Aim: The present study was aimed at screening phytochemicals of Dioscorea bulbifera extracts and evaluating its effects on male rat reproductive system.

Background: Since ancient times, man has found a lot of health benefits from medicinal plants. According to the World Health Organisation (WHO), about 80% of the world population depends on traditional medicine, which is 90% plant-based, for their health needs. In respect of this, men in Africa use herbal medicines in the management of erectile dysfunction and infertility. Amongst thousands of herbs, folklore has implicated Dioscorea bulbifera bulbils in the treatment of piles, dysentery, syphilis, ulcers, cough, leprosy, diabetes, asthma, cancer and infertility. Despite such great health benefits from D. bulbifera, in vitro studies and clinical data in support of its efficacy as an aphrodisiac are scanty.

Objective: The objective of the study was to investigate the effects of Dioscorea bulbifera extracts on Wistar rat sperm parameters, hormonal levels and histology of the testis.

Methods: Thirty healthy adult male Wistar rats were divided into 5 groups of 6 rats each and were given different treatments of Dioscorea bulbifera extracts by oral gavage at 200 and 400 mg kg-1 body weight. After 8 weeks, body and reproductive organ weights, sperm concentration, hormonal levels and histological structure of the testis were evaluated. A calorimetric method was used to assess the quantity of phytochemical constituents.

Results: Testosterone, luteinizing hormone, estradiol and follicle-stimulating hormone levels were significantly (p<0.05) enhanced whereas prolactin levels were significantly (p<0.05) down-regulated in the treated groups. Total sperm motility, sperm concentration and the percentage of progressively motile cells increased compared to the control. All the treated animals showed an increase in body weight, seminiferous tubule diameter and germinal epithelial height with the testes showing all the stages of spermatogenesis. Phytochemical screening of the methanol extracts revealed the presence of alkaloids, steroids, flavonoids, phenols and saponins.

Conclusion: Dioscorea bulbifera has secondary metabolites that seem to stimulate androgenic and anabolic effects. These secondary metabolites appear to be responsible for the positive changes in testicular architecture, serum hormonal levels, caudal sperm concentration and motility parameters. This study supports the ethno-aphrodisiac claims that have been made against it.