guideline. XO inhibitory power was determined by measuring uric acid produced in the xanthine/XO system in vitro. The polyphenol content of the extract was measured using Folin-Ciocalteu reagent spectrophotometrically. The results showed that the quality of sappan semisolid extract fulfilled the required standard. Sappan extract inhibited XO activity by 98% relative to the positive control, allopurinol, at the final extract concentration of 100 µg/mL. The total polyphenol content was 26% of the crude extract. It could be concluded that sappan ethanolic extract has the potential to be developed as an ingredient for hyperuricemia treatment.Keywords: hyperuricemia, sappan, total polyphenol, xanthine, xanthine oxidase ABSTRAKHiperurisemia adalah penyakit yang dicirikan dengan kadar asam urat tinggi dimana prevalensi penderita cenderung meningkat. Penelitian ini bertujuan untuk mempelajari aktivitas esktrak kayu sappan (Caesalpinia sappan L.) dalam menginhibisi enzim XO (xantin oksidase) secara in vitro dan penentuan kadar senyawa polifenol total yang terkandung di dalamnya. Ekstrak dibuat dengan cara maserasi serbuk kayu menggunakan pelarut etanol 70% pada suhu kamar. Kualitas ekstrak dievaluasi mengacu pada parameter karakterisasi ekstrak yang ditetapkan oleh BPOM. Aktivitas inhibisi XO ditetapkan dengan mengukur kadar asam urat yang terbentuk pada sistem xantin/XO in vitro. Kadar polifenol ekstrak diukur menggunakan pereaksi Folin-Ciocalteu secara spektrofotometri. Hasil analisis menyatakan bahwa kualitas ekstrak kental sappan memenuhi persyaratan yang ada. Pengujian inhibisi XO dengan pembanding positif allopurinol pada konsentrasi akhir ekstrak sebesar 100 µg/mL menunjukkan bahwa ekstrak mempunyai kekuatan menginhibisi XO sebesar 98% relatif terhadap pembanding positif allopurinol. Kadar senyawa polifenol total dalam ekstrak sappan sebesar 26% dari ekstrak kasar. Dari penelitian ini dapat disimpulkan bahwa ekstrak sappan mempunyai potensi untuk dikembangkan sebagai bahan untuk mengatasi hiperurisemia.Kata Kunci: hiperurisemia, polifenol total, sappan, xantin, xantin oksidase

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Hardiany, Novi S., Mohamad Sadikin, Nurjati Siregar y Septelia I. Wanandi. "The suppression of manganese superoxide dismutase decreased the survival of human glioblastoma multiforme T98G cells". Medical Journal of Indonesia 26, n.º 1 (16 de mayo de 2017): 19–25. http://dx.doi.org/10.13181/mji.v26i1.1511.

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Background: Glioblastoma multiforme (GBM) is a primary malignant brain tumor which has poor prognosis. High incidence of oxidative stress-based therapy resistance could be related to the high antioxidant status of GBM cells. Our previous study has reported that manganese superoxide dismutase (MnSOD) antioxidant expression was significantly higher in high grade glioma than in low grade. The aim of this study was to analyze the impact of MnSOD suppression toward GBM cell survival.Methods: This study is an experimental study using human glioblastoma multiforme T98G cell line. Suppression of MnSOD expression was performed using in vitro transfection MnSOD-siRNA. The MnSOD expression was analyzed by measuring the mRNA using real time RT-PCR, protein using ELISA technique, and specific activity of enzyme using inhibition of xantine oxidase. Concentration of reactive oxygen species (ROS) intracellular was determined by measuring superoxide radical and hydrogen peroxide. Cell survival was analyzed by measuring viability, proliferation, and cell apoptosis.Results: In vitro transfection of MnSOD-siRNA suppressed the mRNA, protein, and specific activity of MnSOD. This treatment significantly increased the concentration of superoxide radical; however, it did not influence the concentration of hydrogen peroxide. Moreover, viability MnSOD-suppressing cell significantly decreased, accompanied by increase of cell apoptosis without affecting cell proliferation.Conclusion: The suppression of MnSOD expression leads to decrease glioblastoma multiforme cell survival, which was associated to the increase of cell apoptotic.

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Inamoto, Kiyofumi, Maki Shimizu, Noboru Hayama y Tetsutaro Kimachi. "Copper-Catalyzed Intramolecular C–H Amination: A New Entry to Substituted Xanthine Derivatives". Synthesis 49, n.º 18 (9 de mayo de 2017): 4183–90. http://dx.doi.org/10.1055/s-0036-1588821.

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Catalytic synthesis of xanthines was achieved in the presence of a copper catalyst. The process involves copper-catalyzed intramolecular C–H amination of benzamidines that possess a uracil moiety and produces variously substituted xanthines generally in good to high yields. This work introduces a new, facile approach to polysubstituted xanthine compounds.

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Woziwodzka, Anna, Marta Krychowiak-Maśnicka, Grzegorz Gołuński, Anna Felberg, Agnieszka Borowik, Dariusz Wyrzykowski y Jacek Piosik. "Modulatory Effects of Caffeine and Pentoxifylline on Aromatic Antibiotics: A Role for Hetero-Complex Formation". Molecules 26, n.º 12 (14 de junio de 2021): 3628. http://dx.doi.org/10.3390/molecules26123628.

