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
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
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
It has been proposed by Ettema and colleagues, in the two-domain framework for the tree of life, that Eukarya emerged from Heimdallarchaeia, as sister group to Hodarchaeales. Looking at the individual trees of the pro...It has been proposed by Ettema and colleagues, in the two-domain framework for the tree of life, that Eukarya emerged from Heimdallarchaeia, as sister group to Hodarchaeales. Looking at the individual trees of the protein markers used by these authors, I notice that Eukarya are only sister to Hodarchaeales or other Heimdallarchaeia in a minority of trees, whereas they are located far apart from these Asgard archaea in most other trees. Examination of single trees also reveals massive gene transfers from Crenarchaeota and/or Korachaeota to hyperthermophilic Njordarchaeales, explaining why their belonging to Asgard archaea is sometimes difficult to recover. Finally, I discuss several points raised by Ettema and colleagues, such as the phylogeny of Asgard archaea and the hyperthermophilic nature of their last common ancestor. The patchy localization of Eukarya in individual trees relative to Hodarchaeales and other Heimdallarchaeia, as well as the patchy distribution of eukaryotic signature proteins among Asgard archaea, is best explained by suggesting that multiple gene transfers take place between proto-eukaryotes and Asgard archaea in both directions. This suggests that the co-evolution of proto-eukaryotes and Asgard archaea has played a major role in eukaryogenesis but also in shaping the physiology and diversification of Asgard archaea.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
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
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.
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It has been proposed by Ettema and colleagues, in the two-domain framework for the tree of life, that Eukarya emerged from Heimdallarchaeia, as sister group to Hodarchaeales. Looking at the individual trees of the protein markers used by these authors, I notice that Eukarya are only sister to Hodarchaeales or other Heimdallarchaeia in a minority of trees, whereas they are located far apart from these Asgard archaea in most other trees. Examination of single trees also reveals massive gene transfers from Crenarchaeota and/or Korachaeota to hyperthermophilic Njordarchaeales, explaining why their belonging to Asgard archaea is sometimes difficult to recover. Finally, I discuss several points raised by Ettema and colleagues, such as the phylogeny of Asgard archaea and the hyperthermophilic nature of their last common ancestor. The patchy localization of Eukarya in individual trees relative to Hodarchaeales and other Heimdallarchaeia, as well as the patchy distribution of eukaryotic signature proteins among Asgard archaea, is best explained by suggesting that multiple gene transfers take place between proto-eukaryotes and Asgard archaea in both directions. This suggests that the co-evolution of proto-eukaryotes and Asgard archaea has played a major role in eukaryogenesis but also in shaping the physiology and diversification of Asgard archaea.
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.
