Chemical composition, angiotensin I-converting enzyme (ACE) inhibitory, antioxydant and antimicrobial activities of Ononis natrix leaves extracts

Background and aim: The use of synthetic antioxidants has begun to be restricted because of their induction of DNA damage and their toxicity. So, it is an interesting and useful task to find new sources for natural antioxidant and functional food. The health benefits of Ononis natrix leaves were widely investigated. The present study describes for the first time the antioxidant, antibacterial and antihypertensive activities of various solvent extracts of Ononis natrix leaves. Method: The aerial parts (leaves) of O. natrix were collected from the South of Tunisia and different solvent extracts were prepared. The antioxidant activities of extracts at different concentrations were evaluated using various in vitro antioxidant assays, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, reducing power, β-carotene bleaching and DNA nicking assays. The antibacterial and angiotensin I-converting enzyme (ACE) inhibitory were also investigated. Results: All the extracts showed strong antioxidant activity. The radical scavenging activities and reducing powers of all the extracts were close to those of the synthetic antioxidant BHA. The chloroform extract exhibited high inhibition of β-carotene bleaching and also showed a well DNA protection against degradation by hydroxyl radicals. Moreover, the antimicrobial activities of the extracts were tested against nine species of microorganisms, and the results obtained showed significant antibacterial activity against the Gram-positive and Gram-negative bacteria. O. natrix extract showed also important antihypertensive activities. Conclusion: The obtained results demonstrated the health benefit features of Ononis natrix leaves and their potential uses as feedstock of bioactive molecules.