A series of berberine derivatives were synthesized by introducing substituted benzyl groups at C-9.All these synthesized compounds（4a–4m）were screened for their in vitro antibacterial activity against four Gram-pos...A series of berberine derivatives were synthesized by introducing substituted benzyl groups at C-9.All these synthesized compounds（4a–4m）were screened for their in vitro antibacterial activity against four Gram-positive bacteria and four Gram-negative bacteria and evaluated for their antifungal activity against three pathogenic fungal strains.All these compounds displayed good antibacterial and antifungal activities,compared to reference drugs including Ciprofloxacin and Fluconazole;Compounds 4f,4g,and 4l showed the highest antibacterial and antifungal activities.Moreover,all the synthesized compounds were docked into topoisomerase Ⅱ-DNA complex,which is a crucial drug target for the treatment of microbial infections.Docking results showed that H-bond,π-πstacked,π-cationic,andπ-anionic interactions were responsible for the strong binding of the compounds with the target protein-DNA complex.展开更多
OBJECTIVE: To study the resistance mechanism of clinical isolates of Ureaplasma urealyticum resistant to fluoroquinolones. METHODS: Thirteen isolates of Ureaplasma urealyticum resistant to six fluoroquinolones were se...OBJECTIVE: To study the resistance mechanism of clinical isolates of Ureaplasma urealyticum resistant to fluoroquinolones. METHODS: Thirteen isolates of Ureaplasma urealyticum resistant to six fluoroquinolones were selected out of 184 clinical isolates and their QRDRs (quinolone resistance-determining region) gyrA, gyrB, parC and parE were amplified by PCR. Sequencing results were compared to those susceptible reference strains and a comparison of deduced amino acid sequences were performed. RESULTS: Sequence comparison revealed a C to A change at 87nt of gyrA QRDR leading to the substitution of Asp95 with glutamic acid and a C to T change at 50nt of parC QRDR leading to the substitution of Ser80 with leucine. CONCLUSION: These results suggest that a C to A change at 87nt of gyrA QRDR and a C to T change at 50nt of parC QRDR are associated with fluoroquinolone resistance of Ureaplasma urealyticum.展开更多
以印度洋深层海水,用柴油和石油作为混合碳源经富集培养、分离获得一株具有很强的柴油降解能力的菌株P40.菌株P40革兰氏染色阴性,接触酶和氧化酶为阳性,能还原硝酸盐,不能还原亚硝酸盐.16S rDNA B lastn结果表明其与Alcanivorax dieselo...以印度洋深层海水,用柴油和石油作为混合碳源经富集培养、分离获得一株具有很强的柴油降解能力的菌株P40.菌株P40革兰氏染色阴性,接触酶和氧化酶为阳性,能还原硝酸盐,不能还原亚硝酸盐.16S rDNA B lastn结果表明其与Alcanivorax dieseloleiB-5T(柴油食烷菌)及A.dieseloleiNO1A具有最高相似性,均为99.8%.菌株P40的gyrB序列与A.dieseloleiNO1A同源性也高达99.2%,而与A.dieseloleiB-5T只有86.9%.此外,从菌株P40中克隆到两个烷烃羟化酶alkB基因片断,分别命名为P40a-lkB1和P40a-lkB2.其中P40a-lkB1与报道的A.dieseloleiB-5T中的alkB同源性较高,达96.3%,而与同为深海来源的菌株NO1A的alkB的同源性更是达100%,P40a-lkB2则与A.borkum ensisSK2T(泊库岛食烷菌)的alkB1同源性最高,但仅为65%.展开更多
A series of chalcone-benzotriazole conjugates as new potential antimicrobial agents were synthesized and char- acterized by ^1H NMR, ^13C NMR, IR and HRMS spectra. Antimicrobial assay manifested that some target com- ...A series of chalcone-benzotriazole conjugates as new potential antimicrobial agents were synthesized and char- acterized by ^1H NMR, ^13C NMR, IR and HRMS spectra. Antimicrobial assay manifested that some target com- pounds gave moderate to good antibacterial and antifungal activities. The N- 1 derived benzotriazole 5e and N-2 de- rived benzotriazole 6a exhibited valuable inhibitory efficacy against some tested strains. Especially, derivative 6a gave superior antifungal efficacies against C. utilis, S. cerevisiae and A. flavus （MIC^0.01, 0.02, 0.02 gmol/mL, respectively） to Fluconazole. The drug combination of compound 5e or 6a with antibacterial Chloromycin, Nor- floxacin and antifungal Fluconazole respectively showed stronger antimicrobial efficiency with less dosage and broader antimicrobial spectrum than their separated use alone. The preliminary interaction with calf thymus DNA revealed that compound 6a could intercalate into DNA to form 6a-DNA supramolecular complex which might be a factor to exert its powerful bioactivity. Molecular docking study indicated strong binding of compound 6a with DNA gyrase. The structural parameters such as molecular orbital energy and molecular electrostatic potential of compound 6a were also investigated, which provided better understanding for its good antimicrobial activity.展开更多
