POTENTIAL ANTIOXIDANT, ANTI-INFLAMMATORY AND ANTIBACTERIAL EVALUATION OF EXTRACTS OF LEUCAS ASPERA USING IN VITRO MODELS

摘要

Objective: To evaluate the potential antioxidant, anti-inflammatory and antibacterial activities of aqueous and methanolic extracts of leaves of Leucas aspera (Thumbae). Methods: Phytochemical screening of the leaves of L. aspera was followed by analysis of antioxidant activity by means of DPPH (2, 2-diphenyl-1-picrylhydrazyl) radical scavenging activity. In vitro anti‐inflammatory activity was evaluated using lipoxygenase inhibition, albumin denaturation assay, membrane stabilization assay and proteinase inhibitory activity at different concentrations. Aspirin was used as a standard drug for the study of anti‐inflammatory activity. Linear regression analysis was used to calculate half maximal inhibitory concentration, IC50 value. The zone of inhibition was performed against common pathogens to determine the antimicrobial activity at different concentrations of plant extracts (60%, 70%, 80%). Results: The phytochemical analysis revealed the presence of carbohydrates, amino acid, alkaloids, tannins, flavonoids, glycosides, xanthoproteins, and phenols. The total phenolic and flavonoid content was found to be 2.25±0.04 mg GAE/g (gallic acid equivalents) and 1.2±0.05 mg QE/g (Quercetin equivalents) of fresh weight tissue respectively. The IC50 values for hydrogen peroxide scavenging activity were found to be 244.6 μg/ml. The extract inhibited the lipoxygenase enzyme activity with an IC50 value of 356.3 μg/ml. Maximum inhibition of heat-induced protein denaturation of 69% was observed at 400 μg/ml, IC50 249.6 μg/ml. Proteinase activity was also significantly inhibited (IC50 = 421.6 μg/ml). Membrane stabilization assay attributed minor protection by the leaf extract with an IC50 of 206.7. It was observed that E. coli were inhibited at all concentrations, followed by Klebsiella and Pseudomonas . Conclusion: Results indicate that L. aspera possess anti-inflammatory properties due to the strong occurrence of polyphenolic compounds such as alkaloids, flavonoids, tannins and steroids that serve as free radical inhibitors or scavenger. Compounds of the plant L. aspera may hence be used as lead compounds for designing potent anti-inflammatory drug which can be used for treatment of various diseases.