Flavonoids from Chiococca braquiata (Rubiaceae)

A new flavonol 4′-methoxykaempferol-7-(acetyloxy)-3,5-O-α-L- rhamnoside (1), was isolated from the leaves of Chiococca braquiata, along with three known flavonoids apigenin, 7-O-methoxyquercetrin and quercetrin and four triterpenes α-amirin, β-amirin, ursolic and oleanolic acids . Their structures were established on the basis of spectroscopic methods.

New biflavonoid and other flavonoids from the leaves of Chimarrhis turbinata and their antioxidant activities

A new biflavonol, named chimarrhoside (1), and eight known flavonol glycosides (2-9), were isolated from the leaves of Chimarrhis turbinata. Their structures were established on the basis of 1D and 2D NMR experiments as quercetin-3-O-rutinoside (2), kaempferol-3-O-rutinoside (3), kaempferol-3-O-α-L-rhamnopyranosyl-(1→6)-β-D-galactopyranoside (4), quercetin-3-O-α-L-rhamnopyranosyl-(1→6)-β-D- galactopyranoside (5), 6-hydroxy-rutin (6), kaempferol-3-O-D-galactopyranoside (7), kaempferol-3-O-D-glucopyranoside (8) and kaempferol-3-O-α- Lrhamnopyranosyl-(1→6)-α-L-rhamnopyranosyl-(1→4) -β-D-glucopyranoside (9). In addition, catechin (10) and catechin-(4α→8)-catechin-procyanidin B-3) (11) were isolated. The crude extract, fractions and isolated compounds were evaluated for their antioxidative properties using an autographic assay based on β-carotene bleaching on TLC plates, and spectrophotometric detection by reduction of the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical. Flavonoids 2, 5, 6, 10 and 11 displayed strong free radical scavenging activity, when compared with the standards BHT and rutin. ©2005 Sociedade Brasileira de Química.

Flavonoids with gastroprotective activity

Peptic ulcers are a common disorder of the entire gastrointestinal tract that occurs mainly in the stomach and the proximal duodenum. This disease is multifactorial and its treatment faces great difficulties due to the limited effectiveness and severe side effects of the currently available drugs. The use of natural products for the prevention and treatment of different pathologies is continuously expanding throughout the world. This is particularly true with regards to flavonoids, which represent a highly diverse class of secondary metabolites with potentially beneficial human health effects that is widely distributed in the plant kingdom and currently consumed in large amounts in the diet. They display several pharmacological properties in the gastroprotective area, acting as anti-secretory, cytoprotective and antioxidant agents. Besides their action as gastroprotectives, flavonoids also act in healing of gastric ulcers and additionally these polyphenolic compounds can be new alternatives for suppression or modulation of peptic ulcers associated with H. pylori. In this review, we have summarized the literature on ninety-five flavonoids with varying degrees of antiulcerogenic activity, confirming that flavonoids have a therapeutic potential for the more effective treatment of peptic ulcers.

Isolated flavonoids against mammary tumour cells LM2

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Characterization of flavonoids and naphthopyranones in methanol extracts of Paepalanthus chiquitensis herzog by HPLC-ESI-IT-MSn and their mutagenic activity

A HPLC-ESI-IT-MSn method, based on high-performance liquid chromatography coupled to electrospray negative ionization multistage ion trap mass spectrometry, was developed for rapid identification of 24 flavonoid and naphthopyranone compounds. The methanol extracts of the capitulae and scapes of P. chiquitensis exhibited mutagenic activity in the Salmonella/microsome assay, against strain TA97a. © 2013 by the authors.

Characterization of flavonoids and phenolic acids in Myrcia bella cambess. Using FIA-ESI-IT-MSn and HPLC-PAD-ESI-IT-MS combined with NMR

The leaves of Myrcia DC. ex Guill species are used in traditional medicine and are also exploited commercially as herbal drugs for the treatment of diabetes mellitus. The present work aimed to assess the qualitative and quantitative profiles of M. bella hydroalcoholic extract, due to these uses, since the existing legislation in Brazil determines that a standard method must be developed in order to be used for quality control of raw plant materials. The current study identified eleven known flavonoid-O-glycosides and six acylated flavonoid derivatives of myricetin and quercetin, together with two kaempferol glycosides and phenolic acids such as caffeic acid, ethil galate, gallic acid and quinic acid. In total, 24 constituents were characterized, by means of extensive preparative chromatographic analyses, along with MS and NMR techniques. An HPLC-PAD-ESI-ITMS and FIA-ESI-IT-MSn method were developed for rapid identification of acylated flavonoids, flavonoid-O- glycosides derivatives of myricetin and quercetin and phenolic acids in the hydroalcoholic M. bella leaves extract. The FIA-ESI-IT-MS techinique is a powerful tool for direct and rapid identification of the constituents after isolation and NMR characterization. Thus, it could be used as an initial method for identification of authentic samples concerning quality control of Myrcia spp extracts. © 2013 by the authors.

