Xanthones as inhibitors of Epstein-Barr virus activation

To search for possible antitumor promoters, we carried out a primary screen ing of 20 xanthones isolated from plants of the Guttiferae family, using th eir possible inhibitory effects on Epstein-Barr virus early antigen (EBV-EA ) activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells. Some of these xanthones, namely 1,3,7-trihydroxy-2-(3-methyl-2-buten yl)xanthone (8), dulxanthone-B (10) and latisxanthone-C (15), were observed to significantly inhibit the EBV-EA activation. The investigation indicate d that 8, 10 and 15 might be valuable antitumor promoters. (C) 1998 Elsevie r Science Ireland Ltd. All rights reserved.