The Antihypertensive Potential of Aqueous extract of (L.) Merr. is Up-regulation of Cyclic Guanosine Monophosphate and Down-regulation of the Renin-angiotensin System.

Background: Hypertension is a major risk factor for cardiovascular diseases. (PB) is used for the treatment of hypertension, painful sprains, skin diseases, tuberculosis, acute bronchitis, anti-inflammatory conditions, hepatitis, and diabetes. Its antihypertensive potential has been investigated and documented. This study investigated the antihypertensive mechanism of aqueous extract of PB leaf (APB) on L-NAME-induced hypertension.

Methods: Thirty male wistar rats (150-170 g) were grouped into five (n=5). Group 1 received 10 mL/kg of distilled water (control), while groups 2-5 were administered 60 mg/kg of L-NAME (L-NAME60) orally for eight weeks to induce hypertension. After eight weeks, groups 2-5 received L-NAME60+distilled water (HNT), distilled water (HRE), L-NAME60+APB (200 mg/kg, [HAPB]), and L-NAME60+ramipril (10 mg/kg, [HRA]), respectively, for five weeks. The BP was measured by the tail-cuff method. The blood sample was obtained under anesthesia, and tissue samples were obtained after euthanasia. Serum renin, ACE, angiotensin-II, endothelin-1, and cyclic guanosine monophosphate (cGMP) levels were measured using ELISA techniques. Malondialdehyde, superoxide dismutase (SOD), and reduced glutathione (GSH) levels were measured by spectrophotometry. Data were analyzed using ANOVA at α0.05.

Results: The BP significantly decreased in HAPB compared to HNT. Renin, ACE, and angiotensin- II levels significantly decreased while cGMP levels increased in the HAPB group compared to HNT. Malondialdehyde levels significantly decreased, and SOD and GSH levels increased compared to HNT.

Conclusion: aqueous leaf extract reduced blood pressure in hypertensive rats by modulating the cGMP signalling pathway and the renin-angiotensin system.