Flavonoid glycosides from the fruits of Embelia ribes and their anti-oxidant and α-glucosidase inhibitory activities

Three new flavonoid glycosides, embeliaflavosides A-C (1–3), together with eight known flavonoid glycosides (4–11), were isolated from the fruits of Embelia ribes. Their structures were established based on the analyses of spectroscopic data. Compounds 1–11 were evaluated for antioxidant and α-glucosidase inhibitory activities. The results revealed that compounds 1–11 owned significant ABTS radical scavenging activity with IC50 values of 2.52–9.78 µM, and DPPH scavenging activity with IC50 values of 7.56–26.47 µM, respectively. However, α-glucosidase inhibition assay indicated that all the isolates were inactive.