Evaluation of antibacterial effects of Rhizophora apiculata pyroligneous acid on pathogenic bacteria

Aim: Rhizophora apiculata pyroligneous acid is a crude condensate produced from the distillation of smoke generated in the process of charcoal making has the potential to be used as antibacterial agent to treat bacterial infections. In this study, pyroligneous acid (PA), concentrated pyroligneous acid (CPA), Dichloromethane extract of CPA namely DCM A and B were tested against eight Gram positive and eight Gram negative pathogenic bacteria. Methodology and Results: The antimicrobial activities were studied by using disc diffusion method and broth dilution method. The effect of the extract on the growth profile of the bacteria was examined via time-kill assay. Moreover, microscopic observations using scanning electron microscopy (SEM) was done to determine the major alterations of Bacillus subtilis cells after treated with extract. The results exhibited significant inhibition zones within the range of 13.0- 19.0 mm for PA, 19.0-23.0 mm for CPA, 15.0-17.0 mm for DCM A and 14.0-16.0 mm for DCM B. The results also revealed that extract DCM B of CPA was the most potential to be used as antibacterial agent with the minimum inhibitory concentration (MIC) values between 1.56-3.12 mg/mL. Scanning electron micrographs of DCM B treated Bacillus subtilis confirmed the damaged cells caused by the extract. Conclusion, significance and impact of study: Data from this investigation revealed that Rhizophora apiculata pyroligneous acid may be a broad antimicrobial agent against pathogenic bacteria.