79 research outputs found
Antimicrobial Activity of Diffusible and Volatile Metabolites Emitted by Beauveria bassiana: Chemical Profile of Volatile Organic Compounds (VOCs) Using SPME-GC/MS Analysis
: The genus Beauveria includes important entomopathogenic and endophytic fungi; among them, Beauveria bassiana is the most studied species. However, there is little knowledge regarding their antimicrobial activity. The current research has been conducted to evaluate the in vitro antagonistic activity of B. bassiana and the antimicrobial efficacy of its Exo and Endo metabolites against Bacillus cereus, B. megaterium, Clavibacter michiganensis (Gram positive bacteria, G+ve), Xanthomonas campestris, Pseudomonas aeruginosa and P. fluorescence (Gram negative bacteria, G-ve). In addition, solid-phase microextraction (SPME) was coupled with Gas Chromatography-Mass Spectrometry (GC/MS) to qualitatively measure the volatile organic compounds' (VOCs) metabolic profile of the most efficient studied isolate of B. bassiana. The obtained results showed that the isolate UniB2439-3 has a promising antibacterial effect against most of the studied target bacteria. An SPME-GC/MS analysis of VOCs revealed the presence of ethanol, butanal,2-methyl, 2,4-dimethyl-1-heptene, octane, 4-methyl and ÎČ-elemene as the dominant bioactive compounds. The results demonstrated that the efficient isolate of B. bassiana can be potentially used as a biocontrol agent against several bacteria, especially G+ve ones
Biochemical Characterization of New Gemifloxacin Schiff Base (GMFXâoâphdn) Metal Complexes and Evaluation of Their Antimicrobial Activity against Some Phytoâ or Human Pathogens
Four novel ligandâmetal complexes were synthesized through the reaction of Fe(III),
pleaseCo(II), Zn(II), and Zr(IV) with Schiff base gemifloxacin reacted with orthoâphenylenediamine
(GMFXâoâphdn) to investigate their biological activities. Elemental analysis, FTâIR, 1H NMR,
UVâvisible, molar conductance, melting points, magnetic susceptibility, and thermal analyses have
been carried out for insuring the chelation process. The antimicrobial activity was carried out
against Monilinia fructicola, Aspergillus flavus, Penicillium italicum, Botrytis cinerea, Escherichia coli,
Bacillus cereus, Pseudomonas fluorescens, and P. aeruginosa. The radical scavenging activity (RSA%)
was in vitro evaluated using ABTS method. FTâIR spectra indicated that GMFXâoâphdn chelated
with metal ions as a tetradentate through oxygen of carboxylate group and nitrogen of azomethine
group. The data of infrared, 1HNMR, and molar conductivity indicate that GMFXâoâphdn reacted
as neutral tetra dentate ligand (N2O2) with metal ions through the two oxygen atoms of the carâ
boxylic group (oxygen containing negative charge) and two nitrogen atoms of azomethine group
(each nitrogen containing a lone pair of electrons) (the absent of peak corresponding to Μ(COOH)
at 1715 cmâ1, the shift of azomethine group peak from 1633 cmâ1 to around 1570 cmâ1, the signal at
11 ppm of COOH and the presence of the chloride ions outside the complex sphere). Thermal
analyses (TGâDTG/DTA) exhibited that the decaying of the metal complexes exists in three steps
with the final residue metal oxide. The obtained data from DTA curves reflect that the degradation
processes were exothermic or endothermic. Results showed that some of the studied complexes
exhibited promising antifungal activity against most of the tested fungal pathogens, whereas they
showed higher antibacterial activity against E. coli and B. cereus and low activity against P. fluoâ
rescens and P. aeruginosa. In addition, GMFXâoâphdn and its metal complexes showed strong antiâ
oxidant effect. In particular, the parent ligand and Fe(III) complex showed greater antioxidant caâ
pacity at low tested concentrations than that of other metal complexes where their IC50 were 169.7
and 164.6 ÎŒg/mL, respectively
Biochemical Characterization, Phytotoxic Effect and Antimicrobial Activity against Some Phytopathogens of New Gemifloxacin Schiff Base Metal Complexes
String of Fe(III), Cu(II), Zn(II) and Zr(IV) complexes were synthesized with tetradentateamino Schiff base ligand
derived by condensation of ethylene diamine with gemifloxacin. The novel Schiff base (4E,4âE)-4,4â-(ethane-1,2-
