Synthesis and Antibacterial Activity Evaluation of Biphenyl and Dibenzofuran Derivatives as Potential Antimicrobial Agents against Antibiotic-Resistant Bacteria.

The escalating prevalence of antibiotic-resistant bacteria has led to a serious global public health problem; therefore, there is an urgent need for the development of structurally innovative antibacterial agents. In our study, a series of biphenyl and dibenzofuran derivatives were designed and synthesized by Suzuki-coupling and demethylation reactions in moderate to excellent yields (51-94% yield). Eleven compounds exhibited potent antibacterial activities against the prevalent antibiotic-resistant Gram-positive and Gram-negative pathogens, among which compounds 4'-(trifluoromethyl)-[1,1'-biphenyl]-3,4,5-triol (6i) and 5-(9H-carbazol-2-yl) benzene-1,2,3-triol (6m) showed the most potent inhibitory activities against methicillin-resistant Staphylococcus aureus and multidrug-resistant Enterococcus faecalis with MIC (minimum inhibitory concentration) values as low as 3.13 and 6.25 µg/mL, respectively. Compounds 3',5'-dimethyl-[1,1'-biphenyl]-3,4,4',5-tetraol (6e), 4'-fluoro-[1,1'-biphenyl]-3,4,5-triol (6g), and 4'-(trifluoromethyl)-[1,1'-biphenyl]-3,4,5-triol (6i) showed comparable inhibitory activities with ciprofloxacin to Gram-negative bacterium carbapenems-resistant Acinetobacter baumannii. Study of the structure-activity relationship indicated that a strong electron-withdrawing group on the A ring and hydroxyl groups on the B ring of biphenyls were beneficial to their antibacterial activities, and for benzo-heterocycles, N-heterocycle exhibited optimal antibacterial activity. These results can provide novel structures of antibacterial drugs chemically different from currently known antibiotics and broaden prospects for the development of effective antibiotics against antibiotic-resistant bacteria.

Biotransformation of rutin to isoquercitrin using recombinant α-L-rhamnosidase from Bifidobacterium breve.

OBJECTIVES: To biotransform rutin into isoquercitrin. RESULTS: A α-L-rhamnosidase from Bifidobacterium breve was produced by using Escherichia coli BL21 for biotransformation of rutin to isoquercitrin. The enzyme was purified by Ni(2+)-NTA chromatography to yield a soluble protein with a specific activity of 56 U protein mg(-1). The maximum enzyme activities were at pH 6.5, 55 °C, 20 mM rutin, and 1.2 U enzyme ml(-1). Under optimal conditions, the half-life of the enzyme was 96 h. The K m and V max values were 2.2 mM, 56.4 µmol mg(-1) min(-1) and 2.1 mM, 57.5 µmol mg(-1) min(-1) using pNP-Rha and rutin as substrates, respectively. The kinetic behavior indicated that the recombinant α-L-rhamnosidase has good catalytic performance for producing isoquercitrin. 20 mM rutin was biotransformed into 18.25 and 19.87 mM isoquercitrin after 60 and 240 min. CONCLUSION: The specific biotransformation of rutin to isoquercitrin using recombinant α-L-rhamnosidase from B. breve is a feasible method for use in industrial processes.

[Research progress in pathogenesis of IBD: the role of gut flora].

Inflammatory bowel diseases (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), are chronic inflammatory disorders of the intestine. Both the etiology and the pathogenesis of IBD remain unclear. In recent years, the role of gut flora in IBD has become one of the most concerned issues. International metagenomic projects targeting the gut microbiota greatly promote the exploration of the role of gut flora in IBD. What are the characteristics of gut flora in IBD? How does it interact with host susceptibility? This review will discuss the enteric dysbacteriosis in IBD and show the interaction between gut flora, especially the dominant gut flora, and host susceptibility in IBD.