Benzisothiazol‐3‐ones through a Metal‐Free Intramolecular N–S Bond Formation

The highly efficient synthesis of benzoisothiazol‐3‐ones from thiobenzamides has been described with good functional group compatibility and excellent yields. This work represents the first example of selectfluor‐promoted N–S bond formation processes. This method provides a facile approach to access various important bioactive benzoisothiazol‐3‐ones

Insights from the redefinition of Helicobacter pylori lipopolysaccharide O-antigen and core-oligosaccharide domains

H. pylori is a Gram-negative extracellular bacterium, first discovered by the Australian physicians Barry Marshall and Robin Warren in 1982, that colonises the human stomach mucosa. It is the leading cause of peptic ulcer and commonly infects humans worldwide with prevalence as high as 90% in some countries. H. pylori infection usually results in asymptomatic chronic gastritis, however 10-15% of cases develop duodenal or gastric ulcers and 1-3% develop stomach cancer. Infection is generally acquired during childhood and persists for life in the absence of antibiotic treatment. H. pylori has had a long period of co-evolution with humans, going back to human migration out of Africa. This prolonged relationship is likely to have shaped the overall host-pathogen interactions and repertoire of virulence strategies which H. pylori employs to establish robust colonisation, escape immune responses and persist in the gastric niche. In this regard, H. pylori lipopolysaccharide (LPS) is a key surface determinant in establishing colonisation and persistence via host mimicry and resistance to cationic antimicrobial peptides. Thus, elucidation of the H. pylori LPS structure and corresponding biosynthetic pathway represents an important step towards better understanding of H. pylori pathogenesis and the development of novel therapeutic interventions

Network pharmacology and experimental verification reveal the mechanism of safranal against glioblastoma (GBM)

IntroductionSafranal is an active component of the traditional Tibetan medicine (TTM) saffron, which has potential anticancer activity.Methods and resultsHere, we studied the therapeutic effect and mechanism of safranal on GBM. CCK-8, GBM-brain organoid coculture experiments and 3D tumour spheroid invasion assays showed that safranal inhibited GBM cell proliferation and invasion in vitro. Network pharmacology, RNA-seq, molecular docking analysis, western blotting, apoptosis, and cell cycle assays predicted and verified that safranal could promote GBM cell apoptosis and G2/M phase arrest and inhibit the PI3K/AKT/mTOR axis. In vivo experiments showed that safranal could inhibit GBM cell growth alone and in combination with TMZ.ConclusionThis study revealed that safranal inhibits GBM cell growth in vivo and in vitro, promotes GBM cell apoptosis and G2/M phase arrest, inhibits the PI3K/AKT/mTOR axis and cooperate with TMZ

Structural analysis of Bacterial Glycoconjugates

Bacterial glycoconjugates are a group of highly complex macromolecules that are deeply implicated in various biological processes. ey can be crudely divided into several subgroups mainly including bacterial glycolipids and glycoproteins. eir structural complexity once hindered the elucidation of the biological roles they are playing. Based on the development of modern chromatography, mass spectrometry and nuclear magnetic resonance, research described in this thesis analysed the structures of multiple glycoconjugates such as glycolipids and glycoproteins. Lipopolysaccharides are characteristic bacterial glycolipids. e Pseudomonas aeruginosa lipid A and Helicobacter pylori lipopolysaccharide was investigated by a combination of chemical, MS and/or NMR strategies. For the lipid A, it was proved to be modi ed by 4-amino- arabinose, which is associated with bacterial antibiotic resistance. For the lipopolysaccharide, the speci cities of mutiple putative glycosyltransferases, including HP1284, HP1283, HP1578, HP0102 and WaaL ligase, involved in its biosynthesis were characterised. e structural data suggest Helicobacter pylori WaaL ligase has a relaxed speci city in vivo that transfers an un- expected long O-antigen to a short core-oligosaccharide. In addition, our data shed light on the regulation of bacterial O-antigen biosynthesis. e heavily glycosylated mbrial-associated protein 1 of Streptococcus parasanguinis was subjected to in-depth glycomics and glycoproteomics, which helps determine the speci cities of multiple putative glycosyltransferases such as GALT1/2 and GLY. More speci cally, GALT1 was proved to be a bi-functional glycosyltransferase that transfers a glucose and an N-acetyl- glucosamine. GALT2 and GLY was deteremined to transfer a glucose and a rhamnose, respectively. Based on these conclusions, our study helps elucidate the glycosylation pathway of mbrial-associated protein 1. e recent characterisation of bacterial oligosaccharyltransferases has the potential to revolutionise the production of glycoconjugate vaccines. e putative O-linked oligosaccharyltransferases system in Burkholderia thailandensis was investigated based on a zwitterionic hydrophilic interaction liquid chromatography mass spectrometry method, which helps expand the toolbox of glyco-engineering. By using a simpilied liquid chromatography- mass spectrometry method, multiple glycoproteins in Coxiella burnetii were semi-identi ed. During these studies, many classical chemistries were resurrected to inspire novel chemical strategies and facilitate the instrumental analysis. We hope the methods included in this thesis can contribute to further research where comprehensive structural characterisations of complex bacterial glycoconjugates are required.Open Acces

