INHIBITION OF MONKEY SPERM HYALURONIDASE ACTIVITY AND HETEROLOGOUS CUMULUS PENETRATION BY FLAVONOIDS

A microplate assay for hyaluronidase and a heterologous cumulus penetr ation assay were used to determine the effects of four flavonoids (tan nic acid, kaempferol, quercetin, and apigenin) on the function of cyno molgus monkey sperm. All four flavonoids inhibited the activity of hya luronidase extracted from monkey sperm in a concentration-dependent ma nner over the range of 50-200 mu M Tannic acid and apigenin had lower inhibitory effects than kaempferol and quercetin. Kaempferol, querceti n, and apigenin at 100 mu M were shown to significantly inhibit monkey sperm penetration into hamster cumulus. There was a significant linea r relationship between the capacity of the flavonoids to inhibit monke y sperm hyaluronidase activity and their inhibitory effects on hamster cumulus penetration (r = 0.97). Tannic acid was observed to reduce sp erm motility, and it was not used in the cumulus penetration assay. Th e other three flavonoids tested in the cumulus penetration assay did n ot affect sperm motility, nor did they induce acrosome reactions. The results demonstrate that the flavonoids are useful tools for assessing the involvement of hyaluronidase in the functions of monkey sperm tha t are involved in fertilization.