plants Review Breeding Buckwheat for Increased Levels of Rutin, Quercetin and Other Bioactive Compounds with Potential Antiviral Effects Zlata Luthar 1, Mateja Germ 1, Matevž Likar 1 , Aleksandra Golob 1, Katarina Vogel-Mikuš 1,2, Paula Pongrac 1,2 , Anita Kušar 3 , Igor Pravst 3 and Ivan Kreft 3,* 1 Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia;
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[email protected] (P.P.) 2 Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia 3 Nutrition Institute, Tržaška 40, SI-1000 Ljubljana, Slovenia;
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[email protected]; Tel.: +386-1-3007981 Received: 9 October 2020; Accepted: 23 November 2020; Published: 24 November 2020 Abstract: 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.