Changes in poly(ADP-ribosyl)ation patterns in workers exposed to BTX.

Occupational exposure to (benzene, toluene and xylene, BTX is common in the Chinese workplace. Chronic occupational exposure to benzene is associated with an increased risk of hematological malignancies such as acute myeloid leukemia (AML), but the underlying mechanisms are still unclear. This study investigates changes in poly(ADP-ribosyl)ation and DNA methylation in subjects occupationally exposed to a BTX. Blood DNA samples and exposure data were obtained from subjects with different levels of exposure, including 132 decorators, 129 painters, and 130 unexposed referents in a container-manufacturing factory in Shenzhen, China. Occupational exposure assessment included personal monitoring of airborne benzene, toluene and xylene. Hematological parameters were measured and the cytokinesis-block micronucleus (CBMN) assay was used to detect DNA damage in peripheral lymphocytes. Quantitative real-time PCR was used to detect the mRNA expression of poly(ADP-ribose) polymerase 1 (PARP1) and poly(ADP-ribose) glycohydrolase (PARG), DNA methyltransferases (DNMTs) including DNMT1, DNMT3a and DNMT3b, methyl-CpG-binding domain protein 2(MBD2). PARP1 assay was used to measure PARP activity. Airborne levels of benzene, toluene and xylene in the two exposed groups were significantly higher than those of controls (P<0.001). The two exposed groups (decorators, painters) showed decreased PARP1, DNMTs and MBD2 expression relative to controls (P<0.05), and PARP activity was also decreased (P<0.05). Decreased PARP1, DNMT1, DNMT3a, DNMT3b and MBD2 mRNA expression was correlated with increased airborne BTX (Pearson's r: -0.587, -0.314, -0.636, -0.567 and -0.592 respectively, P<0.001). No significant differences in hematological parameters and CBMN were found among the three groups. Together, these results suggest that decreased DNMTs, MBD2 and PARP1 might be involved in the global hypomethylation associated with BTX exposure, and the imbalance of PARP/PARG might participate in the down-regulation of DNMTs. This is the first human study to link altered poly(ADP-ribosyl)ation patterns, which reproduce the aberrant epigenetic patterns found in benzene-treated cells, to chronic occupational exposure to BTX

PARP-1 expression in exposed groups and control.

<p>mRNA level was measured by real-time PCR with input normalization by ACTB mRNA level. The results are expressed as percentage of the controls (mean ± SD) from three independent experiments. *<i>P</i><0.05 versus control.</p

Correlation between the level of target genes' mRNA expression and BTX exposure.

<p>*<i>P</i><0.05, <i>P</i> values were obtained from Pearson correlation.</p><p>Correlation between the level of target genes' mRNA expression and BTX exposure.</p

DNMTs and MBD2 expression in exposed groups and control.

<p>mRNA level was measured by real-time PCR with input normalization by ACTB mRNA level. The results are expressed as percentage of the controls (mean ± SEM) from three independent experiments. *<i>P</i><0.05 versus control and a dose-dependent decrease in gene expression was observed in DNMT3a (<i>P</i><0.05).</p

MN in peripheral lymphocytes in subjects grouped by exposure and smoking habits.

<p>Abbreviations: BN, binucleated cells.</p><p>No significantly different between exposed and control.</p><p>MN in peripheral lymphocytes in subjects grouped by exposure and smoking habits.</p

Comparison of blood test results among the BTX-exposed groups and the control group.

<p><i>P</i> value was obtained from one-way ANOVA.</p><p>Comparison of blood test results among the BTX-exposed groups and the control group.</p