Bioactive metabolites of Alternaria alternata against multidrug resistant Pseudomonas aeruginosa

U S Ezhil Arivudainambi, Chandran Karunakaran and Ayyappan Rajendran

: J Bioengineer & Biomedical Sci

Abstract :

Pseudomonas aeruginosa is a leading pathogen that causes nosocomial pneumonia, bloodstream infections, and urinary tract infections in intensive care units. Infections caused by P. aeruginosa are associated with significant morbidity and mortality. The organism exhibits a high level of intrinsic resistance and only a limited number of antimicrobial agents are active against it. Fungal endophytes are receiving increasing attention by natural product chemists due to their diverse and structurally unprecedented compounds which make them interesting candidates for drug discovery. In the present study, a novel endophytic fungus Alternaria alternata was isolated from the medicinal plant Vitex negundo L. Extracts of Alternaria alternata were obtained using hexane, ethyl acetate and methanol solvents. The fungal extracts exhibited an effective antimicrobial activity against bacterial and fungal strains. The extracts were also analyzed for antibacterial activity against ofloxacin, ciprofloxacin and cephotaxaime resistant P. aeruginosa strains (1-8). The ethyl acetate extract showed an effective antibacterial activity against P. aeruginosa strain 7 with minimal inhibitory concentration of 40 μg/mL. The synergistic action of endophytic fungal extract with antibiotics such as ciprofloxacin and cephotaxime was observed against P. aeruginosa strains 1, 3 and 7. These results clearly indicated that the metabolite of endophytic fungus Alternaria alternata is a potential source for new antibiotic compound.