We developed a novel PCR method aimed at identi- fying and amplifying native codon sequences of muta- tion-prone amino acids in DNA gyrase implicated in quinolone resistance using a naturally occurring co- don bias in...We developed a novel PCR method aimed at identi- fying and amplifying native codon sequences of muta- tion-prone amino acids in DNA gyrase implicated in quinolone resistance using a naturally occurring co- don bias in E. coli DNA gyrase A.展开更多
A large number of Chinese herbal drugs (CHDs) exhibit antibacterial activities both in vivo and in vitro, but until now little is known regarding their inhibitory mechanisms. Bacterial DNA gyrase is a proven target fo...A large number of Chinese herbal drugs (CHDs) exhibit antibacterial activities both in vivo and in vitro, but until now little is known regarding their inhibitory mechanisms. Bacterial DNA gyrase is a proven target for antibacterial agents. Aim of this study was to investigate the in-vitro inhibitory effect of methanol extracts of CHDs against supercoiling activity of bacterial DNA gyrase. Fifteen CHDs were selected and extracted with methanol, respectively. Inhibitory effect of the extracts on DNA gyrase was tested using gel-based DNA supercoiling assay. Among fifteen CHDs tested, methanol extracts of Lonicerae Japonicae Flos (S2), Taraxaci Herba (S7), Glycyrrhizae Radix et Rhizoma Praeparata cum Melle (S8) demonstrated an obvious inhibitory effect against supercoiling activity of DNA gyrase, and the others were either less active or could not be determined with the present method. Moreover, it was likely that S7 and S8 inhibit gyrase in a concentration-dependent manner. In conclusion, DNA supercoiling assay is a promising method to study the inhibitory activity of CHDs on bacterial DNA gyrase. Some CHDs do have gyrase-inhibitory activity as proposed. Further investigations are needed to elucidate the inhibition mechanism of these CHDs on supercoiling activity of gyrase.展开更多
ccdAB系统(control of cell division or death system)是目前已知的一种毒素-抗毒素系统(toxin-antitoxin system,TA系统),存在于致病性大肠杆菌F质粒及染色体骨架上,由ccdA和ccdB两个基因组成。质粒上的ccdAB系统编码一种毒素蛋白CcdB...ccdAB系统(control of cell division or death system)是目前已知的一种毒素-抗毒素系统(toxin-antitoxin system,TA系统),存在于致病性大肠杆菌F质粒及染色体骨架上,由ccdA和ccdB两个基因组成。质粒上的ccdAB系统编码一种毒素蛋白CcdB,在缺乏抗毒素的情况下,CcdB使细胞内促旋酶中毒,从而干扰DNA的合成,杀伤宿主细胞。本文对ccdAB系统的结构和功能,以及所编码CcdB的作用机制进行了综述。展开更多
The DNA gyrase of Escherichia coli plays an essential role in the life of this microorganism.It is unique among all topoisomerases because of its ability to introduce negative supercoils into DNA.This study investigat...The DNA gyrase of Escherichia coli plays an essential role in the life of this microorganism.It is unique among all topoisomerases because of its ability to introduce negative supercoils into DNA.This study investigated the single molecular interaction of E.coli gyrase with DNA using magnetic tweezers.The results showed that,in the absence of ATP,gyrase weakly binds the G and T segments.The stretched force of 0.7 pN can gradually destroy the binding,whereas that of 5.9 pN directly destroys it.Addition of high concentrations of norfloxacin enhances gyrase binding to both segments,making them adapt to 5.9 pN.DNA gyrase reduces the plectonemic dimension,which was determined by the bacterial enzyme and not by the pull force.Moreover,it has different affinities for positive supercoils,which it prefers,and negative supercoils.The time distribution of the dissociation of gyrase from DNA has a double-exponential form.We herein propose a model to explain this distribution and compare the results with those of other models.展开更多
基金supported by the Graduate Students Scientific Research Innovation Projects of Jiangsu Province(No.CXZZ11-0804)Students Training Innovation Program of China Pharmaceutical University(201810316155)
文摘A series of berberine derivatives were synthesized by introducing substituted benzyl groups at C-9.All these synthesized compounds（4a–4m）were screened for their in vitro antibacterial activity against four Gram-positive bacteria and four Gram-negative bacteria and evaluated for their antifungal activity against three pathogenic fungal strains.All these compounds displayed good antibacterial and antifungal activities,compared to reference drugs including Ciprofloxacin and Fluconazole;Compounds 4f,4g,and 4l showed the highest antibacterial and antifungal activities.Moreover,all the synthesized compounds were docked into topoisomerase Ⅱ-DNA complex,which is a crucial drug target for the treatment of microbial infections.Docking results showed that H-bond,π-πstacked,π-cationic,andπ-anionic interactions were responsible for the strong binding of the compounds with the target protein-DNA complex.
