Blood pressure lowering and cardio-protective effects of garlic (Allium sativum) and ginger (Zingiber officinale) extracts in some laboratory animals

The efficacy of Zingiber officinale on dyslipidaemia, blood pressure, and inflammation as cardiovascular risk factors: A systematic review

BACKGROUND & AIMS

Hypertension, dyslipidaemia, and chronic inflammation contribute to the development of cardiovascular disease (CVD). Zingiber officinale has been suggested to reduce these CVD risk factors; however, the clinical evidence remains unclear. This systematic review aims to analyse the effect of Z. officinale as a sole intervention on these risk factors.

METHODS

In this PRISMA-based systematic review, we included randomised clinical trials from PubMed, Scopus and Cochrane Database of Systematic Reviews (July 2020) analysing triglycerides, low- and high-density lipoprotein (LDL, HDL), total cholesterol, C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-α), interleukin 1, 6, 10, systolic and/or diastolic blood pressure as outcomes. Quality of studies was evaluated by JADAD and the Cochrane risk-of-bias tools.

RESULTS

A total of 24 studies were included, mostly (79.2%) showing low risk of bias. These were based on obesity and cardio-metabolic derangements (33.3%), type 2 diabetes mellitus (37.5%), and miscellaneous conditions (29.2%). While total cholesterol and triglycerides levels mostly improved after Z. officinale, results were inconsistent for other blood lipids markers. Inflammatory markers (CRP, TNF-α) were more consistently reduced by Z. officinale, while only 3 studies reported a non-significant reduction of blood pressure.

CONCLUSIONS

Although there remains a paucity of studies, Z. officinale may be beneficial for improving dyslipidaemia and inflammation.

A systematic review with meta-analysis on the antihypertensive efficacy of Nigerian medicinal plants

ETHNOPHARMACOLOGICAL RELEVANCE

Despite the promising effects of herbal preparations in lowering blood pressure (BP), hypertension remains a major clinical challenge in Nigeria. The BP-lowering effects of medicinal plants are due to the presence of bioactive compounds.

AIM OF THE STUDY

This meta-analysis presents a precise estimate of the therapeutic benefits of medicinal plants utilized in Nigeria for the management of hypertension in animals and humans.

METHODS

A systematic literature search was performed through Cochrane, PubMed, Science Direct and Scopus databases from inception until February 28, 2021 using search terms related to randomized controlled trials of Nigerian medicinal plants for hypertension. Additional studies were identified through manual search. BP was the main outcome that was measured after the intervention. Meta-analysis was performed using the Review Manager and Meta-Essential.

RESULTS

Nineteen trials comprising of 16 preclinical and 3 clinical studies were enrolled for the meta-analysis. A total number of 16 plants was identified of which H. sabdariffa was the highest reported plant. The plant extracts significantly lowered the systolic blood pressure (SBP) and diastolic blood pressure (DBP) of the hypertensive subjects compared to control. Weighted mean difference (WMD) for SBP (-43.60 mmHg, 95% CI: -63.18, -24.01; p<0.0001) and DBP (-29.50 mmHg, 95 CI: -43.66, -15.34; p<0.0001) was observed for the preclinical studies. For clinical trials, the WMD was -13.98 mmHg, 95 CI: -19.08, -8.88; p<0.00001 for SBP and -10.00 mmHg, 95 CI: -12.22, -7.78; p<0.00001 for DBP. High heterogeneity was observed for the outcome measures of preclinical studies, but not for the clinical studies. The observed substantial heterogeneity in preclinical studies may be linked to methodological shortcomings as evidenced by the results of the risk of bias assessment. There was no evidence of publication bias in animal trials for BP using the funnel plot and Egger's regression test (SBP, p=0.239 and DBP, p=0.112).

CONCLUSIONS

This study provides evidence of medicinal preparations for the treatment of hypertension. A well-conducted trial with methodological rigour and a longer duration of follow-up is required for their effective clinical utilization.

Therapeutic effects of medicinal plants on isoproterenol-induced heart failure in rats

AIMS

Natural products still serves as a hope for some illnesses which modern medicine fails to cure. Many people, either knowing their effects or not, are using these herbal products. Treatment of chronic heart failure (CHF) is yet a complicated clinical challenge and there is need to improve or make new therapeutic targets. Finding new agents for CHF is an important subject in cardiovascular drug research. In this study, we evaluated the effects of ten herbals on treatment of CHF on isoproterenol-induced model.

METHODS AND RESULTS

Ninety-six male Wistar rats (16 weeks old) were used in 12 groups. Transthoracic echocardiography was performed on the rats for confirmation of CHF model by decreasing ejection fraction. After 4 weeks' treatment, hearts were removed and blood samples were collected in tubes to measure plasma levels of laboratory findings. Our results showed that the mean of ejection fraction in model rats was 51.82 ± 3.49 percent and all of our used natural products could significantly increase the ejection fraction (P < 0.01). The most effective herbals in improving the ejection fraction were Allium sativum (30.69 %), Peganum harmala (26.08 %) and Apium graveolens (24.09 %). The best results in decreasing NT-ProBNP, was obtained from Allium sativum, Peganum harmala and Berberis vulgaris respectively. Our results showed that none of natural products had toxic effect on renal and liver tissues.

CONCLUSION

Our results showed that Allium sativum, Peganum harmala and Berberis vulgaris could significantly improve cardiac function by improvement of left ventricular remodeling, lowering hs-CRP and NT-ProBNP and echocardiographic indexes without liver or renal side effects.