Academic literature on the topic 'Flavonoid luteolin'

Nature gives immense resources that are beneficial to humankind. The natural compounds present in plants provide primary nutritional values to our diet. Apart from food, plants also provide chemical compounds with therapeutic values. The importance of these plant secondary metabolites is increasing due to more studies revealing their beneficial properties in treating and managing various diseases and their symptoms. Among them, flavonoids are crucial secondary metabolite compounds present in most plants. Of the reported 8000 flavonoid compounds, luteolin is an essential dietary compound. This review discusses the source of the essential flavonoid luteolin in various plants and its biosynthesis. Furthermore, the potential health benefits of luteolins such as anti-cancer, anti-microbial, anti-inflammatory, antioxidant, and anti-diabetic effects and their mechanisms are discussed in detail. The activity of luteolin and its derivatives are diverse, as they help to prevent and control many diseases and their life-threatening effects. This review will enhance the knowledge and recent findings regarding luteolin and its therapeutic effects, which are certainly useful in potentially utilizing this natural metabolite.

Foliar flavonoids of Crossostephium chinense in Japan and Taiwan were isolated and further characterized. Eighteen flavonoid aglycones, luteolin, apigenin, hispidulin, chrysoeriol, 5,7,4′-trihydroxy-6,3′,5′-trimethoxyflavone, jaceosidin, cilsimaritin, quercetin 3-methyl ether, axillarin, chrysosplenol-D, cirsiliol, apometzgerin, 5,7,3′-trihydroxy-6,4′,5′-trimethoxyflavone, luteolin 3′,4′-dimethyl ether, cirsilineol, eupatilin, nepetin and 5,7,3′,4′-tetrahydroxy-6,5′-dimethoxyflavone, were identified by UV, 1H and 13C NMR spectroscopic, LC-MS and HPLC comparisons with authentic samples. The compounds existed on the leaf surface. Four flavonoid glycosides, quercetin 3,7-di- O-glucoside, quercetin 3- O-rutinoside, luteolin 7- O-glucoside and apigenin 7- O-rutinoside, were also isolated as the intracellular flavonoids. It was shown by HPLC survey that variation of the species’ flavonoids occurs among the collection sites.

Foliar flavonoids of Tanacetum vulgare var. boreale were isolated. Eight flavonoid glycosides, 7- O-glucosides of apigenin, luteolin, scutellarein and 6-hydroxyluteolin, and 7- O-glucuronides of apigenin, luteolin, chrysoeriol and eriodictyol were identified. Moreover, eight flavonoid aglycones, apigenin, luteolin, hispidulin, nepetin, eupatilin, jaceosidin, pectolinarigenin and axillarin were also isolated and identified. The flavonoid composition of two varieties of T. vulgare, i.e. var. boreale and var. vulgare, were compared. All samples of var. boreale and one sample of var. vulgare had the same flavonoid pattern, and could be distinguished from almost all the samples of var. vulgare. Thus, the occurrence of chemotypes, which are characterized by either the presence or absence of scutellarein 7- O-glucoside, eriodictyol 7- O-glucuronide and pectolinarigenin was shown in T. vulgare sensu lato.

Flowers of Sinningia (syn. Rechsteineria) cardinalis contain glycosides of the flavones apigenin (4′-OH) and luteolin (3′,4′-OH) respectively, and of the related 3-deoxyanthocyanidins apigeninidin and luteolinidin. Studies on substrate specificity of the key enzyme of flavonoid biosynthesis, chalcone synthase, revealed that the 3′,4′-hydroxylated flavonoids are formed by hydroxylation of flavonoid compounds rather than by incorporation of caffeoyl-CoA into the flavonoid skeleton during the condensation reaction. In fact, flavonoid 3′-hydroxylase activity could be demonstrat­ed in the microsomal fraction of the flower extracts. The enzyme catalyses hydroxylation of naringenin and apigenin in the 3′-position to eriodictyol and luteolin, respectively, with NADPH as cofactor. Besides flavanone 3′-hydroxylase a further NADPH-dependent enzyme activity (flavone synthase II) was observed in the microsomal fraction catalysing the oxidation of naringenin to apigenin and of eriodictyol to luteolin. The Cytochrome P-450 inhibitor ancymidol was found to abolish completely flavone synthase II activity, whereas flavonoid 3′-hydroxylase activity was not impaired.

The review describes the distribution of surface flavonoids in Bulgarian plants. More than 100 species of Asteraceae, Lamiaceae, Scrophulariaceae, Geraniaceae and other families have been checked for external flavonoid aglycones. The flavonoid profiles of Asteraceae species are composed of a wide array of flavones and flavonols, mainly based upon 6-substituted derivatives. Flavone aglycones are predominant in the exudates of Lamiaceae species. Apigenin, luteolin and their derivatives were most commonly found in the studied species of Scropulariaceae and Lamiaceae. It has been shown that species of Geraniaceae, Ranunculaceae, and Solanaceae contain flavonoids of the flavonol class as surface constituents. Surface distributed flavonoids appear to have been well studied and useful for chemotaxonomy. If there is not too much infraspecific variation, flavonoid profiles can be used as taxonomic characters to distinguish species. Correlations between external flavonoid formation and local environment are apparent.

Abstract Thymus membranaceus is an endemism of southeastern Spain, which belongs to section Pseudothymbra of genus Thymus. In this work we have achieved an investigation of the flavonoid glycosides present in the aerial parts of this plant. Among the compounds identified are the rare luteolin-7-0-β-D-xyloside, luteolin-7-0-β-D-[rhamnosyl (1→2)glucoside] and luteolin-7-0-β-D-[xylosyl (1→2)glucoside] previously not known to occur in the Labiatae.

