ABSTRACT
Emilia praetermissa is a herb consumed for folkloric management of hypertension. However, its efficacy against hypertension has not been scientifically investigated. This study was carried out to determine the antihypertensive and aphrodisiac potential of aqueous leaf extract of Emilia praetermissa in salt-induced hypertensive male rats. Phytochemical screening and in vitro antioxidant capacity of the extract, and its effect on selected biochemical parameters in plasma, heart, liver and kidney of hypertensive rats were studied. Seven (7) groups of rats (6 per group), were used. Rats in group 1 served as control. Rats in groups 2 and 3 were treated with salt and extract respectively. Group 4 rats received extract prior to saltloading. Group 5 rats were salt-loaded prior to extract treatment. Group 6 rats were salt-loaded prior to captopril administration, while group 7 rats were salt-loaded before administration of hydrochlorothiazide (HCTZ). The extract, captopril and HCTZ were administered at doses of 100, 50 and 10 mg/kg body weight, respectively, by gavage for two weeks. Captopril and HCTZ served as standard drugs. The effect of the extract on blood pressure, antioxidant enzyme activities, lipid profile, hepatic and renal function indices, haematological parameters, angiotensin II (AngII), aldosterone (ALD), 6-keto-prostaglandin F1α, reproductive function and organ histopathology were determined in salt-loaded male Wistar rats, based on extant biochemical procedures. Qualitative analysis revealed the presence of alkaloids, flavonoids, saponins and tannins in the extract. In vitro antioxidant studies revealed that it reduced 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, scavenged hydroxyl and nitric oxide radicals and liberated Fe2+ upon reduction of Fe3+ to Fe2+. The extract significantly decreased (p ≤ 0.05) blood pressure. It also improved liver and kidney function indices (p ≤ 0.05), lipid profile (p ≤ 0.05) and antioxidant enzyme status in plasma, liver, kidney and heart (p ≤ 0.05). Leucocyte and erythrocyte counts, haemoglobin concentration, haematocrit, and % monocytes were increased. Plasma levels of AngII and ALD were lowered, while 6-keto-prostaglandin F1α was significantly increased (p ≤ 0.05). Testicular and epididymal weights, sperm count and sperm motility were decreased. There were increases in number of abnormal sperm cells and post-implantation loss index of female rats mated with extract-treated saltloaded rats (p ≤ 0.05). Plasma testosterone, mounting frequency, intromission frequency and ejaculation frequency were significantly increased (p ≤ 0.05) in extract-treated salt-loaded rats. The extract ameliorated myocardial fibrosis and tunica media thickness in heart and aorta, as well as xxxii ultrastructural changes in kidney and liver of salt-loaded rats, but it caused slight morphological changes in testis and epididymis. Interestingly, the extract did better at reducing blood pressure than captopril and HCTZ treated groups, while its effects on the biochemical parameters and tissue ultrastructure were comparable with those of captopril and HCTZ treated groups. These findings indicate that the extract exerted antihypertensive effect on salt-induced hypertensive male rats, but produced deleterious effect on spermatological parameters without affecting libido. These findings provide a scientific justification for the folkloric use of Emilia praetermissa in treatment of hypertension. However, there is need for caution in the use of this plant, in view of its adverse effects on spermatozoa
