Antiviral Triterpenes from Prunella vulgaris

Two triterpenes 1 and 2 with antiviral activity against Herpes simplex virus type 1 in vitro were isolated from Prunella vulgaris. Each compound caused a significant reduction in viral cytopathic effect when vero cells were exposed to them for 72 hours after viral challenge. They were identified as betulinic acid (1) and $2\alpha, 3\alpha$-dihydroxyurs-12-en-28-oic acid(2) on the basis of their spectroscopic properties. The antiviral activity of them was estimated as $EC_{50}=30\;\mu$g/ml(1) and $8\;\mu$g/ml(2), respectively by plaque reduction assay.