Antiviral and antioxidant activity of flavonoids and proanthocyanidins from Crataegus sinaica

The antiviral and antioxidant activity of some fractions and of a series of flavonoids and proanthocyanidins obtained from Crataegus sinaica (Rosaceae) was evaluated. The O-glycosidic flavonoids and the oligomeric proanthocyanidins exhibited significant inhibitory activity against herpes simplex virus type 1 (HSV-1), which was shown to be due to an extracellular mechanism for procyanidin C-1. Procyanidin C-1 also had the highest antioxidant activity in both the microsomal lipid peroxidation and the hydroxyl radical scavenging assay. In addition to the previously reported phenolic compounds, the pentacyclic triterpenoid ursolic acid (1) and a tetrameric (2) and pentameric procyanidin (3) are reported for the first time.