Bioactive caffeic acid derivatives from Wedelia trilobata

Abstract Two new caffeic acid derivatives, p -hydroxyphenyl caffeate ( 1 ) and methyl 3-(7-methoxy-dihydrocaffeoyl)-5-caffeoyl quinate ( 2 ), were isolated from the whole plant of Wedelia trilobata , along with four known ones, neochlorogenic acid methyl ester ( 3 ), methyl 4,5-di- O -caffeoyl quinate ( 4 ), methyl 3,5-di- O -caffeoyl quinate ( 5 ) and chlorogenic acid methyl ester ( 6 ). Their structures were elucidated on the basis of detailed spectroscopic analysis. They were all isolated from plant W. trilobata for the first time. Compounds 1 , 2 , 4 and 5 showed significantly in vitro α -glucosidase inhibitory activity with IC 50 values from 0.029 to 0.362 mM, which were more potent than the reference compound acarbose (IC 50 0.410 mM). Compound 1 was further revealed to show interesting in vitro tyrosinase inhibitory activity (IC 50 2.00 μM) much stronger than positive control kojic acid (IC 50 12.55 μM).