Sennoside A (SA), a typical prodrug, exerts its laxative effect only after its transformation into rheinanthrone catalyzed by gut microbial hydrolases and reductases. Hydrolases have been identified, but reductases remain unknown. By linking a photoreactive group to the SA scaffold, we synthesized a photoaffinity probe to covalently label SA reductases and identified SA reductases using activity-based protein profiling (ABPP). From lysates of an active strain, Bifidobacterium pseudocatenulatum (B. pseudocatenulatum), 397 proteins were enriched and subsequently identified using mass spectrometry (MS). Among these proteins, chromate reductase/nicotinamide adenine dinucleotide (NADH) phosphate (NADPH)-dependent flavin mononucleotide (FMN) reductase/oxygen-insensitive NADPH nitroreductase (nfrA) was identified as a potent SA reductase through further bioinformatic analysis and The Universal Protein Resource (UniProt) database screening. We also determined that recombinant nfrA could reduce SA. Our study contributes to further illuminating mechanisms of SA transformation to rheinanthrone and simultaneously offers an effective method to identify gut bacterial reductases.

Objective To investigate intraoperative neural monitoring(IONM)for prevention of recurrent laryngeal nerve injury(RLN)during thyroid cancer operation.Methods 288 cases of thyroid cancer admitted from Jun.2011 to Jun.2013 in our hospital were studied and they were divided into the observation group(140 cases) and the control group(148 cases) according to whether IONM was used during surgery.The incidence of RLN injury was compared between the 2 groups.Results The injury rate of RLN was lower in the observation group(0.67％) than in the control group(3.57％)and the operation time is shorter than the latter(P ＜0.001).There was no statistical difference for the operative bleeding volume and the average hospitalization time between the 2 groups (P ＞ 0.05).Conclusion INOM can help to shorten the operation time and reduce the incidence of RLN injury.