Human sperm immobilization effect of Carica papaya seed extracts: an in vitro study

Aim: To examine if the seed extracts of Carica papaya, which showed antispe rmatogenic/sperm immobilization properties in animal models, could cause hu man sperm immobilization in vitro. Methods: Chloroform extract, benzene chr omatographic fraction of the chloroform extract, its methanol and ethyl ace tate sub-fractions and the isolated compounds from the sub-fractions i.e., ECP 1 & 2 and MCP 1 & 2, of the seeds of Carica papaya were used at concent rations of 0.1%, 0.5%, 1% and 2%. Sperm motility was assessed immediately a fter addition of extracts and every 5 minutes thereafter for 30 minutes. Re sults: There were dose-dependent spermicidal effects Showing an instant fal l in the sperm motility to less than 20% at 2% concentration. isolated comp ounds ECP 1&2 were more effective inducing a motility of less than 10%. Man y of the spermatozoa became vibratory on the spot. Total inhibition of moti lity was observed within 20 - 25 min at all concentrations of all products. Scanning and transmission electron microscopy revealed deleterious changes in the plasma membrane of the head and mid-piece of spermatozoa. Sperm via bility test and the number of abnormal spermatozoa after completion of incu bation suggested that the spermatozoa were infertile. The effects were sper micidal but not spermiostatic as revealed by the sperm revival test. Conclu sion: The results reveal spermicidal activity in vitro of the seed extracts of Carica papaya.