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Polymyxin B and polymyxin E (colistin) are increasingly used as last-resort drugs for treatment of infections caused by multidrug-resistant gram-negative pathogens. Unfortunately, the application was limited due to the serious side effects, especially nephrotoxicity. Very recently, the need for developing more tolerated and more effective polymyxin analogues has grown. This study details the design, synthesis, and evaluation of two classes of polymyxin B analogues with varying hydrophobicity and bulkiness at the N-terminal fatty acyl chain or position 6 amino acid. 20 polymyxin B analogues were synthesized and the chemical structures of the analogues were confirmed by HR-MS and 1H NMR spectra. Compounds 7e (MIC: 0.5-4 μg·mL-1) and 7l (MIC: 0.25-2 μg·mL-1) showed similar or better antimicrobial activity against both susceptible and resistant strains of Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa compared to polymyxin B (MIC: 0.5-2 μg·mL-1). Besides, compound 7l (CC50: 217.1±13.2 μg·mL-1) displayed noticeably decreased renal cytotoxicity compared to polymyxin B (CC50: 120.3±6.0 μg·mL-1). This work establishes the base of further study on the structure-activity relationship of polymyxin B.
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Using CBBR as the parent core constructed in our lab, we designed and synthesized 15 novel compounds with diverse structures for evaluation of anti-bacterial activities. Structure activity relationship studies revealed that ① ring C was essential for the activity; ② 7,8- or 8,13-disubstituted CBBR derivatives showed ideal activities, weaker or similar to those corresponding to 7-, 8-, or 13-monosubstituted CBBR derivatives. Among those, compound 9a showed the most potential activity against MRSA/VISA isolates with MIC values of 1-2 μg·mL-1, much better than Lev. 9a also displayed higher stability in the plasma and liver microsomes. Molecular docking indicated that 9a might target bacterial DNA Topo IV ParE subunit, indicating a mode of action distinct from current antibacterial drugs on market. The results provided key scientific evidence for developing such compounds into a new family of anti-MRSA drugs.
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UHPLC-QTOF-MS was applied to non-targeted metabolomics study of mice infected with K. pneumoniae ATCC® BAA 2146 to discover potential biomarkers and metabolic pathways that are associated with sepsis. Fifty-eight metabolites were identified by principal components analysis (PCA) and partial least-squares discriminant analysis (OPLS-DA), which was combined with variable projection importance (VIP) and nonparametric test. Eighteen of the 58 metabolites were further found to be involved in 8 metabolic pathways, including nicotinate and nicotinamide metabolism, pyrimidine metabolism, vitamin B6 metabolism, taurine and hypotaurine metabolism, arginine and proline metabolism, alanine, aspartate and glutamate metabolism, D-glutamine and D-glutamate metabolism and glycerophospholipid metabolism.
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9-Acetoxycycloberberine (1) with a unique skeleton was first identified to display a potent antimicrobial profile against methicillin-resistant Staphylococcus aureus (MRSA) with MIC values of 1-16 μg·mL-1. Taking the compound as a lead, 14 target cycloberberine analogues with diverse structures, such as berberine and chelerythrine derivatives, were synthesized and evaluated for their anti-bacterial activities. Analysis of the structure-activity relationship revealed that:① ring E was essential for the activity; ② the removing of ring B decreased the activity against MRSA. However, the antimicrobial activity against vancomycin-resistant Enterococcus faecium (VRE) was improved; ③ the introduction of a suitable rigid substituent at the 9-position was beneficial for the activity. Among them, compound 9a showed the most potential activity against methicillin-sensitive Staphylococcus aureus (MSSA) and MRSA isolates with MIC values of 0.5-1 μg·mL-1, suggesting a different mechanism from clinical drugs. It displayed higher stability in blood. Therefore, we consider 9a worthy of further investigation. The results provide key scientific evidence for development of such compounds into a new type of anti-MRSA candidates.
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IG-105, N-(2,6-dimethoxypyridine-3-yl)-9-methylcarbazole-3-sulfonamide, a novel antimicrotubule agent, showed potent anticancer activity in a variety of human tumor cells in vitro and in vivo. In order to characterize the metabolism and the possible drug-drug interaction of IG-105, we carried out a series of experiments. Drug metabolizing enzymes involved in IG-105 metabolism were investigated by using pooled human liver microsomes (HLMs) and recombinant cytochrome P450 isoforms (rP450s) respectively. The possible metabolites were analyzed by liquid chromatography-orbitrap-mass spectrometry (LC-Orbitrap-MS). The inhibitory effect of IG-105 on main P450 enzymes was also evaluated. The results showed that IG-105 can be metabolized by a series of rP450s, including CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP3A4 and CYP3A5, with the major contribution enzymes being CYP1A2, CYP2B6, CYP2C19, and CYP3A. Three metabolites (M1-M3) were identified and demethylation was the major phase I metabolic reaction for IG-105. IG-105 moderately inhibited CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A enzyme activities with IC50 values of 6.42, 23.64, 0.39, 1.4, and 3.14 μmol·L-1, respectively. Since the biotransformation of IG-105 involves multiple enzymatic pathways, the compound is less likely to be a victim of a concomitantly used medicine which inhibits activity of one of the CYPs. However, as IG-105 showed medium to strong inhibition on CYP1A2, CYP2D6, CYP3A, and CYP2C19, caution is particularly needed when IG-105 is co-administrated with other anticancer drugs which are mainly metabolized by the above enzymes.