文摘OBJECTIVE: To study the resistance mechanism of clinical isolates of Ureaplasma urealyticum resistant to fluoroquinolones. METHODS: Thirteen isolates of Ureaplasma urealyticum resistant to six fluoroquinolones were selected out of 184 clinical isolates and their QRDRs (quinolone resistance-determining region) gyrA, gyrB, parC and parE were amplified by PCR. Sequencing results were compared to those susceptible reference strains and a comparison of deduced amino acid sequences were performed. RESULTS: Sequence comparison revealed a C to A change at 87nt of gyrA QRDR leading to the substitution of Asp95 with glutamic acid and a C to T change at 50nt of parC QRDR leading to the substitution of Ser80 with leucine. CONCLUSION: These results suggest that a C to A change at 87nt of gyrA QRDR and a C to T change at 50nt of parC QRDR are associated with fluoroquinolone resistance of Ureaplasma urealyticum.
基金This work was partially supported by the National Natural Science Foundation of China [（Nos. 21372186, 21672173）, the Research Fund for International Young Scientists from International （Regional） Cooperation and Exchange Program （No. 81650110529）] and Chongqing Special Foundation for Postdoctoral Research Proposal （Xm2015031 ）.
文摘A series of chalcone-benzotriazole conjugates as new potential antimicrobial agents were synthesized and char- acterized by ^1H NMR, ^13C NMR, IR and HRMS spectra. Antimicrobial assay manifested that some target com- pounds gave moderate to good antibacterial and antifungal activities. The N- 1 derived benzotriazole 5e and N-2 de- rived benzotriazole 6a exhibited valuable inhibitory efficacy against some tested strains. Especially, derivative 6a gave superior antifungal efficacies against C. utilis, S. cerevisiae and A. flavus （MIC^0.01, 0.02, 0.02 gmol/mL, respectively） to Fluconazole. The drug combination of compound 5e or 6a with antibacterial Chloromycin, Nor- floxacin and antifungal Fluconazole respectively showed stronger antimicrobial efficiency with less dosage and broader antimicrobial spectrum than their separated use alone. The preliminary interaction with calf thymus DNA revealed that compound 6a could intercalate into DNA to form 6a-DNA supramolecular complex which might be a factor to exert its powerful bioactivity. Molecular docking study indicated strong binding of compound 6a with DNA gyrase. The structural parameters such as molecular orbital energy and molecular electrostatic potential of compound 6a were also investigated, which provided better understanding for its good antimicrobial activity.
文摘We developed a novel PCR method aimed at identi- fying and amplifying native codon sequences of muta- tion-prone amino acids in DNA gyrase implicated in quinolone resistance using a naturally occurring co- don bias in E. coli DNA gyrase A.
文摘A large number of Chinese herbal drugs (CHDs) exhibit antibacterial activities both in vivo and in vitro, but until now little is known regarding their inhibitory mechanisms. Bacterial DNA gyrase is a proven target for antibacterial agents. Aim of this study was to investigate the in-vitro inhibitory effect of methanol extracts of CHDs against supercoiling activity of bacterial DNA gyrase. Fifteen CHDs were selected and extracted with methanol, respectively. Inhibitory effect of the extracts on DNA gyrase was tested using gel-based DNA supercoiling assay. Among fifteen CHDs tested, methanol extracts of Lonicerae Japonicae Flos (S2), Taraxaci Herba (S7), Glycyrrhizae Radix et Rhizoma Praeparata cum Melle (S8) demonstrated an obvious inhibitory effect against supercoiling activity of DNA gyrase, and the others were either less active or could not be determined with the present method. Moreover, it was likely that S7 and S8 inhibit gyrase in a concentration-dependent manner. In conclusion, DNA supercoiling assay is a promising method to study the inhibitory activity of CHDs on bacterial DNA gyrase. Some CHDs do have gyrase-inhibitory activity as proposed. Further investigations are needed to elucidate the inhibition mechanism of these CHDs on supercoiling activity of gyrase.
文摘ccdAB系统(control of cell division or death system)是目前已知的一种毒素-抗毒素系统(toxin-antitoxin system,TA系统),存在于致病性大肠杆菌F质粒及染色体骨架上,由ccdA和ccdB两个基因组成。质粒上的ccdAB系统编码一种毒素蛋白CcdB,在缺乏抗毒素的情况下,CcdB使细胞内促旋酶中毒,从而干扰DNA的合成,杀伤宿主细胞。本文对ccdAB系统的结构和功能,以及所编码CcdB的作用机制进行了综述。
基金supported by the National Natural Science Foundation of China (10834014,10974248)the National Basic Research Program of China (2009CB930704)
文摘The DNA gyrase of Escherichia coli plays an essential role in the life of this microorganism.It is unique among all topoisomerases because of its ability to introduce negative supercoils into DNA.This study investigated the single molecular interaction of E.coli gyrase with DNA using magnetic tweezers.The results showed that,in the absence of ATP,gyrase weakly binds the G and T segments.The stretched force of 0.7 pN can gradually destroy the binding,whereas that of 5.9 pN directly destroys it.Addition of high concentrations of norfloxacin enhances gyrase binding to both segments,making them adapt to 5.9 pN.DNA gyrase reduces the plectonemic dimension,which was determined by the bacterial enzyme and not by the pull force.Moreover,it has different affinities for positive supercoils,which it prefers,and negative supercoils.The time distribution of the dissociation of gyrase from DNA has a double-exponential form.We herein propose a model to explain this distribution and compare the results with those of other models.