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Antimicrobial resistance is a major healthcare threat globally. Xanthines, including caffeine and pentoxifylline, are attractive candidates for drug repurposing, given their well-established safety and pharmacological profiles. This study aimed to analyze potential interactions between xanthines and aromatic antibiotics (i.e., tetracycline and ciprofloxacin), and their impact on antibiotic antibacterial activity. UV-vis spectroscopy, statistical-thermodynamical modeling, and isothermal titration calorimetry were used to quantitatively evaluate xanthine-antibiotic interactions. The antibacterial profiles of xanthines, and xanthine-antibiotic mixtures, towards important human pathogens Staphylococcus aureus, Enterococcus faecium, Escherichia coli, Acinetobacter baumannii, Klebsiella pneumoniae, and Enterobacter cloacae were examined. Caffeine and pentoxifylline directly interact with ciprofloxacin and tetracycline, with neighborhood association constant values of 15.8–45.6 M−1 and enthalpy change values up to −4 kJ·M−1. Caffeine, used in mixtures with tested antibiotics, enhanced their antibacterial activity in most pathogens tested. However, antagonistic effects of caffeine were also observed, but only with ciprofloxacin toward Gram-positive pathogens. Xanthines interact with aromatic antibiotics at the molecular and in vitro antibacterial activity level. Given considerable exposure to caffeine and pentoxifylline, these interactions might be relevant for the effectiveness of antibacterial pharmacotherapy, and may help to identify optimal treatment regimens in the era of multidrug resistance.

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Agustine, Pinkan, Riska Putri Damayanti y Nia Ariani Putri. "KARAKTERISTIK EKSTRAK KAFEIN PADA BEBERAPA VARIETAS KOPI DI INDONESIA: REVIEW". JITIPARI (Jurnal Ilmiah Teknologi dan Industri Pangan UNISRI) 6, n.º 1 (18 de marzo de 2021): 78–89. http://dx.doi.org/10.33061/jitipari.v6i1.5014.

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Kopi adalah minuman popular dari jenis tumbuhan yang mengandung kafein. Kafein yaitu senyawa alkaloid turunan xantine (basa purin) yang dapat larut dalam air, mempunyai aroma wangi tetapi rasanya sangat pahit. Kafein bersifat basa mono-cidic yang lemah yang dapat memisah dengan penguapan air. Dengan asam, kafein akan membentuk reaksi garam yang tidak stabil sedangkan dengan basa akan membentuk garam yang stabil. Kafein mudah terurai dengan alkali panas membentuk kafeidin. Kopi robusta lebih berpotensi menghasilkan ekstrak kafein dibandingkan kopi arabika dengan perbedaan ±1% dari berat kering. Kandungan kafein dalam kopi Robusta (Toraja) selama 3, 6, 9, 12, 15 siklus berturut-turut adalah 1.439 mg/L, 2.158 mg/L, 2.695 mg/L, 2.887 mg/L dan 3.700. mg/L. Kandungan kafein yang diperoleh kopi Arabika (Jawa) selama 3, 6, 9, 12, 15 siklus berturut-turut adalah 0.474 mg/L, 0.478 mg/L, 1.056 mg/L, 1.540 mg/L dan 1.926 mg/L. Kopi Gayo menunjukkan dua sampel dari sepuluh sampel tidak memenuhi persyaratan yang ditetapkan SNI, yaitu sampel 2 dan 4, dengan kadar berturut-turut adalah 126,9 mg; 197,1 mg; 134,3 mg; 174,6 mg; 109,2 mg; 51 mg; 119,5 mg; 88,8 mg; 108,6 mg dan 141,7 mg. Sebaliknya kopi Sareng mendapatkan hasil semua sampel memenuhi persyaratan SNI, dengan kandungan berturut-turut adalah 124,7 mg; 64,4 mg; 131,9 mg; 138,3 mg; 103,9 mg; 110,1 mg; 35,3 mg; 117,5 mg; 125,7 mg dan 36,2 mg. Kafein memiliki beberapa manfaat farmakologi seperti menstimulasi sistem saraf pusat, relaksasi otot polos terutama otot polos bronkus dan stimulasi otot jantung.

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Gibson, Christopher M. y Patrick W. Fowler. "Aromaticity of caffeine, xanthine and the dimethyl xanthines". Tetrahedron Letters 55, n.º 13 (marzo de 2014): 2078–81. http://dx.doi.org/10.1016/j.tetlet.2014.02.027.

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Oishi, Jorge Camargo, Tereza Cristina Buzinnari, Cezar Rangel Pestana, Thiago Francisco De Moraes, Izabela Pereira Vatanabe, David Anderson Wink, Roberto Santana Da Silva, Lusiane Maria Bendhack y Gerson Jhonatan Rodrigues. "In vitro Treatment with cis-[Ru(H-dcbpy-)2(Cl)(NO)] Improves the Endothelial Function in Aortic Rings with Endothelial Dysfunction". Journal of Pharmacy & Pharmaceutical Sciences 18, n.º 5 (9 de noviembre de 2015): 696. http://dx.doi.org/10.18433/j3cc9k.

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Purpose: The ruthenium complex cis-[Ru(H-dcbpy-)2(Cl)(NO)] (DCBPY) is a nitric oxide (NO) donor and studies suggested that the ruthenium compounds can inactivate O2-. The aim of this study is to test if DCBPY can revert and/or prevent the endothelial dysfunction. Methods: Normotensive (2K) and hypertensive (2K-1C) wistar rats were used. To vascular reactivity study, thoracic aortas were isolated, rings with intact endothelium were incubated with: DCBPY: 0.1; 1 and 10μM, DCBPY plus hydroxocobalin (NO scavenger) or tempol during 30 minutes, and concentration effect curves to acetylcholine were performed. The potency values (pD2) and maximum effect (ME) were analyzed. The O2- was generated using hypoxantine xantine oxidase and the reduction of cytochrome c, NO consumption by O2- and the effect in avoid NO consumption was measured. Results: In 2K-1C DCBPY at 0.1; 1 or 10μM improved the relaxation endothelium dependent induced by acetylcholine in aortic rings compared to control 2K-1C, and also improved ME. In rings from 2K incubation with DCBPY (0.1; 1.0 and 10 μM) did not change pD2 or ME. Incubation with 0.1 μM of DCBPY plus hydroxocobalamin did not modify the potency and ME in 2K-1C compared to DCBPY (0.1 μM). DCBPY and SOD inhibits the reduction of cytochrome c and inhibited the NO consumption by O2-, showing that O2- has been removed from the solution. Conclusion: Our results suggest that DCBPY at a lower concentration (0.1 µM) is not an NO generator, but can inactivate superoxide and improves the endothelial function. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.

