Hibiscus acid from hibiscus sabdariffa (malvaceae) has a vasorelaxant effect on the rat aorta

Ahmed M. Zheoat, Alexander I. Gray, John O. Igoli, Valerie A. Ferro, Robert M. Drummond

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)
114 Downloads (Pure)


Hibiscus sabdariffa (Malvaceae) is a plant that is widely recognised for its antihypertensive properties; however the constituent(s) responsible for this biological activity are presently unknown. The aim of this study was to identify the potential compounds that are responsible for the vasorelaxant activity of H. sabdariffa. Thereafter, the mechanisms involved in producing the vasorelaxation were investigated. The plant was extracted consecutively with hexane, ethyl acetate and methanol. The methanolic extract was subjected to bioassay-guided fractionation in order to isolate pure compounds that possessed vasorelaxant activity. The vascular effects of the pure compounds were studied on the rat aorta in vitro using myography techniques. Hibiscus acid produced a concentration-dependent relaxation of the rat aorta pre-contracted with either phenylephrine (3 μM) or KCl (60 mM), irrespective of the presence of the endothelium. When the tissue was pre-contracted with phenylephrine, the concentration required to produce 50% relaxation (IC50), was 0.09 ± 0.01 mg/ml. Hibiscus acid had no effect on the phasic contraction induced by phenylephrine in Ca2+-free physiological solution; but it did affect the component of the contraction that is due to Ca2+ influx. In parallel studies, garcinia acid, a diastereoisomer of hibiscus acid, was found to have an almost identical vasorelaxant effect. The vasorelaxant action of both compounds is most likely due to the inhibition of Ca2+ influx via voltage-dependent Ca2+ channels.

Original languageEnglish
Pages (from-to)5-13
Number of pages9
Early online date25 Jan 2019
Publication statusPublished - 30 Apr 2019


  • Ca channels
  • garcinia acid
  • hibiscus acid
  • hibiscus sabdariffa
  • vascular smooth muscle
  • vasorelaxation


Dive into the research topics of 'Hibiscus acid from hibiscus sabdariffa (malvaceae) has a vasorelaxant effect on the rat aorta'. Together they form a unique fingerprint.

Cite this