INHIBITION OF PHOSPHOLIPASE C-GAMMA-1 ACTIVITY BY AMENTOFLAVONE ISOLATED FROM SELAGINELLA-TAMARISCINA

Amentoflavone was isolated as an inhibitor of phospholipase C gamma 1 (PLC gamma 1) and phosphoinositides (PI)-turnover in PLC gamma 1 overe xpressing NIH3T3 fibroblasts (NIH3T3 gamma 1) from Selaginella tamaris cina (Selaginellaceae) together with other related biflavonoids, isocr yptomerin and cryptomerin B. Only amentoflavone inhibited the PLC gamm a 1 activity with an IC50 of 29 mu M and the formation of total inosit ol phosphates (IPt) in PDGF-stimulated NIH3T3 gamma 1 with an IC50 of 9.2 mu M but did not show inhibitory activity against protein kinase C . Isocryptomerin and cryptomerin B did not show inhibitory activity ag ainst PLC gamma 1 at the concentration of 1 50 mu M, and did not inhib it IPt production in PDGF-induced NIH3T3 gamma 1 at the concentration of 180 mu M.