New triterpenoid saponins from cacti and anti-type I allergy activity of saponins from cactus.

The research in our laboratory focuses on the isolation of saponins from cactus. In this study, we report five new triterpenoid saponins, dumortierinoside A methyl ester (1), pachanoside I1 (2), pachanoside D1 (3), gummososide A (4), and gummososide A methyl ester (5). Compounds 1-3 isolated from Isolatocereus dumortieri Backbg., and compounds 4 and 5 were isolated from Stenocereus alamosensis A. C. Gibson & K. E. Horak. Compound 2 possessed a new pachanane-type triterpene skeleton, pachanol I, in its aglycon. The aglycon of 3 was pachanol D, while those of 4 and 5 were both gummosogenin, which we have previously reported, but this is the first report of pachanol D and gummosogenin in their aglycon forms. Additionally, we evaluated the anti-type I allergy activity of the saponins with RBL-2H3 (Rat basophilic leukemia) cells by measuring the β-hexosaminidase release inhibitory activity. As a result of these studies, gummososide A methyl ester (5) was found to show activity (IC(50)=99.5 μM) and thurberoside A exhibited mild activity (IC(50)=166.9 μM).