Antibacterial and antifungal activity of Terminalia arjuna Wight & Arn. bark against multi-drug resistant clinical isolates

Abstract

Objective: To evaluate antimicrobial activity of Terminalia arjuna (T. arjuna) bark against clinical strains of multi-drug resistant bacteria, and Candida spp. isolated from patients, as well as the corresponding reference strains. Methods: The antimicrobial activity of water, methanol and chloroform extracts of T. arjuna bark were evaluated by agar-well diffusion method, followed by determination of minimum inhibitory concentration (MIC) by broth micro-dilution method. The clinical isolates were studied for antibacterial susceptibility by Kirby and Bauer disk diffusion technique. Results: The water and methanolic extracts of T. arjuna bark produced significant zones of inhibition against twenty-two tested bacteria including eight uropathogens. MIC values against the bacteria were found in the range of 0.16 to 2.56 mg/mL. The chloroform extract did not exhibit antibacterial activity. The polar extracts of T. arjuna also demonstrated strong antifungal effect against eight species of Candida, with MIC between 0.16 and 0.64 mg/mL. The antimicrobial efficacy of the polar extracts was found to be commensurate with high polyphenol content in contrast to the non-polar (chloroform fraction). Conclusions: This study has revealed the therapeutic prospect of T. arjuna bark for the treatment of microbial diseases. The polar fraction of the bark could be used for development of novel antimicrobial agents, particularly against urinary tract infections, and candidiasis/candidaemia.