Immunomodulatory and anticancer activities of flavonoids extracted from litchi (Litchi chinensis Sonn) pericarp.

The litchi pericarp extract was subjected to partition by hexane, ethyl acetate and water. Epicatechin, proanthocyanidin B2 and proanthocyanidin B4 were isolated and purified from the ethyl acetate fraction by reverse-phase high performance liquid chromatography. The immunomodulatory activities of epicatechin, proanthocyanidin B2, proanthocyanidin B4 and the ethyl acetate fraction were examined using proliferation of mouse splenocytes. The results showed all these samples had much higher stimulatory effects on splenocyte proliferation than that of the reference, rutin. Epicatechin and the ethyl acetate fraction showed a significantly (P<0.05) stimulatory effect when the concentration was up to 12.5 micro g/ml. Proanthocyanidin B2 and proanthocyanidin B4 exhibited little lower stimulatory effects than epicatechin and the ethyl acetate fraction. The anti-breast cancer activities of epicatechin, proanthocyanidin B2, proanthocyanidin B4 and the ethyl acetate fraction were also evaluated. Epicatechin and proanthocyanidin B2 had lower cytotoxicities to human breast cancer cell MCF-7 and human embryolic lung fibroblast than paclitaxel.