Biofilm associated, multidrug resistant Pseudomonas aeruginosa infection remain a challenging problem in the clinical field since the conventional antibiotic therapy are largely inefficient and new approaches are needed. Inactivating the QS virulence mechanism with anti-infective agent is an attractive approach to prevent bacterial infections without resistance development. Seagrass Halodule pinifolia (Miki) Hartog has been shown to exhibit potential antimicrobial activities against harmful pathogens. Our study investigated the effects of seagrass H. pinifolia leaf extract and its bioactive constituents on QS-mediated virulence factors and biofilm formation in P. aerugonasa PAO1. Preliminary screening on antibiofilm activity showed that the methanolic extract of H. pinifolia exhibited potential inhibition of biofilm formation (96%) as compared to the control respectively. Further, the potential extract was column fractionated and the active fraction was characterized by GC-MS. In total eight active compounds (protocatacheuic acid (69.3%), rosmarinic acid (63.5%), caffeic acid (59.18%), p-coumaric acid (59.08%), 4-methoxybenzoic acid (53.19%), naringenin (52.9%), vanillic acid (49.19%), 4-hydroxybenzoic acid (41.73%)) were profiled from fraction 2 and were purified by HPLC, structurally confirmed by NMR. Among the eight compounds studied, 4-methoxybenzoic acid (4-MBA) showed an effective inhibition of bacterial growth and was considered as a lead molecule with minimum inhibitory concentration (MIC) of 62.5 μg/mL. Further the effect of 4-MBA on QS mediated virulence factors demonstrated that the compound at MIC concentration reduced the virulence factor production such as elastase (87.5%), protease (79.38%), pyocyanin (91.46%), rhamnolipid (86%), alginate (86%), chitinase (55%), exopolysaccharide production (83.72%) and CSH (78.39%) over the control respectively. Moreover, 4-MBA down regulated the QS-mediated virulence transcript levels upon treatment with 4-MBA. The present findings suggests that seagrasses may act as a newer source for the marine based drug discovery and the lead compound 4-MBA derived from H. pinifolia may act as anti-infective agent against P. aeruginosa as it controls the QS-mediated virulence production.

与生物膜相关的，多药耐药的铜绿假单胞菌感染在临床领域仍然是一个具有挑战性的问题，因为常规抗生素治疗效率低下，需要新的方法。用抗感染剂灭活QS毒力机制是防止细菌感染而不产生耐药性的一种有吸引力的方法。海草Halodule pinifolia（Miki）Hartog已显示出对有害病原体的潜在抗菌活性。我们的研究调查了海草H. pinifolia叶提取物及其生物活性成分对铜绿假单胞菌QS介导的毒力因子和生物膜形成的影响。PAO1。上抗生物膜活性初步筛选表明的甲醇提取物H. pinifolia分别与对照相比表现出生物膜形成（96％）的潜在抑制作用。此外，将潜在的提取物进行柱分离，并通过GC-MS对活性组分进行表征。在总共八个活性化合物（protocatacheuic酸（69.3％），迷迭香酸（63.5％），咖啡酸（59.18％），p从馏分2中分离出-香豆酸（59.08％），4-甲氧基苯甲酸（53.19％），柚皮素（52.9％），香草酸（49.19％），4-羟基苯甲酸（41.73％））并通过HPLC纯化，通过NMR在结构上证实。在研究的八种化合物中，4-甲氧基苯甲酸（4-MBA）表现出对细菌生长的有效抑制作用，被认为是最小抑菌浓度（MIC）为62.5μg/ mL的先导分子。此外，4-MBA对QS介导的毒力因子的影响表明，化合物在MIC浓度下降低了毒力因子的产生，例如弹性蛋白酶（87.5％），蛋白酶（79.38％），绿脓素（91.46％），鼠李糖脂（86％），海藻酸盐（86％），几丁质酶（55％），胞外多糖的产生（83.72％）和CSH（78.39％）分别高于对照组。此外，用4-MBA治疗后，4-MBA下调QS介导的毒力转录水平。目前的发现表明，海草可能作为海洋药物发现的新来源，而海藻类的主要化合物4-MBA由于其控制QS介导的毒力产生，因此，H。pinifolia可以作为抗铜绿假单胞菌的抗感染剂。