Prosopis africana extract inhibits critical enzymes associated with hypertension in vitro and in cyclosporine-induced hypertensive rats

Abstract

This study evaluated the antihypertensive properties of leaf extracts of Prosopis africana (PA) in vitro and in hypertensive rats. Ethanol (ELPA) and differential solvent fractions [ethyl-acetate (EAPA), butanol (BLPA), and aqueous (ALPA)] were prepared using standard protocols. Hypertension was induced in female albino Wistar rats intraperitoneally using cyclosporine (25 mg/kg/day) while extracts were administered via oral route. Forty female rats were grouped into 5 ( n = 8). Group 1 received 2 ml distilled water, Group 2: (cyclosporine + 2 ml distilled water); Group 3: cyclosporine + captopril (10 mg/kg/day); Group 4: cyclosporine + 1000 mg/kg ELPA and Group 5: cyclosporine + 1500 mg/kg ELPA. The blood pressure of anesthetized rats was measured using LabScribe coupled to a Lab-Trax-4/24T, and the activities of angiotensin-converting enzyme (ACE), arginase, phosphodiesterase-5 (PDE-5), acetylcholinesterase (AChE) and adenosine deaminase (ADA) were evaluated using standard methods. All the fractions exerted significantly ( p < 0.05) higher ACE inhibitory effect (ELPA = 64.36 ± 0.50%; EAPA = 86.31 ± 0.60%; BLPA= 85.28 ± 2.30 % ; ALPA= 82.27 ± 2.10 % ) than the reference, lisinopril (40.22±0.50 % ); while the butanol fraction (67.05±0.40 % ) showed higher PDE-5 inhibition than the reference, sildenafil (23.06±0.70 % ). Administration of cyclosporine caused notable ( p < 0.05) elevation of systolic/diastolic blood (131.00 ± 1.22/93.25 ± 1.49 mmHg) pressure plus elevated heart rate when in comparison with the normotensive rats (106.25 ± 1.65/85.25 ± 1.18 mmHg). Treatment of hypertensive rats with ELPA significantly reduced elevated activities of ACE, PDE-5, AChE, and arginase to values that are not significantly ( p < 0.05) different from those of the rats treated with the reference drug. This result could validate the use of P. africana as an antihypertensive agent in folklore.