Synthesis,characterisation and antibacterial studies of carbon nanoparticle and carbon nanoparticle encapsulated in functionally modified β-cyclodextrin with {5-[4-(dimethylamino) benzylidene]-4-oxo-2-thioxo-1, 3-thiazolidin-3-yl} acetic acid

This paper describes the synthesis of carbon nanoparticle (CNP) from natural sources such as kitchen soot, synthesis of a chromophoric system {5-[4-(dimethylamino) benzylidene]-4-oxo-2-thioxo1, 3-thiazolidin-3-yl} acetic acid and its incorporation into β-cyclodextrin (β-CD) through the esterification of the hydroxyl group with the free carboxyl function of the chromophoric system by DCC coupling. Encapsulation of CNP into functionally modified β-CD system was achieved. Characterisation of the products was undertaken by UV–visible, FT-IR, NMR, fluorescence spectroscopic methods, SEM, TEM and X-ray diffraction methods. Their antibacterial activities were addressed. The antibacterial activity of CNP and functionally modified β-CD-CNP products were tested against various pathogenic bacterial strains such as Streptcoccus haemoliticus (+ve), Staphylococcus aureus (+ve), Klebsiella pneumonia (?ve) and E. coli (MTCC1687) (?ve) by disc diffusion method. The results showed that the CNPs and functionally modified products have good antibacterial activity against selected pathogenic bacterial strains.     

A detailed chemical kinetic model for high temperature ethanol oxidation

A detailed chemical kinetic model for ethanol oxidation has been developed and validated against a variety of experimental data sets. Laminar flame speed data (obtained from a constant volume bomb and counterflow twin‐flame), ignition delay data behind a reflected shock wave, and ethanol oxidation product profiles from a jet‐stirred and turbulent flow reactor were used in this computational study. Good agreement was found in modeling of the data sets obtained from the five different experimental systems. The computational results show that high temperature ethanol oxidation exhibits strong sensitivity to the fall‐off kinetics of ethanol decomposition, branching ratio selection for C₂H₅OH + OH ↔ Products, and reactions involving the hydroperoxyl (HO₂) radical. The multichanneled ethanol decomposition process is analyzed by RRKM/Master Equation theory, and the results are compared with those obtained from earlier studies. The ten‐parameter Troe form is used to define the C₂H₅OH(+M) ↔ CH₃ + CH₂OH(+M) rate expression as k^∞ = 5.94E23 T^−1.68 exp(−45880 K/T) (s⁻¹) k^o = 2.88E85 T^−18.9 exp(−55317 K/T) (cm³/mol/sec) F_cent = 0.5 exp(−T/200 K) + 0.5 exp(−T/890 K) + exp(−4600 K/T) and the C₂H₅OH(+M) ↔ C₂H₄ + H₂O(+M) rate expression as k^∞ = 2.79E13 T^0.09 exp(−33284 K/T) (s⁻¹) k^o = 2.57E83 T^−18.85 exp(−43509 K/T) (cm³/mol/sec) F _cent = 0.3 exp(−T/350 K) + 0.7 exp(−T/800 K) + exp(−3800 K/T) with an applied energy transfer per collision value of <ΔE_down> = 500 cm⁻¹. An empirical branching ratio estimation procedure is presented which determines the temperature dependent branching ratios of the three distinct sites of hydrogen abstraction from ethanol. The calculated branching ratios for C₂H₅OH + OH, C₂H₅OH + O, C₂H₅OH + H, and C₂H₅OH + CH₃ are compared to experimental data. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 183–220, 1999     

Structures,binding energies,temperature effects,infrared spectroscopy of [Mg(NH3)n = 1−10]+ clusters from DFT and MP2 investigations

The possible isomers of [Mg(NH₃)_{n = 1 − 10}]⁺ clusters have been investigated using both M06-2X/6-31++G(d,p) and MP2/6-31++G(d,p) levels of theory. The isomeric distribution for each n size has been studied as a function of temperatures ranging from 25 to 400 K. To the best of our knowledge, for clusters size n > 6, this is the first theoretical study available in the literature. From the calculated values in the considered clusters and using a fitting procedure, we have evaluated the binding energies (−14.0 kcal/mol), clustering energies (−10.1 kcal/mol), clustering free energies (−2.8 kcal/mol), and clustering enthalpies (−10.3 kcal/mol). On the basis of our structural and infrared (IR) spectroscopy outcomes, we find that the first solvation shell can hold up to six ammonia molecules. © 2019 Wiley Periodicals, Inc.     

