Two New Flavonoid Glycosides from Viscum album ssp. album

Rheum ribes Linn (Polygonaceae) root is used traditionally to treat diabetes, hemorrhoids, ulcers, and diarrhea. Here, the hypoglycemic effect of R. ribes root extract in healthy mice was investigated. Fasted mice were given a single dose of 50?mg/kg of three extracts of different polarity from R. ribes by gastric feeding and the blood glucose was measured 0, 1, 2, 4, and 24?h later. The aqueous extract showed a significant hypoglycemic effect. In vitro, the aqueous extract stimulated insulin release from INS-1E cells at both stimulatory (20?mM) and non-stimulatory (1?mM) glucose concentrations, thus suggesting a mechanism for the in vivo effect. The hypoglycemic active fraction was found to contain anthraquinone glycosides of aloe emodin, emodin, physcion, and chrysophanol derivatives.