Phytotherapy of Hypertension: An Updated Overview.

Background: Cardiovascular disorders are the leading cause of morbidity and mortality throughout the globe. Hypertension is the main risk factor that contributes to the development of many diseases. The use of herbal therapies, medicinal plants and their derivatives for the remedy and management of hypertension is well-recognized and popular among a wide part of the world population.
Methods: The aim of the current review was to collect, treat, and critically analyze the published research studies relative to experimental and clinical investigations which have studied the blood pressure lowering abilities of medicinal plant derivatives in the last decade. This review was organized into three principal axes; the first axis was attributed to the in vivo and in vitro experimental studies; the second treated the clinical trials; while, the last one is devoted to analyze the mechanisms of action underlying the therapeutic antihypertensive effectiveness of phytochemicals.
Results: Different types of extracts and isolated molecules obtained from a large variety of species demonstrated their efficiency in improving the increase of blood pressure either experimentally or clinically. Medicinal species such as garlic (Allium sativum), celery (Apium graveolens), Black Cumin (Nigella sativa) and Ginseng (Panax) are among the most common and therapeutically used plant derivatives for controlling hypertension while Asteraceae, Apiaceae and Rosaceae are among the botanical families which were frequently studied in the last decade. Isolated compounds such as allicin and apigenin have received more interest in this field. Recent evidence from clinical trials suggests that a wide variety of herbal preparations and plant extracts or natural isolated compounds have a favorable therapeutic impact on blood flow. Interestingly, phytochemicals can either act directly on blood vessels via a vasorelaxant effect involving a variety of signaling cascades or indirectly through inhibiting or stimulating diversity of systems such as angiotensin-converting enzyme (ACE), renin-angiotensin system (RAS) or the diuretic activity. Hence, based on the findings of the present review medicinal plant derivatives could be used as preventive and curative agents in the case of cardiovascular disorders, particularly hypertension and could play a promoting function for the discovery of new antihypertensive agents.
Conclusion: The analysis of the published data shows that a great effort remains to be done to investigate the medicinal plants cited as antihypertensive through published ethnopharmacological surveys. The analysis of the literature in this field shows the lack of standardization at the level of experimental study methods as well as the need to study purified molecules. Moreover, the mechanistic studies when they exist remain in the whole partial. On the other hand, few advanced clinical studies have been conducted. Finally, the determination of the efficacy/safety ratio remains absent in almost all studies.
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