Inhibition of angiotensin converting enzyme by Rhazya stricta, Moringa peregrina and Achillea fragrantissima, used in traditional system of medicine in Arabian Peninsula: Implication in the management of hypertension

In recent years, there has been a marked increase in the popularity of medicinal plants derived from the traditional sources of knowledge. This is in congruence to the associated benefits of ease of accessibility and low cost of disease management. Additionally, most of the potent drugs being used currently for chronic diseases are derivatives of natural products. In the current study, the potential of hydro-alcoholic extracts of Rhazya stricta, Moringa peregrina and Achillea fragrantissima to inhibit angiotensin converting enzyme (ACE) which is involved in the etiology of hypertension and cardiovascular disorders, were examined. The herbal derivatives of these plants have been used for a long time now, in traditional systems of various ethno-pharmacological cultures in Arabian Peninsula and worldwide. The study also evaluated the anti-oxidative properties of these extracts which are reflected by their ability to inhibit DPPH radicals. The phytochemical analysis which focused on the tannin contents of the three extracts demonstrated a direct proportionality between the tannin content and the ACE inhibition activity of the tested extracts in the order: R. stricta > M. peregrina > A. fragrantissima. The results partially support the use of these plants as nutraceuticals and warrant the need for further studies on isolation and characterization of the bioactive constituents of these plants that are responsible for the associated pharmacological property of inhibiting ACE. Key words: Medicinal plants, hypertension, angiotensin converting enzyme, oxidative stress.