Ya-Samarn-Phlae (YaSP) is a traditi

Ya-Samarn-Phlae (YaSP) is a traditional Thai polyherbal formula for the treatment of chronic wounds. Although its ethanol extract has been proven to possess several wound-related biological activities, there is no scientific information available for the infused oil of YaSP, which is its traditionally prepared form. This present study therefore aimed to evaluate the efficacy of different infused oils obtained from either fresh or oven-dried herbal parts of YaSP (F-YaSP and D-YaSP) against biofilms of Pseudomonas aeruginosa, which reside in chronic wounds. Its main active herbal component, Garcinia mangostana (F-GM and D-GM), as well as α-mangostin were also tested in this study. All infused oils significantly inhibited the biofilm formation of P. aeruginosa with a percentage of reduction ranging from 50 to 90%. Visualization of the inhibition of biofilm development was confirmed using scanning electron and atomic force microscopes. All tested agents resulted in a reduction in the mean average roughness of the biofilm, whereas only treating with D-YaSP, D-GM, and α-mangostin led to a decrease in both peak height and peak-valley height