Antimicrobial, antioxidant, and synergistic properties of two nutraceutical plants: Terminalia catappa L. and Colocasia esculenta L.

Antibiotics have been effective in treating infectious diseases, but resistance to these drugs has led to the emergence of new and reemergence of old infectious diseases. Using a combination of plant extracts and antibiotics is one way of combating these multidrug-resistant microorganisms. The aim of this investigation was to evaluate the antimicrobial and antioxidant properties of 2 nutraceutical plants: Terminalia catappa and Colocasia esculenta. The antimicrobial activity of the plants was evaluated against 25 microorganisms by agar well diffusion method. C. esculenta did not show any antimicrobial activity against bacteria and fungi. Therefore, only methanol extract of T. catappa was selected for further study of synergistic activity with standard antibiotics. Maximum synergistic activity was seen against fungi as compared to individual extracts. The methanol extract of T. catappa showed good antioxidant and antimicrobial activity. The synergistic effect demonstrates the potential of this plant as a candidate for antibiotic-resistance-modifying compounds. The results suggest that the leaves of T. catappa are a good source of natural antioxidants and antimicrobics.