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Chuangxinmycin (CM) from Actinoplanes tsinanensis was an antibiotic discovered by Chinese scientists about 40 years ago. It contains a new heterocyclic system of indole fused with dihydrothiopyran, whose biosynthetic mechanism remains unclear. CM is used as an oral medicine in the treatment of bacterial infections in China. The simple structure makes CM as an attractive candidate of structure modification for improvement of antibacterial activity. Recently, we analyzed the secondary metabolites of Actinoplanes tsinanensis CPCC 200056, a CM producing strain, as a natural CM analogue. We discovered the first natural CM analogue 3-demethylchuangxinmycin (DCM) as a new natural product. Compared to CM, DCM exhibited a much weaker activity in the inhibition of the bacterial strains tested. The finding provides valuable information for the structure-activity relationship in the biosynthesis of CM.
ABSTRACT
Chuangxinmycin (CM) from Actinoplanes tsinanensis was an antibiotic discovered by Chinese scientists about 40 years ago. It contains a new heterocyclic system of indole fused with dihydrothiopyran, whose biosynthetic mechanism remains unclear. CM is used as an oral medicine in the treatment of bacterial infections in China. The simple structure makes CM as an attractive candidate of structure modification for improvement of antibacterial activity. Recently, we analyzed the secondary metabolites of Actinoplanes tsinanensis CPCC 200056, a CM producing strain, as a natural CM analogue. We discovered the first natural CM analogue 3-demethylchuangxinmycin (DCM) as a new natural product. Compared to CM, DCM exhibited a much weaker activity in the inhibition of the bacterial strains tested. The finding provides valuable information for the structure-activity relationship in the biosynthesis of CM.
Subject(s)
Anti-Bacterial Agents , Chemistry , China , Indoles , Chemistry , Micromonosporaceae , Chemistry , Structure-Activity RelationshipABSTRACT
Objective To observe the influences of different doses of sodium arsenite on mRNA transcription of keratinizing related and nuclear factor E2-related factor 2(Nrf2) genes in HaCaT cells.Methods Cell proliferation was evaluated by Cell Counting Kit-8(CCK-8) assay after the HaCaT cells were exposed to 0.00,3.13,6.25,12.50,25.00,50.00,75.00,100.00 μ mol/L sodium arsenite for 48 h,respectively.Based on the previous results of cell proliferation,0.00(control),6.25,12.50,and 25.00 μmol/L of sodium arsenite were selected to treat HaCaT cells for 48 h,respectively.The mRNA expression of keratin 1,keratin 10,involucrin,loricrin and Nrf2 were detected by real-time fluorescent quantitative PCR.ResultsCompared with the control group (100.05％),HaCaT cell proliferation rates(83.06％,51.04％,39.52％,24.51％,16.99％ and 9.04％) were significantly lower in 6.25,12.50,25.00,50.00,75.00 and 100.00 μ mol/L of sodium arsenite groups and the 50％ inhibiting concentration was 12.38 μmol/L.Compared with the control group( 1.06 ± 0.28,1.00 ± 0.12,1.00 ± 0.08),the mRNA expression of keratin 1,involucrin and loricrin (0.08 ± 0.04,0.13 ± 0.12,0.05 ± 0.03;0.47 ± 0.11,0.21 ± 0.09,0.10 ± 0.15; 0.50 ± 0.27,0.31 ± 0.10,0.57 ± 0.23) were significantly decreased(all P ＜ 0.05) in HaCaT cells treated with 6.25,12.50,25.00 μmol/L sodium arsenite,respectively.But keratin 10 mRNA expression showed a rise trend and the 6.25 μmoL/L sodium arsenite group (1.83 ± 0.45) was significantly higher than that of the control( 1.07 ± 0.14,P ＜ 0.05 ).The Nrf2 mRNA expressions of HaCaT cells in 12.50,25.00 μmol/L sodium arsenite groups(0.13 ± 0.07,0.69 ± 0.33) were significantly lower than that of the control ( 1.00 ± 0.09,all P ＜ 0.05 ).ConclusionsThe cellular proliferation and keratinization are decreased when HaCaT cells are exposed to sodium arsenite,which may be regulated by lowering Nrf2 mRNA transcription.
