Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA.
Bioorg Med Chem Lett. 2011 Sep 15;21(18):5583-8. doi: 10.1016/j.bmcl.2011.06.082. Epub 2011 Jun 25.
We have recently characterized sliding motility in Bacillus subtilis strains that lack functional flagella, and here describe the discovery of inhibitors of colony spreading in these strains as well as the aflagellate pathogen, Bacillus anthracis. Aflagellate B. subtilis strains were used to screen for new types of antibacterials that might inhibit colony spreading on semi-solid media. From a diverse set of organic structures, p-nitrophenylglycerol (NPG), an agent used primarily in clinical laboratories to control Proteus swarming, was found to inhibit colony spreading. The four stereoisomers of NPG were synthesized and tested, and only the 1R,2S-(1R-anti) and 1R,2R-(1R-syn) NPG isomers had significant activity in a quantitative colony-spreading assay. Twenty-six NPG analogs and related structures were synthesized and tested to identify more active inhibitors. p-Methylsulfonylphenylglycerol (p-SPG), but not its ortho or meta analogs, was found to be the most effective of these compounds, and synthesis and testing of all four p-SPG stereoisomers showed that the 1R-anti-isomer was the most active with an average IC(50) of 16 μM (3-5 μg mL(-1)). For B. anthracis, the colony-spreading IC(50) values for 1R-anti-SPG and 1R-anti-NPG are 12 μM (2-4 μg mL(-1)) and >150 μM, respectively. For both Bacillus species tested, 1R-anti-SPG inhibits colony spreading of surface cultures on agar plates, but is not bacteriostatic or bacteriocidal in liquid cultures. Work is in progress to find the cellular target(s) of the NPG/SPG class of compounds, since this could lead to an understanding of the mechanism(s) of colony spreading as well as design and development of more potent inhibitors for the control of B. anthracis surface cultures.
我们最近研究了缺乏功能性鞭毛的枯草芽孢杆菌菌株的滑动运动，并在此描述了这些菌株以及无鞭毛病原体炭疽芽孢杆菌的菌落扩散抑制剂的发现。无鞭毛枯草芽孢杆菌菌株用于筛选可能抑制半固体培养基上菌落扩散的新型抗菌药物。从一组不同的有机结构中，发现了主要用于临床实验室控制变形杆菌群集的对硝基苯甘油（NPG）抑制菌落扩散。合成并测试了 NPG 的四个立体异构体，只有 1R,2S-（1R-anti）和 1R,2R-（1R-syn）NPG 异构体在定量菌落扩散测定中具有显著活性。合成并测试了 26 种 NPG 类似物和相关结构，以鉴定更有效的抑制剂。发现对甲基磺酰基苯甘油（p-SPG），而不是其邻位或间位类似物，是这些化合物中最有效的，并且所有四个 p-SPG 立体异构体的合成和测试表明 1R-anti-异构体最活跃，平均 IC50 为 16 μM（3-5 μg mL(-1)）。对于炭疽芽孢杆菌，1R-anti-SPG 和 1R-anti-NPG 的菌落扩散 IC50 值分别为 12 μM（2-4 μg mL(-1)）和>150 μM。对于测试的两种芽孢杆菌，1R-anti-SPG 抑制琼脂平板表面培养物的菌落扩散，但在液体培养物中既无抑菌作用也无杀菌作用。目前正在努力寻找 NPG/SPG 类化合物的细胞靶标，因为这可能有助于理解菌落扩散的机制，并设计和开发更有效的抑制剂来控制炭疽芽孢杆菌的表面培养物。
