(-)-Epigallocatechin gallate derivatives for inhibiting proteasome

Abstract

(-)-EGCG, the most abundant catechin, was found to be chemopreventive and anticancer agent. However, (-)-EGCG has at least one limitation: it gives poor bioavailability. This invention provides compounds of generally formulae below, wherein R₁₁, R₁₂, R₁₃, R₂₁, R₂₂, R₂, R₃, and R₄ are each independently selected from the group consisting of --H, and C₁ to C₁₀ acyloxyl group; and R₅ is selected from the group consisting of --H, C₁-C₁₀-alkyl, C₂-C₁₀-alkenyl, C₂-C₁₀-alkynyl, C₃-C₇-cycloalkyl, phenyl, benzyl and C₃-C₇-cycloalkenyl, whereas each of the last mentioned 7 groups can be substituted with any combination of one to six halogen atoms; at least one of R₁₁, R₁₂, R₁₃, R₂₁, R₂₂, R₂, R₃ and R₄ is --H, which were found to be more potent than their non-protected counterparts, which can be used as proteasome inhibitors to reduce tumor cell growth.