Green tea polyphenol (-)-epigallocatechin-3-gallate enhances the inhibitory effect of huperzine A on acetylcholinesterase by increasing the affinity with serum albumin.

The green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) was investigated for its enhancement effect of huperzine A on inhibiting acetylcholinesterase (AChE). The inhibitory effect of huperzine A on acetylcholinesterase is quite weak in the whole phase. EGCG hardly inhibits the AChE activity within the range 10-300 mg/kg. However, upon addition of EGCG to the huperzine A groups, a remarkably enhanced inhibitory effect was observed. The EGCG also can largely prolong the inhibitory time. These results indicate that addition of EGCG to huperzine A can reduce the dose of huperzine A required compared with huperzine A alone. The enhancement and complementary effect of EGCG on huperzine A activity may partly be due to the antioxidant property of EGCG. One of the beneficial effects of green tea is to induce a feeling of relief. It is conceivable that this function may be regulated by EGCG in the central nervous system since EGCG is distributed in the brain after oral administration. EGCG can be used as an enhanced supplement for huperzine A to treat Alzheimer's disease.