Mechanical characterization of a new Kevlar/Flax/epoxy hybrid composite in a sandwich structure

Natural fibers are inexpensive, biodegradable, and have similar specific properties to some synthetic fibers. Hardly any previous investigations exist of a composite made of multiple layers of pure Kevlar fiber fabric and pure Flax fiber fabric in a “sandwich structure”, but it only measured impact properties. The composite was made of 12 Flax/epoxy layers at the core in 3 possible configurations (i.e. [0]_12F, [0/90]_6F, or [±45]_6F) that were sandwiched by 2 Kevlar/epoxy layers (i.e. plain weave) on each side. This study showed maximum change in the mechanical properties with respect to Flax/Epoxy for tension (+137.85% in E_T, and +171.22% in σ_UT), compression (+171.22% in E_c, and −10.6% in σ_UC), 3-point bending (−11.54% in E_B, and +2.19 in σ_UB), torsion (−5.31% in G, and 395.82% in τ), and water absorption (60.04%). This novel hybrid composite may be useful for research and industry applications.     

Synthesis of biologically active phenoxy derivatives of substituted benzothiazole organophosphates

The reaction of S‐(phenyl benzothiazolyl‐2)phosphorodichloridothioate/phosphorodichloridodithioate with 2 mol of phenol/4‐chlorophenol/4‐nitrophenol in the presence of stoichiometric amounts of triethylamine in dry THF/CH₂Cl₂ has afforded a series of the corresponding organophosphate phenoxy derivatives ( 1a , 1b , 2a , 2b , and 3a , 3b ). Plausible structures have been proposed on the basis of elemental analysis, IR, ¹H NMR, ³¹P NMR, and mass spectral studies. The antibacterial activity of these organophosphate phenoxy derivatives has been evaluated against pathogenic bacteria Staphylococcus aureus (+ve) and Escherichia coli (−ve). The antifungal activity of these organophosphate phenoxy derivatives has been evaluated against pathogenic fungi Aspergillus niger and Fusarium oxysporium. The results indicate that organophosphate phenoxy derivatives are found more active than the parent compounds. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:84–88, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20582     

Mutagenicity of silver nanoparticles synthesized with curcumin (Cur-AgNPs)

IntroductionSilver nanoparticles (AgNPs) are of particular interest for their antibacterial properties and are produced by the action of reducing agents on silver ions. Curcumin from Curcuma longa (Zingiberaceae) has been used as a precursor for obtaining biogenic AgNPs, to act as a potential drug.ObjectivesThis study aimed to evaluate the toxicity of AgNPs synthesized with curcumin (Cur-AgNPs 0.081 mg/mL, ~130 nm) through the Salmonella/microsome (Ames test), one of the first required assays for evaluating toxicity.MethodsThe study design was experimental and in vitro. After defining the preliminary toxicity, the mutagenicity was assessed in a concentration range of 0.0010–0.0081 mg/plate Cur-AgNPs using histidine negative (His−) Salmonella Typhimurium strains TA97a, TA98, TA100, and TA102, with (+S9) and without metabolic activation (−S9), in triplicate. Assays were monitored by positive and negative controls. The results were statistically analyzed by Salanal software with p < 0.05 values considered significant.ResultsThe data obtained in the absence of metabolic activation showed that Cur-AgNPs is not mutagenic, but when exposed to the presence of S9, Cur-AgNPs became mutagenic to TA98 and TA100 strains, showing the significance of metabolizer enzymes to activate Cur-AgNPs on these bacteria, which recovered their abilities in synthesizing histidine (His+).ConclusionCur-AgNPs is mutagenic in the presence (+S9), but not in the absence (−S9) of metabolic activation, being able to act as indirect mutagens potentially to organisms that share the same genotype vulnerabilities found in TA98 and TA100 strains to cause a frameshift and base-pair substitution mutations, respectively.     

