Abstract
The essential oils of Callistemon viminalis and Schinus molle leaves from plants grown in Egypt, obtained by hydrodistillation in a Clevenger type apparatus were investigated by GC/MS. The main components of C. viminalis oil were 1,8-cineole (65.92%), alpha-pinene (12.34%) while the results showed that the major components of S. molle oil were a-phellandrene (25.81%), elemol (11.02%). Both C. viminalis and S. molle oils exhibited strong DPPH scavenging activity, with IC50 values of 72.98 mu g/mL and 172.41 mu g/mL respectively. The antiviral assays were performed with herpes simplex virus type 1 (HSV-1) and using RC-37 cells as a host cell. TC50 (50% cytotoxic concentration) of C. viminalis oil (676.35 mu g/mL) demonstrated significantly lower toxicities towards the RC-37 cells than the S. molle oil (476.48 mu g/mL). IC50 (inhibitory concentration for 50% of plaques) for HSV-1 of C. viminalis and S. molle oils were 63.73 and 48.06 mu g/mL respectively, while SI (Selectivity index = TC50/IC50) of C. viminalis oil (10.61) was higher than S. molle oil (9.91). Both essential oils exhibited high anti-HSV-1 activity by direct interaction with free virus particles. To conclude, C. viminalis and S. molle oils could be a promising source of natural antioxidants, and antiviral agents.