In the first detailed study of the flavonoid pattern of Achillea roseo-alba rutin, apigenin-7-O-ß-glucopyranoside, luteolin-7-O-ß-glucopyranoside, isorhamnetin-3-O-rutinoside, schaftoside, luteolin-4’-O-ß-glucopyranoside and 6-OH-luteolin-7-O-ß-glucopyranosid were proven in the methanolic extract of aerial parts of the plant. Additionally quercetin-3-O-[ß-apiofiranosyl-(1′′′→2′′)-ß-glucopyranoside] was identified for the first time in the genus Achillea.

Epidemiological studies suggest that a diet high in flavonoids protects against chronic diseases such as CVD and cancer. The objective of the present study was to evaluate the relationship between the intake of quercetin, kaempferol, isorhamnetin, apigenin and luteolin and their corresponding plasma concentrations, and further to explore whether these flavonoids can serve as biomarkers of their intake. Flavonoid intake and their plasma concentrations were analysed in ninety-two subjects consuming their habitual diet. Flavonoid intake was estimated with 7-d dietary records using available data on the flavonoid content of food. Plasma flavonoid concentrations were quantified by HPLC. In addition, we undertook a dietary intervention study to investigate plasma apigenin concentration after the consumption of celery leaf. The mean intake estimates of quercetin, kaempferol, isorhamnetin, apigenin and luteolin amounted to 13·58, 14·97, 12·31, 4·23 and 8·08 mg/d, respectively. The corresponding mean plasma concentrations were 80·23, 57·86, 39·94, 10·62 and 99·90 nmol/l. The mean 7 d intake of five flavonoids was positively correlated to their corresponding plasma concentrations, with correlation coefficients ranging from 0·33 to 0·51 (P < 0·05). In the dietary intervention study, the plasma apigenin concentration rose after celery leaf ingestion, and fell within 28 h to below the limit of detection (2·32 nmol/l). The present results suggest that quercetin, kaempferol, isorhamnetin, apigenin and luteolin are bioavailable from the diet. The levels of fasting plasma flavonoids seem to be suitable biomarkers of short-term intake. The combination of plasma flavonoids with their intake may prove useful when the possible health-protective effects of flavonoids are studied.

ABSTRACT NodD1 is a member of the NodD family of LysR-type transcriptional regulators that mediates the expression of nodulation (nod) genes in the soil bacterium Sinorhizobium meliloti. Each species of rhizobia establishes a symbiosis with a limited set of leguminous plants. This host specificity results in part from a NodD-dependent upregulation of nod genes in response to a cocktail of flavonoids in the host plant's root exudates. To demonstrate that NodD is a key determinant of host specificity, we expressed nodD genes from different species of rhizobia in a strain of S. meliloti lacking endogenous NodD activity. We observed that nod gene expression was initiated in response to distinct sets of flavonoid inducers depending on the source of NodD. To better understand the effects of flavonoids on NodD, we assayed the DNA binding activity of S. meliloti NodD1 treated with the flavonoid inducer luteolin. In the presence of luteolin, NodD1 exhibited increased binding to nod gene promoters compared to binding in the absence of luteolin. Surprisingly, although they do not stimulate nod gene expression in S. meliloti, the flavonoids naringenin, eriodictyol, and daidzein also stimulated an increase in the DNA binding affinity of NodD1 to nod gene promoters. In vivo competition assays demonstrate that noninducing flavonoids act as competitive inhibitors of luteolin, suggesting that both inducing and noninducing flavonoids are able to directly bind to NodD1 and mediate conformational changes at nod gene promoters but that only luteolin is capable of promoting the downstream changes necessary for nod gene induction.

