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Paper | Special issue | Vol 76, No. 1, 2008, pp.485-505
Published online, 21st April, 2008
DOI: 10.3987/COM-08-S(N)34
Enantioselective Synthesis and Proteasome Inhibition of A-Ring Analogs of (-)-Epigallocatechin Gallate (EGCG), the Active Ingredient of Green Tea Extract

Kumi Osanai, Vesna Milacic, Q. Ping Dou, and Tak Hang Chan*

*Department of Chemistry, McGill University, Montreal, Quebec, Canada

Abstract

The A-ring analog compound 8 of (-)-EGCG (1), the active ingredient of green tea, and compound 9, analog of the natural catechin 6 from C. salvifolius, as well as their enantiomers 10 and 11 have been synthesized enantioselectively. They show proteasomal inhibitory activities under cell free conditions, at a potency lower than that of (-)-EGCG. The results suggest that the hydroxyl groups in A-ring of (-)-EGCG play a role in enhancing the activity. The acetylated derivatives of these compounds, 12-15, show cytotoxic activities and proteasomal inhibition after cellular intake, presumably acting as pro-drugs.