In vitro effect of azadirachtin-A, a tetranortritarpinoid of neem seed kernel, on rat spermatozoa

Since, there is only few documented evidence referring to assessment of the clear specific actions of medicinal plant source or active constituents in rodent model, the present study is undertaken to evaluate the effective concentration of technical azadirachtin-A, a tetranortritarpinoid of neem seed kernel, to immobilizes the cauda epididymal spermatozoa within 20 seconds and effectively inhibits sperm motility, viability and plasma membrane integrity in a dosedependent manner. Spermicidal efficacy was evaluated in vitro by a modified Sander–Cramer test using different concentrations. The mode of spermicidal action was evaluated by (a) Sperm morphology and viability tests (b) hypo-osmotic swelling (HOS) tests and (c) transmission electron microscopy. The minimum effective concentration (MEC) of azadirachtin-A for 100 % immobilization of sperm in 20 secs was around 4.50μg/million sperm. No morphological changes were found in the sperm head, midpiece or tail and no viable sperm seen. Further, sperm membrane integrity observations, ultra studies shown that most of most of the principal pieces of treated sperm were without plasma membrane and azadirachtin-A exposed spermatozoa lost their response, by curling of the tail, to hypo osmotic medium in a dose-dependent manner, indicating the impairment of functional integrity of the plasma membrane. The present study therefore appears reasonable that azadirachtin-A provides the sperm-immobilizing effect either directly executing its effects by structural and functional modulation of the plasma membrane or by way of its synergism with blockage of some biochemical pathway like energy utilization. Keywords— Azadirachtin-A, spermatozoa, MEC, HOS and rat Ravindranath H. Aladakatti Central Animal Facility, Indian Institute of Science, Bangalore560012, Karnataka (India) Umadevi C. Jadaramkunti Department of Zoology, Government First Grade College, Hubli580032, Karnataka (India)