Aqueous Extract of Emilia praetermissa Milne-Redh. (Asteraceae) Leaf Attenuates Salt-induced Hypertension in Male Wistar Rats: Biochemical Evidence

Emilia praetermissa is a herb consumed for folkloric management of hypertension. However, its efficacy against hypertension has not been scientifically investigated. This study evaluated the antihypertensive effects of its aqueous leaf extract in salt-induced hypertensive male Wistar rats. Seven groups (n=6 each) were treated: Group 1 (control), Group 2 (8% NaCl for hypertension induction), Group 3 (extract alone at 100 mg/kg), Group 4 (extract before salt-loading), Group 5 (salt-loading before extract), Group 6 (salt-loading followed by captopril at 50 mg/kg), and Group 7 (salt-loading followed by hydrochlorothiazide (HCTZ) at 10 mg/kg). All treatments were administered orally by gavage daily for two weeks. Blood pressure measurements—systolic (SBP), diastolic (DBP), mean arterial pressure (MAP), and heart rate (HR)—were recorded using the tail-cuff method. The extract’s oral acute toxicity (LD50) exceeded 5000 mg/kg. At 100 mg/kg, it significantly (p ≤ 0.05) reduced blood pressure in hypertensive rats, improved liver and kidney function indices (p ≤ 0.05), lipid profiles (p ≤ 0.05), and antioxidant enzymes levels in heart tissue (p ≤ 0.05). Angiotensin II (AngII) and aldosterone (ALD) levels decreased significantly (p ≤ 0.05), while 6-keto-prostaglandin F1α increased (p ≤ 0.05). Histopathological analysis revealed that the extract improved myocardial fibrosis and reduced tunica media thickness in the heart and aorta, while also mitigating ultrastructural changes in the kidney and liver of hypertensive rats. The extract demonstrated a significant antihypertensive effect in 8% NaCl-induced hypertensive male rats. These results provide scientific support for the traditional use of Emilia praetermissa in managing hypertension.