Anti-HSV activity of camptothecin analogues

In order to explore the range of biological activities of the camptothecin compound class, the in vitro antiviral efficacies of series I-IV of representative members from camptothecin analogues on herpes simplex virus type 2 (HSV-2) were evaluated on vero cells. Several compounds exhibited similar or better antiviral activity against HSV-2 in vitro than acyclovir. Among them, compound 6 showed the highest anti-HSV-2 activity, with IC(50) values of 1.3 microg mL(-1) and SI values of 27.04, respectively. On the basis of preliminary biological testing results, it is suggested that the intact E lactone ring and 20-hydroxy group should be not a prerequisite for camptothecin-like antiviral activity, and CPT substitution at the C-20 hydroxy group may be optimal for synthesising more potent antiviral compounds, suggesting that CPT has the potential to be a lead structure for semi-synthetic antiviral agents.