Many human diseases, including cystic fibrosis lung infections, are caused or exacerbated by bacterial biofilms. Specialized modes of motility, including swarming and twitching, allow gram-negative bacteria to spread across surfaces and form biofilms. Compounds that inhibit these motilities could slow the spread of biofilms, thereby allowing antibiotics to work better. We previously demonstrated that a set of plant-derived triterpenes, including oleanolic acid and ursolic acid, inhibit formation of Escherichia coli and Pseudomonas aeruginosa biofilms, and alter expression of genes involved in chemotaxis and motility. In the present study, we have prepared a series of analogs of oleanolic acid. The analogs were evaluated against clinical isolates of E. coli and P. aeruginosa in biofilm formation assays and swarming assays. From these analogs, compound 9 was selected as a lead compound for further development. Compound 9 inhibits E. coli biofilm formation at 4 µg/mL; it also inhibits swarming at ≤1 µg/mL across multiple clinical isolates of P. aeruginosa, E. coli, Burkholderia cepacia, and Salmonella enterica, and at <0.5 µg/mL against multiple agricultural strains. Compound 9 also potentiates the activity of the antibiotics tobramycin and colistin against swarming P. aeruginosa; this is notable, as tobramycin and colistin are inhaled antibiotics commonly used to treat P. aeruginosa lung infections in people with cystic fibrosis. qPCR experiments suggested that 9 alters expression of genes involved in regulating Type IV pili; western blots confirmed that expression of Type IV pili components PilA and PilY1 decreases in P. aeruginosa in the presence of 9.

中文翻译：

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优化的植物化合物，具有跨革兰氏阴性物种有效的抗生物膜活性。

细菌生物膜可导致或加剧许多人类疾病，包括肺囊性纤维化。包括群聚和抽搐在内的特殊运动模式使革兰氏阴性细菌可在整个表面扩散并形成生物膜。抑制这些功能的化合物可以减缓生物膜的扩散，从而使抗生素更好地发挥作用。我们以前证明了一组植物来源的三萜，包括齐墩果酸和熊果酸，抑制大肠杆菌和铜绿假单胞菌生物膜的形成，并改变涉及趋化性和运动性的基因表达。在本研究中，我们制备了一系列齐墩果酸的类似物。在生物膜形成测定和群体测定中，针对大肠杆菌和铜绿假单胞菌的临床分离物评估了类似物。从这些类似物中，选择化合物9作为进一步开发的先导化合物。化合物9以4 µg / mL抑制大肠杆菌生物膜的形成；在多种铜绿假单胞菌，大肠杆菌，伯克霍尔德菌，洋葱肠炎沙门氏菌和多种临床菌株中，它还能以≤1µg / mL的浓度抑制蜂群，而对多种农用菌株的蜂群抑制率<0.5 µg / mL。化合物9还增强了妥布霉素和粘菌素的抗药性，使其能抵抗大量铜绿假单胞菌。这是值得注意的，因为妥布霉素和粘菌素是吸入性抗生素，通常用于治疗囊性纤维化患者的铜绿假单胞菌肺部感染。qPCR实验表明，有9种改变了参与调节IV型菌毛的基因的表达。免疫印迹证实在存在9的情况下，铜绿假单胞菌中IV型菌毛成分PilA和PilY1的表达降低。