Novel pyrazole-biphenyl-carboxamides for SARS-CoV2 entry-level restriction and microbial infections

Microbial diseases including viral infection are big issues globally. Effective medicinal discovery for them is the need for the day. In this study, we report pyrazole-biphenyl-carboxamides ( 4a-l ) validated for their SARS-CoV2 entry-level restriction effect over studying the protein–protein interaction of SARS-CoV2 with human ACE protein. Their extended antimicrobial properties were also evaluated. Online and offline software tools predicted MD simulation and ADMET druggability in silico. The antimicrobial efficacy of all compounds was also evaluated against Gram+^ve Streptococcus pneumoniae (MTCC 1936), Staphylococcus aureus (MTCC 737) and Gram-^ve Escherichia coli (MTCC 443), Pseudomonas aeruginosa (MTCC 424) (bacteria). In the results, compounds 4g and 4i were evenly active against both bacteria at a low concentration range (MIC: 1.00 to 9.5 μg/mL) and displayed lesser toxicity to tested mammalian cells (EC₁₀₀ = 75 μg/mL). Furthermore, it was able to kill metabolically inactive bacterial cells and eradicate established biofilms of Methicillin-resistant Staphylococcus aureus (MRSA). Both the compounds inhibited DNA gyrase well with an IC₅₀ 0.25 μM (96% relative activity) and 0.52 μM (97% relative activity) respectively. Compounds ( 4a-l ) showed restrictive efficiency of SARS-CoV2 spike protein (SC2SP) and human angiotensin-converting enzyme 2 (hACE2) entry-level association in COVID-19 in silico. To assess this ability, firstly, we identified the crucial amino acid residues involved in the interface of SARS-CoV-2 and hACE2 virtually. We recognized the ability of 4a-l binding to the binding interface to SARS-CoV2; thus, the interaction of SC2SP-hACE2 was effectively inhibited.     

Three novel Ni(II), VO(II) and Cr(III) mononuclear complexes encompassing potentially tridentate imine ligand: Synthesis,structural characterization,DNA interaction,antimicrobial evaluation and anticancer activity

Three novel Cr(III),VO(II) and Ni(II) imine complexes derived from the condensation of 2‐aminophenol (AP) with 2‐hydroxynaphthaldehyde (HN) were synthesized. The prepared HNAP imine ligand and its complexes were investigated via various physicochemical tools. The results suggest that the parent ligand behaves as a dibasic tridentate ONO ligand, when coordinated to Cr(III) in octahedral and to Ni(II) in tetrahedral geometry. In the case of VO(II), it coordinates in distorted square pyramidal geometry. Also, the prepared compounds were screened for their antimicrobial activities against pathogenic bacteria, Escherichia coli (−ve), Bacillus subtilis (+ve) and Staphylococcus aureus (+ve), and some types of fungi, Aspergillus niger , Candida glabrata and Trichophyton rubrum . The results indicate that the complexes show a stronger antimicrobial efficiency compared to the pro‐ligand. The interaction of the prepared complexes with calf thymus DNA was investigated using spectral, viscosity and gel electrophoresis measurements. The obtained results clearly demonstrate that the binding affinity with calf thymus DNA follows the order HNAPCr > HNAPV > HNAPNi. The cytotoxic activity of the prepared compounds on human colon carcinoma cells (HCT‐116 cell line), hepatic cellular carcinoma cells (HepG‐2cell line) and breast carcinoma cells (MCF‐7cell line) was examined. From these results it is found that the investigated complexes have potent cytotoxicity against growth of carcinoma cells compared to the corresponding imine pro‐ligand.     

Theoretical study and rate constants calculation for the reactions of SiH3 radical with SiH3CH3 and SiH2(CH3)2

The multiple‐channel reactions SiH₃ + SiH₃CH₃ → products and SiH₃ + SiH₂(CH₃)₂ → products are investigated by direct dynamics method. The minimum energy path (MEP) is calculated at the MP2/6‐31+G(d,p) level, and energetic information is further refined by the MC‐QCISD method. The rate constants for individual reaction channels are calculated by the improved canonical variational transition state theory (ICVT) with small‐curvature tunneling (SCT) correction over the temperature range of 200–2400 K. The theoretical three‐parameter expression k₁(T) = 2.39 × 10⁻²³T^4.01exp(−2768.72/T) and k₂(T) = 9.67 × 10⁻²⁷T^4.92exp(−2165.15/T) (in unit of cm³ molecule⁻¹ s⁻¹) are given. Our calculations indicate that hydrogen abstraction channel from SiH group is the major channel because of the smaller barrier height among eight channels considered. © 2009 Wiley Periodicals, Inc. J Comput Chem 2010     

A computational study of the reaction kinetics of methyl radicals with trifluorohalomethanes

Ab initio calculations have been used to characterize the transition states for halogen abstraction by CH₃ in reactions with CF₄, CF₃Cl, CF₃Br, and CF₃I (1–4). Geometries and frequencies were obtained at the HF/6-31G(d) and MP2=full/6-31G(d) levels of theory. Energy barriers were computed via the Gaussian-2 methodology, and the results were employed in transition state theory analyses to obtain the rate constants over 298–2500 K. There is good accord with literature measurements in the approximate temperature range 360–500 K for reactions (2–4), and the computed activation energies are accurate to within ±6 kJ mol⁻¹. Recommended rate constant expressions for use in combustion modeling are k;₁=1.6×10⁻¹⁹ (T/K)^2.41 exp(−13150 K/T), k₂=8.4×10⁻²⁰(T/K)^2.34 exp(−5000 K/T), k₃=4.6×10⁻¹⁹ (T/K)^2.05 exp(−3990 K/T), and k₄=8.3×10⁻¹⁹ (T/K)^2.18 exp(−1870 K/T) cm³ molecule⁻¹ s⁻¹. The results are discussed in the context of flame suppression chemistry. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 179–184, 1998.     

O‐Glycosylation/Alkylation and Antimicrobial Activity of 4,6‐Diaryl‐2‐Oxonicotinonitrile Derivatives

A series of glycosylation and alkylation reactions of 6‐phenanthernyl‐2‐pyridone derivatives 1a , 1b containing electron withdrawing and electron donating substituents at 4‐position is reported. Regioselective 2‐O‐ alkylated/glycosylated products were obtained exclusively, irrespective of the electronic nature of alkylating or the glycosyling agent. Glycosylation of 1a , 1b with glucosyl/galactosyl and lactosyl bromides afforded 2a , 2b ; 4a , 4b ; and 6a , respectively. Alkylation of 1a , 1b with epichlorohydrin, propargyl, allyl bromides, and 3‐chloropropanol resulted in compounds 8 , 9 , 10 and 13 , respectively. Deprotection of O‐glycosylated products under conventional conditions provided the free glycosides 3a , 3b ; 5a , 5b ; 7a , 12 ; and 13 , respectively. The minimal inhibitory concentration for some of the newly synthesized compounds showed high significant activity against Gram (+ve) and Gram (−ve) and antifungal activities. Among the screened compounds, the 4‐trifluromethyl phenyl derivatives 2a , 3a , 4a , 8a , and 11a exhibited strong antimicrobial activity.     

Design,Synthesis and Computational Studies of Novel Carbazole N‐phenylacetamide Hybrids as Potent Antibacterial,Anti‐inflammatory,and Antioxidant Agents

The present study deals with the synthesis of N‐phenylacetamide‐functionalized carbazole derivatives and their antibacterial, anti‐inflammatory, and antioxidant assays. In vitro antibacterial studies of synthesized compounds shows prominent activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. In addition, in silico molecular docking studies corroborated that the methyl substituent ( 3g ), ( 3h ), and ( 3i ) showed promising activity with lower ∆G (kcal/mol) values. This study envisages that these compounds can serve as a new leading template in the chemotherapy of various bacterial ailments.     