Colorectal cancer is one of the most common malignancies and a leading cause of cancer death in the world. More powerful and safer therapeutic approaches are urgently needed to reduce mortality and garner better curative effects. In this regard, dietary supplements capable of preventing carcinogenesis and inhibiting the growth of colon carcinoma cells have generated intense interest. Luteolin (LU), a common dietary flavonoids, has emerged as a powerful anticancer agents able to sensitize different cancer cells, including colon cancer ones, to therapeutic-induced cytotoxicity. However, the molecular mechanisms underlying LU effects in colon cancer are largely unknown. Sphingolipids have critical functions as signaling molecules. In particular, Ceramide (Cer) and Sphingosine-1-phosphate (S1P) are involved as key antagonist mediators in regulating crucial cell responses such as proliferation and apoptosis. Cer can act as a second messenger, and, by activating a variety of signaling pathways, is able to promote growth arrest, apoptosis, or cell differentiation. To the opposite, the sphingoid mediator S1P can act as a potent mitogen and survival factor for a variety of cell types. These two lipids together form the “sphingolipid rheostat” regulating the balance between cell growth and cell death. The objective of our study was to investigate the effects and the molecular mechanisms of LU in colon cancer, focusing on the role of the bioactive sphingoid molecules Cer and S1P. To this purpose, we used the Caco-2 cell line, obtained from a human colon adenocarcinoma, as cell model of both colon cancer cells, and differentiated intestinal enterocytes. Indeed, in long-term culture, these cells undergo a spontaneous differentiation into polarized cells, representing so far the best available in vitro model of absorptive enterocytes. These two models might thus allow to distinguish the potential LU effects on colon cancer cells in comparison to their healthy counterparts. At first, we characterized the morphological and biochemical features of both models. We found that Caco-2 cell differentiation was accompanied by the formation of “domes” across the monolayer, known as characteristic structures of differentiated cells, and indicative of their property of absorptive epithelium. In addition, the activity of the alkaline phosphatase, a membrane-associated hydrolase was found significantly increased in differentiated Caco-2 cells compared to the tumoural cancer ones. Furthermore, we found that Caco-2 differentiation was associated with a reduction of the phospholipids/protein ratio, and whereas phosphatidylcholine was the most abundant phospholipid species of tumoural cells, phosphatidylethanolamine prevailed in the differentiated ones. Moreover, phosphatidylethanolamine plasmalogen, a quantitative relevant species in the cancer cells, exhibited a marked decrease with intestinal differentiation. As far as the sphingolipid composition concerns, we first demonstrated that Caco-2 differentiation was associated to an increase in the total amount of sphingolipids, including Sphingomyelin (SM), the major component and precursor of both Cer and S1P, and above all ceramide. Since the SM hydrolysis, triggered by Sphingomyelinases (SMases), has been implicated in colon tumourigenesis, we then evaluated whether changes in the activity of the known different SMases (the neutral (N-SMase) and alkaline (Alk-SMase) enzymes) occur with cell differentiation. We found that the Alk-SMase activity which was barely detectable in tumoural cancer cells, significantly increased in differentiated ones. The high level of this enzyme is consistent with its presence in the apical brush border, characteristic of intestinal cells. Interestingly a significant increase in the N-SMase was observed in the differentiated Caco-2 cells suggesting a role for this enzyme in intestinal cells. Prompted by these data indicating that the SM hydrolytic potential is enhanced in differentiated Caco-2 cells, we then investigated SM metabolism in both tumoural and differentiated cells. We found that the tumoural cells were much more rapid in the production of Cer from SM than the differentiated ones, and that Cer turnover was present and rapid in both cell types. Inhibition of N-SMase activity, the most abundant enzyme, resulted in no variation of Cer formation in both types of cells, suggesting that the lysosomal acid SMase (A-SMase) is involved in SM degradation. After this characterization, we then evaluated the effect of LU on the tumoural and intestinal cells. Interestingly, we found that the flavonoid exhibited a potent cytotoxic effect on tumoural cells, by inducing apoptosis, without affecting the viability of differentiated cells. Instead, we found that LU induces an increase in intracellular Cer level with a more pronounced trend in tumoural cells. Based on these results we examined whether Cer is involved in the mechanism of LU-induced apoptosis. Notably we obtained that conditions leading to enhance the Cer content in colon cancer cells, as treatment with short-chain Cer analogues and inhibitor of sphingomyelin synthase (SM-synthase) were succeeded by inducing apoptosis in tumoural cells, thus mimicking the LU effect. Furthermore, we evaluated the possible effect of LU on the formation of Cer and S1P in tumoural Caco-2 cells. Pulse experiments showed that treatment with LU induced a dose-dependent increase in Cer, paralleled by a concomitant decrease of both SM and glycosphingolipids synthesis. This result suggested that LU most probably acts by reducing the availability of Cer as a substrate for both SM-synthase and glucosylceramide synthase enzymes localized in the Golgi complex, possibly by inducing a defect in the common vesicular route responsible for complex SLs biosynthetic process. Fluorescent studies using a BODIPY-C5-CER, a ceramide analogue known to mimic the ER-Golgi traffic of natural Cer in living cells, supported the presence of an aberrant traffic of Cer during LU treatment. Furthermore, pulse experiments using treatment with Brefeldin A, known to induce a retrograde merging of Golgi membranes with the ER, demonstrated that LU was not more able to exert alterations of Cer metabolism, thus indicating that the ER-Golgi traffic of Cer is the site of LU action. In parallel, different protein kinases, including Akt have been shown to regulate ER to Golgi traffic. In addition, a study in our laboratory reported for the first time a putative role of PI3K /Akt pathway in the regulation of the vesicle-mediated movements of Cer in the ER-Golgi district. Prompted by these findings, pulse experiments using LY294002, a representative PI3K inhibitor, showed that, LY294002 and subsequently the inhibition of PI3K/Akt had the same effect on the Cer metabolism observed during LU treatment. Furthermore, we obtained that LU strongly inhibited the Akt phosphorylation as a downstream response to PI3K inhibition. Taken together, it emerges that blockade of PI3K by LU and subsequently the downregulation of PI3K/Akt pathway is considered at least one of the mechanisms responsible for the effect of this flavonoid on Cer trafficking observed in our tumoural cell model Further analyses revealed that LU was able to alter not only Cer content but also to decrease the endogenous S1P level inducing thereby a shift of the “sphingolipid balance” to the side of death. Based on this result, we demonstrated for the first time that LU was able to act as inhibitor of Sphingosine kinase (SPHK) activity in tumoural cells, especially SPHKII, the up-regulated isoform in our cancer cell model, exhibiting only a modest effect on SPHKI. Furthermore, in order to gain deeper insights into the role of the “Sphingolipid rheostat” in mediating the effect of LU, we attempted to push the balance towards S1P with addition of exogenous S1P. The results demonstrated that S1P conferred a significant resistance of colon cancer cells to the cytotoxic effect of LU. The mechanism by which S1P acts as LU-antagonist was proved to be mainly by the up-regulation of the PI3K/Akt pathway, which is able to rescue colon cancer cells from the apoptotic effect of the LU-induced increase of Cer. Taken together, our results demonstrate, for the first time, that the dietary natural flavonoid LU induces apoptosis in colon cancer cells by targeting the “sphingolipid rheostat”, and directing the balance in favor of Cer. As the balance between Cer and S1P appears to be an important target for development of new and effective therapeutic strategies against tumour progression, LU could be a novel antitumoural agent not only in colon cancer but possibly in the treatment of other solid tumours.

