Synthesis,antibacterial and antifungal activities of some carbazole derivatives

A series of N-substituted carbazole derivatives were synthesized and evaluated for antibacterial and antifungal activities against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Bacillus proteus, Candida albicans and Aspergillus fumigatus by two fold serial dilution technique. Some of the synthesized compounds displayed comparable or even better antibacterial and antifungal activities than reference drugs fluconazole, chloramphenicol and norfloxacin against tested strains.     

Synthesis and evaluation of a class of new coumarin triazole derivatives as potential antimicrobial agents

A series of new coumarin-based 1,2,4-triazole derivatives were designed, synthesized and evaluated for their antimicrobial activities in vitro against four Gram-positive bacteria (Staphylococcus aureus, MRSA, Bacillus subtilis and Micrococcus luteus), four Gram-negative bacteria (Escherichia coli, Proteus vulgaris, Salmonella typhi and Shigella dysenteriae) as well as three fungi (Candida albicans, Saccharomyces cerevisiae and Aspergillus fumigatus) by two-fold serial dilution technique. The bioactive assay showed that some synthesized coumarin triazoles displayed comparable or even better antibacterial and antifungal efficacy in comparison with reference drugs Enoxacin, Chloromycin and Fluconazole. Coumarin bis-triazole compounds exhibited stronger antibacterial and antifungal efficiency than their corresponding mono-triazole derivatives.     

Novel purine benzimidazoles as antimicrobial agents by regulating ROS generation and targeting clinically resistant Staphylococcus aureus DNA groove

A novel series of purine benzimidazole hybrids were designed and synthesized for the first time with the aim to circumvent the increasing antibiotic resistance. Hexyl appended hybrid 3c gave potent activities against most of the tested bacteria and fungi especially against multidrug-resistant strains Staphylococcus aureus (MIC?=?4?µg/mL). Structure-activity relationships revealed that the benzimidazole fragment at the 9-position of purine played an important role in exerting potentially antibacterial activity. Both cell toxicity and ROS generation assays indicated that the purine derivative 3c showed low cytotoxicity and could be used as a safe agent. Molecular modeling suggested that hybrid 3c could bind with the residues of Topo IA through hydrogen bonds and electrostatic interactions. Quantum chemical studies were also performed on the target compound 3c to understand the structural features essential for activity. The active molecule 3c could effectively interact with S. aureus DNA to form 3c–DNA complex through groove binding mode, which might block DNA replication to display their powerful antimicrobial activity.     

Synthesis and biological evaluation of a class of quinolone triazoles as potential antimicrobial agents and their interactions with calf thymus DNA

A novel series of quinolone triazoles were synthesized and characterized by IR, NMR, MS and HRMS spectra. All the newly prepared compounds were screened for their antimicrobial activities against seven bacteria and four fungi. Bioactive assay manifested that most of new compounds exhibited good or even stronger antibacterial and antifungal activities against the tested strains including multi-drug resistant MRSA in comparison with reference drugs Norfloxacin, Chloromycin and Fluconazole. The preliminary interactive investigations of compound 6b with calf thymus DNA by fluorescence and UV–vis spectroscopic methods revealed that compound 6b could effectively intercalate DNA to form compound 6b–DNA complex which might block DNA replication and thus exert its antimicrobial activities.     

Synthesis and bioactive evaluation of novel hybrids of metronidazole and berberine as new type of antimicrobial agents and their transportation behavior by human serum albumin

A series of novel hybrids of metronidazole and berberine as new type of antimicrobial agents were synthesized and characterized by ¹H NMR, ¹³C NMR, IR, MS and HRMS spectra. Bioactive assay manifested that most of the prepared compounds exhibited effective antibacterial and antifungal activities and some showed comparable or superior potency against Methicillin-resistant Staphylococcus aureus to reference drugs Norfloxacin, Chloromycin and Berberine. The transportation behavior of human serum albumin (HSA) to the highly active compound 5g was evaluated and revealed that the association of imidazole derivative 5g with HSA was spontaneous and the electrostatic interactions played important roles in the transportation of HSA to 5g. The calculated parameters indicated that compound 5g could be effectively stored and carried by HSA.     

