Phytopharmacological Evaluation of ACE Inhibitors from Medicinal Plants of Ayurveda

Abstract

Hypertension is a becoming a major threat to the world. In the search of lead molecules from plant origin as a substitute for toxic synthetic drugs, 26 Indian medicinal plants and foods were screened for their ACE (Angiotensin Converting Enzyme) inhibitory activity. IC50 (50% inhibition of ACE) values of hydroalcoholic crude extracts and fraction were determined by a colorimetric method. Active fractions were further screened to determine the enzyme kinetics, newlinemode, specificity and mechanism of inhibition. Standardization was done by determining total phenolics and flavonoids as gallic acid and quercetin equivalents/mg of extract respectively. Among 26 crude extracts, Cynara scolymus extract showed the best activity, IC50 value 356.62and#956;g/mL. ACE inhibition resulting from protein precipitation was highest in Coscinium newlinefenestratum. Lineweaver-Burk plots revealed a competitive mode of inhibition for Punica newlinegranatum ethyl acetate fraction. Fractions of Cassia occidentalis, Cynara scolymus and Embelia ribes were found to be non-specific inhibitors of ACE. Embelia ribes, Cassia occidentalis and Coscinium fenestratum fractions inhibited the ACE by Zn2+ ion chelation. Further, in the search for safe and effective lead molecules from natural sources, (MP) Mucuna pruriens L. (Fabaceae) seeds were utilized for exploring the antihypertensive potential. Traditionally it is used as diuretic and Hypotensive. Bioassay-guided fractions were utilized for newlinethe isolation of active compounds by column chromatography. IC50 value, enzyme kinetics and inhibition mechanism were determined. In vivo time and dose-dependent hypotensive study\ followed by changes in the MAP (Mean arterial pressure) induced by angiotensin I (3 nmol/kg), newlineangiotensin II (3 nmol/kg), and to bradykinin (10 nmol/kg) in anesthetized rats was done. Plasma newlineand tissue ACE activities were also determined. Phytochemical analysis by spectroscopic newlinetechniques revealed the presence of known compounds like genistein, ursolic acid and L-DOPA from the ethyl acetate and water fracti