Magister Pharmaceuticae - MPharm
Artemisia afra (A. afra) is traditionally used for a variety of ailments and contain flavonoids e.g. luteolin which may contribute to some of its activity. It is generally administered as a tea or decoction, and such liquid dosage forms present challenges as far as long term storage and stability are concerned, as well as sub-optimal oral bioavailability of actives they contain. Freeze dried aqueous extracts (FDAE) can alleviate such problems but may be hygroscopic and unstable. The use of modified forms of FDAE can counter the problem of hygroscopicity (e.g. use of alginate) and alleviate the issue of sub-optimal bioavailability of plant actives (e.g. polymethylmethacrylate). The objectives of this study, were to: (1) prepare the freeze dried aqueous extract (FDAE) and modified forms, which include alginate-extract beads (alginate-FDAE) and polymethylmethacrylate coated alginate matrix beads of herbal extract (PMMA-alginate-FDAE) of the FDAE of A. afra, (2) determine and compare the pharmaceutical characteristics of the above mentioned preparations of A. afra,(3) quantify and compare the total flavonoid and specifically luteolin levels of the different forms of A. afra,(4) evaluate and compare the release characteristics of FDAE of A. afra from the alginate-FDAE and PMMA-alginate-FDAE beads in gastrointestinal fluids and (5) determine the intestinal permeability of luteolin contained in selected modified Artemisia afra extract preparations. It was hypothesized that making the alginate beads and the polymethylmethacrylate coated alginate beads would make the FDAE less hygroscopic with a lower moisture content, that the rate of release of luteolin from A. afra FDAE into gastrointestinal fluids would be faster than from the modified forms, and that the effective gastrointestinal permeability of luteolin in the alginate-FDAE and PMMA-alginate-FDAE beads of A. afra is equal to that in FDAE. To realize these objectives, the FDAE was prepared by freeze drying the aqueous extract of the A. afra dried leaves, alginate-FDAE prepared by dispersing FDAE into 4% sodium alginate solution, then adding the resulting stock solution into a 2% calcium chloride solution and drying resulting beads and PMMA-alginate-FDAE prepared by a modified water-in-oil-in-water emulsion solvent evaporation method using water as an internal aqueous phase. Using pharmacopoeial methods and methods adapted from other workers the organoleptic and pharmaceutical characteristics were determined to compare the pharmaceutical quality of these preparations of A. afra. To identify and determine the levels of luteolin in the plant preparations, a validated HPLC assay was developed. Finally, the in situ perfused rat intestine model was used to determine the in vitro bioavailability, i.e. gastrointestinal permeability, of luteolin from solutions containing luteolin in pure form, FDAE, alginate-FDAE and PMMA-alginate-FDAE. The A. afra forms were obtained in moderate to good yields and FDAE was brown and hygroscopic in nature, the alginate beads dark brown free flowing and spherical in shape and the PMMA-alginate beads light brown in colour with rough edges. The A. afra plant forms on average contained 0.185 ± 0.24, 0.067 ± 0.014, 0.012 ± 0.071 μg/mg of free luteolin (n=3) in FDAE, alginate-FDAE and PMMA-alginate-FDAE respectively and 0.235 ± 0.026, 0.079 ± 0.093, 0.058 ± 0.082 μg/mg of total luteolin (n=3) in FDAE, alginate-FDAE and PMMAalginate- FDAE respectively. The Plumen values for intestinal uptake of luteolin were significantly higher from solutions of A. afra forms than the pure luteolin solution (i.e. Plumen values in the range of 0.02 - 0.035 cm/s for all plant forms vs Plumen values in the range of 0.010 - 0.014 cm/s for pure luteolin, t-test p = 0.0252). The permeability of luteolin in FDAE appeared to be slighter greater than that of the modified forms (Plumen values >0.03 cm/s for FDAE and Plumen values <0.03 cm/s for both modified forms). In summary, the results showed that, the modified A. afra forms; alginate-FDAE and PMMAalginate- FDAE were of acceptable pharmaceutical quality with luteolin better taken up in the plant forms than in its pure form. The A. afra forms prepared had similar rates of uptake (permeability) of free and total luteolin with the rates being highest for the FDAE. Collectively, these results indicate that alginate-FDAE and PMMA-alginate-FDAE bead forms should be suitable for use in a solid dosage form (e.g. tablet or capsule) of A. afra.

The aim of this study was to investigate the effect the plant matrix and the structure of the flavonoid (i.e. whether aglycone or glycoside) may have on the gastrointestinal uptake and metabolism of luteolin derivatives from Artemisia afra traditional plant medicine. Specifically, how these two factors influenced the intestinal uptake and disposition of luteolin derivatives in pure and in Artemisia afra plant extract forms were to be assessed by investigating the uptake and metabolism of the luteolin derivatives in human intestinal epithelial Caco-2 cells and the perfused rat intestinal loop. To realize this aim, the following were determined: (1) identification and characterization of major luteolin derivatives found in Artemisia afra, (2) the effect of the plant matrix on the uptake of luteolin derivatives in Artemisia afra aqueous-extract forms across the Caco-2 cell monolayer, (3) the effect of the plant matrix on the absorption and metabolism of luteolin derivatives in Artemisia afra aqueous-extract forms in the perfused rat small intestine, (4) the effect of gut contents on the uptake and metabolism of luteolin derivatives in intestinal loop and (5) the metabolic profiles of luteolin derivatives obtained for the pure solutions versus plant aqueous extract solutions in Caco-2 cells and the rat intestine.

