Synthesis and Antibacterial Activity of (S)-5-(Heterocycle Methylene) -3-(3-Fluoro-4-morpholin-4-yl-phenyl)-Oxazolidin-2-one Derivatives

Aim To study the structure-activity relationship of antibacterial oxazolidinone derivatives. Methods Seven （S） -5- （ heterocycle methylene） -3- （3-fluoro-4-morpholin-4-yl-phenyl） -oxazoli- din-2-ones were synthesized by the substitution of （S）-[ 3-（3-fluoro-4-morpholin-4-yl-phenyl）-oxazohdin-2-one-5-yl]-methanol mesylate with some secondary amines and the structures of the product were confirmed by ^1H NMR and elemental analyses or MS. Results None of the seven compounds showed potent activity against the tested 20 strains of bacteria in vitro. Conclusion The replacement of 5- acetylaminometyl of Linezolid by 5-（heterocycle methylene） lost the antibacterial activity.

SYNTHESIS AND ANTIBACTERIAL ACTIVITY OF 3,6-DISUBSTITUTED S-TRIAZOLO[3,4-b]-1,3,4-THIADIAZOLES

A series of 3,6-disubstituted s-triazolo[3,4-b]-1,3,4-thiadiazoles have been synthesized,whose structures were determined by elemental and spectral analyses;all the new compounds showed significant antibacterial activity.

Novel dihydropyrazole derivatives linked with multi(hetero)aromatic ring:Synthesis and antibacterial activity

Eight novel heterocycle-substituted dihydropyrazole derivatives were synthesized and characterized by ESI-MS, ^1H NMR and ^13C NMR. All of the compounds have been screened for their antibacterial potential in vitro against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The results show that compounds 9b, 9g and 9h displayed significant activity with MIC values in the range of 0.39-1.562 μlmL against B. subtilis.

Synthesis and antibacterial activity of new layered perovskite compounds,Ag_xNa_(2-x)La_2Ti_3O_(10)

Three kinds of new layered perovskite compounds with Ruddlesden-Popper （R-P） phase, AgrNa2-xLa2Ti3O10 （x = 0.2, 0.3 and 0.5）, were synthesized by an ion-exchange reaction of Na2La2Ti3O10 with AgNO3 solution. The structures of the compounds were characterized by EDX and XRD, and their antibacterial activity and light-resistance property were evaluated. The results indicated that the molecular formula of AgxNa2-xLa2Ti3O10 （x = 0.2, 0.3 and 0.5） was confirmed, and that the crystalline structure of Na2La2Ti3O10 was not obviously affected by exchange of silver ion. The minimum inhibitory concentrations （MICs） of Ag0.3Na1.7La2Ti3O10 against Escherichia coli （E. coli）, Staphylococcus aureus （S. aureus） were 180 μg/mL and 240 μg/mL, respectively, while its discoloration was not observed after 24 h light ageing test.

Synthesis, Crystal Structure and Antibacterial Activity of 4,4'-Hydrazine-1,2- diylidenebis(methanylylidene)bis(2-ethoxyphenol)

A new Schiff base compound, 4,4′-hydrazine-1,2-diylidenebis（methanylylidene）- bis（2- ethoxyphenol） （C18H20N2O4）, has been synthesized by the condensation of 3-ethoxy-4- hydroxybenzaldehyde and 80% hydrazine hydrate in an ethanol solution. The compound was characterized by 1H NMR, MS and single-crystal X-ray diffraction. The crystal belongs to the monoclinic system, space group P21/n with a = 5.2421（5）, b = 10.3700（8）, c = 14.9906（11）A, β = 97.6030（10）°, Z = 2, V= 807.73（12） A, Dc = 1.350 g/cm3, Mr = 328.36, λ（MoKa） = 0.71073 A,μ = 0.096 mm-1, F（000） = 348, R = 0.041 and wR = 0.0136. The two benzene rings are coplanar. The molecule adopts an E,E configuration about the central C=N functional bonds. A total of 3938 unique reflections were collected, of which 1440 with I 〉 2σ（I） were observed. A different type of intermolecular hydrogen bond, O-H…N, exists in the crystal. The title complex molecules are connected through hydrogen bonds to generate a two-dimensional network. The preliminary antibacterial activity results showed that the title compound exhibits antibacterial activity against Staphylococcus aureus.

