Antimicrobial activity of Stevia rebaudiana against antibiotic resistant ESBL producing uropathogens and evaluation of its antioxidant activity

Abstract

Worldwide, about 150 million people are diagnosed with urinary tract infections (UTI) annually. Treatment of these common infectious diseases has become difficult due to the emergence of antibiotic resistant strains like ESBL (extended spectrum βlactamase) producers. Pathogenic organisms are unlikely to develop resistance against herbs that are blend of active compounds. The plant used in present study was Stevia rebaudiana which is traditionally used as a source of natural sweetener. Antibacterial activity of aqueous extract and four solvent extracts (petroleum ether, chloroform, methanol and ethanol) of Stevia rebaudiana leaves were investigated against 49 ESBL producing uropathogens. The methanol extract showed zone of inhibition in the range of 18-24mm as compared to aqueous extract which showed negligible zone of inhibition against the uropathogens. Minimum bactericidal concentration (MBC) was found to be in range of 10 mg/ml 20mg/ml. Methanolic extract of Stevia rebaudiana also showed synergistic activity along with ampicillin, thereby reducing the MBC of ampicillin from 10mg/ml to 200-300μg/ml. The antioxidant activity of Stevia rebaudiana was checked by DPPH method. The IC50 values of methanolic extract of Stevia rebaudiana and standard ascorbic acid were found to be 32.765 μg/ml and 6.474μg/ml respectively. The phytochemicals present in Stevia rebaudiana were analysed by HR-LCMS and confirmed the presence of eight major components including terpenes, flavanoids and Quinones that might be responsible for its antibacterial activity.