Effects of aqueous extract of Hibiscus sabdariffa on the renin-angiotensin-aldosterone system of Nigerians with mild to moderate essential hypertension: A comparative study with lisinopril

Daniel Chukwu Nwachukwu, Eddy Ikemefuna Aneke, Leonard Fidelis Obika, Nkiru Zuada Nwachukwu, Daniel Chukwu Nwachukwu, Eddy Ikemefuna Aneke, Leonard Fidelis Obika, Nkiru Zuada Nwachukwu

Abstract

Objectives: The present study investigated the effects of aqueous extract of Hibiscus sabdariffa (HS) on the three basic components of renin-angiotensin-aldosterone system: Plasma renin, serum angiotensin-converting enzyme (ACE), and plasma aldosterone (PA) in mild to moderate essential hypertensive Nigerians and compared with that of lisinopril, an ACE inhibitor.

Materials and methods: A double-blind controlled randomized clinical study was used. Seventy-eight newly diagnosed but untreated mild to moderate hypertensive subjects attending Medical Outpatients Clinic of Enugu State University Teaching Hospital, Enugu were recruited for the study. Those in Group A received placebo (150 mg/kg/day), Group B were given lisinopril (10 mg once daily) while those in Group C received aqueous extract of HS (150 mg/kg/day). After 4 weeks of treatment, the levels of plasma renin, serum ACE, and PA were determined.

Results: HS and lisinopril significantly (P < 0.001) reduced PA compared to placebo by 32.06% and 30.01%, respectively. Their effects on serum ACE and plasma renin activity (PRA) were not significant compared to placebo; they reduced ACE by 6.63% and 5.67% but increased plasma PRA by 2.77% and 5.36%, respectively.

Conclusion: HS reduced serum ACE and PA in mild to moderate hypertensive Nigerians with equal efficacy as lisinopril. These actions are possibly due to the presence of anthocyanins in the extract.

Keywords: Aldosterone and essential hypertension; Hibiscus sabdariffa; angiotensin-converting enzyme; lisinopril; renin.

Figures

Figure 1
Figure 1
Effect of drug treatments on systolic blood pressure in mild to moderate hypertensive subjects. Each point on the graph represents the average of at least 25 independent measurements. Error bars are standard error of mean. **P < 0.01, ***P < 0.001 (placebo vs. Hibiscus sabdariffa), αααP < 0.001 (placebo vs. lisinopril) and βP < 0.05 (Hibiscus sabdariffa vs. lisinopril) two-way analysis of variance with Bonferroni posttest
Figure 2
Figure 2
Effect of drug treatments on diastolic blood pressure each point on the graph represents the average of at least 25 independent measurements. Error bars are standard error of mean; ***P < 0.001 (placebo vs. Hibiscus sabdariffa). αααP < 0.001 (placebo vs. lisinopril) two-way analysis of variance with Bonferroni posttest
Figure 3
Figure 3
Mean arterial pressure measurements following drug treatments. Each point on the graph represents the average of at least 25 independent measurements. Error bars are standard error of mean. *P< 0.05, ***P < 0.001 (placebo vs. Hibiscus sabdariffa) and ααP < 0.01, αααP < 0.001 (placebo vs. lisinopril) two-way analysis of variance with Bonferroni posttest
Figure 4
Figure 4
Plasma renin activity following drug treatments in mild to medium hypertensive subjects. Each point on the graph represents the average of at least 25 independent measurements. Error bars are standard error of mean
Figure 5
Figure 5
Serum angiotensin-converting enzyme measurements following the administration of test drugs in mild to medium hypertensive subjects. Each point on the graph represents the average of at least 25 independent measurements. Error bars are standard error of mean
Figure 6
Figure 6
Plasma aldosterone measurements following the administration of placebo (control), lisinopril and Hibiscus sabdariffa on mild to medium hypertensive subjects. Each point on the graph represents the average of at least 25 independent measurements. Error bars are standard error of mean. *P < 0.001 (placebo vs. Hibiscus sabdariffa) and ααP < 0.01, αααP < 0.001 (placebo vs. lisinopril) two-way analysis of variance with Bonferroni posttest

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