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19

Sinha, H. K., L. Chantranupong y R. P. Steer. "Vibrational Spectra of Xanthione and Xanthone". Journal of Molecular Spectroscopy 169, n.º 2 (febrero de 1995): 302–14. http://dx.doi.org/10.1006/jmsp.1995.1025.

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20

da Silva, Daniel Leite, Bruna Silva Terra, Mateus Ribeiro Lage, Ana Lúcia Tasca Góis Ruiz, Cameron Capeletti da Silva, João Ernesto de Carvalho, José Walkimar de Mesquita Carneiro, Felipe Terra Martins, Sergio Antonio Fernades y Ângelo de Fátima. "Xanthenones: calixarenes-catalyzed syntheses, anticancer activity and QSAR studies". Organic & Biomolecular Chemistry 13, n.º 11 (2015): 3280–87. http://dx.doi.org/10.1039/c4ob02611j.

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21

Nagel, Wolfram y Uri Katz. "Xanthine derivatives without PDE effect stimulate voltage-activated chloride conductance of toad skin". American Journal of Physiology-Cell Physiology 284, n.º 2 (1 de febrero de 2003): C521—C527. http://dx.doi.org/10.1152/ajpcell.00276a.2002.

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The effect of xanthine derivatives on the voltage-activated Cl− conductance ( G Cl) of amphibian skin was analyzed. 3-Isobutyl-1-methylxanthine (IBMX) and the recently synthesized xanthine derivatives 3,7-dimethyl-1-propyl xanthine (X-32) and 3,7-dimethyl-1-isobutyl xanthine (X-33), which lack inhibitory effects on phosphodiesterases in CHO and Calu-3 cells, increased voltage-activated G Cl without effect on baseline conductance at inactivating voltage. Half-maximal stimulation of G Cl occurred at 108 ± 9 μM for X-32 and X-33 after apical or basolateral application. The stimulation of G Cl, which occurs only in the presence of Cl− in the mucosal solution, is caused by a shift of the voltage sensitivity to lower clamp potentials and an increase of the maximally activated level. Furosemide reversed both the shift of sensitivity and the increase in magnitude. These patterns are fundamentally different from those seen after application of membrane-permeant, nonmetabolized analogs of cAMP, and they indicate that the xanthines stimulate G Cl directly. This notion is strengthened by the lack of influence on intracellular cAMP content, which is consistent with the observations in CHO and Calu-3 cells. We propose that the xanthine derivatives increase the voltage sensitivity of a regulative component in the conductive Cl− pathway across amphibian skin.

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22

Hu, Lina, Honggang Hu, Weifeng Wu, Xiaoyun Chai, Jianfei Luo y Qiuye Wu. "Discovery of novel xanthone derivatives as xanthine oxidase inhibitors". Bioorganic & Medicinal Chemistry Letters 21, n.º 13 (julio de 2011): 4013–15. http://dx.doi.org/10.1016/j.bmcl.2011.04.140.

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23

Miao, Weihang, Pingting Ye, Mengjiao Bai, Zhixin Yang, Suyue Duan, Hengpan Duan y Xuequan Wang. "Iodine-catalyzed efficient synthesis of xanthene/thioxanthene-indole derivatives under mild conditions". RSC Advances 10, n.º 42 (2020): 25165–69. http://dx.doi.org/10.1039/d0ra05217e.

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24

Han, Yutong, Xingyu Li, Chaonan Yuan, Ronghui Gu, Edward J. Kennelly y Chunlin Long. "Chemical Constituents From the Bark of Garcinia oblongifolia". Natural Product Communications 15, n.º 8 (agosto de 2020): 1934578X2094466. http://dx.doi.org/10.1177/1934578x20944660.

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The phytochemical investigation of the methanol extract of bark of Garcinia oblongifolia yielded a new xanthone derivative 1,3,8-trihydroxy-6’,6’-dimethylpyrano (2’,3’:5,6) xanthone (5) along with 8 known compounds, including 1,2,5-trihydroxy-6-methoxyxanthone (1), 1,3,6,7-tetrahydroxy-2,5-bis (3-methylbut-2-enyl) xanthen-9-one (2), xanthone V1 (3), isojacareubin (4), methyl protocatechuate (6), isoxanthochymol (7), euxanthone (8), and protocatechuic acid (9). The structures of these compounds were verified based on extensive spectroscopic data analysis as well as comparison with the literature data.

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25

Cazzola, Mario, Luigino Calzetta, Peter J. Barnes, Gerard J. Criner, Fernando J. Martinez, Alberto Papi y Maria Gabriella Matera. "Efficacy and safety profile of xanthines in COPD: a network meta-analysis". European Respiratory Review 27, n.º 148 (2 de mayo de 2018): 180010. http://dx.doi.org/10.1183/16000617.0010-2018.

