Methanolic extract of swietenia macrophylla exhibits antibacterial and antibiofilm efficacy against gram-positive pathogens

Abstract

Gram-positive pathogens cause infections such as pneumonia, skin infections, anthrax, and sinusitis. The objective of this study was to determine the phytochemical profile, antibacterial and antibiofilm efficacy of Swietenia macrophylla methanolic extract (SMME) against Gram-positive pathogens. The secondary metabolites of SMME were analyzed using GC-MS while the antibacterial efficacy of SMME against Staphylococcus aureus ATCC 33862, Bacillus cereus ATCC 11778, Streptococcus pneumonia ATCC 19615, and Clostridium sporogenes ATCC 13124 was assessed using MIC and MBC assays. Biofilm biomass assay and time-kill assay were performed to determine the antibiofilm activity of SMME against the pathogens. Results demonstrated that six common antibacterial secondary metabolites were present in the SMME. The major compound was found to be β-amyrin (22.8%). The SMME showed the lowest MIC values against B. cereus (31.25 μg/mL) and C. sporogenes (31.25 μg/mL) and the lowest MBC value against S. aureus (1000 μg/mL). The SMME also significantly (p<0.05) inhibited all the biofilms. It started to inhibit S. pneumonia and C. sporogenes biofilms after 12 h of exposure. On the other hand, the BIC50 value showed that the SMME was most effective against B. cereus. In conclusion, the secondary metabolites in the SMME may contribute to the antibacterial and antibiofilm efficacy against Gram-positive pathogens.