ABSTRACT

Plants have been recognized and used either to improve sensory characteristics, foods or treatment of diseases since the creation of the world. The plant Xylopia aethiopica (Negro pepper), is one of such commonly used plant.  It is of public interest to scientifically verify the toxicity and health benefits of this plant. The aim of this study was to investigate the antimicrobial, toxicity, fertility enhancement potential and phyto-nutrient properties of the leaves and fruits (with and without seeds) of X. aethiopica in Wistar Rats. Hydro-ethanolic extracts of the leaves and fruits (with and without seeds) were processed using Soxhlet extraction technique. Phytochemical constituents, proximate and nutritional analyses were conducted using Gas Chromatography-Mass spectrophotometric technique. Antibacterial and anti-fungal activities were determined using Cup-plate agar diffusion technique. Wistar rats were administered with 125mg/Kg, 250mg/Kg, 500mg/Kg of the extracts by oral gavage for 30 days, 60 days and 90 days while the control group received feeds and water ad libitum. After the treatment periods, rats were sacrificed by cervical dislocation and blood collected by cardiac puncture while ovary and testis were removed. Full blood count was conducted using automated haematology analyser. Liver enzymes, urea, electrolytes and creatinine were determined using spectrophotometric and Ion-selective electrodes technique. The fertility hormone levels were determined using enzyme-linked immunosorbent assay technique. While the histo-morphology of the ovary and testes were done using microscopic technique. Data were compared using analysis of variance (ANOVA) and a p-value of 0.05 was considered significant. The leaves had no antibacterial effect at 50mg/mL but inhibited the growth of Escherichia coli and Staphylococcus aureus at 100mg/mL, 150mg/mL and 200mg/mL concentrations respectively. The fruits with seeds inhibited the growth of Escherichia coli and Pseudomonas aeruginosa at 50mg/mL, 100mg/mL, 150mg/mL and 200mg/mL. The fruits without seeds were effective against only Staphylococcus aureus at 100mg/mL, 150mg/mL and 200mg/mL concentrations. However, none of the extracts at the concentrations used had antifungal activity against any of the fungal isolates used. The LD50 for all the extracts was greater than 5000mg/Kg. The full blood count parameters were not sighificantly differet from the controls except white blood cell count (WBC) (p=0.01) and platelet count (PLT) (p = 0.01) which were significantly higher in a dose dependent manner after three months treatment. The serum levels of urea, electrolytes, creatinine, and the liver enzymes were not significantly different from the controls (p>0.05). Serum estrogen (p=0.01) and FSH (p=0.02) levels among female Wistar rats were significantly increased compared with controls. The testosterone (p=0.001), FSH (p=0.02) and LH (p=0.03) levels among male rats were significantly increased compared with cotrols. In the female Wistar rats treated with extracts, there were an enhancement in the development of follicular cells, corpus luteum with varying eccentrically located oocytes and stroma within the ovary. Also, the testes of male Wistar rats showed increasing sections of tubules and active interstitial congestion of the lumen by spermatozoa as well as Leydig cell hyperplasia indicating increased spermatogenesis in dose-dependent manner. The phytoconstituent analyses revealed the presence of alkaloids, glycoside, steroids, triterpenes, flavooids and saponins in the leaves and fruits (with and without seeds). Tannin was found only in the leaves and anthraquinones and cyanogenetic glycosides were completely absent in the three parts of the plant used. Carbohydrate, protein, fat, vitamin and moisture were identified in the leaves and fruits of X. aethiopica though in varying amounts. Toxic metals; lead, nickel, chromium were within acceptable limits and cadmium was not detected. Forty- one main bioactive compounds including cyclohexatetriol, erythritol, hexadiene and benzopyranone were quantitated. X. aethiopica is safe for consumption even above 5g/Kg body weight per day. Conclusively, it exhibited antibacterial activity against Gram positive and Gram-negative bacteria, enhanced the levels of serum testosterone, FSH and LH in male rats and estrogen and FSH in female rats which were corroborated by the histological morphology of the transverse sections of the reproductive organs. No anti-fungal activity was identified.