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Theophylline can still have a role in the management of stable chronic obstructive pulmonary disease (COPD), but its use remains controversial, mainly due to its narrow therapeutic window. Doxofylline, another xanthine, is an effective bronchodilator and displays a better safety profile than theophylline. Therefore, we performed a quantitative synthesis to compare the efficacy and safety profile of different xanthines in COPD.The primary end-point of this meta-analysis was the impact of xanthines on lung function. In addition, we assessed the risk of adverse events by normalising data on safety as a function of person-weeks. Data obtained from 998 COPD patients were selected from 14 studies and meta-analysed using a network approach.The combined surface under the cumulative ranking curve (SUCRA) analysis of efficacy (change from baseline in forced expiratory volume in 1 s) and safety (risk of adverse events) showed that doxofylline was superior to aminophylline (comparable efficacy and significantly better safety), bamiphylline (significantly better efficacy and comparable safety), and theophylline (comparable efficacy and significantly better safety).Considering the overall efficacy/safety profile of the investigated agents, the results of this quantitative synthesis suggest that doxofylline seems to be the best xanthine for the treatment of COPD.

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26

Kasabova-Angelova, Alexandra, Diana Tzankova, Javor Mitkov, Maya Georgieva, Virginia Tzankova, Alexander Zlatkov y Magdalena Kondeva-Burdina. "Xanthine Derivatives as Agents Affecting Non-dopaminergic Neuroprotection in Parkinson’s Disease". Current Medicinal Chemistry 27, n.º 12 (23 de abril de 2020): 2021–36. http://dx.doi.org/10.2174/0929867325666180821153316.

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Parkinson's Disease (PD) is a neurodegenerative and debilitating disease that affects 1% of the elderly population. Patient’s motor disability results in extreme difficulty to deal with daily activities. Conventional treatment is limited to dopamine replacement therapy, which fails to delay disease’s progression and is often associated with a number of adverse reactions. Recent progress in understanding the mechanisms involved in PD has revealed new molecular targets for therapeutic approaches. Among them, caffeine and xanthine derivatives are promising drug candidates, because of the possible symptomatic benefits in PD. In fact, consumption of coffee correlates with a reduced risk of PD. Over the last decades, a lot of efforts have been made to uncover the therapeutic potential of xanthine structures. The substituted xanthine molecule is used as a scaffold for the synthesis of new compounds with protective effects in neurodegenerative diseases, including PD, asthma, cancer and others. The administration of the xanthines has been proposed as a non-dopaminergic strategy for neuroprotection in PD and the mechanisms of protection have been associated with antagonism of adenosine A2A receptors and Monoamine Oxidase type B (MAO-B) inhibition. The current review summarizes frequently suspected non-dopaminergic neuroprotective mechanisms and the possible beneficial effects of the xanthine derivatives in PD, along with some synthetic approaches to produce perspective xanthine derivatives as non-dopaminergic agents in PD treatment.

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27

Das, Sumit, Shantonu Roy, Arup Bhowmik, Writhabrata Sarkar, Imtiaj Mondal, Aniket Mishra, Shubhra Jyoti Saha, Sudip Karmakar y Indubhusan Deb. "A radical–radical cross-coupling reaction of xanthene with sulfonyl hydrazides: facile access to xanthen-9-sulfone derivatives". Chemical Communications 58, n.º 17 (2022): 2902–5. http://dx.doi.org/10.1039/d1cc07143b.

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A straightforward strategy for the direct incorporation of sulfonyl units into a xanthene moiety for accessing xanthen-9-sulfone derivatives has been established via metal-free radical–radical cross-coupling reaction of xanthenes and sulfonyl hydrazides.

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28

Lippold, Tim, Jörg M. Neudörfl y Axel Griesbeck. "New Acridone- and (Thio)Xanthone-Derived 1,1-Donor–Acceptor-Substituted Alkenes: pH-Dependent Fluorescence and Unusual Photooxygenation Properties". Molecules 26, n.º 11 (31 de mayo de 2021): 3305. http://dx.doi.org/10.3390/molecules26113305.

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A synthetic route to new heterocyclic 1,1-donor–acceptor-substituted alkenes starting with N-methyl-acridone, xanthone, and thioxanthone was investigated, leading to the acridone- and xanthone-derived products methyl 2-methoxy-2-(10-methylacridin-9 (10H)-ylidene)acetate (7) and methyl 2-methoxy-2-(9H-xanthen-9-ylidene)acetate (10) in low yields with the de-methoxylated product methyl 2-(10-methylacridin-9 (10H)-ylidene)acetate (8) and the reduced compound methyl 2-methoxy-2-(9H-xanthen-9-yl)acetate (11) as the major products from N-methyl acridone and xanthone. From thioxanthone, only the rearrangement and reduction products (14) and (15) resulted. The photophysical properties of compounds (7), (8), and (10) were investigated in the presence and absence of the Brønsted acid TFA by NMR, UV–VIS absorption, and fluorescence spectroscopy. Protonation of the acridone-derived alkenes (7) and (8) led to strong bathochromic and hyperchromic fluorescence shifts and a substantial increase in Stokes shift. The photooxygenation experiments with these substrates showed an unusual reactivity pattern in the singlet oxygen processes: whereas the electron-rich enolether (7) was chemically unreactive, (8) and (10) were oxidatively cleaved, presumably via intermediate 1,2-dioxetanes.

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29

Mourya, Shruti, Ramesh Bodla, Ravikant Taurean y Akanksha Sharma. "Simultaneous estimation of xanthine alkaloids (Theophylline, Theobromine and Caffeine) by High-Performance Liquid Chromatography". International Journal of Drug Regulatory Affairs 7, n.º 2 (16 de junio de 2019): 35–41. http://dx.doi.org/10.22270/ijdra.v7i2.315.