Activation of the maternal immune system and resultant maternal cytokine expression due to prenatal infection has been implicated as a significant contributor to the pathology of neuropsychiatric and neurodevelopmental disorders such as schizophrenia and Autism Spectrum Disorder (ASD). Increased maternal interleukin-6 (IL-6) expression, observed clinically and in animal models of prenatal infection, and resultant activation of key signaling pathways, has been shown to be a biological indicator of pathology, and a central component of the pathological mechanism. In animal models of prenatal infection and clinically in pregnancy disorders hallmarked by immunological irregularities and increased IL-6 expression, inhibition of IL-6 has been shown to reduce pathological symptoms both maternally and in the exposed offspring. This study aims to demonstrate the ability of IL-6 expression, resulting from prenatal infection, to induce neuropathological and behavioral outcomes that mirror clinical observations seen in disorders such as ASD. More importantly, it shows how flavones luteolin and diosmin, a subclass of the flavonoid family, through inhibition of IL-6 mediated activation of Signal Transducer and Activator of Transcription-3 (Stat3) can reduce these pathologies both in vitro and in vivo. Evidence suggests that flavonoids, a polyphenolic class of naturally occurring plant secondary metabolites, are potent anti-inflammatory agents that can attenuate the expression of cytokines such as IL-6, possibly through the modulation of tyrosine kinase activity. They have been shown to have significant therapeutic potential in disorders hallmarked by increased inflammation or disruptions in immune regulation, such as neurodegenerative disorders and certain cancers. Members such as diosmin have also been shown to be safe during pregnancy, and are currently utilized in the treatment of certain vascular disorders associated with pregnancy. In vitro work undertaken in this study showed that co-administration of luteolin with IL-6 in neural stem cells (NSC) was able to attenuate pathological outcomes induced by IL-6 including aberrant proliferation, over expression of astroglial marker, glial fibrillary acidic protein (GFAP) and changes in cellular morphology. In vivo studies involving luteolin and diosmin further confirmed the therapeutic efficacy of these compounds as similar attenuation of IL-6 mediated maternal and fetal pro-inflammatory cytokine expression and abnormal behaviors in prenatally exposed offspring was observed. Mechanistically, these effects were mediated through inhibition of Stat3 activation although other pathways activated by IL-6 were modulated by flavone co-treatment. Flavonoid treatment during periods of prenatal infection may prove to be a therapeutic intervention for the resultant pathological outcomes seen in offspring through attenuation of the maternal and fetal immune response to infection as well as modulation of signaling pathways in the fetal brain. These compounds may prove therapeutically efficacious for the application in perinatal conditions hallmarked by increased inflammation during pregnancy.

Ces travaux portent principalement sur l’étude de trois plantes tinctoriales : la garance, le nerprun et la gaude. Ces végétaux ont fait l’objet de nombreuses cultures en Provence et constituaient la principale matière première en colorants rouges et jaunes pour les teinturiers et les artistes. Une optimisation des conditions d’extraction des colorants de la garance assistée par ultrasons a été effectuée en utilisant un modèle statistique. Ce procédé d’extraction simple, rapide et efficace, a été comparé à deux autres techniques utilisées conventionnellement. Une étude cytohistologique des racines de garance a permis d’examiner les effets apportés par les différents procédés d’extraction. Les cellules traduisent après extraction par ultrasons, de profondes déstructurations fournissant une explication au plus important rendement en colorant extraits en comparaison aux extractions classiques. Une étude fondamentale sur l’identification des colorants extraits à partir des fruits immatures d’espèces appartenant au genre Rhamnus a été effectuée. Une approche chromatographique utilisant la CLHP/UVVisible/ SM a permis d’identifier la partie flavonol. Elle présente principalement des composés glycosylés dont la partie rhamninoside est liée sur le flavonol en position 3 ou 4'. Des flavonols 3-O-acétyl-rhamninoside ont également été caractérisés et sont spécifiques de Rh. saxatilis. Les fruits matures renferment aussi des anthraquinones qui ont été séparées des flavonols et concentrées en utilisant l’Extraction sur Phase Solide (SPE). Après analyse par RMN, des dérivés rhamnoside et arabinoside acétylés de l’émodine, jamais décrits dans la littérature, ont été identifiés dont le 6-O-(3',4' diacétyl)-arabinopyranoside d’émodine et 6-O-(2',3',4'-triacétyl)- arabinopyranoside d’émodine présents seulement dans Rh. alaternus. Les colorants jaunes de la gaude (Reseda luteola) ont été analysés par électrophorèse capillaire. En comparaison avec la CLHP, un gain important de la durée d’analyse a été observé tout en conservant une séparation convenable. L’ensemble de ces résultats expérimentaux a pu être appliqué avec succès à l’étude de colorants extraits à partir d’objets et d’échantillons historiques provenant de collections muséales et comprenant notamment des indiennes du XIXème siècle. Enfin, des essais de teintures ont été réalisés, en collaboration avec la société Les Olivades dans le but de développer une gamme de tissus à base de colorants naturels
This work concerns the study of three tinctorial plants: madder, buckthorn and weld. These plant species produced many cultures in Provence and represented the principal raw material in red and yellow dyes for dyers and artists. An optimisation of extraction conditions for madder dyes, using ultrasounds, was carried out with a statistical model. This easy, fast and effective extraction process was compared with two other conventional techniques. A cytohistological study on madder roots permits to examine effects produced by the different extraction processes. Cells reveal, after ultrasonic extraction, profound structural alterations, explaining the high yield in extracted dyes in comparison with classical methods. A fundamental study on the dyes identification extracted from Rhamnus species green fruits was carried out. A chromatographic approach using HPLC-UV-MS permits to identify the flavonol fraction. It is mainly composed of glycosiled compounds where the rhamninosid part is linked in position 3 or 4’ on the flavonol nucleus. 3-O-acetyl-rhamninosid derivatives were also characterised and they are specific to Rh. saxatilis species. Ripe fruits contained anthraquinonic compounds that were separated from flavonols and concentrated using Solid Phase Extraction (SPE). After NMR analyse, acetyl rhamnosid and arabinosid derivatives of émodine, never described in the specialised literature, were identified as emodin-6-O-(3',4'-diacetyl)-arabinopyranosid and emodin-6-O-(2',3',4' triacetyl)-arabinopyranosid were only present in Rh. alaternus. Yellow dyes of weld (Reseda luteola) were analysed by capillary electrophoresis. In comparison with HPLC, a reduced run time was observed while preserving a suitable separation. These experimental results were successfully applied to the study of ancient samples belonging from museums and including “indiennes” of the XIXth century. Finally, dying tests were carried out, in collaboration with Les Olivades society, in the aim to develop textiles containing natural dyes

