Background: Hypertension is a common debilitating illness among people in both developed and developing countries. This study investigated the effect and possible mechanism of the antihypertensive activity of lycopene-rich extract of Solanum lycopersicon (LRESL) on Wistar rats. Methods: Sixty (60) hypertensive Wistar rats were divided into seven experimental groups viz: Group A served as a normotensive group and received feed and clean distilled water ad libitum. Group B was the hypertensive untreated group; Groups C-E served as hypertensive group administered with 100, 200, and 400 mg/kg LRESL, respectively. While groups F and G were hypertensive and received 10 mg/kg amlodipine and G received 200 mg/kg of LRESL+ 0.5 mg/kg Lisinopril respectively. Results: There was a statistical significant decrease (P<0.05) in the Systolic and Diastolic Blood Pressure (SBP and DBP) and the decrease was in a dose-dependent manner. The mean heart rate (MHR) showed no statistical significant difference (P>0.05) among the groups. The total cholesterol (TC) increased in the positive and normal control compared to other groups. There was a significant decrease in the triglyceride (Tg), low density lipoprotein cholesterol (LDL-C) of all hypertensive treated groups. The decrease in the LRESL treated groups was in a dose – dependent manner and there was no significant (P>0.05) difference between the groups compared to the normotensive and positive control. Moreover, the high density lipoprotein cholesterol (HDL-C) had a significant reverse effect of the LDL-C as there was a significant (P<0.05) increase in HDL-C and the increase was more significant in group E and G respectively. The serum cardiac arginase (SCAr) activity also decreased significantly (P<0.05) in all groups except group B compared to the normotensive and positive control groups and in a dose –dependent manner. The serum nitric oxide (SNO) concentration also increased in all test groups except the positive control group and in a dose- dependent pattern. Conclusion: This study therefore suggests that LRESL has an antihypertensive property and elicited this through multiple mechanisms involving a decrease in SCAr, LDL-C, body weight and marked elevation of SNO and could be used as a novel compound channeled into the production of antihypertensive drugs.

Keywords: : Lycopene, Cardiac arginase, Nitric oxide, Lipid profile, and body weights.