EFFECT OF CAFFEINE AND CAFFEIC ACID ON SELECTED BIOCHEMICAL PARAMETERS IN L-NAME INDUCED HYPERTENSIVE RATS

Abstract

Caffeine and caffeic acid are two bioactive compounds found richly distributed in many plant foods especially cocoa and coffee. Hence, this study investigated the effect of caffeine, caffeic acid and their various combinations on the activities of angiotensin-1-converting enzyme (ACE) and arginase as well as malondialdehyde (MDA) content and nitric oxide (NO) level in hypertensive rats. Aqueous solutions of caffeine and caffeic acid were prepared (1 mg/ml). Thereafter, the ability of the compounds to inhibit pro-oxidants (FeSO4 and sodium nitroprusside) induced lipid peroxidation in rat heart was assessed in vitro. Also, the effect of aqueous solutions of caffeine, caffeic acid and their various combination on some enzymes relevant to cardiovascular disease (phosphodiesterase-5, ACE and arginase) were determined in vitro. Thereafter, the effect of caffeine, caffeic acid and their various combinations were assessed in Nω-Nitro-L-arginine methylester (L-NAME) induced hypertensive rats. Animals were divided into eleven groups of six animals each. All administration was done orally and the experiment lasted for 20 days. Haemodynamic parameter of normal and hypertensive rats was determined by tail-cuff plethysmography. The results showed that caffeine, caffeic acid and their combinations elicited antioxidant properties via scavenging of free radicals and inhibitory effect on enzymes relevant to hypertension in vitro. Furthermore, caffeine, caffeic acid and their various combinations demonstrated anti-hypertensive properties by lowering systolic blood pressure in L-NAME induced hypertensive rats. In addition, the test compounds and their various combinations reduced MDA levels, ACE and arginase activities and increased NO level in L-NAME-induced hypertensive rats. Conclusively, caffeic acid exhibited higher cardioprotective properties than caffeine, while the combination of high percentage caffeic acid and low caffeine exhibited the best cardioprotective properties.