Structure-activity relationships for unsaturated dialdehydes 8∗. Comparative effects of 10 sesquiterpenoids on the sea urchin gamete fertilization☆

Abstract The effects of 10 sesquiterpenoids with unsaturated dialdehyde functionalities were studied on fertilization, first cleavage, and calcium permeability of egg membranes of sea urchin gametes. Fertilization was inhibited by nine compounds when sperm was exposed and by five compounds when eggs were exposed (50 μg/ml for 5 min). All compounds except one (9α-hydroxymerulidial) inhibited the first cleavage in a dose-response manner. Only one compound (velleral) increased the Ca 2+ permeability of egg membranes at 20 μg/ml. All compounds reduced to a varying extent the ATP-driven Ca 2+ sequestration by non-mitochondrial intracellular compartments. In general, when hydroxylated and non-hydroxylated derivatives of the compounds are compared, the hydroxylated ones present a lower toxicity when measuring fertilization and cleavage inhibition, and reduction of intracellular Ca 2+ sequestration.