These authors contributed equally to this work.Pseudomonas aeruginosa (P. aeruginosa) colonize on most wounds and live as biofilm, which causes antibiotic resistance and wounds unhealed. To investigate the effects of 5-substituted 3,4-dihalo-5H-furan-2-one compounds on biofilm formation of P. aeruginosa, a set of 5-(aryl-1¢-hydroxy-methyl)-or 5-(aryl-2-methylene)-3,4-dihalo-5H-furan-2-one compounds were designed and synthesized. Their inhibitory activities on biofilm formation of P. aeruginosa were studied by MIC assay, quantitative analysis of biofilm inhibition, and observation of biofilm formation with SEM. It was found that compounds 2i, 3f, 3i showed remarkable effects of biofilm formation inhibition on P. aeruginosa. Furthermore, molecular docking was performed to identify the key structural features of these compounds with the binding site of LasR receptor. The bacterium produce, release, and detect the autoinducers (AI) to engage in multicellular behavior and co-ordinate gene expression with some changes of physiology such as biofilm formation and virulence factor secretion. This chemical communication among bacterium is called quorum sensing (QS) (1). Pseudomonas aeruginosa are found in most chronic wounds (2,3). They colonized in this specialized surface, living as a biofilm style (4,5) with the help of quorum-sensing communication, and they may cause serious antibiotics resistance and immunology dysfunction of bodies (2,6,7). As wounds are easily colonized by bacterium, infection has been regarded as one of the most important factors that aggravate wounds and even make them unhealed (8).Developing the QS antagonists, which can block the QS system of P. aeruginosa with the mechanism of reducing biofilm formation and virulence factor secretion, is a new strategy to counteract bacterial infection. The N-acyl homoserine lactones (AHLs) were identified as the QS autoinducer-1 (AI-1) of P. aeruginosa by the way of binding with key receptor LasR to form complex-complex dimeride and then combine on the definite site of DNA that eventually resulted in changes of gene transcription (9). The natural furanones (a, b) isolated from the macro-algae Delisea pulchra are revealed to be inhibitors of biofilm formation for several bacterial species, and their analogues (c, d) have also been found to be potential inhibitors (10-13).Recent study (14) has revealed that vinyl bromide moiety of brominated furanones is essential for their quorum-sensing-inhibitory activities. The ring vinyl bromide was proposed to covalently modify and inactivate LuxS. The LuxS is a key enzyme in biomass producing autoinducer-2 (AI-2) that was the signal of both Gram-negative and Gram-positive bacterium QS systems. Once the path of AI-2 agonist was interfered, the QS system may be blocked to a large extent. It was reported (15) that AHLs modified with substituted aromatic nucleus would exhibit a remarkable improvement for quorum-sensing-inhibitory effect.Based on scientific evidences as mentioned earlier, we aim to develop a series of new QS ...