Synthesis and antibacterial activity of 4″-O-carbamoyl analogs of clarithromycin

A series of novel 4'-O-carbamoyl analogs of clarithromycin were synthesized and evaluated for their in vitro antibacterial activity. All of the desired compounds showed excellent activity against erythromycin-susceptible S.pneumoniae.Particularly,4-fluorobenzyl carbamate 7a demonstrated potent activity against erythromycin-resistant S.pneumoniae encoded by the mef gene,and remarkably improved activity against erythromycin-resistant S.pneumoniae encoded by the erm gene,and the erm and mef genes.

Studies on Condensed Heterocyclic Compounds(Ⅲ)——Synthesis and Antibacterial Activity of 3-(4-Pyridyl)-6-Alkyl/Aromatic Heterocyclyl-s-Triazolo[3,4-b]-1, 3,4-Thiadiazoles and 1,4-Bis [6-(4-Pyridyl)-s-Triazolo [3,4-b]-1, 3,4-Thiadiazol-3-yl]-n-Butane

In recent years, fused heterocycles have been reported to possess important properties in synthesis and pharmacology. Especially, s-triazolo, 3,4-thiadiazole derivatives have been attracting much attention for chemists and pharmacologists because they show broad spectra of biological activities, such as antifungal, antibacterial, hy-

Synthesis and Antibacterial Activity of Novel Oxazolidinone Analogs Containing Substituted Thiazole/Fused-Bicyclic Groups

Sixteen novel oxazolidinone analogs containing substituted thiazole/fused-bicyclic（imidazo[ 1,2-b] pyridazine/ imidazo[2,1-b] thiazole） groups were designed and synthesized. A new method for the preparation of the key intermediate compound 11 was proposed. The structures of the target compounds were confirmed by ^1H NMR, IR and MS, and their in vitro antibacterial activities against staphylococcus aureus were evaluated. Among them, compound 16a displays a promising antibacterial activity comparable to that of linezolid.

Efficient Synthesis, Crystal Structure and Antibacterial Activity of Two Novel 1,3-Oxazin Derivatives

Two new 1,3-oxazin derivatives, C22H24N2O5 （3I） and C19H16N2O5（3II）, have been synthesized via an unusual cascade reaction. The attractive aspect of this cascade reaction is that the novel construction of 1,3-oxazine and the direct C-N bond formation from C-C bond can be easily achieved via pyridine-mediated acylation in a one-pot operation. Both compounds have been synthesized and characterized by elemental analysis, IR, NMR spectra and X-ray single-crystal diffraction. Compound 3I crystallizes in monoclinic, space group P21/n with α = 16.282（4）, b = 7.4117（18）, c = 17.256（5） A, β = 103.193（9）°, V = 2027.4（9） A3, Mr = 396.43, Z = 4, Dc= 1.299 g/cm3, F（000） = 840, MoKa radiation （λ = 0.71073 A）, the final R = 0.0771 and wR = 0.1582 for 3662 were observed reflections with I 〉 2σ（I）. Compound 3II crystallizes in triclinic, space group Pī with α = 7.1265（9）, b = 10.1071（13）, c = 23.529（3） A, α = 97.463（9）, β = 96.981（9）, γ = 94.345（9）°, V = 1600.5（4） A3, Z = 4, Dc = 1.409 g/cm3, F（000） = 736, CuKa radiation （λ = 1.54186 A）, the final R = 0.0515 and wR = 0.1241 for 4920 observed reflections with I 〉 2σ（I）. The preliminary antibacterial activities of 2 and 3 against E. coli and S. aureuswere investigated. The results showed that the inhibiting effect of 3 was higher than that of 2.

