MTT reduction assays revealed that the metabolic activity of P. aeruginosa mature biofilms decreased considerably up to 50% after only 3 h of incubation and after only 9 h of exposure to D-YaSP. Confocal laser scanning micrographs illustrated that a maximum biofilm eradication was found when treated with the extracts for 3 h, whereas the biomass, the average thickness, maximum thickness, and the surface to volume ratio of the treated biofilm was reduced after up to 18 h of contact time. It can be concluded that D-YaSP can effectively inhibit biofilm formation and eradicate mature biofilms of P. aeruginosa. It should be noted that G. mangostana and α-mangostin contribute in YaSP as principle active agents for anti-biofilm efficacy