Eupha-7,9(11),24-trien-3β-ol (“Antiquol C”) and Other Triterpenes from Euphorbia antiquorum Latex and Their Inhibitory Effects on Epstein−Barr Virus Activation

The structures of three triterpene alcohols isolated from the latex of Euphorbia antiquorum were established to be eupha-7,9(11),24-trien-3 beta -ol (2; antiquol C), 19(10 arrow right 9)abeo-8 alpha ,9 beta ,10 alpha -eupha-5,24-dien-3 beta -ol (3; antiquol B), and 24-methyltirucalla-8,24(24 super(1))-dien-3 beta -ol (4; euphorbol) on the basis of spectroscopic methods. Compounds 3 and 4 have previously been assigned the erroneous structures of 10 alpha -cucurbita-5,24-dien-3 alpha -ol and 24-methyleupha-8,24(24 super(1))-dien-3 beta -ol, respectively. Compounds 2-4 and four other known compounds isolated from the latex, euphol (1), lemmaphylla-7,21-dien-3 beta -ol (5), isohelianol (6), and camelliol C (7), showed potent inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA).