RESUMEN

The formation of biofilms by clinical pathogens typically leads to chronic and recurring antibiotic-resistant infections. High cellular levels of cyclic diguanylate (c-di-GMP), a ubiquitous secondary messenger of bacteria, have been proven to be associated with a sessile biofilm lifestyle of pathogens. A promising antibiofilm strategy involving the induction of c-di-GMP to form dysfunctional G-quadruplexes, thereby blocking the c-di-GMP-mediated biofilm regulatory pathway, was proposed in this study. In this new strategy, a series of novel c-di-GMP G-quadruplex inducers were designed and synthesized for development of therapeutic biofilm inhibitors. Compound 5h exhibited favorable c-di-GMP G-quadruplex-inducing activity and 62.18 ± 6.76% biofilm inhibitory activity at 1.25 µM without any DNA intercalation effect. Moreover, the favorable performance of 5h in interfering with c-di-GMP-related biological functions, including bacterial motility and bacterial extracellular polysaccharide secretion, combined with the reporter strain and transcriptome analysis results confirmed the c-di-GMP signaling-related action mechanism of 5h.

Asunto(s)

RESUMEN

Schisandrae Chinensis Fructus in six growth stages was taken as materials to study the species and content changes of material basis, which were detected by UPLC, GC and MS chromatography, including lignans, nucleosides, aroma components and fatty acids. The results showed that the texture, color and taste of Schisandrae Chinensis Fructus in six growth stages were different. On the material basis, 12 lignans were detected by UPLC-MS, and the content of total lignans was higher in the samples from late August to early September, among which the highest content of schisandrin was 0.67%±0.01%, followed by schizandrol B, angeloylgomisin H and schisandrin B, and the total content increased with the maturity of Schisandrae Chinensis Fructus. Thirteen kinds of nucleosides were detected by UPLC. The total nucleoside content was the highest in late July samples, in which the contents of uridine and guanosine were higher and decreased after maturity. Aroma components and fatty acids were identified by GC-MS. A total of 53 aroma components were detected and the highest total content was appeared in late August samples, of which ylangene was higher and bergamotene was followed. A total of 24 kinds of fatty acids were detected. The fruits matured basically in August, and the content of fatty acids in the samples was the highest, among which linoleic acid content was top the list and oleic acid was the second. To sum up, the maturity of Schisandra chinensis fruit is related to the content and variety of various material bases, and the growth period has different influences on the quality of Schisandrae Chinensis Fructus. Therefore, the appropriate harvesting time should be determined according to the change law of target components. The results of this study can provide reference for the quality evaluation of Schisandrae Chinensis Fructus material basis.

Asunto(s)

RESUMEN

The dinucleotide 3',5'-cyclic diguanylic acid (c-di-GMP) is a critical second messenger found in bacteria. High cellular levels of c-di-GMP are associated with a sessile, biofilm lifestyle in many bacteria, which is associated with more than 70% of clinically resistant infections. Cellular c-di-GMP concentrations are regulated by diguanylate cyclases (DGCs) and phosphodiesterases (PDEs), which are responsible for the production and degradation, respectively, of c-di-GMP. Therefore, DGCs and PDEs might be attractive drug targets for controlling biofilm formation. In this study, a simple and universal high-throughput method based on a c-di-GMP-specific fluorescent probe for the determination of DGC and PDE activity was described. By using the proposed method, the c-di-GMP content in samples was rapidly quantified by measuring the fluorescence intensity in a 96-well plate by using a microplate reader. In addition, the probe molecule A18 directly interacted with the substrate c-di-GMP, and the method was not limited by the structure of enzymes.

RESUMEN

3',5' Cyclic diguanylic acid (c-di-GMP) has been shown to play a central role in the regulation of bacterial physiological processes such as biofilm formation and virulence production, and is regarded as a potential target for the development of anti-infective drugs. A method for the facile detection of the bacterial level of cellular c-di-GMP is required to explore the details of c-di-GMP signaling and design drugs on the basis of this pathway. Current methods of c-di-GMP detection have limited sensitivity or difficultly in probe preparation. Herein a new fluorescent probe is reported for the detection of c-di-GMP at concentrations as low as 500 nM. The probe was developed on the basis of the G-quadruplex formation of c-di-GMP induced by aromatic molecules. When used on crude bacterial cell lysates, it can effectively distinguish between the low c-di-GMP levels of bacteria in plankton and the high c-di-GMP levels in biofilm. The method described here is simple, inexpensive, sensitive, and suitable for practical applications involving the rapid detection of cellular c-di-GMP levels in vitro after simple bacterial lysis and filtration.