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Methylxanthines are mainly a group of phytochemicals which are derived from purine base xanthine. These xanthines are obtained from plant as a result of secondary metabolism. There are various physiological actions that have been attributed to these derivatives in neurogenerative diseases, respiratory diseases, cancer and diabetes. The aim of this study is to develop a suitable qualitative and quantitative method for these xanthine derivatives. HPLC method is suitable for simultaneous estimation of methylxanthines, based on their physicochemical properties. Theobromine, Theophylline and Caffeine that belongs to alkaloids possess their economic effects. They have various stimulant effects on cardiovascular system, gastrointestinal system, respiratory system, central nervous system etc. that results in increased motivation to work, increased energy and increased alertness. High performance liquid chromatography is used for simultaneous determination of theophylline, theobromine and caffeine from different tea leaves.

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30

Huang, Zhen, Ge-Biao Sun, S. Kawi, Yan Shi, Rui Wen y Shi-Wei Song. "Solubilities of xanthone and xanthene in supercritical CO2". Fluid Phase Equilibria 238, n.º 1 (noviembre de 2005): 26–32. http://dx.doi.org/10.1016/j.fluid.2005.09.008.

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31

Sánchez-Eleuterio, Alma, Carlos Mendoza-Merlos, Ricardo Corona Sánchez, Alejandra M. Navarrete-López, Anatolio Martínez Jiménez, Elsie Ramírez-Domínguez, Leticia Lomas Romero, Ricardo Orozco Cruz, Araceli Espinoza Vázquez y Guillermo E. Negrón-Silva. "Experimental and Theoretical Studies on Acid Corrosion Inhibition of API 5L X70 Steel with Novel 1-N-α-d-Glucopyranosyl-1H-1,2,3-Triazole Xanthines". Molecules 28, n.º 1 (3 de enero de 2023): 460. http://dx.doi.org/10.3390/molecules28010460.

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A series of novel 1-N-α-d-glucopyranosyl-1H-1,2,3-triazole xanthines was synthesized from azido sugars (glucose, galactose, and lactose) and propargyl xanthines (theophylline and theobromine) using a typical copper (I)-catalyzed azide–alkyne 1,3-dipolar cycloaddition. The corrosion inhibition activities of these new carbohydrate-xanthine compounds were evaluated by studying the corrosion of API 5 L X70 steel in a 1 M HCl medium. The results showed that, at 10 ppm, a 90% inhibition efficiency was reached by electrochemical impedance spectroscopy. The inhibitory efficiency of these molecules is explained by means of quantum chemical calculations of the protonated species with the solvent effect, which seems to better represent the actual situation of the experimental conditions. Some quantum chemical parameters were analyzed to characterize the inhibition performance of the tested molecules.

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32

Safitri, Ayu N., Nurlelasari, Tri Mayanti, Darwati y Unang Supratman. "5,5′-Oxybis(1,3,7-trihydroxy-9H-xanthen-9-one): A New Xanthone from the Stem Bark of Garcinia porrecta (Clusiaceae)". Molbank 2020, n.º 3 (12 de agosto de 2020): M1153. http://dx.doi.org/10.3390/m1153.

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A new polyoxygenated dimer-type xanthone, namely 5,5′-oxybis(1,3,7-trihydroxy-9H-xanthen-9-one (1), has been isolated from the stem bark of Garcinia porrecta. The structure of 1 was determined based on spectroscopic data, including 1D and 2D-NMR as well as high resolution mass spectroscopy analysis.

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33

Hidayah, Himyatul, Neni Sri Gunarti, Hardiyanti Pajri Rizki y Surya Amal. "POTENSI TANAMAN SAMBUNG NYAWA (Gynura procumbens) SEBAGAI ANTIHIPERURISEMIA BERDASARKAN KANDUNGAN ZAT AKTIFNYA: LITERATURE REVIEW ARTICLE". Jurnal Ilmiah Farmako Bahari 14, n.º 1 (31 de enero de 2023): 59. http://dx.doi.org/10.52434/jfb.v14i1.1344.

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Hiperurisemia merupakan suatu kondisi di mana terjadi peningkatan produksi kadar asam urat di dalam tubuh. Penggunaan obat antihiperurisemia dapat menimbulkan efek samping, sehingga penggunaan obat tradisional dengan bahan alam dapat digunakan sebagai alternatif pengobatan. Oleh karena itu, diperlukan pengembangan senyawa dengan aktivitas penghambat xantin oksidase yang berasal dari tumbuhan alam dengan efek samping yang lebih rendah. Salah satunya yaitu menggunakan daun Sambung Nyawa (Gynura procumbens) sebagai antihiperurisemia. Literature review article ini bertujuan untuk mengetahui kandungan senyawa aktif Sambung Nyawa yang digunakan sebagai antihiperurisemia dengan mengkaji beberapa literatur yang berkaitan dengan hal tersebut. Pencarian literatur yang akan digunakan hanya terbatas pada senyawa aktif Sambung Nyawa sebagai antihiperurisemia yang dipublikasikan pada tahun 2011-2021. Proses pencarian dilakukan menggunakan Google Scholar, PubMed dam ScienceDirect dengan kata kunci “Gynura procumbens, antihiperurisemia, sambung nyawa, xantin oksidase, Activity flavonoid of antihyperuricemic” dan “Mechanism of flavonoids as antihyperuricemia”. Hasil akhir pencarian tersebut didapatkan 7 artikel yang digunakan. Berdasarkan literature review yang telah dilakukan menunjukkan bahwa golongan flavonoid dengan kandungan senyawa aktif kuersetin, kaempferol, apigenin, myricetin dan rutin dari Sambung Nyawa yang paling banyak memiliki kemampuan sebagai antihiperurisemia yang ditandai dengan penghambatan xanthine oxidase.