Synthesis and antibacterial activity of brominated 2′(4′)-nitro-3-hydroxy diphenyl ethers

Eight new brominated 2＇（4＇）-nitro-3-hydroxy diphenyl ethers have been designed and synthesized. The structures of new compounds were confirmed by ^1H NMR, IR and HRMS. The bioactivity tests showed that these compounds possessed antibacterial activities against the tested bacteria. These new compounds cannot be transformed into dioxins when they were manufactured and used.

Synthesis and Antibacterial Activity of New Cephalosporin Compounds

Five new cephalosporin compounds were designed and synthesized, and the antibacterial activities were evaluated by the standard serial 2-fold agar dilution method in vitro. The results showed that the activities of the compounds Ia and lb against ESBL E. coli and K. pneumoniae are comparable to those of Cefepime.

Efficient Synthesis,Crystal Structure and Antibacterial Activity of Two Novel Thieno[2,3-d]pyrimidin-4(3H)-one Derivatives

Two new thieno[2,3-d]pyrimidin-4（3H）-one derivatives,C24H22 Cl N3O2S（5a） and C25H25N3O2S（5b）,have been synthesized via a tandem aza-Wittig reaction.This tandem reaction has many attractive aspects such as easily accessible and versatile starting materials,mild conditions and high yields.Both compounds have been characterized by elemental analysis,HR-MS,IR,NMR spectra and X-ray single-crystal diffraction.Compound 5a crystallizes in monoclinic,space group P21/c with a = 9.986（3）,b = 14.263（4）,c = 15.530（5）A,β = 93.806（5）o,V = 2207.1（11） A^3,Mr = 451.96,Z = 4,Dc = 1.360 g/cm3,F（000） = 944,μ = 0.294 mm-1,Mo Kα radiation（λ = 0.71073 A）,the final R = 0.0444 and w R = 0.1219 for 3407 observed reflections with I 〉 2σ（I）.Compound 5bcrystallizes in triclinic,space group P1 with a = 8.974（4）,b = 10.766（5）,c = 12.260（6） A,β = 93.047（7）o,V = 1122.1（9） A^3,Mr = 431.54,Z = 2,Dc = 1.277 g/cm3,F（000） = 456,μ = 0.170 mm-1,Mo Kα radiation（λ = 0.71073 A）,the final R = 0.0378 and w R = 0.1072 for 3806 observed reflections with I 〉 2σ（I）.The preliminary antibacterial activities of 5a and 5b were investigated.Compound 5a showed 71.3% and 79.2% in vitro inhibition against Fusarium oxysporium and Rhizoctonia solani,respectively.Compound 5b showed 75.3% in vitro inhibition against Rhizoctonia solani.

Synthesis,Crystal Structure and Antibacterial Activity of (2E,3E)-N^1,N^2-Bis(2,3,4-trimethoxy-6-methylbenzylidene)ethane-1,2-diamine

The title compound （2E,3E）-N1,N2-bis（2,3,4-trimethoxy-6-methylbenzylidene）- ethane-l,2-diamine （C24H32N2O6, Mr = 444.52） was synthesized and characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction. The crystal belongs to triclinic, space group P2/c, with a = 8.5480（10）, b = 9.3710（12）, c = 15.280（2）A, β = 90.780（2）°, V= 1223.9（3）A3, Z = 2, Dc= 1.206 g/cm3, 2 = 0.71073A,μ（MoKa） = 0.087 mm^-1, F（000） = 476, the final R = 0.0680 and wR = 0.1450 for 2144 observed reflections with I 〉 2σ（I）. X-ray diffraction analysis reveals that the molecule adopts an E configuration about the central C=N functional bond. The phenyl rings of two 2,3,4-trimethoxy-6-methylbenzaldehyde groups are symmetrically parallel. The molecules are linked through C-H…O hydrogen bonding interactions. The title compound possesses moderate antibacterial activity.

