Mechanism of action of the suppression of herpes simplex virus type 2 replication by pterocarnin A.

The purpose of this study was to investigate the in vitro antiviral properties of pterocarnin A, extracted from the bark of Pterocarya stenoptera (Juylandaceae). Results showed that pterocarnin A exhibited anti-herpes simplex virus (HSV) activity. It had a low selectivity index (SI) value and only possessed some level of cell cytotoxic effect at high antiviral concentrations. Mechanism studies demonstrated that pterocarnin A inhibited herpes simplex virus type 2 (HSV-2) from attaching and penetrating into cells. It also actively suppressed HSV-2 multiplication in Vero cells even when added 12 h after infection. This observation indicated that pterocarnin A affected the late stage(s) of HSV-2 infection cycle. Pterocarnin A also significantly reduced viral infectivity at high concentrations. From these observations, it was concluded that pterocarnin A suppressed both early and late in the replication cycle of HSV-2. The various modes of action of pterocarnin A in interfering with certain steps of viral infection thus merit further investigation.