Anti-herpes simplex virus type 2 activities of some Thai medicinal plants

Abstract

To explore for plants possessing anti-herpes simplex virus type 2 (anti-HSV-2) activity, 80 extracts prepared from 16 medicinal plants collected in Thailand were investigated in vitro using the plaque reduction assay including the inactivation, pre-treatment and post-treatment methods. It was found that 53 extracts from 15 plants contained high anti-HSV-2 activity with 50% inhibitory concentration (IC50) less than 20 µg/ml. In the evaluation of cytotoxicity, 19 fractions from 9 plants demonstrated a potent antiviral activity with selectivity index (SI) more than 10 and IC50 less than 20 µg/ml. An ethanol fraction of Barleria lupulina showed the highest SI (781.5) in the inactivation method. An aqueous-ethanol fraction of Nephelium lappaceum exhibited highly selective anti-herpetic activity in all the 3 assays. The results indicated that B. lupulina and N. lappaceum are potential candidates for the development of anti-HSV-2 drugs.