Evaluation of Estrogenic Potential of Flavonoids Using a Recombinant Yeast Strain and MCF7/BUS Cell Proliferation Assay

Phytoestrogens are of interest because of their reported beneficial effects on many human maladies including cancer, neurodegeneration, cardiovascular disease and diabetes. Furthermore, there is a search for compounds with estrogenic activity that can replace estrogen in hormone replacement therapy during menopause, without the undesirable effects of estrogen, such as the elevation of breast cancer occurrence. Thus, the principal objective of this study was to assess the estrogenic activity of flavonoids with different hydroxylation patterns: quercetin, kaempferol, luteolin, fisetin, chrysin, galangin, flavone, 3-hydroxyflavone, 5-hydroxyflavone and 7-hydroxyflavone via two different in vitro assays, the recombinant yeast assay (RYA) and the MCF-7 proliferation assay (E-screen), since the most potent phytoestrogens are members of the flavonoid family. In these assays, kaempferol was the only compound that showed ERα-dependent transcriptional activation activity by RYA, showing 6.74±1.7 nM EEQ, besides acting as a full agonist for the stimulation of proliferation of MCF-7/BUS cells. The other compounds did not show detectable levels of interaction with ER under the conditions used in the RYA. However, in the E-screen assay, compounds such as galangin, luteolin and fisetin also stimulated the proliferation of MCF-7/BUS cells, acting as partial agonists. In the evaluation of antiestrogenicity, the compounds quercetin, chrysin and 3-hydroxyflavone significantly inhibited the cell proliferation induced by 17-β-estradiol in the E-screen assay, indicating that these compounds may act as estrogen receptor antagonists. Overall, it became clear in the assay results that the estrogenic activity of flavonoids was affected by small structural differences such as the number of hydroxyl groups, especially those on the B ring of the flavonoid. © 2013 Resende et al.

Antifungal activity of flavonoids from Heteropterys byrsonimifolia and a commercial source against Aspergillus ochraceus: In silico interactions of these compounds with a protein kinase

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Electrochemical investigations on the capacity of flavonoids to protect DNA against damage caused by textile disperse dyes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Differences in the hydroxylation pattern of flavonoids alter their chemoprotective effect against direct- and indirect-acting mutagens

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

HPLC-DAD based method for the quantification of flavonoids in the hydroethanolic extract of Tonina fluviatilis Aubl. (Eriocaulaceae) and their radical scavenging activity

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dimeric Flavonoids from Arrabidaea brachypoda and Assessment of Their Anti-Trypanosoma cruzi Activity

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ineraction Model Between HRSV G-Protein and Flavonoids

Background: Acute respiratory infections (ARI) are the leading cause of infant mortality in the world, and human respiratory syncytial virus (HRSV) is one of the main agents of ARI. One of the key targets of the adaptive host immune response is the RSV G-protein, which is responsible for attachment to the host cell. There is evidence that compounds such as flavonoids can inhibit viral infection in vitro. With this in mind, the main purpose of this study was to determine, using computational tools, the potential sites for interactions between G-protein and flavonoids. Results: Our study allowed the recognition of an hRSV G-protein model, as well as a model of the interaction with flavonoids. These models were composed, mainly, of -helix and random coil proteins. The docking process showed that molecular interactions are likely to occur. The flavonoid kaempferol-3-O-α-L-arabinopyranosil-(2 → 1)-α-L-apiofuranoside-7-O-α-L-rhamnopyranoside was selected as a candidate inhibitor. The main forces of the interaction were hydrophobic, hydrogen and electrostatic. Conclusions: The model of G-protein is consistent with literature expectations, since it was mostly composed of random coils (highly glycosylated sites) and -helices (lipid regions), which are common in transmembrane proteins. The docking analysis showed that flavonoids interact with G-protein in an important ectodomain region, addressing experimental studies to these sites. The determination of the G-protein structure is of great importance to elucidate the mechanism of viral infectivity, and the results obtained in this study will allow us to propose mechanisms of cellular recognition and to coordinate further experimental studies in order to discover effective inhibitors of attachment proteins.