N-Methylflindersine (2,2,6-Trimethyl-2H,5H-pyrano[3,2-c]quinolin-5-one) shows strong toxicity towards brine shrimp larvae, with an LD(50) value of 1.39 microg ml. It also exhibits potent inhibition against N -formylmethionylleucylphenylalanine-induced superoxide production with IC(50) values less than 12 microM.