Isovitexin

Abstract: The inhibition of xanthine oxidase activity by various flavonoids was assessed. All of the tested flavonoids were competitive inhibitors, and from the kinetic analysis suggested that flavonoids bind to the reactive site. To further understand the stereochemistry between these flavonoids and xanthine oxidase, structure-based molecular modeling was performed. Apigenin was the most potent inhibitor which showed the most favorable interaction in the reactive site. The bicyclic benzopyranone ring of apigenin stacked with phenyl of Phe 914, and the phenolic group stretched to the space surrounding with several hydrophobic residues. Quercetin and myricetin composed a 3-hydroxyl group on benzopyranone which resulting in reduction of binding affinity. The phenolic group of genistein positioned in opposite orientation comparison with apigenin, and resulted in a weaker interaction with xanthine oxidase. Isovitexin showed the weakest inhibitory effect among the compounds tested. The bulky group of sugar in isovitexin may hamper its interaction with xanthine oxidase.

Abstract: Six flavonoids have been isolated and identified in buckwheat grain. These are rutin, orientin, vitexin, quercetin, isovitexin, and isoorientin. Rutin and isovitexin are the only flavonoid components of buckwheat seeds while hulls contain all six identified compounds. The total flavonoid concentration in the seeds was 18.8 and in the hulls 74 mg/100 g of dry matter. Dehulling the grain by using different temperature regimes resulted in drastic reductions of the total flavonoid concentration in the grain (by 75% of the control) and smaller but significant (15-20%) reduction in the hulls.

Abstract: The anti-glycation activity of four kinds of beans including mung bean, black bean, soybean and cowpea were evaluated. Aqueous alcohol extract of mung bean exhibited the strongest inhibitory activity against the formation of fluorescent advanced glycation endproducts (AGEs) in a bovine serum albumin (BSA)-glucose model, and the inhibitory activities of extracts of the four beans were found to be highly correlated with their total phenolic contents ( R 2 = 0.95). Subsequent HPLC analysis of mung bean extract revealed two major phenolics which were purified and identified as vitexin and isovitexin by spectral methods. In the anti-glycation assays, both vitexin and isovitexin showed significant inhibitory activities against the formation of AGEs induced by glucose or methylglyoxal with efficacies of over 85% at 100 μM. In another assay, vitexin and isovitexin failed to directly trap reactive carbonyl species, such as methylglyoxal, suggesting that their anti-glycation activities may mainly be due to their free radical scavenging capacity.

Abstract: Vitexin and isovitexin are active components of many traditional Chinese medicines, and were found in various medicinal plants. Vitexin (apigenin-8-C-glucoside) has recently received increased attention due to its wide range of pharmacological effects, including but not limited to anti-oxidant, anti-cancer, anti-inflammatory, anti-hyperalgesic, and neuroprotective effects. Isovitexin (apigenin-6-C-glucoside), an isomer of vitexin, generally purified together with vitexin, also exhibits diverse biological activities. Latest research has suggested that vitexin and isovitexin could be potential substitute medicines for diversity diseases, and may be adjuvants for stubborn diseases or health products. This review summarized recent findings on various pharmacological activities and associative signalling pathways of vitexin and isovitexin to provide a reference for future research and clinical applications.

Abstract: Ethanolic extracts of buckwheat (Fagopyrum esculentum Moench) hulls were separated by Sephadex LH-20 column chromatography into eight fractions. Five of the fractions exhibited peroxyl radical-scavenging activity by inhibiting the oxidation of methyl linoleate in solution. Two of the antioxidant fractions contained proanthocyanidins (condensed tannins) from the color reaction of these fractions with HCl under heat treatment. Five antioxidant compounds were isolated by preparative HPLC and identified as quercetin, hyperin, rutin, protocatechuic acid, and 3,4-dihydroxybenzaldehyde. The contents of these active compounds in the buckwheat hulls were as follows: protocatechuic acid (13.4 mg/100 g of dried hulls), 3,4-dihydroxybenzaldehyde (6.1 mg/100 g), hyperin (5.0 mg/100 g), rutin (4.3 mg/100 g), and quercetin (2.5 mg/100 g). Besides the isolation of these compounds, two major compounds that showed no peroxyl radical-scavenging activity in the extract were isolated and identified as vitexin and isovitexin.