Inhibition of phospholipase C gamma 1 by the prenylated flavonoids from Sophora flavescens

The effect on the phospholipase C gamma 1 activity of eleven prenylated flavonoids from Sophora flavescens was investigated. These flavonoids exhibited relatively strong inhibitory activity with IC50 values ranged from 7.5 x 10(-6) M to 35 x 10(-5) M with the exception of kushenol H (4) (IC50 value; > 5.3 x 10(-4) M). The presence of C3-OH resulted in a significant diminution of activity and the configuration of C3-OH is likely to be another factor influencing the activity. In addition, hydration of the C-4"'-C-5"' double bond of the lavandulyl side chain caused complete loss of activity. These data suggest that the presence and configuration of C3-OH are related to the inhibitory activity and the lavandulyl side chain is also important for high inhibitory activity against PLC gamma 1.