Breeding Buckwheat for Increased Levels of Rutin, Quercetin and Other Bioactive Compounds with Potential Antiviral Effects

Common buckwheat (Fagopyrum esculentum Moench) and Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) are sources of many bioactive compounds, such as rutin, quercetin, emodin, fagopyrin and other (poly)phenolics. In damaged or milled grain under wet conditions, most of the rutin in common and Tartary buckwheat is degraded to quercetin by rutin-degrading enzymes (e.g., rutinosidase). From Tartary buckwheat varieties with low rutinosidase activity it is possible to prepare foods with high levels of rutin, with the preserved initial levels in the grain. The quercetin from rutin degradation in Tartary buckwheat grain is responsible in part for inhibition of α-glucosidase in the intestine, which helps to maintain normal glucose levels in the blood. Rutin and emodin have the potential for antiviral effects. Grain embryos are rich in rutin, so breeding buckwheat with the aim of producing larger embryos may be a promising strategy to increase the levels of rutin in common and Tartary buckwheat grain, and hence to improve its nutritional value.

Irreversible UV-induced quercetin and rutin degradation in solution, studied by UV-spectrophotometry and HPLC chromatography

Irreversible degradation of quercetin and rutin, dissolved in methanol and water, induced by continuous UV-irradiation from two different sub-ranges (UV-B and UV-C) has been studied in this work. The degradation of both flavonoids is related to formation of UV-induced degradation products: both processes follow first-order kinetics. The degradation and products formation rate constants are both dependent on the involved UV-photons energy input in both solvents.

Isolation and identification of rumen bacteria capable of anaerobic rutin degradation

Fifteen strains of bacteria capable of degrading rutin anaerobically were isolated from bovine rumen contents and identified by morphological and biochemical evidence as strains of Butyrivibrio sp. Three cultures from a laboratory collection of 53 strains of rumen bacteria also used rutin anaerobically. Two, Butyrivibrio fibrisolvens D1 and Selenomonas ruminantium GA192, cleaved the glycosidic bond of rutin and fermented the sugar but did not degrade the insoluble aglycone produced; the third strain, Peptostreptococcus sp. B178, degraded the substrate to soluble products. Butyrivibrio sp. C3 degraded rutin, quercitrin, and naringin to water-soluble products, showing that the organism cleaved the heterocyclic ring of these compounds. Butyrivibrio sp. C3 fermented the sugar moiety of hesperidin but did not cleave the heterocyclic ring. It did not attack quercetin, taxifolin, protocatechuic acid, or phloroglucinol. In a medium containing rumen fluid, Butyrivibrio sp. C3 degraded rutin more than twice as fast as it did in a medium containing enzymatic casein hydrolyzate, volatile fatty acids, yeast extract, and hemin in place of rumen fluid.The observations reported in this paper are believed to represent the first recorded demonstration of degradation of the heterocyclic ring structure of rutin and other bioflavonoids in pure cultures of anaerobic bacteria.