Inhibition of Phospholipase Cγ1 Activity by Amentoflavone Isolated fromSelaginella tamariscina

Amentoflavone was isolated as an inhibitor of phospholipase C gamma 1 (PLC gamma 1) and phosphoinositides (PI)-turnover in PLC gamma 1 overexpressing NIH3T3 fibroblasts (NIH3T3 gamma 1) from Selaginella tamariscina (Selaginellaceae) together with other related biflavonoids, isocryptomerin and cryptomerin B. Only amentoflavone inhibited the PLC gamma 1 activity with an IC50 of 29 microM and the formation of total inositol phosphates (IPt) in PDGF-stimulated NIH3T3 gamma 1 with an IC50 of 9.2 microM but did not show inhibitor activity against protein kinase C. Isocryptomerin and cryptomerin B did not show inhibitor activity against PLC gamma 1 at the concentration of 150 microM, and did not inhibit IPt production in PDGF-induced NIH3T3 gamma 1 at the concentration of 180 microM.