Ces travaux portent principalement sur l'étude de trois plantes tinctoriales : la garance, le nerprun et la gaude. Ces végétaux ont fait l'objet de nombreuses cultures en Provence et constituaient la principale matière première en colorants rouges et jaunes pour les teinturiers et les artistes. Une optimisation des conditions d'extraction des colorants de la garance assistée par ultrasons a été effectuée en utilisant un modèle statistique. Ce procédé d'extraction simple, rapide et efficace, a été comparé à deux autres techniques utilisées conventionnellement. Une étude cytohistologique des racines de garance a permis d'examiner les effets apportés par les différents procédés d'extraction. Les cellules traduisent après extraction par ultrasons, de profondes déstructurations fournissant une explication au plus important rendement en colorant extraits en comparaison aux extractions classiques. Une étude fondamentale sur l'identification des colorants extraits à partir des fruits immatures d'espèces appartenant au genre Rhamnus a été effectuée. Une approche chromatographique utilisant la CLHP/UVVisible/ SM a permis d'identifier la partie flavonol. Elle présente principalement des composés glycosylés dont la partie rhamninoside est liée sur le flavonol en position 3 ou 4'. Des flavonols 3-O-acétyl-rhamninoside ont également été caractérisés et sont spécifiques de Rh. saxatilis. Les fruits matures renferment aussi des anthraquinones qui ont été séparées des flavonols et concentrées en utilisant l'Extraction sur Phase Solide (SPE). Après analyse par RMN, des dérivés rhamnoside et arabinoside acétylés de l'émodine, jamais décrits dans la littérature, ont été identifiés dont le 6-O-(3',4' diacétyl)-arabinopyranoside d'émodine et 6-O-(2',3',4'-triacétyl)- arabinopyranoside d'émodine présents seulement dans Rh. alaternus. Les colorants jaunes de la gaude (Reseda luteola) ont été analysés par électrophorèse capillaire. En comparaison avec la CLHP, un gain important de la durée d'analyse a été observé tout en conservant une séparation convenable. L'ensemble de ces résultats expérimentaux a pu être appliqué avec succès à l'étude de colorants extraits à partir d'objets et d'échantillons historiques provenant de collections muséales et comprenant notamment des indiennes du XIXème siècle. Enfin, des essais de teintures ont été réalisés, en collaboration avec la société Les Olivades dans le but de développer une gamme de tissus à base de colorants naturels

The present work was mainly addressed to provide an extensive phenotypic investigation of the luteolin effects on the phenotypes of E. meliloti to get an interpretative framework in modeling luteolin-induced metabolic switches. In the context of the luteolin-responsive phenotypes, the changes dependent or independent from the NodD regulation (i.e the major luteolin sensor) were elucidated using a deletion nodD mutant of E. meliloti and the possible contribution of other luteolin mediators, beyond NodD, was then investigated.

Dissertação de mestrado em Química Farmacêutica Industrial, apresentada à Faculdade de Farmácia da Universidade de Coimbra.
A eficácia terapêutica de activos farmacêuticos, APIs, para administração oral, a estabilidade físico-química, a processabilidade, são, com frequência, condicionadas pelas características estruturais da forma sólida. A investigação de ocorrência de polimorfos e, recentemente, a pesquisa de co-cristais são de elevada relevância para o avanço da ciência e em pré-formulação farmacêutica. O trabalho desenvolvido nesta tese incide sobre um flavonóide, a luteolina. Trata-se um composto de origem natural, de uma família que tem vindo a ganhar destaque pelas suas potencais aplicações farmacológicas. Foi efectuada a pesquisa de polimorfos/solvatos por cristalização em solução e a investigação de formação de co-cristais com co-formadores que têm capacidade de formar diferentes sintões supramoleculares com a luteolina. Para a análise dos sólidos obtidos recorreu-se a espectroscopia de infravermelho, a vários métodos de análise térmica, calorimetria diferencial de varrimento, termogravimetria e termomicroscopia, e ainda a difracção de raios-X de pó. O estudo preliminar dos sólidos obtidos por cristalização em solventes permitiu identificar quatro novas formas sólidas, duas das quais se propõe serem solvatos. Foi identificado e caracterizado um outro polimorfo de luteolina, forma 2, obtido por aquecimento do hemi-hidrato comercial e dos sólidos obtidos por cristalização em solução. Obtiveram-se novas entidades cristalinas, co-cristais (1:1) com os co-formadores isonicotinamida, teofilina e cafeína, utilizando métodos de síntese com recurso a quantidades diminutas de solvente ou memso na ausência deste. Com os dois anti-inflamatórios nãoesteróides estudados, ácidos carboxílicos, e com a pirazinamida não ocorreu formação de novas estruturas cristalinas, nas condições utilizadas. Palavras-chave:
The therapeutic efficacy of active pharmaceutical ingredients, APIs, for oral administration, their physicochemical stability and processability are often constrained by the structural characteristics of the solid form. The investigation of polymorphs and, recently, the research of co-crystals are of high relevance to science and also in the context of applications in pharmaceutical pre-formulation. The work presented in this thesis focuses on a flavonoid, luteolin. It is a compound of natural origin, from a family that has been gaining prominence for its potencial pharmacological applications. In this work, research on polymorphs/solvates of luteolin by crystallization from solution, and on co-crystal formation with co-formers which are able of giving rise to different supramolecular heterosynthons, was performed. The solids obtained were analysed by infrared spectroscopy, thermal analysis methods, differential scanning calorimetry, thermogravimetry and thermomicroscopy, and also by X-ray powder diffraction. The preliminary study of the solids obtained by crystallization from solvents allowed the identification of four new solid forms, two of which are proposed to be solvates. Another luteolin polymorph, Form 2, was identified and characterized. It is obtained by heating the commercial hemihydrate or the solid formss obtained by crystallization from solution. Novel crystal entities, (1:1) co-crystals, were obtained with the co-formers, isonicotinamide, theophylline and caffeine. In the methods used for their synthesis only small quantities of solvent were used or no solvent at all. With both anti-inflammatory nonsteroidal drugs used, carboxylic acids, and with pyrazinamide there was no formation of new crystalline structures, in the experimental conditions used.