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34

Altieri, Alessandro, Antonello Alvino, Stephan Ohnmacht, Giancarlo Ortaggi, Stephen Neidle, Daniele Nocioni, Marco Franceschin y Armandodoriano Bianco. "Xanthene and Xanthone Derivatives as G-Quadruplex Stabilizing Ligands". Molecules 18, n.º 11 (30 de octubre de 2013): 13446–70. http://dx.doi.org/10.3390/molecules181113446.

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35

Katori, Akane, Eriko Azuma, Hina Ishimura, Kouji Kuramochi y Kazunori Tsubaki. "Fluorescent Dyes with Directly Connected Xanthone and Xanthene Units". Journal of Organic Chemistry 80, n.º 9 (22 de abril de 2015): 4603–10. http://dx.doi.org/10.1021/acs.joc.5b00479.

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36

Ghahsare, Aref G., Zahra S. Nazifi y Seyed M. R. Nazifi. "Structure-Bioactivity Relationship Study of Xanthene Derivatives: A Brief Review". Current Organic Synthesis 16, n.º 8 (20 de enero de 2020): 1071–77. http://dx.doi.org/10.2174/1570179416666191017094908.

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: Over the last decades, several heterocyclic derivatives compounds have been synthesized or extracted from natural resources and have been tested for their pharmaceutical activities. Xanthene is one of these heterocyclic derivatives. These compounds consist of an oxygen-containing central heterocyclic structure with two more cyclic structures fused to the central cyclic compound. It has been shown that xanthane derivatives are bioactive compounds with diverse activities such as anti-bacterial, anti-fungal, anti-cancer, and anti-inflammatory as well as therapeutic effects on diabetes and Alzheimer. The anti-cancer activity of such compounds has been one of the main research fields in pharmaceutical chemistry. Due to this diverse biological activity, xanthene core derivatives are still an attractive research field for both academia and industry. This review addresses the current finding on the biological activities of xanthene derivatives and discussed in detail some aspects of their structure-activity relationship (SAR).

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37

Rádl, Stanislav. "Preparation of 1-Hydroxyxanthen-9(9H)-ones and 1-Hydroxyacridin-9(10H)-ones via Corresponding 3,4-Dihydro-1,9(2H)-diones". Collection of Czechoslovak Chemical Communications 60, n.º 12 (1995): 2127–36. http://dx.doi.org/10.1135/cccc19952127.

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Target 10-cyclopropyl-7-fluoro-1-hydroxy-6-(4-methyl-1-piperazinyl)acridin-9(10H)-one (IVc) and 7-fluoro-1-hydroxy-6-(4-methyl-1-piperazinyl)-9H-xanthen-9-one (IVd) were obtained from corresponding difluoro derivatives IVa and IVb, respectively. These intermediates were synthesized via respective 3,4-dihydro-1,9(2H)-diones Va and Vb. Acridine derivative (10-cyclopropyl-6,7-difluoro-3,4-dihydro-1H-acridine-1,9(2H,10H)-dione, Va) was synthesized from 1-cyclopropyl-6,7-difluoroisatoic anhydride (XI) and xanthene derivative (6,7-difluoro-3,4-dihydro-1H-xanthen-1,9(2H)-dione, Vb) from cyclohexenone derivative VIb. Several unsuccessful attempts to prepare hydroxyacridone IVc and/or some useful intermediates of its synthesis are also described.

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38

Ravidas, Cherry Mae T., Teofila D. C. Villar, Leon O. Namuco y Hidelisa P. Hernandez. "Isolation, Purification and Structure Elucidation of a Xanthone from the Pericarp of Kamandiis (Garcinia rubra Merr.)". KIMIKA 30, n.º 1 (28 de junio de 2019): 40–44. http://dx.doi.org/10.26534/kimika.v30i1.40-44.

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The pericarp of Garcinia rubra, an endemic Garcinia species in the Philippines was extracted with dichloromethane. An isolate of the extract was acetylated giving monoacetyl and diacetyl derivatives. Analysis of these derivatives led to the elucidation of the xanthone 1,3,7-trihydroxy-2,4-bis(3-methylbut-2-enyl)-9H-xanthen-9-one. The compound was isolated and characterized through column chromatography, acetylation, FTIR, NMR and LCMS analyses.

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39

Rockitt, Sven, Rudolf Wartchow, Helmut Duddeck, Anna Drabczynska y Katarzyna Kiec-Kononowicz. "Modes of Xanthine Complexation to Dirhodium Tetrakis[(R)-α-methoxy-α- (trifluoromethyl)-phenylacetate] in Solution and in the Solid State". Zeitschrift für Naturforschung B 56, n.º 3 (1 de marzo de 2001): 319–24. http://dx.doi.org/10.1515/znb-2001-0317.

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Abstract It is show n by IR and NMR studies that the xanthines 1-5 prefer a side-on com plexation to the chiral dirhodium tetrakis[(R)-α-methoxy-α-(trifluoromethyl)phenylacetatel (Rh*) in solution whereas carbonyl groups are involved in the solid state. For 6, at least the carbonyl group C-6 contributes to complexation in solution as well. A lternating strands of 6 and Rh* exist in the solid state as revealed by X-ray diffraction analysis described in detail. The determination of enantiomeric excess of the chiral xanthine 6 can easily be accomplished by the “dirhodium method ” (1H and 13C NMR in the presence of Rh*).

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40

Elix, JA, H. Jiang y JH Wardlaw. "A New Synthesis of Xanthones. 2,4,7-Trichloronorlichexanthone and 4,5,7-Trichloronorlichexanthone, Two New Lichen Xanthones". Australian Journal of Chemistry 43, n.º 10 (1990): 1745. http://dx.doi.org/10.1071/ch9901745.

