Antioxidant and antibacterial activities of different solvent extracts of Citrus acida leaf and correlation with phenolic content

Plants belonging to Citrus sp. are rich in phenolics which are of great medicinal value. The present study focuses on antioxidant and antibacterial potential of various extracts of a locally grown variety of Citrus acida leaves and their correlation with phenolic content. Multiple in-vitro models have been used to evaluate the free radical scavenging potential. Ethanol extract showed the highest DPPH (1,1-diphenyl-2-picrylhydrazyl), nitric oxide, superoxide scavenging and iron chelation activity with IC50 values 40.44±1.41, 132.89±4.69, 94.64±4.44 and 281.88±6.49 μg/ml, respectively. The highest ABTS (2, 2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) and hydrogen peroxide scavenging activities with IC50 value 34.95±1.23 and 117.50±2.70 μg/ml, respectively were exhibited by hexane extract. Dose dependent reducing power was observed with all the extracts. The antioxidant potential of the extracts showed significant correlation with the total phenolic content in four assay models with Pearson's correlation coefficient (r) values ranging from 0.846–0.989. The extracts showed antibacterial activity against all the test isolates with zone of inhibition ranging from 7.33±1.53 to 28.00±1.00 mm. Maximum antibacterial activity was recorded by ethyl acetate extract against Pseudomonas aeruginosa. Ethyl acetate and ethanol extract exhibited the lowest MIC values of 2.5 mg/ml against Shigella dysenteriae and Vibrio mimicus, respectively. The results suggest that citrus leaves can play a promising role in the development of herbal drugs with antioxidant and antibacterial activities.