Flavones

Natural flavonoids are currently receiving much attention because of their estrogenic and antiestrogenic properties. Six isoflavones (isoprunetin, isoprunetin 7-O-β-d-glucopyranoside, isoprunetin 4′,7-di-O-β-d-glucopyranoside, genistein, genistein 7-O-β-d-glucopyranoside, daidzein), four flavones (luteolin, luteolin 7-O-β-d-glucopyranoside, luteolin 4′-O-β-d-glucopyranoside, licoflavone C), isolated from Genista morisii and G. ephedroides (two Leguminosae plants of the Mediterranean area) together with two structurally related pterocarpans, bitucarpin A and erybraedyn C, isolated from Bituminaria bituminosa (Leguminosae), were tested for the antagonist activity by a yeast based estrogen receptor assay (Saccharomyces cerevisiae RMY326 ER-ERE). Most compounds inhibited the estradiol-induced transcriptional activity in a concentration dependent manner. In particular, for the flavone luteolin 77% inhibition of the induced β-galactosidase activity was observed. Interestingly, licoflavone C exhibited a dose-dependent antagonistic activity at concentrations up to 10−4 m, but stimulated β-galactosidase expression at higher concentrations resulting in a U-shaped-like dose-response curve. Copyright © 2007 John Wiley & Sons, Ltd.

In this work, we illustrate the usefulness of cyclodextrins, namely, methyl-β-cyclodextrin (MβCD), an amorphous, methylated derivative of the natural β-cyclodextrin (βCD), as a tool to form an inclusion complex with omeprazole (OME), a poorly water soluble drug. Solid binary systems between OME and MβCD were prepared experimentally in a stoichiometry 1:1 by different techniques (physical mixing, kneading, spray-drying and freeze-drying).

Oxidative stress is tightly involved in various neurodegenerative diseases such as Parkinson's and Alzheimer's diseases, and conditions such as ischemia. Astrocytes, the most abundant glial cells in the brain, protect neurons from reactive oxygen species (ROS) and provide them with trophic support. Therefore, any damage to astrocytes will affect neuronal survival. In a previous study we have demonstrated that an extract prepared from the plant Achillea fragrantissima (Af) prevented the oxidative stress-induced death of astrocytes and attenuated the intracellular accumulation of ROS in astrocytes under oxidative stress. In the present study, using activity guided fractionation, we have purified from this plant the active compound, determined to be a flavonoid named 3,5,4'-trihydroxy-6,7,3'-trimethoxyflavone (TTF). The effects of TTF in any biological system have not been studied previously, and this is the first study to characterize the anti-oxidant and protective ef...

Background Due to the indiscriminate use of antimicrobial drugs, the emergence of human pathogenic microorganisms resistant to major classes of antibiotics has been increased and has caused many clinical problems in the treatment of infectious diseases. Thus, the aim of this study was to evaluate for the first time the in vitro antimicrobial activity and brine shrimp lethality of extracts and isolated compounds from Zeyheria tuberculosa (Vell.) Bur., a species used in Brazilian folk medicine for treatment of cancer and skin diseases. Methods Using the disc diffusion method, bioautography assay and brine shrimp toxicity test (Artemia salina Leach), we studied the antimicrobial activity and lethality of extracts and isolated compounds against three microorganisms strains, including Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacteria and yeasts (Candida albicans). Results In this study, the extracts inhibited S. aureus (8.0 ± 0.0 to 14.0 ± 0.0 mm) and C. albicans (15.3 ± 0.68 to 25.6 ± 0.4 mm) growth. In the brine shrimp test, only two of them showed toxic effects (LC50 29.55 to 398.05 μg/mL) and some extracts were non-toxic or showed weak lethality (LC50 705.02 to > 1000 μg/mL). From these extracts, four flavones [5,6,7,8-tetramethoxyflavone (1), 5,6,7-trimethoxyflavone (2), 4'-hydroxy-5,6,7,8-tetramethoxyflavone (3), and 4'-hydroxy-5,6,7-trimethoxyflavone (4)] were isolated through bioassay-guided fractionation and identified based on the 1D and 2D NMR spectral data. By bioautography assays, compounds 1 [S. aureus (16.0 ± 0.0 mm) and C. albicans (20.0 ± 0.0 mm)] and 3 [S. aureus (10.3 ± 0.6 mm) and C. albicans (19.7 ± 0.6 mm)] inhibited both microorganisms while 2 inhibited only S. aureus (11.7 ± 0.6 mm). Compound 4 did not restrain the growth of any tested microorganism. Conclusion Our results showed that extracts and isolated flavones from Z. tuberculosa may be particularly useful against two pathogenic microorganisms, S. aureus and C. albicans. These results may justify the popular use this species since some fractions tested had antimicrobial activity and others showed significant toxic effects on brine shrimps. However, in order to evaluate possible clinical application in therapy of infectious diseases, further studies about the safety and toxicity of isolated compounds are needed.

Two new flavanones, (2S)-5-hydroxy-7,4'-di-O-(gamma,gamma-dimethylallyl)flavanone (1) and 6-hydroxy-E-3-(2,5-dimethoxybenzylidine)-2',5'-dimethoxyflavanone (2), together with three known compounds, tephrowatsin C, afrormosin and kaempferol 3-O-beta-D-glucopyranoside were isolated from the roots of Tephrosia calophylla. The structures of 1 and 2 were established by extensive 2D NMR spectral studies.

A new methylated flavonol, 5,7,2 ′,4 ′-tetrahydroxy-3-methoxyflavone (1), had been isolated from the methanol extract of the wood of Morus australis, along with nine known compounds, kuwanon C (2), morusin (3), morachalcone A (4), oxyresveratrol (5), 4 ′-(2-methyl-2-buten- 4-yl)oxyresveratrol (6), moracins M (7) and C (8), alboctalol (9), and macrourin B (10). The structures of these compounds were determined based on spectral evidence, including UV, IR, NMR, and mass spectra. Cytotoxic properties of compounds 1 →10 were evaluated against murine leukemia P-388 cells. The prenylated stilbene 6 and 2-arylbenzofuran 8, and morusin (3) were found to have strong cytotoxic effects with IC50 values of 6.9, 8.7, and 10.1 μM, respectively.

Soy glycinin (SG) and soy trypsin inhibitor (STI) were derivatized by chlorogenic- and caffeic acid (cinnamic acids, C(6)-C(3) structure), and by gallic acid representing hydroxybenzoic acids (C(6)-C(1) structure). Further, the flavonoids, flavone, apigenin, kaempferol, quercetin and myricetin (C(6)-C(3)-C(6) structure) were also caused to react with soy proteins to estimate the influence of the number and the position of hydroxy substituents. The derivatization caused a reduction of lysine, cysteine and tryptophan residues in the soy proteins. The isoelectric points of the derivatives were shifted to lower pH values and formation of high molecular fractions was documented. The derivatives were characterized in terms of their solubility at different pH-values to document the influence on the functional properties. The structural changes induced were studied using circular dichroism (CD), differential scanning calorimetry (DSC), intrinsic fluorescence, and binding of anilinonaphthalenesulfonic acid. The influence of derivatization on the in-vitro digestibility with trypsin, chymotrypsin, pepsin and pancreatin was also assessed. The effect on the trypsin inhibitor activity of all the resulting STI derivatives was studied, the latter being reduced.