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A new synthetic route to norlichexanthone (1,3,6-trihydroxy-8-methyl- 9H-xanthen-9-one) derivatives has been developed by using a Smiles rearrangement of an appropriately substituted depside in the key step. 2,4,7-Trichloronorlichexanthone (22) and 4,5,7- trichloronorlichexanthone (29) have been prepared by this method. The former xanthone (22) was shown to be a constituent of the lichens Lecanora sulphurata and L. flavo-pallescens and the latter (29) a constituent of Micarea austroternaria var. isabellina.

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41

Resende, Diana I. S. P., Patrícia Pereira-Terra, Joana Moreira, Joana Freitas-Silva, Agostinho Lemos, Luís Gales, Eugénia Pinto, Maria Emília de Sousa, Paulo Martins da Costa y Madalena M. M. Pinto. "Synthesis of a Small Library of Nature-Inspired Xanthones and Study of Their Antimicrobial Activity". Molecules 25, n.º 10 (21 de mayo de 2020): 2405. http://dx.doi.org/10.3390/molecules25102405.

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A series of thirteen xanthones 3–15 was prepared based on substitutional (appendage) diversity reactions. The series was structurally characterized based on their spectral data and HRMS, and the structures of xanthone derivatives 1, 7, and 8 were determined by single-crystal X-ray diffraction. This series, along with an in-house series of aminated xanthones 16–33, was tested for in-vitro antimicrobial activity against seven bacterial (including two multidrug-resistant) strains and five fungal strains. 1-(Dibromomethyl)-3,4-dimethoxy-9H-xanthen-9-one (7) and 1-(dibromomethyl)-3,4,6-trimethoxy-9H-xanthen-9-one (8) exhibited antibacterial activity against all tested strains. In addition, 3,4-dihydroxy-1-methyl-9H-xanthen-9-one (3) revealed a potent inhibitory effect on the growth of dermatophyte clinical strains (T. rubrum FF5, M. canis FF1 and E. floccosum FF9), with a MIC of 16 µg/mL for all the tested strains. Compounds 3 and 26 showed a potent inhibitory effect on two C. albicans virulence factors: germ tube and biofilm formation.

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42

Mincsovics, Emil, Márta Garami, László Kecskés, Barnabás Tapa, Zoltán Végh, György Kátay y Ernó Tyihák. "Personal Overpressured-Layer Chromatography (OPLC) Basic System 50, Flexible Tool in Analytical and Semipreparative Work". Journal of AOAC INTERNATIONAL 82, n.º 3 (1 de mayo de 1999): 587–98. http://dx.doi.org/10.1093/jaoac/82.3.587.

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Abstract A new automated overpressured-layer chromatographic (OPLC) system called the Personal OPLC Basic System 50 is suitable for analytical and semi preparative separations. The automatic microprocessor-controlled system ensures rapid and reproducible off-line isocratic and stepwise gradientseparations. High external pressure (5 MPa) makes the sorbent layer more homogeneous, yielding more efficient off-line separation compared with those by early Chrompres chambers. A theoretical plate height of 10–30 μm can be achieved on an analytical high-performance thin-layer chromatographic (HPTLC) layer made of irregular silica gel with an average particle size of 5 μm if an optimal linear velocity (20–40 mm/min) and a nonviscous solvent system are used. On an analytical layer of 3 μm spherical silica gel, a theoretical plate height of 6–15 μm can be reached. Rapid analytical separations of resveratrol (1555 s) and xanthine by one-(498s) and two-directional (274 s) off-line developments were accomplished. On-line separation and detection combined with off-line sample application and fully on-line processing (including on-line sample application, separation, and detection) were fulfilled with a TLC plate for xanthine separation. Semi preparative isolation of xanthines was achieved through a fully on-line OPLC operating mode and scaled-up chromatography.

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43

Resende, Diana, Patrícia Pereira-Terra, Ângela Inácio, Paulo Costa, Eugénia Pinto, Emília Sousa y Madalena Pinto. "Lichen Xanthones as Models for New Antifungal Agents". Molecules 23, n.º 10 (12 de octubre de 2018): 2617. http://dx.doi.org/10.3390/molecules23102617.

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Due to the emergence of multidrug-resistant pathogenic microorganisms, the search for new antimicrobial compounds plays an important role in current medicinal chemistry research. Inspired by lichen antimicrobial xanthones, a series of novel chlorinated xanthones was prepared using five chlorination methods (Methods A–E) to obtain different patterns of substitution in the xanthone scaffold. All the synthesized compounds were evaluated for their antimicrobial activity. Among them, 3-chloro-4,6-dimethoxy-1-methyl-9H-xanthen-9-one 15 showed promising antibacterial activity against E. faecalis (ATCC 29212 and 29213) and S. aureus ATCC 29213. 2,7-Dichloro-3,4,6-trimethoxy-1-methyl-9H-xanthen-9-one 18 revealed a potent fungistatic and fungicidal activity against dermatophytes clinical strains (T. rubrum, M. canis, and E. floccosum (MIC = 4–8 µg/mL)). Moreover, when evaluated for its synergistic effect for T. rubrum, compound 18 exhibited synergy with fluconazole (ΣFIC = 0.289). These results disclosed new hit xanthones for both antibacterial and antifungal activity.

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44

Tian, Xiang-Yu y Qin-Hua Song. "(E)-2-Methoxy-9-(2-methoxy-9H-xanthen-9-ylidene)-9H-xanthene". Acta Crystallographica Section E Structure Reports Online 69, n.º 7 (29 de junio de 2013): o1167. http://dx.doi.org/10.1107/s1600536813017297.

