Exploring the Anti-Hypertensive Potential of Lemongrass-A Comprehensive Review

Abstract

Lemongrass (Cymbopogon citratus (DC) Stapf) is a herb commonly used in folk medicine for many purposes. However, its anti-hypertensive potential has not yet been thoroughly studied. This paper reviews the anti-hypertensive effects of both lemongrass and its main compound citral in in vitro, ex vivo, preclinical and clinical studies. Lemongrass essential oil contains terpenes and their derivatives, whereas extracts contain different classes of polyphenols. Both citral and lemongrass display vasorelaxant activity ex vivo, acting by the promotion of endothelial nitric oxide/prostanoids secretion together with the blockage of calcium channels in the vascular smooth muscle. Citral also displays a negative chronotrope effect, probably due to a centrally mediated enhancement of parasympathetic activity. In both healthy and hypertensive animals, the acute administration of lemongrass results in a decrease in blood pressure, sometimes accompanied by a compensatory increase in heart rate. Similarly, in healthy and hypertensive human subjects, the consumption of lemongrass tea decreases blood pressure. Additionally, a weak/moderate diuretic activity has also been reported in animals and humans, although the mechanisms of action remain elusive. Future preclinical studies are necessary to identify other compounds with anti-hypertensive activity and additional pharmacological pathways. Although well tolerated, the safety profile of lemongrass should be better characterized.

Keywords: anti-hypertensive; cardiovascular; lemongrass; review; vasorelaxant.

Figure 1

Aerial parts of Cymbopogon citratus (DC) Staph. Photograph by Forest and Kim Starr from Jardim Botânico UTAD, Flora Digital de Portugal (https://jb.utad.pt, accessed on 1 August 2022).

Figure 2

Chemical structures of the most prevalent bioactive compounds identified in lemongrass essential oil: geranial (A) and neral (B), whose mixture constitutes citral, β-myrcene (C), citronellal (D), geraniol (E) and limonene (F). These structures were drawn by Chem Spider Draw software.

Figure 3

Scheme of the probable vasorelaxation mechanisms of citral and of lemongrass products (LP). An endothelial cell is represented on top and a vascular smooth muscle cell at the bottom (GC—guanylyl cyclase; MLCP—myosin light-chain phosphatase; NO—nitric oxide; NOS—nitric oxide synthase; ROCK—Rho-associated protein kinase; ROS—reactive oxygen species; VGCC—voltage-gated calcium channel).