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ObjectiveTo investigate the protective effect of all-trans retinoic acid (ATRA) on injury of human immortalized hepatocytes (HHL-5 cells ) induced by sodium arsenite and possible mechanisms.Methods After cultured for 48 h,HHL-5 cells were divided into four groups:normal group,ATRA group,sodium arsenite group and ATRA + sodium arsenite group.HHL-5 cell viability was tested by using cell proliferation experiment (WST).Superoxide dismutase(SOD),glutathione peroxidase(GSH-Px) activity,malondialdehyde(MDA) content,and aspartate aminottransferase (AST) activity in each group were determined by biochemical method.The microstructure of HHL-5 cells in each group was observed under transmission electron microscopy.ResultsHHL-5 cell viability(0.57 ± 0.02) of sodium arsenite group was compared with that of normal group(0.70 ± 0.01 ),the difference was statistically significant(P ＜ 0.05).Levels of SOD,GSH-Px,MDA and AST[ (153.84 ± 2.35),(0.08 ±0.02)U/mg Prot,(4.15 ± 0.50)nmol/mg Prot,(265.43 ± 4.62) × 103 U/L] of sodium arsenite group were compared with that of normal group[(237.41 ± 18.30),(0.93 ± 0.02)U/mg Prot,(2.26 ± 0.40)nmol/mg Prot,(177 ± 9.85) ×103 U/L],and the difference was statistically significant (all P ＜ 0.05).HHL-5 cell viability (0.65 ± 0.04) of ATRA + sodium arsenite group was compared with that of sodium arsenite group, and the difference was statistically significant (P ＜ 0.05).Levels of SOD,GSH-Px,MDA and AST[ (286.85 ± 3.39),(0.56 ± 0.09)U/mg Prot,(3.36 ± 0.37)nmol/mg Prot, (220.02 ± 1.07) × 103 U/L] of ATRA+ sodium arsenite group were compared with that of sodium arsenite group,the difference was statistically significant(all P ＜ 0.05).Compared with normal group and ATRA group,the surface microvilli of HHL-5 cells of sodium arsenite group decreased,double-membrane structure was unclear,vacuolar degeneration was seen in the cytoplasm,and glycogen was aggregated.The damage level of ATRA + sodium arsenite group was decreased.ConclusionsATRA plays a protective role through increasing intracellular antioxidant enzyme activity of HHL-5 cells,removal or reduction of oxygen free radicals produced by sodium arsenite.
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<p><b>OBJECTIVE</b>To investigate the anti-angiogenic effects and mechanisms of Zengmian Yiliu Granule (ZMYLG) on ovarian carcinoma xenograft.</p><p><b>METHODS</b>The SKOV3 ovarian carcinoma bearing mouse model was established. The tumor-bearing mice were randomly divided into the control group, the paclitaxel group, the high, medium, and low dose ZMYLG group, 8 in each group. The medication was lasted for ten days. The microvessel density (MVD) in the xenograft was calculated by the method of using cell membrane differentiation antigen 34 (CD34) antibody marking new vascular endothelial cells. The protein and mRNA expressions of vascular endothelial growth factor (VEGF) and its receptor fetal liver kinase-1 (FLK-1), hypoxia inducible factor-1alpha (HIF-1alpha) in the tumor were determined using immunohistochemical assay and RT-PCR.</p><p><b>RESULTS</b>The MVD of ovarian carcinoma xenografts in the paclitaxel group, the high, medium, and low dose ZMYLG group obviously decreased, showing statistical difference when compared with the control group (P < 0.01, P < 0.05). Each ZMYLG dose group could down-regulate the protein and mRNA expressions of VEGF, FLK-1, and HIF-1alpha (P < 0.01, P < 0.05).</p><p><b>CONCLUSIONS</b>ZMYLG could inhibit neogenesis of tumor vessels. Its mechanisms might be associated with down-regulating the expression of HIF-1alpha, modifying the hypoxic state, inhibiting the expressions of VEGF and FLK-1, and exerting its anti-angiogenic effects.</p>
Subject(s)
Animals , Female , Humans , Mice , Angiogenesis Inhibitors , Pharmacology , Cell Line, Tumor , Drugs, Chinese Herbal , Pharmacology , Hypoxia-Inducible Factor 1, alpha Subunit , Metabolism , Mice, Inbred BALB C , Neoplasms, Glandular and Epithelial , Drug Therapy , Neovascularization, Pathologic , Ovarian Neoplasms , Drug Therapy , Vascular Endothelial Growth Factor A , Metabolism , Vascular Endothelial Growth Factor Receptor-2 , Metabolism , Xenograft Model Antitumor AssaysABSTRACT
An in vitro screening model was applied to test the inhibitory activities of 17 Salvia species on protein tyrosine phosphatase 1B (PTP1B). Root methanol extracts from wild-collected Salvia species were analyzed using this model. Most of the samples tested showed positive activities on human PTP1B. The inhibition rates of Salvia crude extracts varied from 9.76% to 100% at 30 microg x mL(-1), with the most convincing effects coming from Salvia evansiana and Salvia castanea. HPLC analysis revealed seven components shared by Salvia samples could be related to the inhibitory activities.