Six stilbene derivatives isolated from Mulberry leaves including Kuwanon X, Mulberrofuran C, Mulberrofuran G, Moracin C, Moracin M 3'-O-b-glucopyranoside and Moracin M were found to have antiviral effects against herpes simplex virus type 1 and 2 (HSV-1 and HSV-2) at different potencies except for