A potential prodrug for a green tea polyphenol proteasome inhibitor: evaluation of the peracetate ester of (−)-epigallocatechin gallate [(−)-EGCG]

Autor: Deborah J. Kuhn, Albert S. C. Chan, Larry M.C. Chow, Aslamuzzaman Kazi, Wai Har Lam, Q. Ping Dou, Tak Hang Chan
Rok vydání: 2004
Předmět:
Zdroj: Bioorganic & Medicinal Chemistry. 12:5587-5593
ISSN: 0968-0896
DOI: 10.1016/j.bmc.2004.08.002
Popis: Green tea has been shown to have many biological effects, including effects on metabolism, angiogenesis, oxidation, and cell proliferation. Unfortunately, the most abundant green tea polyphenol (-)-epigallocatechin gallate or (-)-EGCG is very unstable in neutral or alkaline medium. This instability leads to a low bioavailability. In an attempt to enhance the stability of (-)-EGCG, we introduced peracetate protection groups on the reactive hydroxyls of (-)-EGCG (noted in text as 1). HPLC analysis shows that the protected (-)-EGCG analog is six times more stable than natural (-)-EGCG under slightly alkaline conditions. A series of bioassays show that 1 has no inhibitory activity against a purified 20S proteasome in vitro, but exhibits increased proteasome-inhibitory activity in intact leukemic cells over natural (-)-EGCG, indicating an intercellular conversion. Inhibition of cellular proteasome activity by 1 is associated with induction of cell death. Therefore, our results indicate that the protected analog 1 may function as a prodrug of the green tea polyphenol proteasome inhibitor (-)-EGCG.
Databáze: OpenAIRE