Ocimum sanctum L. a potential angiotensin converting enzyme (ACE) inhibitor useful in hypertension

Abstract

The main objective of this study was to determine the in vitro Angiotensin Converting Enzyme (ACE) inhibition and antioxidant activity of standardized extract of the Ocimum sanctum L. leaves and its fractions. The ACE inhibition activity and antioxidant activity were investigated by UV method. In ACE inhibition method, the synthetic substrate hippuryl-L-histidyl-L-leucine was allowed to react with a test sample containing ACE, to produce hippuric acid. Dried hippuric acid was dissolved in distilled water, the absorbance of the solution was determined in the ultraviolet region and from the concentration of hippuric acid and the ACE inhibition activity was calculated. The antioxidant activity of the plant extract/fractions were examined on the basis of the scavenging effect on the stable DPPH free radical activity. Different concentrations of methanol extract of O. sanctum L. and eugenol were subjected to HPLC analysis using the mobile phase (methanol: water: acetic acid; 60 %: 40 %: 1 %). O. sanctum L. oil, eugenol and ethyl acetate fractions showed the maximum ACE inhibition activity in a concentration-dependent manner with IC₅₀ value of 32.11 ± 3.6, 42.16 ± 2.7 and 56.83 ± 2.8 µg/mL, respectively. Strong DPPH radical scavenging was also found in O. sanctum L. oil, methanol extract and ethyl acetate fractions, showing IC₅₀ value of 40.31± 3.5µg/mL, 105.62 ± 4.6 and 145.31 ± 5.8µg/mL, respectively. O. sanctum L. extract/fractions, eugenol and O. sanctum L. oil inhibited ACE in concentration-dependent manner.