Activity-guided fractionation for complement inhibitors led to the isolation of 22 known compounds from Viola kunawarensis. Chemical types include six sterol compounds, three coumarin compounds, five megastigmane compounds, two triterpenoid compounds, two phenylpropanoid compounds, one chlorophyll, one amide, and two lipid compounds. Among which, two sterols (stigmasta-4-ene-3β,6β-diol and saringosterone), one amide (aurantiamide acetate) and a norsesquiterpenoid (solalyratin B) exhibited better anti-complementary effects with CH50 values ranging from 0.02 to 0.08 mM, which are plausible candidates for developing potent anti-complementary agents.
Keywords: Viola kunawarensis; Violaceae; anti-complementary activity; chemical constituents.