The effect of some of the polyphenolic compounds on sperm motility in vitro: a structure-activity relationship.

Many of the common polyphenolic compounds which are naturally present in abundance in plant extracts, exercise inhibitory effects on mammalian sperm motility in vitro, which could be the cause of the antifertility effects of the crude plant extracts. The action of these polyphenolic compounds seems to be structure-dependent. Their activity was found to be dependent on the positions of hydroxyl groups and modulated by the positions of methyl groups on the benzene ring. Carbon-carbon double bond on the side chain of cinnamic acid series compounds was essential for their activity. One of the plausible actions of polyphenols on spermatozoa seems to be the augmentation of the generation of superoxide radicals by them, which might be involved in the inhibition of their motility in vitro.