Inhibition of phospholipase Cγ1 and cancer cell proliferation by lignans and flavans fromMachilus thunbergii
Thirteen compounds were isolated from the CH2CI2 fraction ofMachilus thunbergii as phospholipase Cγ1 (PLCγ1) inhibitors. These compounds were identified as nine lignans, two neolignans, and two flavans by spectroscopic analysis. Of these, 5,7-di-O-methyl-3′,4′-methylenated (-)-epicatechin (12) and 5,7,3′-tri-O-methyl (-)-epicatechin (13) have not been reported previously in this plant. In addition, seven compounds, machilin A (1), (-)-sesamin (3), machilin G (5), (+)-galbacin (9), licarin A (10), (-)-acuminatin (11) and compound12 showed dose-dependent potent inhibitory activities against PLCγ1in vitro with IC50 values ranging from 8.8 to 26.0 υM. These lignans, neolignans, and flavans are presented as a new class of PLCγ1 inhibitors. The brief study of the structure activity relationship of these compounds suggested that the benzene ring with the methylene dioxy group is responsible for the expression of inhibitory activities against PLCγ1. Moreover, it is suggested that inhibition of PLCγ1 may be an important mechanism for an antiproliferative effect on the human cancer cells. Therefore, these inhibitors may be utilized as cancer chemotherapeutic and chemopreventive agents.
Key wordsMachilus thunbergii Lauraceae Phospholipase Cγ1 Lignan Flavan Methylene dioxy group Antiproliferation of human cancer cells
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