[Chemical constituents of rhizoma imperatae and their anti-complementary activity].

Objective: To study the chemical constituents of Rhizoma Imperatae and their anti-complementary activity.

Methods: By the hemolysis test, the petroleum extraction, ethyl acetate extraction, n-butanol extraction and the water extraction was tested for anti-complementary activity. Compounds were isolated and purified by silica gel column chromatography, Sephadex LH-20 and reversed-phase column chromatography. The structures were identified by the various spectroscopic data of ESI-MS, 1H-NMR, 13C-NMR. The compounds were evaluated for anti-complementary activity in vitro.

Results: The petroleum extraction, ethyl acetate extraction showed significant anti-complementary activity. Ten compounds were isolated from the petroleum and EtOAc soluble fractions and identified as cylindrin (1), arundoin (2), friedelin (3), beta-sitosterol (4), siderin (5), ethyl p-hydroxybenzoate (6), 5-methoxyflavone (7), vanillic acid (8), trans-p-coumaric acid (9), 5-hydroxymethylfurfural (10).

Conclusion: Compounds 6, 7, 8, and 10 are isolated from the genus for the first time, and compounds 3, 8 and 9 inhibited the complement system towards the classical pathway.