Synthesis and structure-activity relationship of 3-O-acylated (-)-epigallocatechins as 5α-reductase inhibitors

Abstract

A series of 3-O-acylated (-)-epigallocatechins were synthesized and their inhibition of steroid 5α-reductase was studied. They were prepared from the reaction of EGCG with tert-butyldimethylsilyl chloride followed by reductive cleavage of the ester bond. The resultant (-)-epigallocatechins penta-O-tert-butyldimethylsilyl ether was esterified with different fatty acids then desilylated to provide the corresponding products. The activity of 3-O-acylated (-)-epigallocatechins increased with the increasing carbon numbers of the fatty acid moiety, reaching maximum for 16 carbon atoms (compound 4h) with an IC50 of 0.53 μM, which was ∼12-fold more potent than EGCG (IC50=6.29 μM). Introduction of monounsaturated fatty acid provided the most potent compound 6 (IC50=0.48 μM), which showed moderate anti-tumor activity in vivo.