Synthesis,Crystal Structure and Antibacterial Activity of(E)-N^1,N^4-Bis(2,3,4-trimethoxy-6-methylbenzylidene)butane-1,4-diamine

The title compound （E）-N1,N4-bis（2,3,4-trimethoxy-6-methylbenzylidene） butane- 1,4- diamine （C26H36N2O6, Mr = 472.57） was synthesized and characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction. The crystal belongs to triclinic, space group C2/c with a = 36.102（4）, b = 5.6620（11）, c = 13.015（2）A,β = 105.491 （2）°, V = 2563.7（7）A3, Z = 4, Dc = 1.224 g/cm3, 2 = 0.71073 A,μ（MoKα） = 0.087 mm^-1, F（000） = 1016, the final R = 0.0456 and wR = 0.1257 for 2255 observed reflections with I 〉 2σ（I）. X-ray diffraction analysis reveals that the molecule adopts an E configuration about the central C=N functional bond. The phenyl rings of two 2,3,4-trimethoxy-6-methylbenzaldehyde groups are parallel by symmetry. The molecules are linked through π-π and C-H…π stacking interactions and C-H…O hydrogen bonding interactions. The title compound possesses moderate antibacterial activity.

Green Synthesis, Characterization and Antibacterial Activity of ZnO Nanoparticles

In the present study, mehendi extract (Lawsonia inermis) was used for phytosynthesis of ZnO nanoparticles using 0.1 M Zn(NO3)2 as precursor under alkaline condition using NaOH with vigorous stirring for 2 h. ZnO NPs obtained were characterized by UV-Vis spectroscopy, XRD, SEM and TEM that showed change in shape and size. Hexagonal particles were formed due to plant extract relative to the rod shaped particles in absence of plant extract. Further the antibacterial property of ZnO NP synthesized by green method was more effective than those synthesized in absence of plant extract. The antibacterial activity study of both the synthesized ZnO nanoparticles reveals that the nanoparticles synthesized using mehendi extract are more effective than the particle synthesized without mehendi extract. Thus, the use of leaf extract as capping agent would improve the antibacterial property of ZnO nanoparticle. However, bacteriocidal effect of these nanoparticles varies with respect to the organism tested.

Design, Synthesis and Antibacterial Activity Evaluation of 4,5-Diphenyl-1<i>H</i>-Imidazoles Derivatives

Due to the continuous emergence and rapid spread of drug-resistant strains of bacteria, there is an urgent need for the development of novel antimicrobials. Along this line, the synthesis and antibacterial activity of 4,5-diphenylimidazol-2-thiol derivatives 2a-g and 6a-e are reported. The structures of the synthesized compounds were confirmed by Nuclear Magnetic Resonance (NMR) and High Resolution Mass Spectrometry (HRMS). All compounds were screened in vitro for their antibacterial activity against Pseudomonas aeruginosa and Escherichia coli (Gram-negative bacteria) and also against Staphyloccocus aureus and Enterococcus faecalis (Gram-positive bacteria). The results showed most of the synthesized compounds have no antibacterial activity. However compound 6d was two-fold potent than ciprofloxacin against Staphylococcus aureus with Minimum Inhibitory Concentration (MIC) of 4 μg/mL and 6c showed moderate biological activity against Staphylococcus aureus (16 μg/mL) and Enterococcus faecalis (16 μg/mL).

Synthesis,Characterization and Antibacterial Activity of 3-(2-(Heterocyclo-2-ylthio)-ethoxy)benzo[d]isothiazoles

Seven novel 3-（2-（heterocyclo-2-ylthio）ethoxy）benzo[d]isothiazoles（3a^3g） have been synthesized and characterized by ESI-MS and 1H and 13 C NMR spectra. The crystal structures of 3a and 3g have been determined. Compound 3a（C（11）H（11）N5O1S2） belongs to the monoclinic system and 3g（C（12）H（11）N3OS3） to the triclinic system. The title compounds show excellent in vitro antibacterial activities, with the minimum inhibitory concentrations varying from 4 to 32 ug/m L.

