Effect of Azadirachta indica (Neem) Leaf Aqueous Extract on the Functional Parameters of Human Spermatozoa in Vitro

The neem leaf extract (NLE) has been reported to exhibit spermicidal and oocidal activities under in vitro cultured conditions but the effect of NLE on various sperm function parameters have not been studied. Therefore, in the present study we have assessed effect of different concentrations of NLE on various sperm functions characteristics to develop a water-based vaginal contraceptive. The human sperm (10 million sperm/mL), were exposed to different concentrations of NLE (3, 9, 15, and 30mg/mL) for 20 seconds at 37°°C. Thereafter, sperm function characteristics such as motility, viability, hypo-osmotic swelling (HOS), nuclear decondensation (NDC), acrosome intactness (AI) and deoxyribonucleic acid (DNA) stability were analyzed. A dose-dependent inhibition of sperm motility was observed, while 15mg/mL dose immobilized 100% of spermatozoa. Whereas other sperm functional parameters like viability, DNA intactness, HOS, NDC and AI decreased from 94% to 9%, 71% to 29%, 77% to 25%, 62% to 29% and 53% to 25%, respectively. The data obtained in the present study reveal that treatment of NLE causes reduction in functional parameters to infertility range. Therefore, a preparation containing 15mg of NLE in 150 μl of 0.9% NaCl was tested in rat as a vaginal contraceptive, and the data revealed 100% efficacy in mating studies after 21 days of vaginal application. The findings indicate the potential use of NLE for developing water-based vaginal contraceptive.