Synthesis of 1-(N-arylaminomethyl)-3-methyl-1,8-dihydrocycloheptapyrazol-8-ones

Reactions of 3-methyl-1,8-dihydrocycloheptapyrazol-8-one ( 2 ) with arylamines in the presence of formaldehyde gave 1-(N-arylaminomethyl)-3-methyl-1,8-dihydrocycloheptapyrazol-8-ones 5a-l in good yields. 1,3,5-Tris(phenyl- and 4-methoxyphenyl)hexahydro-1,3,5-triazines or bis(3-nitroanilino)methane, which were condensation products of arylamines and formaldehyde, also reacted with compound 2 to afford 5a,c,j , respectively.     

Catalyst Control over Threefold Stereogenicity: Selective Synthesis of Atropisomeric Sulfones with Stereogenic C−S Axes

Catalyst control over higher-order stereogenicity addresses significantly extended stereochemical space, but selective methods to govern threefold stereogenic units remained elusive. Herein, we report the stereoselective synthesis of threefold stereogenic triptycyl sulfones with atropisomerism arising from a C(sp³)−S bond. An oxidation of a stereodynamic thioether controlled by a chiral phosphoric acid catalyst allowed selective access to enantioenriched triptycyl sulfoxides. The ensuing enantiospecific and diastereoselective catalytic oxidation to a threefold stereogenic sulfone provided overall control over the stereogenic C−S axis. All three stereoisomers were addressable with enantio- and diastereodivergence and a stereoselectivity of up to (−sc): (+sc) : (ap)=94 : 6 :<1.     

Synthesis and Antimicrobial Studies of Organophosphates Derived From 2-(2″-Hydroxynaphthyl)Benzoxazole

Abstract

A series of biologically active phenoxy derivatives of 2-substituted benzoxazole organophosphates have been synthesized by the reaction of O-(naphthyl benzoxazolyl-2-) phosphorodichloridate/phosphorodichloridothioate with phenol/4-chlorophenol/4-nitroph- enol in 1:1 and 1:2 molar ratios. These compounds have been characterized on the basis of elemental analysis, IR, ¹H NMR, ³¹P NMR, and mass spectral studies. The antibacterial activity of these 2-substituted benzoxazole phenoxy derivatives has been evaluated against pathogenic bacteria Staphylococcus aureus (+ve) and Escherichia coli (?ve). The antifungal activity of these 2-substituted benzoxazole phenoxy derivatives has been evaluated against pathogenic fungi Aspergillus niger and Fusarium oxysporium. All compounds were found to have significant antibacterial and antifungal activity.     

Anti‐cancer Herbal Drug Berberine – Sensitive Determination Using Boron‐doped Diamond Electrode

Determination of berberine, an isoquinoline plant alkaloid, with antibacterial, antiparasitic, antifungal, hypotensive and antitumoral effects, was proposed by introducing square wave voltammetry on boron‐doped diamond electrode. At optimized experimental parameters, in Britton‐Robinson buffer solution pH 5 berberine provides 3 oxidation peaks (+0.63; +1.14 and +1.34 V) and one reduction (+0.15 V) (vs. Ag/AgCl electrode), with good repeatability (relative standard deviation of 2.6 % and 1.9 % for 8 measurements at 0.5 and 10 µM concentration level, respectively). Calibration curve was linear in wade linear range from 0.1 to 50 µM with limit of detection of 0.04 µM. The proposed procedure was successfully applied for the determination of berberine in seed extract from Argemone mexicana with satisfactory recovery (102–102.6 %). The developed method may represent a sensitive alternative to highly toxic mercury electrodes, modified electrodes and chromatographic methods.     

