O. Nakamura et al., AGAPANTHUSSAPONINS A-D, NEW POTENT CAMP-PHOSPHODIESTERASE INHIBITORS FROM THE UNDERGROUND PARTS OF AGAPANTHUS-INAPERTUS, Chemical and Pharmaceutical Bulletin, 41(10), 1993, pp. 1784-1789
The saponin fraction prepared from the methanolic extract of the under
ground parts of Agapanthus inapertus was found to exhibit inhibitory a
ctivity on cAMP phosphodiesterase (55.2%) at a concentration of 100 mu
g/ml. From this fraction, four new steroidal saponins, designated as a
gapanthussaponin A (1), B (2), C (3) and D (4), were isolated as the a
ctive principles, along with an inactive new furostanol saponin (5). T
he structures of 1-5 were determined by spectroscopic data and hydroly
sis. The IC50 of 1-4 on cAMP phosphodiesterase were 0.7, 1.2, 1.1 and
2.0 (x 10(-5)M), respectively, which are more potent than that of papa
verine (IC50 3.0 x 10(-5)M).