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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 anticomplement 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 3alpha,23-isopropylidenedioxyolean-12-en-27-oic acid (1), 3-oxoolean-12-en-27-oic acid (2), 3alpha-hydroxyolean-12-en-27-oic acid (3), beta-peltoboykinolic acid (4), 3alpha,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 IC (50) values of 71.4, 98.5, and 180.7 microM, 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.

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Three new lignans, 4'-methoxymagndialdehyde ( 1), 4'-methoxymagnaldehyde B ( 2), and 4'-methoxymagnaldehyde E ( 3), were isolated from hexane- and EtOAc-soluble fractions of the stem bark of Magnolia officinalis, together with eight known compounds ( 4- 11). The structures of compounds 1- 3 were determined on the basis of spectroscopic and physicochemical data analysis. Compounds 1- 11 were tested in vitro for their cytotoxic activity against the K562, HeLa, and A549 cancer cell lines. Among the compounds tested, compound 1 showed the most potent cytotoxic activity against these cancer cell lines, with IC50 values of 3.9, 1.5, and 3.7 microg/mL, respectively.