In vitro antibacterial potential of 1'S-1'-acetoxychavicol acetate (ACA) on oral opportunistic pathogens

Oral opportunistic pathogens resulting from poor oral health can lead to serious issues in elderly and immunocompromised individuals, including lower respiratory tract infections and aspiration pneumonia (AP). The main objective of this study is to evaluate the antibacterial effect 1'S-1'-acetoxychavicol acetate (ACA) isolated from Alpinia conchigera rhizome extract against selected oral opportunistic pathogens which are Staphylococcus aureus, Streptococcus pneumoniae, Klebsiella pneumoniae and Pseudomonas aeruginosa. In this study, a total of 13 respondents were recruited to obtain the clinical isolates of selected oral opportunistic pathogens. From these samples, 3 strains of S. aureus, 1 strain of S. pneumoniae, 3 strains of K. pneumoniae and 1 strain of P. aeruginosa were obtained and further tested. To achieve the objective, disc diffusion assay (DDA), minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and time kill assay were carried out to determine the antibacterial properties. Based on DDA results, ACA displayed good antibacterial activity against clinical isolates and ATCC strains of S. aureus, S. pneumoniae and P. aeruginosa with the zone of inhibition recorded at 25.07 ± 0.09 mm, 36.83 ± 0.85 mm and 14.00 ± 0.82 mm respectively while clinical isolates and ATCC strains of K. pneumoniae did not show any inhibition diameter. The range of MIC and MBC values for ACA recorded were between 0.39 mg/mL until 12.50 mg/mL. ACA exhibited both bacteriostatic and bactericidal properties mostly when treated with concentration of 2 × MIC and MIC at different time intervals. In conclusion, ACA possesses antibacterial effect against clinical isolates and ATCC strains of S. aureus, S. pneumoniae, K. pneumoniae and P. aeruginosa.