Vitexicarpin, a flavonoid from the fruits of Vitex rotundifolia, inhibits mouse lymphocyte proliferation and growth of cell lines in vitro

Certain flavonoids having a C-2,3-double bond were reported to show an inhibitory activity against T-lymphocyte proliferation, but not against B-lymphocyte proliferation in vitro. In the course of these studies, vitexicarpin (3',5-dihydroxy-3,4',6,7-tetra methoxyflavone) isolated from the fruits of Vitex rotundifolia was found to show potent inhibition against lymphocyte proliferation. Vitexicarpin inhibited T-lymphocyte proliferation as well as B-lymphocyte proliferation at > 0.1 mu M. IC50's were approximately 0.7 mu M both for T- and B-cell proliferation. The inhibitory activity of vitexicarpin was reversible. Vitexicarpin also inhibited the growth of certain cancer cell lines, EL-4 and P815.9 (IC50 = 0.25-0.3 mu M). These results suggest that vitexicarpin may be a potential therapeutic agent involved in inflammatory/immunoregulatory disorders such as rheumatoid arthritis and lymphomas.