Simultaneous determination of three 5-nitroimidazoles in foodstuffs by differential pulse voltammetry and chemometrics

The voltammetric behaviour of three 5-nitroimidazoles,metronidazole,tinidazole and ornidazole,was investigated,and a method was developed for the simultaneous determination of these compounds,based on their reduction at a hanging mercury drop electrode（HMDE） in pH 8.95 buffer with differential pulse voltammetric（DPV） approach.Well defined voltammetric waves with peak potentials of -692,-640 and -652 mV were observed for these compounds,respectively.It is difficult to determine them individually from their mixtures without preseparation,for their voltammetric peaks overlapped seriously,so the chemometrics were used to resolve the overlapped voltammogram and quantify the mixtures.The proposed method was successfully applied to the determination of three 5-nitroimidazoles in milk and honey samples.

Discovery of natural berberine-derived nitroimidazoles as potentially multi-targeting agents against drug-resistant Escherichia coli

A series of natural berberine-derived nitroimidazoles as novel antibacterial agents were designed, synthesized and characterized by nuclear magnetic resonance(NMR), infrared spectra(IR), and high resolution mass spectra(HRMS) spectra. The antimicrobial evaluation showed that some target molecules exhibited moderate to good inhibitory activities against the tested bacteria and fungi including clinical drug-resistant strains isolated from infected patients. Especially, 2-fluorobenzyl derivative8 f not only gave strong activity against drug-resistant E. coli with the minimal inhibitory concentration(MIC) value of0.003 m M, 33-fold more active than norfloxacin, but also exhibited low toxicity toward RAW 264.7 cells and less propensity to trigger resistance. The aqueous solubility and Clog P values of target compounds were investigated to elucidate the structureactivity relationships. Molecular docking and quantum chemical studies for compound 8 f rationally explained its antibacterial effect. The further exploration of antibacterial mechanism revealed that the highly active compound 8 f could effectively permeabilize E. coli cell membrane and intercalate into DNA isolated from resistant E. coli to form 8 f-DNA complex that might block DNA replication to exert the powerful bioactivities. Compound 8 f could also selectively address resistant E. coli from a mixture of various strains.

Prediction of Enhancement Effect of Nitroimidazoles on Irradiation by Gene Expression Programming

A novel machine learning method, gene expression programming（GEP）, was employed to build quatitative structure-activity relationship（QSAR） models for predicting the enhancement effect of nitroimidazole compounds on irradiation. The models were based on descriptors which were calculated from the molecular structures. Four descriptors were selected from the pool of descriptors by best multiple linear regression（BMLR） method. After that, three regression methods, multiple linear regression（MLR）, support vector machine（SVM） and GEP, were used to build QSAR models. Compared to MLR and SVM, GEP produced a better model with the square of correlation coefficient（R2）, 0.9203 and 0.9014, and the root mean square error（RMSE）, 0.6187 and 0.6875, for training set and test set, respectively. The results show that the GEP model has better predictive ability and more reliable than the MLR and SVM models. This indicates that GEP is a promising method on relevant researches in radiation area.

Postoperative Crohn’s disease recurrence: A practical approach

Crohn's disease is a chronic inflammatory condition that may involve any segment of the gastrointestinal tract. Although several drugs have proven efficacy in inducing and maintaining disease in remission, resectional surgery remains as a cornerstone in the management of the disease, mainly for the treatment of its stenosing and penetrating complications. However, the occurrence of new mucosal (endoscopic) lesions in the neoterminal ileum early after surgery is almost constant, it is followed in the mid-term by clinical symptoms and, in a proportion of patients, repeated intestinal resections are required. Pathogenesis of postoperative recurrence (POR) is not fully understood, but luminal factors (commensal microbes, dietary antigens) seem to play an important role, and environmental and genetic factors may also have a relevant influence. Many studies tried to identify clinical predictors for POR with heterogeneous results, and only smoking has repeatedly been associated with a higher risk of POR. Ileocolonoscopy remains as the gold standard for the assessment of appearance and severity of POR, although the real usefulness of the available endoscopic score needs to be revisited and alternative techniques are emerging. Several drugs have been evaluated to prevent POR with limited success. Smoking cessation seems to be one of the more beneficial therapeutic measures. Aminosalicylates have only proved to be of marginal benefit, and they are only used in low-risk patients. Nitroimidazolic antibiotics, although efficient, are associated with a high rate of intolerance and might induce irreversible side effects when used for a long-term. Thiopurines are not widely used after ileocecal resection, maybe because some concerns in giving immunomodulators in asymptomatic patients still remain. In the era of biological agents and genetic testing, a well-established preventive strategy for POR is still lacking, and larger studies to identify good clinical, serological, and genetic predictors of early POR as well as more effective drugs (or drug combinations) are needed.

A neutrophil-biomimic platform for eradicating metastatic breast cancer stem-like cells by redox microenvironment modulation and hypoxia-triggered differentiation therapy

Metastasis accounts for 90%of breast cancer deaths,where the lethality could be attributed to the poor drug accumulation at the metastatic loci.The tolerance to chemotherapy induced by breast cancer stem cells(BCSCs)and their particular redox microenvironment further aggravate the therapeutic dilemma.To be specific,therapy-resistant BCSCs can differentiate into heterogeneous tumor cells constantly,and simultaneously dynamic maintenance of redox homeostasis promote tumor cells to retro-differentiate into stem-like state in response to cytotoxic chemotherapy.Herein,we develop a specifically-designed biomimic platform employing neutrophil membrane as shell to inherit a neutrophil-like tumor-targeting capability,and anchored chemotherapeutic and BCSCs-differentiating reagents with nitroimidazole(NI)to yield two hypoxia-responsive prodrugs,which could be encapsulated into a polymeric nitroimidazole core.The platform can actively target the lung metastasis sites of triple negative breast cancer(TNBC),and release the escorted drugs upon being triggered by the hypoxia microenvironment.During the responsiveness,the differentiating agent could promote transferring BCSCs into non-BCSCs,and simultaneously the nitroimidazole moieties conjugated on the polymer and prodrugs could modulate the tumor microenvironment by depleting nicotinamide adenine dinucleotide phosphate hydrogen(NADPH)and amplifying intracellular oxidative stress to prevent tumor cells retro-differentiation into BCSCs.In combination,the BCSCs differentiation and tumor microenvironment modulation synergistically could enhance the chemotherapeutic cytotoxicity,and remarkably suppress tumor growth and lung metastasis.Hopefully,this work can provide a new insight in to comprehensively treat TNBC and lung metastasis using a versatile platform.