Phytochemical Composition and Inhibitory Activities of Hibiscus sabdariffa and Cucumis sativus Infusions Against Angiotensin-Converting Enzyme

Abstract

Hibiscus sabdariffa and Cucumis sativus are often used in ethnomedicinal practice for treating several health conditions, including hypertension. The present study aimed to investigate the in vitro inhibitory activities of H. sabdariffa and C. sativus against angiotensin-converting enzyme (ACE) and their phytochemical properties directly from their infusions. Each infusion was prepared with a concentration of 10, 20, and 30 grams of plant material in 300 ml of hot distilled water. Combinations of both plants were also prepared in 1:1, 2:1, and 1:2 ratios. The inhibitory activities were determined by the colorimetric method. The results showed that the highest inhibition rates of H. sabdariffa and C. sativus infusions were 88.741±0.001% and 92.180±0.001%, respectively. Meanwhile, the highest inhibition rate of the combination infusion was obtained from the ratio of H. sabdariffa: C. sativus (1:2), which was 96.062±0.001%, although this result was still below the inhibitory activity of Captopril (97.393±0.001%). The phytochemical screening results indicated that H. sabdariffa infusions contain saponins and tannins, and C. sativus infusions contain alkaloids, saponins, and terpenoids. This study concluded that the infusion with the ratio of H. sabdariffa: C. sativus (1:2) demonstrated the strongest inhibitory activity against ACE and, therefore, could potentially be utilized as a functional drink for managing hypertension.