Synthesis and activities of naphthalimide azoles as a new type of antibacterial and antifungal agents

Naphthalimide-derived azoles as a new type of antimicrobial agents were synthesized and evaluated for their efficiency in vitro against eight bacteria and two fungi by two fold serial dilution technique. Most title compounds exhibited good antimicrobial potency with low MIC values ranging from 1 to 16 μg/mL. Notably, some synthesized compounds displayed comparable or even better antibacterial and antifungal activities against some tested strains than the reference drugs Orbifloxacin, Chloromycin and Fluconazole, respectively.     

Novel potentially antifungal hybrids of 5-flucytosine and fluconazole: Design,synthesis and bioactive evaluation

A series of novel potentially antifungal hybrids of 5-flucytosine and fluconazole were designed, synthesized and characterized by ¹H NMR, ¹³C NMR, IR and HRMS spectra. Bioactive assay manifested that some prepared compounds showed moderate to good antifungal activities in comparison with fluconazole and 5-flucytosine. Remarkably, the 3,4-dichlorobenzyl hybrid 7h could inhibit the growth of C. albicans ATCC 90023 and clinical resistant strain C. albicans with MIC values of 0.008 and 0.02?mM, respectively. The active molecule 7h could not only rapidly kill C. albicans but also efficiently permeate membrane of C. albicans. Molecular docking study revealed that compound 7h could interact with the active site of CACYP51 through hydrogen bond. Quantum chemical studies were also performed to explain the high antifungal activity. Further preliminary mechanism research suggested that molecule 7h could intercalate into calf thymus DNA to form a steady supramolecular complex, which might block DNA replication to exert the powerful bioactivities.     

Design, synthesis and evaluation of clinafloxacin triazole hybrids as a new type of antibacterial and antifungal agents

A series of clinafloxacin triazole hybrids as a new type of antibacterial and antifungal agents were synthesized for the first time and screened for their antimicrobial efficacy against four Gram-positive bacteria, four Gram-negative bacteria and two fungi by two fold serial dilution technique. The bioactive assay indicated that most of the target compounds displayed broad antimicrobial spectrum and good antibacterial and antifungal activities with low MIC values ranging from 0.25 to 2μg/mL against all the tested strains which exhibited comparable or even better efficiency in comparison with the reference drugs Chloramphenicol, Clinafloxacin and Fluconazole, respectively. Notably, some synthesized clinafloxacin triazoles showed stronger efficacy against methicillin-resistant Staphylococcus aureus than their parent Clinafloxacin.     

Mitogenome of Knodus borki (Cypriniformes: Characidae): genomic characterization and phylogenetic analysis

Background

The taxonomic status of Knodu in the family Characidae is not yet clear. This study aimed to address this by sequencing and annotating Knodu borki Zarske, 2008.

Materials and results

K. borki Zarske, 2008 was sequenced using a Hiseq platform and the complete mitogenome was assembled in SPAdes v3.15.2 and SOAPdenovo2 v.2.01. The mitogenome of K. borki from Guangzhou, the first sequenced species of the genus Knodu, is 16,837 bp in length and contains 13 protein-coding genes (PCGs), two ribosomal (r) RNAs, 22 transfer (t) RNAs, and one D-loop. Among these 37 genes, 28 are encoded by the heavy strand, while nine are encoded by the light strand. Twenty-one of the tRNAs can form typical cloverleaf secondary structures, except tRNA-Ser1, which lacks dihydrouridine arms. All PCGs have the same start codon (ATG), with the exception of COI (GTG). Four PCGs (ND1, ATP8, ND4L, and ND5) have TAA as the stop codon, ND6 has TAG as the stop codon, COI has AGG as the stop codon, and the remaining seven genes have incomplete stop codons of TA-/T-(ND2, COII, COIII, ND3, ND4, and Cyt b as T-, ATP6 as TA-). Phylogenetic analysis showed that K. borki belongs to the family Characidae.

Conclusions

Our findings demonstrate that K. borki belongs to the family Characidae, due to consistency with the morphological identification. This study provides molecular information for further research on the phylogeny of the genus Knodus and for analyses of the taxonomic status of Characidae.

     

三分体形成是大白菜2n雄配子发生的主要途径

用能自然产生２ｎ配子的二倍体大白菜ＢＰ０５８为材料,研究了２ｎ雄配子发生的细胞学机制。结果表明,大白菜２ｎ雄配子的形成主要是由于减数分裂过程中,中期Ⅱ两个纺锤体的定向发生改变所致,即由正常的相互垂直定向改变为八字形和平行形定向。