Evaluation of the antibacterial and antifungal activities of the extracts of Aerides multiflora Roxb. a native medicinal orchid

Abstract

The present study was conducted to evaluate the antimicrobial activity of Aerides multiflora, an important epiphytic medicinal orchid in Bangladesh. Extracts from whole plants and seed pods were collected using methanol, chloroform, petroleum ether, and aqueous extract to testify their antibacterial activities against five bacterial strains, namely Bacillus cereus, E. coli, Staphylococcus aureus, Pseudomonas sp., and Shigella boydii. Four pathogenic fungi, namely Rhizopus oryzae, Aspergillus flavus, Aspergillus niger and Fusarium oxysporum were also tested. The antibacterial activities were evaluated using the disc diffusion method, and the antifungal activities were tested using the poison feeding technique. The whole plant methanol extract was superior to the other solvent extracts against the bacteria and fungi tested. The highest zone of inhibition by the whole plant methanol extract was recorded against Staphylococcus aureus (14.33 ± 0.19) and the highest percentage inhibition of mycelial growth was observed against A. flavus (62.19 ± 0.57). The value of minimum inhibitory concentration of the extracts was also analyzed. The whole plant methanol extract gave the lowest MIC value against both the tested bacteria and fungi. The results could be used for the isolation and characterization of the novel phytochemical effects on various infectious diseases, especially in view of the emergence of drug-resistant microorganisms such as antimicrobial and antifungal agents.