1‐(β‐d‐Erythrofuranosyl)adenosine

The title compound, also known as β‐erythroadenosine, C₉H₁₁N₅O₃, (I), a derivative of β‐adenosine, (II), that lacks the C5′ exocyclic hydroxymethyl (–CH₂OH) substituent, crystallizes from hot ethanol with two independent molecules having different conformations, denoted (IA) and (IB). In (IA), the furanose conformation is ^OT₁–E₁ (C1′‐exo, east), with pseudorotational parameters P and τ_m of 114.4 and 42°, respectively. In contrast, the P and τ_m values are 170.1 and 46°, respectively, in (IB), consistent with a ²E–²T₃ (C2′‐endo, south) conformation. The N‐glycoside conformation is syn (+sc) in (IA) and anti (−ac) in (IB). The crystal structure, determined to a resolution of 2.0 Å, of a cocrystal of (I) bound to the enzyme 5′‐fluorodeoxyadenosine synthase from Streptomyces cattleya shows the furanose ring in a near‐ideal ^OE (east) conformation (P = 90° and τ_m = 42°) and the base in an anti (−ac) conformation.     

Three New Polyyne (=Polyacetylene) Glucosides from the Edible Roots of Codonopsis cordifolioidea

Three new linear C₁₄ polyyne (=polyacetylene) glucosides, cordifolioidynes A–C ( 1 – 3 ), together with two known polyynes, lobetyol ( 4 ) and lobetyolin ( 5 ), and five known phenylpropanoids, i.e., sinapinaldehyde ( 6 ), coniferaldehyde ( 7 ), coniferoside ( 8 ), sachaliside ( 9 ), and isoconiferin ( 10 ), were isolated from the roots of Codonopsis cordifolioidea. The structures of 1 – 3 were established from spectral evidences and by characterization of their hydrolysis products. Acid hydrolysis of 1 afforded the aglycone 1a , while hydrolysis of 2 and 3 gave the cyclization products 2a and 3a , respectively. Compounds 4 – 10 were isolated from this plant for the first time. The antibacterial activity of compounds 1 – 5 were assessed against eight microbial strains by the agar dilution method, none of them exhibited antibacterial effects at concentrations up to 100 μg/ml.     

Citronellol-Based Long-Lasting Antibacterial Cotton Fabrics without Bacterial Resistance

Antibacterial cotton helps prevent the growth and spread of harmful microorganisms, reduces the risk of infection, and has a prolonged service life by reducing bacterial degradation. However, most antibacterial agents used are toxic to humans and the environment. Citronellol-poly(N,N-dimethyl ethyl methacrylate) (CD), a highly effective antibacterial polymer, is synthesized from natural herbal essential oils (EOs). CD exhibited efficient, rapid bactericidal activity against Gram-positive, Gram-negative, and drug-resistant bacteria. Citronellol's environmental benignity makes CDs less hemolytic. Notably, negligible drug resistance developed after 15 bacterial subcultures. The CD-treated cotton fabric displayed better antibacterial performance than AAA-grade antibacterial fabric, even after repeated washing. This study extends the practical application of EOs to antibacterial surfaces and fabrics, which is promising for use in personal care products and medical settings.     

Urea derivatives of piperazine doped with pyrazole-4-carboxylic acids: Synthesis and antimicrobial evaluation

A series of novel N-cycloalkyl/aryl-4-(1,3-diphenyl-1H-pyrazole-4-carbonyl)piperazine-1-carboxamides 9a-g has been synthesized for biological interest by simple base catalyzed reaction of various N-cycloalkyl/aryl isocyanates with (1,3-diphenyl-1H-pyrazol-4-yl)(piperazin-1-yl)methanone hydrochloride 8 . The compound 8 was synthesized in excellent yield by the reaction of 1,3-diphenyl-1H-pyrazole-4-carbonyl chloride with boc-piperazine followed by deprotection of boc group with dioxane-HCl. All the novel intermediates and urea derivatives have been screened for antimicrobial activity. The compound 9a was found an excellent compound to be active against all Gram (−ve) and Gram (+ve) bacterial strains E. coli, Y. enterocolitica, B. cereus, and S. aureus. It also showed comparable antifungal activity against C. albicans with MIC 78.1 μg/ml as compared to reference standard miconazole.