diyldiazanylylidene)bis{7-[(4Z)-3-(aminomethyl)-4-(methoxyimino)pyrrolidin-1-yl]-1-cyclopropyl-6-fluoro-1,4-dihydro-
1,8-naphthyridine-3-carboxylic acid} (GMFX-en) and its metal complexes were identified and confirmed by
elemental analyses, FT-IR, UV/VIS, 1H-NMR spectra, magnetic susceptibility, conductometric measurements and
thermal analyses. The FT-IR spectral data showed the chelation behavior of GMFX-en toward the metal ions
through oxygen of carboxylate group and nitrogen of azomethine group. In the light of all spectral data, these
complexes presumably have octahedral geometry configurations. Thermal analysis specified that the decaying of
the metal complexes exist in two or three steps with the final residue metal oxides. Antimicrobial activity of the
new prepared metal complexes was screened against some common phytopathogens and their mode of action
has been also discussed. The potential phytotoxic effectiveness of the new complexes was furthermore inspected
on two commonly experimental plants. The complexes showed significant antimicrobial and phytotoxic effects
against the majority of tested phytopathogens and the two tested plants, respectively. The potential
antimicrobial activity of the complexes proved their possibility to be used successfully in agropharmacutical
industry to control many serious phytopathogens. The phytotoxicity of the studied complexes also indicated
their possibility as potential bio-based herbicides alternatives to weed control in crop fields
Biological and spectroscopic investigations of new tenoxicam and 1.10-phenthroline metal complexes
In the present work, tenoxicam (H2Ten) reacted with Mn(II), Co(II), Ni(II), Cu(II) and Zn (II) ions in the presence of 1.10-phenthroline (Phen), forming new mixed ligand metal complexes. The properties of the formed complexes were depicted by elemental analyses, infrared, electronic spectra, proton nuclear magnetic resonance (1H NMR), mass spectrometry, thermogravimetric (TGA) and differential thermogravimetric (DTG) analysis, molar conductance and magnetic moment. IR spectra demonstrated that H2Ten acted as a neutral bidentate ligand, coordinated to the metal ions via the pyridine-N and carbonyl group of the amide moiety, and Phen through the nitrogen atoms. Kinetic thermodynamics parameters activation energy (E*), enthalpy of activation (ÎH*), entropy of activation (ÎS*), Gibbs, free energy (ÎG*) associated to the complexes have been evaluated. Antibacterial screening of the compounds was carried out in vitro against Clavibacter michiganensis, Xanthomonas campestris and Bacillus megaterium. Antifungal activity was performed in vitro against Monilinia fructicola, Penicillium digitatum and Colletotrichum acutatum. The possible phytotoxic effect of the studied compounds was also investigated on Solanum lycopersicum (tomatoes) and Lepidium sativum (garden cress) seeds. The anticancer activity was screened against cell cultures of HCT-116 (human colorectal carcinoma), HepG2 (human hepatocellular carcinoma) and MCF-7 (human breast adenocarcinoma)
Infrared spectra, thermogravimetric analysis and antifungal studies of noval Cr(III), Fe(III) and Cu(II) 2-methyl-quinazolinone complexes
Some new solid complexes [CrCl3(L)3]Ă6H2O, [FeCl3(L)3]Ă6H2O and [Cu(CH3COO)2(L)3]Ă2H2O have been synthesized quantitatively by the interactions of 2-methyl-quinazolinone (L) with CrCl3.6H2O, FeCl3.6H2O and Cu(CH3COO)2.2H2O in a mixture of an ethanol-bidistilled water (1:1), at 60 °C. They were characterized by melting point, molar conductivity, magnetic moment, elemental analysis, infrared spectra and thermal analyses. The results supported the formation of the complexes and indicated that the ligand reacted as a monodentate ligand bound to the metal ion through the oxygen atom. The antifungal activity of the free ligand and their metal complexes were evaluated against several species, such as Fusarium solani, Rizoctonia solani, Sclortium rolfsii and Botryodiplodia and they showed a good antifungal activity to some selected fungal strain as compared with free ligand. KEY WORDS: Quinazolinone; Cr(III); Fe(III); Cu(II); Antifungal activity, Thermal analyses Bull. Chem. Soc. Ethiop. 2014, 28(1), 53-66.DOI: http://dx.doi.org/10.4314/bcse.v28i1.
