Abstract
Hibiscus species (Malvaceae) have been long used as an antihypertensive folk remedy. The aim of our study was to specify the optimum solvent for extraction of the angiotensin-converting enzyme inhibiting (ACEI) constituents from Hibiscus sabdariffa L. The 80% methanol extract (H2) showed the highest ACEI activity, which exceeds that of the standard captopril (IC50 0.01255 ± 0.00343 and 0.210 ± 0.005 µg/mL, respectively). Additionally, in a comprehensive metabolomics approach, an ultra-performance liquid chromatography (UPLC) coupled to the high resolution tandem mass spectrometry (HRMS) method was used to trace the metabolites from each extraction method. Interestingly, our comprehensive analysis showed that the 80% methanol extract was predominated with secondary metabolites from all classes including flavonoids, anthocyanins, phenolic and organic acids. Among the detected metabolites, phenolic acids such as ferulic and chlorogenic acids, organic acids such as citrate derivatives and flavonoids such as kaempferol have been positively correlated to the antihypertensive potential. These results indicates that these compounds may significantly contribute synergistically to the ACE inhibitory activity of the 80% methanol extract.
Highlights
Hibiscus sabdariffa Linn. (HS), Malvaceae (Syn: Roselle, Rozelle, red sorrel, Sour tea and Karkade) has been extensively used in different systems of medicine as antihypertensive tea [1]
It is worthy to mention that the activity of H2 and H3 exceed that of the standard captopril with IC50 0.210 ± 0.005 μg/mL
We investigated the 80% methanol extract for the abundant metabolites identified from the ultra-performance liquid chromatography (UPLC)/MS analysis
Summary
Hibiscus sabdariffa Linn. (HS), Malvaceae (Syn: Roselle, Rozelle, red sorrel, Sour tea and Karkade) has been extensively used in different systems of medicine as antihypertensive tea [1]. Animal studies have shown that consumption of HS extract reduces blood pressure in a dose dependent manner [4,5]. Administration of the HS aqueous extract to salt-induced hypertensive albino rats for 28 days showed a significant reduction in diastolic and Molecules 2020, 25, 2307; doi:10.3390/molecules25102307 www.mdpi.com/journal/molecules. Another study showed that the crude methanolic extract of HS possessed a vasodilator effect in the isolated aortic rings of hypertensive rats [1]. The aqueous extract of HS showed a dose dependent diuretic and natriuretic that may be mediated by nitric oxide release [8]. HS aqueous extract (150 mg/kg/day for 4 weeks) reduced the serum angiotensin converting enzyme (ACE) and plasma aldosterone in mild to moderate hypertensive Nigerians with equal efficacy as Lisinopril [9]. The anthocyanin rich fraction of HS calyces showed ACE inhibition activity [10]
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