Inhibitory Effects of Cucurbitane Glycosides and Other Triterpenoids from the Fruit of Momordica grosvenori on Epstein−Barr Virus Early Antigen Induced by Tumor Promoter 12-O-Tetradecanoylphorbol-13-acetate

Two new triterpene benzoates, 5-dehydrokarounidiol dibenzoate (1) and karounidiol dibenzoate (2), and two new triterpene glycosides, 5α,6α-epoxymogroside IE1 (8) and 11-oxomogroside A1 (9), along with 15 known triterpenoids (one triterpene benzoate, 3; three triterpene mono-ols, 4−6; one triterpene aglycon, 7; and 10 triterpene glycosides, 10−19), were isolated from the ethanol extract of the fruit of Momordica grosvenori. The structures of 1, 2, 8, and 9 were determined on the basis of spectroscopic and chemical methods. Among the known triterpene glycosides, mogroside I E1 (12) was a new naturally occurring compound. Eighteen triterpenoids (2−19) and 11-oxomogrol (20), a hydrolysis product of 9, were evaluated with respect to their inhibitory effects on the induction of Epstein−Barr virus early antigen (EBV-EA) by 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells, which is known to be a primary screening test for antitumor promoters. All of the compounds tested showed potent inhibitory effects on EBV-EA induction (70−100% inhibition at 1 × 103 mol ratio/TPA). Keywords: Momordica grosvenori; fruit; Cucurbitaceae; sweet principle; triterpenoids; cucurbitane glycosides; antitumor promoter; Epstein−Barr virus early antigen