No
Potential protective effects of the flavonoids quercetin and luteolin have been examined against the oxidative stress of MC3T3-E1 osteoblast-like cells. Although hydrogen peroxide and menadione reduced cell viability, the toxicity was prevented by desferrioxamine or catalase but not superoxide dismutase, suggesting the involvement of hydrogen peroxide in both cases. Quercetin and luteolin reduced the oxidative damage, especially that caused by hydrogen peroxide. When cultures were pre-incubated with quercetin or luteolin, protection was reduced or lost. Protection was also reduced when a 24 h pre-incubation with the flavonoids was followed by exposure to menadione alone. Pretreating cultures with luteolin impaired protection by quercetin, whereas quercetin pretreatment did not affect protection by luteolin. It is concluded that quercetin and luteolin suppress oxidative damage to MC3T3-E1 cells, especially caused by peroxide. The reduction in protection by pretreatment implies a down-regulation of part of the toxic transduction pathway.

The different infections caused by protozoan parasites, such as malaria, leishmaniasis, toxoplasmosis, balantidiasis, trichomoniasis, giardiasis, Chagas disease, amoebic dysentery, are responsible for considerable morbidity and mortality worldwide with desolating social and economic consequences. These protozoan diseases occur all over the world. For the treatment of these diseases, there is a lack of effective, safe, and affordable therapies. Due to the lack of vaccines in most instances and the development of resistant strains to the available synthetic therapeutics, it is important to search for alternative sources of anti-parasitic drugs. Since ancient times, natural products have been used as sources of potential drugs to cure diseases. It has been reported that 80% of drug molecules are natural products. The diversity of natural products can vary, i.e., it may be found in plants, fungi, algae and marine organisms. The plant-based natural products (secondary metabolites), i.e., alkaloids, phenolics, terpenes, and lipids, are potent anti-protozoal molecules. The natural products (secondary metabolites) obtained from microbial origin showed promising anti-protozoal activity. These bio-active molecules 2-(hept-1-enyl)-3-(hydroxymethyl)- 5-(3-methyl but-2-enyl)benzene-- ,4-diol, flavoglaucin, tetrahydroauroglaucin, auroglaucin, 2-(20,3-epoxy-10- 30-heptadienyl)-6-hydroxy-5-(3-methyl-2-butenyl)benzaldehyde, obtained from the fungus Eurotium repens, showed anti-malarial activities even chloroquine-sensitive and chloroquine-resistant strains of Plasmodium falciparum. Some of the flavonoid compounds, i.e., eupatilin, jaceosidin and nepetin, isolated from the plant Eupatorium arnottianum, showed the highest activity against Chagas disease. The three most important flavonoids, namely kaempferol, (–)-epicatechin and tiliroside showed promising activity against Entamoeba histolytica. The isoquinoline alkaloid berberine is found in several medicinal plants. Berberine salts have profound inhibitory activity against Giardia trophozoites. Two flavonoids, i.e., luteolin and quercetin, isolated from Vitex negunsdo and Fagopyrum esculentum, showed anti-leishmanial activity. An aclerodane diterpene isolated from an ethanolic extract of Polyalthia longifolia displayed anti-leishmanial activity against Leishmania donovani. A novel triterpene Astrakurkurone isolated from the wild edible mushroom, Astraeus hygrometricus, has a definitive effect on promastigote and amastigote form both in vitro and in vivo against L. donovani. Natural products have displayed promising activity against different protozoan infections, but most of these studies on natural products have been performed in vitro only. The transitions from in vitro study to in vivo trials and also the clinical trials of the new compounds are urgently required to prove their efficacy and safety.

Os análogos de flavonas são compostos naturais da classe dos flavonoides que apresentam ampla gama de atividades biológicas. O presente estudo objetivou predizer com auxílio de metodologias in silico a biodisponibilidade oral e análises farmacocinéticas e toxicológicas para três análogos de flavonas (apigenina, crisina e luteolina). O estudo revelou que os análogos apresentam boa disponibilidade oral, parâmetros farmacocinéticos e toxicológicos favoráveis. O Screening Virtual realizado para predição da biodisponibilidade oral revelou que todos os análogos não violaram a Regra de Lipinski. O estudo farmacocinético in silico revelou que todos os análogos possuem elevada absorção intestinal, não atravessam a barreira hematoencefálica, são permeáveis pelas células Caco-2 e não inibem a glicoproteína P. O estudo ADME in silico mostrou que todos os análogos inibem as enzimas do complexo citocromo P450 (CYP4501A2, CYP4502C9, CYP4502C19, CYP4503A4) e que apenas a enzima CYP4502D6 não sofre inibição. O estudo Toxicológico in silico indicou que os análogos não apresentam toxicidade pelo Teste de AMES e não são carcinogênicos. A apigenina e a crisina apresentam baixa toxicidade, enquanto a luteolina possui toxicidade moderada.

