Antiviral properties of isoborneol, a potent inhibitor of herpes simplex virus type 1

Isoborneol, a monoterpene and a component of several plant essential oils, showed dual viricidal activity against herpes simplex virus 1 (HSV-1). Firs t, it inactivated HSV-1 by almost 4 log(10) values within 30 min of exposur e, and second, isoborneol at a concentration of 0.06% completely inhibited viral replication, without affecting viral adsorption. Isoborneol did not e xhibit significant cytotoxicity at concentrations ranging between 0.016% an d 0.08% when tested against human and monkey cell lines. Isoborneol specifi cally inhibited glycosylation of viral polypeptides based on the following data: (1) the mature fully glycosylated forms of two viral glycoproteins gB and go were not detected when the virus was replicated in the presence of isoborneol, (2) no major changes were observed in the glycosylation pattern of cellular polypeptides between untreated and isoborneol treated Vero cel ls, (3) isoborneol did not affect the glycosylation of gB produced from a c opy of the gB gene resident in the cellular genome, and (4) other monoterpe nes such as 1,8-cineole and borneol, a stereoisomer of isoborneol, did not inhibit HSV-I glycosylation. (C) 1999 Elsevier Science B.V. All rights rese rved.