Xuerui Bai,Maiqian Nie,Zhenjun Diwu,Hongyun Nie,Yan Wang
Pseudomonas stutzeri N2 and Rhodococcus qingshengii FF were combined to enhance phenol degradation, and the interaction mechanism of microorganisms was investigated. The cells in the culture of mixed strain degrading 1000 mg/L phenol exhibited a rapid growth and proliferation, and the maximum cell density of mixed strain was 34.6 ± 0.3% and 60.8 ± 0.2% higher than the single strain N2 and strain FF respectively. The degradation of phenol by mixed strain was completed within 24 h, and the phenol mineralization efficiency was up to 84.9 ± 0.4%. In addition, two ring-cleavage products of catechol accumulating from the culture of mixed strain were markedly reduced. Through the analysis of intermediates and functional groups, the enhanced phenol degradation by mixed strain was found to mainly depend on the synergistic effect of strain N2 served as an oxidant and strain FF acted as a reductant. Based on the synergic mechanism, the mixed strain might be used as a promising bacterial agent for removing phenolic compounds from the industrial wastewater.
An efficient one-pot four-component reaction for the synthesis of a new family of novel bridgehead nitrogen-containing pyrido[1,2-d][1,4]diazepines has been described and its mechanism has been proposed, which follows a ring-closure and ring-cleavage pathway. The protocol involved a cyclization through γ-selective C–C bond formation, an intramolecular Michael addition and a ring-opening of a pyranone ring under refluxing conditions with high to excellent yields. The advantages of this methodology, including the use of easily available raw materials and an inexpensive catalyst, an open-air reaction setup, wide functional group tolerance, and gram-scale synthesis, make the developed methodology a practical way to access novel pyrido[1,2-d][1,4]diazepines and functionalized tricyclic or polycyclic fused 1,4-diazepines as well as novel analogs of important biologically active molecules.
Rationale Tebipenem pivoxil (TBPM-PI) has been developed as the first oral carbapenem drug in the world to treat otolaryngological and respiratory infections in pediatric patients. Due to its structural properties and external factors, some related impurities, which may cause side effects in patients, might be formed during the synthesis and storage of TBPM-PI. It was vital to rapidly separate and identify the related impurities to guarantee the safe use of TBPM-PI. Methods A method using ultra-high-performance liquid chromatography (UHPLC) coupled with quadrupole time-of-flight tandem mass spectrometry (QTOF-MS/MS) was developed to separate and detect TBPM-PI and related impurities in an oral pharmaceutical formulation. LC/MS and MS/MS spectra of these compounds in the formulation were acquired to confirm their elemental compositions and propose their structures based on LC/MS data and fragmentation pathways of available reference substances. Results LC/MS parameters and MS/MS fragmentation pathways of reference substances of TBPM-PI and related impurities were summarized in detail. Based on this, a total of 23 related impurities were found and characterized in the oral pharmaceutical formulation. Eight of these were verified by comparison with reference substances and the structures of the other 15 were proposed for the first time. In addition, four of these compounds were produced by the reaction of excipients and pre-existing related impurities. Conclusions A UHPLC/QTOF-MS method was established and used for the separation and identification of 23 related impurities in a TBPM-PI oral pharmaceutical formulation. Moreover, it was proved that new related impurities could be produced by the reaction of excipients in the pharmaceutical formulation and related impurities in the corresponding active pharmaceutical ingredient (API).
危险品化学品经营许可证（带存储）