Luffa cylindrica, popularly known as sponge gourd is a tropic and sub-tropical fibrous plant with fruits containing black seeds. The fruit is consumed by humans as a vegetable in many parts of Asia, while different parts of the plant are used for cosmetics and as medicine in many parts of the globe. The plant has been used in the treatment of many ailments including nose cancer, snake venom, wound healing, edema, enterobiasis, filaria, whooping cough, stomach upset, stomach pain and malaria. Many health-promoting compounds such as flavonoids (apigenin-7- glucuronide luteolin-7-O-β-D-glucuronide methyl ester, -O-feruloyl-β-D-glucose, luteolin-7-O-β-D-glucuronide methyl ester), phenolics acids (p-Coumaric, gallic, caffeic, chlorogenic), triterpenoids (oleanolic acid and echinocystic acid), saponins (Lucyoside A-M), tannins (catechin), ribosome-inactivating proteins (α- luffin), carotenoids (9 -cis neoxanthin, all-trans-lutein, all-trans-β-carotene), chlorophylls (chlorophyll a and b, pheophytin), cucurbitacin B and gypsogenin have been detected or isolated from different parts of the plants. Extracts of the plant and isolated compounds have wide spectrum pharmacological activities and have been shown to possess antiemetic, antidiabetic, antiviral, wound healing, anticancer, antipyretic, anti-inflammatory, antifungal, anti-bacteria, anthelmintic, hypoglycemic and antihyperglycemic, anti-inflammatory, antioxidant activity, and hepato-protective effects in animal models. However, further information is needed on its safety and mechanisms of action. The present article is an updated review of the ethnobotanical uses, pharmacological actions, phytochemistry, safety, and future application of Luffa cylindrica in translational medicine.

Plants, especially herbs and spices, have always been the major sources of numerous natural compounds with antioxidant activity and other beneficial properties and, specifically, Rosemary (Rosmarinus officinalis L.) has been widely accepted as one of the spices with highest antioxidant activities which appear to be related to their richness of phenolic compounds. This study was undertaken with the aim to estimate the total phenolic content, identify and quantify the polyphenolic compounds of the methanolic extracts from post-distilled rosemary, collected from two different bioclimatic areas from Tunisia. Total phenolic content (TPC) was determined by Folin–Ciocalteu method. Identification and quantification of polyphenolic compounds was performed using high-performance liquid chromatography (HPLC) analysis. TPC ranged from 85.8 to 137.3 mg GAE/g DE in rosemary extracts. HPLC analysis showed the presence of carnosic acid and carnosol, wich were found to be the most abundant compounds in all analyzed extracts (46.3 to 76.4 and 22.4 to 43.5 mg/g of plant dry weight respectively), rosmarinic acid and caffeic acid as phenolic acids, besides some flavonoids such as apigenin, luteolin, genkwanin and hesperidin. This study revealed that rosemary post-distilled residues were shown to be promising with regard to their incorporation into various foods, cosmetics and fragrances.Therefore, supplementing a balanced diet with herbs may have beneficial health effects.

Plants are prone to encounter some environmental stresses that include both biotic and abiotic. Plants in response to these stress conditions alter their metabolism at the genetic level with consequential effects at the metabolite production. Phenolic compounds, which are secondary metabolites are one such chemical entity which plays a significant role in various physiological processes of the plant. They are mainly formed by three different types of metabolic pathways that produce phenyl propanoid derivatives, flavonoids, terpenoids based on the needs of the plant and the rate of their production is solely dictated by the type of stress condition. A number of phenolic compounds like phytoalexins, phytoanticipins and nematicides exhibit negative response to biotic stress against several soil borne pathogens and nematodes. But some of the phenolic compounds like acetosyringone, umbelliferone, vanillyl alcohol, p-hydroxybenzoic acid, 3,4-dihydroxybenzoic acid, apigenin and luteolin are found to exhibit beneficial effects to plants by encouraging rhizosphere formation particularly in Leguminosae family. Some of the ROS produced in various stress conditions are effectively dealt by various phenolics with antioxidant activity like hydroxyl benzoic acids and hydroxyl cinnamic acids. As the in vivo production of phenolics in plants is influenced by external factors it can certainly provide information for the adoption of agronomic practices to yield the full befits of commercial exploitation. As the in vivo production of phenolics in plants is influenced by external factors it can certainly provide information for the adoption of agronomic practices to yield the full befits of commercial exploitation.

A team of scientists from the Department of Food Technology from Plant Raw Materials conducts a set of studies aimed at finding ways to extract phytochemical compounds to create functional food systems. Laboratory methods have been developed for the extraction of watersoluble and fat-soluble biologically active substances from plant raw materials (tocopherols, carotenoids and phospholipids). Supercritical liquid extraction was chosen as the most suitable method to replace organic solvent extraction protocols. In order to develop laboratory methods for extracting flavonoids, as well as methods adapted to industrial conditions, the following vegetable raw materials were chosen: as a source of apigenin - parsley, luteolin and genistein - lupin, isoramnetin - sea buckthorn berries, cyanidine and petunidine - chokeberry, flavons, flavanones, flavanonols - root dandelion.