Antibacterial and Biofilm Formation Inhibitory Activities of Kratom (Mitragyna speciosa Korth.) Leaf Extract Against Cutibacterium acnes

Abstract

Kratom (Mitragyna speciosa Korth.) is a tropical plant native to Southeast Asia and has demonstrated antibacterial activity; however, information regarding its activity against biofilm formation by Cutibacterium acnes remains limited. This study aimed to evaluate the antibacterial and biofilm formation inhibitory activities of ethanolic kratom leaf extract against C. acnes. Antibacterial activity was evaluated using the disc diffusion assay. Biofilm formation inhibition was assessed using a microtiter plate crystal violet assay with optical density measurement at 595 nm. The extract was tested at 1%, 0.5%, 0.25%, and 0.125% (w/v). The 1% extract produced the largest antibacterial inhibition zone among the extract treatments (10.8 mm). In the biofilm assay, the 1% extract produced 70.67% inhibition after 24 h and 58.75% after 48 h. The lowest tested concentration producing at least 50% biofilm inhibition was 0.5% (w/v) at both time points. These findings indicate concentration-related antibacterial and biofilm formation inhibitory activities of kratom leaf extract against C. acnes. The specific active compounds responsible for these effects remain to be identified.