A comparative study of the anti-hypertensive effect of aloe secundiflora (aloe), azadirachta indica (neem) and urtica dioica (stinging nettle) leaf extract syrup on new zealand white male rabbits
Herbal medicine has been extensively used across the globe dating back to the Ayurvendic medicine. Even though existing literature and practices show that Aloe secundiflora (Aloe), Azadirachta indica (neem) and Urtica Dioica (stinging nettle) are among the most commonly used plant extracts in the treatment of hypertension in powder or aqueous form, no comparative studies on their hypotensive effects had been done. In addition, literature on the extracts' significant dosage and associated physiological side effects was rare. Standardized method of extracting A. indica and Urtica Dioica syrups which are often distributed and administered in raw form was also not documented. In this study, 60% ethanol and water was used to produce standardized extracts of A. indica and U. Dioica leaves. Total extract yield of three stages and one stage and, cold and hot extraction was compared. Cold 60% ethanolic extracts of A. indica and U. Dioica powder and, dried A. secundiflora juice were formulated into syrup. The syrups were used to comparatively determine their hypotensive effect at doses of 10, 20, 40 and 80mglkg on normotensive while 80mg/kg was used on 10% salt loaded unilaterally renal constricted and nephrectomized hypertensive male rabbits. In addition, their physiological side effects were also compared. Extraction using 60% three stage process produced significantly high total extract yield (P < 0.0001) both in A. indica 7.8g (15.5%) and U. dioica 5.8g (11.6%) than one stage 3.9g (7.8%) and 3.46g (6.92%) respectively. Hot extraction produced higher total extract yield (P < 0.0001) in both A. indica 10.6g (21.2%) 60% ethanolic extract and U. dioica 15.lg (30.2%) aqueous extract. These results suggest that use of hot three stages extraction process is the most efficient using 60% ethanol for A. indica and water for U. dioica. The lowest significant hypotensive dosage for A. secundiflora was 20mglkg (P < 0.0016); it decreased mean arterial pressure (MAP) by 9.4mmHg (10.4%) and 16.02mmHg (17.6%) by the second and sixth hour respectively. U. dioica was significant at 40mg/kg (P < 0.0001) and decreased MAP by 15.1mmHg (18.3%) and 5.8mmHg (6.7%) by the second and sixth hour respectively while A. indica was significant at 40mg/kg (P < 0.0001) both at the second and sixth hour and decreased MAP by 12.2mmHg (13.9%) and 13.8mmHg (15.l %) respectively. All the three extracts showed significant anti-hypertensive effect on unilaterally nephrectomised hypertensive rabbits; A. secundiflora (P < 0.005), A. indica (P < 0.039) and U. Dioica (P < 0.012). They also significantly decreased MAP in renal constricted hypertensive rabbits; A. secundiflora (P < 0.0001), A. indica (P < 0.0028) and U. Dioica (P < 0.0019). A. secundiflora and U. dioica had significant diuretic effect (P < 0.0001) unlike A. indica. They decreased serum sodium ions (q = 5.042 and q = 4.338) respectively and chloride ions (q=10.04 and 6.792 respectively) but only A. secundiflora significantly decreased potassium ions (q=6. 731) and showed laxative effect as well. The diuretic and laxative effects suggest why A. secundiflora demonstrated the highest hypotensive and anti-hypertensive effect while A. indica had the lowest. Both A. indica and A. secundiflora had significant hypothermic effect (P = 0.034 and P = 0.023 respectively) while U. dioica was not (P = 1.735). The study concluded that the most effective antihypertensive plant extracts with minimum physiological side effects was U. dioica followed by A. indica while A. secundiflora demonstrated the highest toxicity effect.