Anticomplementary activity of triterpenoids from the whole plant of Aceriphyllum rossii against the classical pathway

Abstract

To provide a better understanding of the anti-complement activity of triterpenoids, seven unusual pentacyclic triterpenoids bearing a carboxyl group at C-27 were evaluated for their anti-complement activities against the classical pathway of the complement system. The triterpenoids were isolated from the whole plant of Aceriphyllum rossii of the family Saxifragaceae and were determined to be 3α,23-isopropylidenedioxyolean-12-en-27-oic acid (1), 3-oxoolean-12-en-27-oic acid (2), 3α-hydroxyolean-12-en-27-oic acid (3), β-peltoboykinolic acid (4), 3α,23-diacetoxyolean-12-en-27-oic acid (5), 23-hydroxy-3-oxoolean-12-en-27-oic acid (6) and aceriphyllic acid A (7). Among them, compounds 2, 3, and 5 showed significant anticomplement activity on the classical pathway with IC50 values of 71.4, 98.5, and 180.7 μM, respectively, whereas compounds 1, 4, 6, and 7 were inactive. Our findings suggest that both the ketone at C-3 and the methyl at C-23 in the oleanane triterpenoids with a carboxyl group at C-27 are important for the anticomplement activity against the classical pathway.