Highly sensitive liquid chromatographic method combined with online ion suppression to remove interfering anions and mass spectrometry for impurity profiling of paromomycin sulfate.

A previously developed high-performance liquid chromatography method combined with pulsed amperometric detection allowed to separate many impurities of paromomycin. However, due to the presence of ion pairing agents and sodium hydroxide in the mobile phase, direct coupling to mass spectrometry for the identification of the chemical structures of the impurities was not an option. Indeed, ion suppression was encountered by trifluoroacetic acid and pentafluoroproponic acid in the mobile phase.

Disturbances of the Gut Microbiota and Microbiota-Derived Metabolites in Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD), comprising Crohn's disease (CD) and ulcerative colitis (UC), is characterized as a chronic and recurrent inflammatory disease whose pathogenesis is still elusive. The gut microbiota exerts important and diverse effects on host physiology through maintaining immune balance and generating health-benefiting metabolites. Many studies have demonstrated that IBD is associated with disturbances in the composition and function of the gut microbiota.

Analysis of impurity profiling of arbekacin sulfate by ion-pair liquid chromatography coupled with pulsed electrochemical detection and online ion suppressor-ion trap-time off light mass spectrometry.

Ion-pair liquid chromatography with pulsed electrochemical detection (LC-PED) was established for the analysis of impurities in arbekacin (ABK) sulfate. APursuit pentafluorophenylpropyl (PFP) column was used as stationary phase. This novel method showed greater separation and sensitivity ability.

Characterization and inhibition of four fungi producing citrinin in various culture media.

Purpose: This study aimed to investigate the effects of different fermentation conditions (culture medium, temperature, incubation time, pH value and additive) on citrinin production by four fungi.

Results: Among the culture media, potato dextrose medium had lowest citrinin production, followed by yeast sucrose medium and monosodium glutamate medium. The lowest citrinin contents were produced by Monascus anka (M.

A novel approach for mitigation of membrane fouling: Concomitant use of flocculant and magnetic powder.

Membrane fouling alleviation by addition of poly dimethyl diallyl ammonium chloride (PDMDAAC) and magnetic powder (Fe3O4) was investigated. It was found that magnetic powder associated with PDMDAAC had a good performance on mitigation of membrane fouling, improvement in dehydrogenase activity and enhancement of biomass growth. The optimal dose of PDMDAAC was determined by using constant pressure dead-end filtration unit.

Transformation of salvianolic acid B to salvianolic acid a in aqueous solution and the in vitro liver protective effect of the main products.

Salvianolic acid A (Sal A) was considered to be the compound with highest activity in Salvia miltiorrhiza (danshen). Due to its low content in raw materials, many studies reported its preparation from salvianolic acid B (Sal B). However, the process of this transformation is still unknown.

Production of ramoplanin analogues by genetic engineering of Actinoplanes sp.

Ramoplanins are lipopeptides effective against a wide range of Gram-positive pathogens. Ramoplanin A2 is in Phase III clinical trials. The structure-activity relationship of the unique 2Z,4E-fatty acid side-chain of ramoplanins indicates a significant contribution to the antimicrobial activities but ramoplanin derivatives with longer 2Z,4E-fatty acid side-chains are not easy to obtain by semi-synthetic approaches.

Biotransformation of 14-deoxy-14-methylenetriptolide into a novel hydroxylation product by Neurospora crassa.

The biotransformation of 14-deoxy-14-methylenetriptolide by Neurospora crassa CGMCC AS 3.1604 to produce a new hydroxylation derivative was studied. The structure of this novel compound was determined using spectral data.