Biochemical Characterization and Antimicrobial Activity Against Some Human or Phyto-Pathogens of New Diazonium Heterocyclic Metal Complexes
String of vanadium (IV), zirconium (IV), palladium (II), platinum (IV) and uranium (VI) chelates of 2-cyano-2-[(2-
nitrophenyl)hydrazono]thioacetamide (Cnphta) were prepared and characterized by physicochemical, spectroscopic and thermal analyses. The formulae of the isolated solid complexes were assigned as [VO-
(Cnphta)2(H2O)]SO4 ·5H2O (1), [ZrO(Cnphta)2(H2O)]Cl2 ·4H2O (2), [Pd(Cnphta)2]Cl2 (3), [Pt(Cnphta)2Cl2]Cl2 (4) and
[UO2(Cnphta)2](NO3)2 ·5H2O (5). The infrared assignments clearly showed that Cnphta ligand coordinated as a
bidentate feature through the hydrazono nitrogen and the thioacetamide nitrogen for V(IV), Zr(IV) and U(VI) but
displayed different behavior for Pd(II) and Pt(IV). Results of the molar conductivities measurements showed that
the metal complexes were electrolytes in contrast with Cnphta ligand. The interpretation, mathematical analysis
and evaluation of kinetic parameters were also carried out. In addition, the studied ligand and its new chelates
were tested for their antimicrobial activity against some human or phytopathogenic microorganisms. The new
metal complexes explicated promising antibacterial activity against all tested bacteria especially Staphylococcus
aureus and Bacillus subtilis. Regarding the antifungal activity, all metal complexes were able to inhibit the
mycelium growth of both tested pathogenic fungi. In particular Zr(IV) and Pt(IV) complexes showed the highest
significant fungicidal effect against A. fumigatus similar to positive contro
Meloxicam and study of their antimicrobial effects against phyto- and human pathogens
Recently, the design of new biological metal-ligand complexes has gained a special interest all over the world. In this research, new series of mixed ligand complexes from meloxicam (H2mel) and glycine (Gly) were synthesized. Structures of the compounds were investigated employing elemental analyses, infrared, electronic absorption, 1H NMR, thermal analyses, effective magnetic moment and conductivity. The estimated molar conductivity of the compounds in 1*10-3 M DMF solution indicates the non-electrolyte existence of the examined complexes. Additionally, the effective magnetic moment values refer to the complexes found as octahedral molecular geometry. The data of the infrared spectra showed the chelation of H2mel and Gly with metal ions from amide oxygen and nitrogen of the thyizol groups of H2mel and through nitrogen of the amide group and oxygen of the carboxylic group for Gly. Thermal analyses indicated that the new complexes have good thermal stability and initially lose hydration water molecules followed by coordinated water molecules, Gly and H2mel. The kinetic parameters were calculated graphically using Coats-Redfern and Horowitz-Metzeger methods at n = 1 and n 6= 1. The density functional theory (DFT) calculations were performed at B3LYP levels. The optimized geometry of the ligand and its complexes were obtained based on the optimized structures. The data indicated that the complexes are soft with n value in the range 0.114 to 0.086, while n = 0.140 for free H2mel. The new prepared complexes were investigated as antibacterial and antifungal agents against some phyto- and human pathogens and the minimum inhibitory concentration (MIC) data showed that complex (A) has the lowest MIC for Listeria and E. coli (10.8 ug/mL)
Spectroscopic properties, molecular structure, anticancer and antimicrobial evaluation of some new moxifloxacin metal complexes in the presence of 1,10-phenanthroline
