Wound Healing Activity of a Skin Substitute from Residues of Culinary-Medicinal Winter Mushroom Flammulina velutipes (Agaricomycetes) Cultivation.

A skin substitute TG05 obtained from residues of the culinary-medicinal mushroom Flammulina velutipes cultivation process was developed in this study for the first time. Pre-column derivatization high-performance liquid chromatography fingerprints analysis revealed that TG05 was composed of water-insoluble fibers containing xylose (57%), glucose (19.5%), and arabinose (16.3%) as major monomers. Porous and opaque structure of TG05 was demonstrated by scanning electron microscopy. Animal experiments conducted on mice and rats indicated that TG05 notably accelerated the wound-healing process. In addition, TG05 induced proliferation and migration of human keratinocytes time- and dose-dependently. Taken together, the skin substitute TG05 with new structure promotes wound healing in vitro and in vivo. This study provided a novel method to produce functional biomaterial from abundant and low-cost agricultural residues generated during edible mushroom cultivation.

Preparation of a Major Metabolite of Iguratimod and Simultaneous Assay of Iguratimod and Its Metabolite by HPLC in Rat Plasma.

Iguratimod is a new synthetic disease-modifying antirheumatic drug intended to treat patients with rheumatoid arthritis. A new method using recombinant human CYP450s yeast cells containing c-DNA expressed P450s was applied to identify the metabolic pathways of iguratimod and to prepare its metabolite. The metabolite was isolated, and its structure was identified by quadrupole time-of-flight-mass spectrometry and nuclear magnetic resonance. Furthermore, a selective and sensitive high performance liquid chromatography (HPLC) method was developed for the simultaneous quantification of iguratimod and its major metabolite in rat plasma for the first time. The results indicated that iguratimod was mainly metabolized to a metabolite by CYP2C9 and CYP2C19 in in-vitro study. The structure of the metabolite was identified as M2 (N-[3-(acetamido)-4-oxo-6-phenoxy-4H-chromen-7-yl]methanesulfonamide). HPLC assay was achieved on a C18 column using methanol-water containing 0.1% trifluoroacetic acid (55:45 v/v) at a flow rate of 1 mL/min with UV detection at 257 nm. Standard calibration curves were obtained in the concentration range of 0.5-20 µg/mL for iguratimod and its metabolite M2. The lower limits of detection of iguratimod and M2 in rat plasma were 0.1 and 0.25 µg/mL, respectively. The intra- and inter-day precision (RSD%) were within 5% for the two analytes. The average recoveries of the analytes were greater than 90%. In conclusion, recombinant human CYP450s whole-yeast transformation system could be successfully used to identify and prepare the major metabolite of iguratimod. The HPLC method we developed could be successfully applied to evaluate pharmacokinetics of iguratimod and its metabolite M2 in rats.

Efflux pumps AcrAB and OqxAB contribute to nitrofurantoin resistance in an uropathogenic Klebsiella pneumoniae isolate.

Klebsiella pneumoniae is a common cause of urinary tract infections (UTIs). Nitrofurantoin (NIT), with high therapeutic concentrations in urine, is recommended as the first-line drug for both empiric treatment and chemoprophylaxis of UTIs. Although NIT resistance in K. pneumoniae is relatively high, the resistance mechanism is not well understood. This study collected a NIT-resistant K. pneumoniae [NRKP, minimum inhibitory concentration (MIC)=128 mg/L] and investigated the resistance mechanism. Addition of efflux pump inhibitors increased the susceptibility of NRKP to NIT (MIC decreased from 128 to 32 mg/L), implying the important role of efflux pumps in NIT resistance. Quantitative reverse transcriptase polymerase chain reaction analysis showed that NRKP had >100-fold increased expression of ramA, which was demonstrated to be caused by ramR mutation. Deletion of ramA led to a four-fold decrease in the MIC of NIT, and the expression levels of efflux pumps acrB and oqxB were downregulated by four- to seven-fold. Complementation of ramA restored both the MIC value and the expression level of acrB and oqxB in the ramA mutant strain. In order to confirm the role of acrB and oqxB in NIT resistance, gene knockout strains were constructed. Deletion of acrB or oqxB alone led to a four-fold decrease in the MIC of NIT, and deletion of acrB and oqxB simultaneously led to a 16-fold decrease in the MIC of NIT. These results demonstrate that AcrAB and OqxAB contribute to NIT resistance in K. pneumoniae.