Abstract:
Tiger nut (Cyperus esculentus L.) and walnut (Tetracarpidium conophorum Müll. Arg.) have been reportedly used in folk medicine for the treatment of erectile dysfunction in male, but the mechanism of action remains unexplored. Hence, this study investigated the effect of these nuts on some biomolecules relevant to erectile function in male rats. Aqueous, phenolic and alkaloid extraction of the defatted samples of the nuts were performed (1:10 w/v). Subsequently, 1,1-diphenyl–2 picrylhydrazyl (DPPH), 2, 2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS), reducing power and iron chelating abilities were carried out in vitro. The ability of the extract to prevent Fe2+/ H2O2 induced decomposition of deoxyribose and inhibition of FeSO4 induced lipid peroxidation in rat penile tissue were also assessed in vitro. Then, the effect of the extracts on some key enzymes relevant to erectile function [arginase and acetylcholinesterase (AChE)] was also determined in vitro. Thereafter, the effect of dietary supplementation of both nuts on sexual behaviour, hormone and some biomolecules relevant to erectile function in normal and Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME) induced sexual dysfunctional rats were evaluated. In addition, the physioactive phenolic constituents were characterized using high performance liquid chromatography (HPLC). The results revealed that both nuts exhibited antioxidant properties, inhibited arginase and AChE activities in vitro. Dietary supplementation of tiger nut and walnut improved antioxidant status in the dietary supplemented group compared to the control group. The groups with supplemented diet containing tiger nut and walnut showed significantly increased sexual behaviour, sexual hormone levels as well as had inhibitory effect on enzyme AChE and arginase but modulatory effect on ectonucleotidase (NTPDase, 5-nucleotidase and ADA activities). Therefore, the antioxidant capacity and modulatory/inhibitory effect on enzyme activities and other biomolecules relevant to erectile function exhibited by both nuts could further buttress their aphrodisiac benefits in folk medicine. These activities may be directly/indirectly attributed to the phenolic constituents. However, tiger nut showed a better aphrodisiac potential.