New series of Y(III), Zr(IV), Pd(II), La(III) and U(VI) complexes with moxifloxacin (MOX) and 1,10-phenanthroline (Phen) were synthesized and the chelation behaviours have been investigated. The complexes were characterized using elemental analysis, molar conductance, magnetic properties, thermal studies and various spectral techniques such as FT-IR, UV-Vis, 1H NMR and mass spectra. The kinetic and thermodynamic parameters (E*, ÎH*, ÎS* and ÎG*) were calculated using Coats-Redfern and Horowitz-Metzeger methods. The bond length and force constant, F(U=O), for the uranyl complex was calculated. The DFT calculations were carried out to understand the optimized molecular geometry for the compounds. The calculated data indicated that Pd(II) complex with smaller energy gap value (âE = 0.136 au) is more reactive than all compounds and La(III) complex with greater energy gap (âE = 0.192 au) is less reactive. All studied compounds are treated as soft (η = 0.068-0.096) except MOX treated as hard (η = 0.16). The HOMO of all complexes is localized on MOX (100%) without any density on the Phen (0%) except Pd(II) complex, the HOMO is localized on Phen (61%). The LUMO in U(VI) complex is localized mainly on the U(VI) ion (63%), and in the Y(III) complex is localized mainly on Phen (89%). The cytotoxic activities against MCF-7, HCT-116 and the antimicrobial activity were tested.
KEY WORDS: Moxifloxacin, 1,10-Phenanthroline, Spectroscopy, Thermal analysis, DFT, Antitumor agents
Bull. Chem. Soc. Ethiop. 2020, 34(2), 295-312
DOI: https://dx.doi.org/10.4314/bcse.v34i2.
Synthesis, structural characterization and nematicidal studies of some new N2O2 Schiff base metal complexes
ABSTRACT. Cobalt(II), copper(II), yttrium(III), zirconium(IV), lanthanum(III) and uranium(VI) complexes of 1,4-di(2-hydroxybenzylidene)thiosemicarbazide (H2L) were prepared and characterized. The proposed structures were determined from their elemental analyses, molar conductivities, magnetic moment, IR, Proton NMR, UV-Vis., mass spectra, X-ray diffraction and thermal analyses measurements. The high conductance data supply evidence for the electrolytic nature of the complexes. The changes in the selected bands in IR of Schiff base ligand upon coordination showed that Schiff base exhibits as a neutral tetradentate manner with oxygen and nitrogen donor sites. The complexes are thermally steady at room temperature and break up to two or three steps. The kinetic and thermodynamic parameters of complexes have been determined by using Coats-Redfern and Horowitz-Metzeger methods at n=1 and nâ 1 and values suggest more ordered activated complex formation. The calculated bond length and force constant, F(U=O), in the uranyl complex are 1.744 Ă
and 664.886 Nm-1. The nematicidal activity of free Schiff base and all complexes were investigated and showed a low inhibition percentage (%I) of complexes compared with H2L.
KEY WORDS: Schiff base, IR, Thermal, XRD, Nematicidal activity
Bull. Chem. Soc. Ethiop. 2021, 35(2), 315-335.
DOI: https://dx.doi.org/10.4314/bcse.v35i2.
Behavior Of Trapezoidal Corrugated Girders webs with cutouts: Experimental and Analytical Solution
Corrugated steel-plate girders (GCWs) are nowadays used as structural elements in many applications for their high strength against shear buckling, otherwise cutouts are always provided in these plate elements to enable inspection and servicing. This study presents an experimental and analytical study for investigating the behavior of girders with corrugated webs (GCWs) having cutouts under shear loading. The experimental program was conducted on three full-scale plate girders, which have been tested under central load at mid-span. The theoretical analysis was conducted using ANSYS V20 to perform a nonlinear technique for the determination of the ultimate shear capacity of the tested girders. Finally, experimental, and finite element model were used to define the ratio of decreasing in carrying capacity for corrugated web, having cutout under shear loading. As expected from the ultimate strength, failure mechanism, and load-deflection curves that results of ultimate load carrying capacity decreased with the appearance of one or more cut-outs
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