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45

Huang, Zhen, Xue-Wen Yang, Ge-Biao Sun, Shi-Wei Song y S. Kawi. "The solubilities of xanthone and xanthene in supercritical carbon dioxide: Structure effect". Journal of Supercritical Fluids 36, n.º 2 (diciembre de 2005): 91–97. http://dx.doi.org/10.1016/j.supflu.2005.04.002.

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46

Britigan, Bradley E., Sovitj Pou, Gerald M. Rosen, Diane M. Lilleg y Garry R. Buettner. "Hydroxyl radical is not a product of the reaction of xanthine oxidase and xanthine. The confounding problem of adventitious ironb ound to xanthineo xidase." Journal of Biological Chemistry 266, n.º 8 (marzo de 1991): 6006. http://dx.doi.org/10.1016/s0021-9258(19)67796-3.

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47

Hille, Russ y Takeshi Nishino. "Xanthine oxidase and xanthine dehydrogenase". FASEB Journal 9, n.º 11 (agosto de 1995): 995–1003. http://dx.doi.org/10.1096/fasebj.9.11.7649415.

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48

Cervin, Anders, Sven Lindberg, Jan Dolata y Ulf Mercke. "Cyclic Adenosine Monophosphate Stimulation of Mucociliary Activity in the Upper Airways in Vivo". Annals of Otology, Rhinology & Laryngology 104, n.º 5 (mayo de 1995): 388–93. http://dx.doi.org/10.1177/000348949510400509.

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Xanthine derivatives are known to accelerate mucociliary transport in the lower airways, probably by preventing degradation of cyclic adenosine monophosphate (cAMP) and thereby increasing its intracellular concentration. The purpose of this study was to investigate the effects of cAMP on mucociliary activity in the upper airways. The effect on the mucociliary activity in the rabbit maxillary sinus of the xanthine derivatives theophylline and enprophylline was compared to that of the cAMP analog dibutyryl cAMP. The compounds were administered into the maxillary artery, and the response was recorded with a photoelectric technique. Infusions of theophylline (1.0 and 10 mg/kg) increased mucociliary activity (22.8% ± 5.9%, n = 6, and 21.6% ± 4.9%, n = 7, p < .05, respectively). Infusions of enprophylline (1.0 and 10.0 mg/kg) accelerated mucociliary activity (at the highest dosage tested, 24.3% ± 4.1%). Infusions of dibutyryl cAMP (0.1 and 1.0 mg/kg) stimulated mucociliary activity, with the maximum increase (20.1% ± 3.0%, n = 13, p < .05) being observed at a dosage of 0.1 mg/kg. The infused substances increased mucociliary activity within 1 minute after the start of the infusion, the duration of the response being approximately 20 minutes for theophylline, 22 minutes for enprophylline, and 12 minutes for dibutyryl cAMP. The present results support the view that cAMP is involved in regulating mucociliary activity in the upper airways. It remains to be elucidated whether xanthines such as theophylline and enprophylline are beneficial in upper airway disease in which mucociliary function is impaired (eg, chronic sinusitis).

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Barlinski, J., A. Lockhart y N. Frossard. "Modulation by theophylline and enprofylline of the excitatory non-cholinergic transmission in guinea-pig bronchi". European Respiratory Journal 5, n.º 10 (1 de noviembre de 1992): 1201–5. http://dx.doi.org/10.1183/09031936.93.05101201.

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The mechanism of action of xanthines in asthma remains controversial. Since sensory innervation may play a role in the pathogenesis of asthma, we investigated whether xanthines were capable of reducing the contractile response of the bronchi to nerve stimulation. In guinea-pig bronchi in vitro, electrical field stimulation (EFS: 40 V, 16 Hz, 0.2 ms during 10 s) induces a rapid cholinergic contraction followed by a long-lasting contraction due to a local release of neuropeptides from C-fibre endings. We measured isometric neuronally-mediated contractions of bronchial smooth muscle and studied the effects of increasing concentrations of two xanthine derivatives, theophylline, an antagonist of adenosine receptors, and enprofylline, which has no effect on adenosine receptors. Both enprofylline (1-50 microM) and theophylline (10-100 microM) inhibited, in a concentration-dependent manner, the peptidergic contraction, an effect which was more marked with enprofylline than theophylline (EC50 = 9.6 +/- 0.7 microM and 62.0 +/- 4.7 microM, respectively). Conversely, the cholinergic response was unaffected. Contractions induced by exogenous substance P (0.03-3 microM) were also unaffected by theophylline and enprofylline at the above mentioned EC50s. Our results suggest that concentrations of theophylline, similar to those used therapeutically, reduce the release of sensory neuropeptides from C-fibre endings. This effect is unrelated to adenosine receptor blockade, since enprofylline had a similar inhibitory effect.

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50

Chehaibar, Teresa y Rosaura Grether. "Anatomía de la madera de algunas especies del género Mimosa (Leguminosae)". Botanical Sciences, n.º 50 (10 de abril de 2017): 3. http://dx.doi.org/10.17129/botsci.1374.

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The macroscopic and microscopic features of the secondary xylem of treelets included in the series Xantiae, genus Mimosa are described: M. lactiflua with 3 varieties: var. lactiflua, var. psilocarpa and var. goldmanii, M. tricephala with 2 varieties: var. xanti and var. nelsonii, and M. sicyocarpa var. mellii. The organization of the wood elements of these species is very similar, however it is possible to distinguish 2 groups, according to some macroscopic and microscopic differences: one group corresponds to the varieties of M. lactiflua and the other groups the rest of these taxa. The taxonomic value of these characters at series level in the genus is discussed, as we ll as the 1mportance of the anatomical criterium in taxonomic studies.

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