Preparation,Single-crystal Structure and Antibacterial Activity of N-((6-Bromine-2-methoxylquinoline-3-yl)benzyl)-3-morpho-line-N-(naphthalene-1-yl)propionamide

The halogenated hydrocarbon amination reaction between the original raw mate-rial N-（（6-bromine-2-methoxylquinoline-3-yl）benzyl）-3-chlorine-N-（naphthalene-1-yl）propionamide and morpholine produces the target molecule N-（（6-bromine-2-methoxylquinoline-3-yl）benzyl）-3-morpholine-N-（naphthalene-1-yl）propionamide （C34H32BrN3O3,Mr=610.54）,and its structure was characterized by 1H NMR,IR,H RMS and X-ray single-crystal diffraction.This crystal is of triclinic system,space group P1 with a=9.315（2）,b=10.3449（12）,c=15.901（3）,α=80.981（14）,β=76.996（17）,γ=74.917（13）°,V=1433.6（5）3,Z=2,Dc=1.414 g/cm3,F（000）= 632,μ（MoKα）=1.47 mm-1,the final R=0.0735 and wR=0.2457.In total,5585 independent reflections including 3727 observed ones with I 〉 2σ（I） were collected.The dihedral angle between naphthyl and substituted quinolyl and that between phenyl and substituted quinolyl are 61.2（1） and 108.2（1）°,respectively.Through C-H…O and C-H…N hydrogen bonds among molecules,the whole molecule is stacked into a three-dimensional structure.In addition,π-π stacking among adjacent naphthalene rings makes the molecule more stable,and the morpholine ring adopts a chair conformation.The target molecule exhibits good antibacterial activity.

Structure, Antibacterial Activity and Theoretical Study of the Forming Mechanism of Compound [(5-Methyl-3-oxo-2-phenyl-1H-pyrazol-4-yl)-thiophen-2-yl-methylene] Thiosemicarbazide

A new thiosemicarbazone compound derived from 1-phenyl-3-methyl-4-（2-thenoyl） pyrazolone-5 （HPMTP） and thiosemicarbazide has been synthesized and characterized by IR, H- NMR, MS, elemental analysis, UV and single-crystal X-ray diffraction. The compound crystallizes in monoclinic system, Cc space group with a = 7.5925（8）, b = 20.263（2）, c = 11.4669（13） A, r= 107.825（8）°, V = 1679.5（3） A3, Z = 4, R = 0.0316 and wR = 0.0687. The results of antibacterial activity test against Escherichia coli and Bacillus subtilis indicate that the compound possesses the same antibacterial activity as the contrast （Norfloxacin）. Theoretical study of the forming mechanism to the title compound at the RHF/6-31G（d） level shows that there are two steps. The distal amino group of thiosemicarbazide is added to the 4-carbonyl group of HPMTP which forms TM. Then a dehydration reaction occurs in TM and generates a stable product PC.

Comparative Study of Antibacterial Activity of Bacterial Cellulose/AgNPs Composites Prepared by Different Methods

Bacterial cellulose(BC) is a type of nanoscale cellulose produced by microorganisms.In this work,BC films were utilized as a template to in situ synthesize silver nanoparticles(AgNPs) by a variety of simple chemical strategies,including chemical reduction with NaBH4 or vitamin C,hydrothermal treatment and UV radiation.A comparative study of the formation of AgNPs such as the silver particle size and silver content,as well as the antibacterial activity of the BC-AgNPs nanocomposites by different preparation methods and reaction conditions was investigated.A beneficial support was provided for future applications of AgNPs contained BC composites with antibacterial properties.