Pathogenic Gram Research Articles

Controlled release and enhanced biological activity of chitosan-fabricated carbenoxolone nanoparticles

Nanotechnology based antimicrobial drugs are developed to enhance their properties to combat multidrug resistant microbes. Carbenoxolone (CBX) is a semi-synthetic derivate of a natural substance from the licorice plant, with anti- (inflammatory, fungal, viral, microbial, fibrotic and cancer) properties. Though used to treat gastric ulcers, its low aqueous stability, low bioavailability and toxicity limited the drug's utility. To enhance its antimicrobial activity and reduce cytotoxicity, a controlled release nanoformulation was developed using natural biodegradable polymer chitosan (CS) as a carrier which is biocompatible, nontoxic with placid antimicrobial property. UV–visible spectroscopy, electron microscopy, and Fourier transform infrared spectroscopy were used for characterization of the resultant CS-CBX nanoparticles (NPs). They were spherical with uniform dispersion, ~200 nm in size with surface charge of +18.6 mV and drug encapsulation of >80%. Drug release kinetics exhibited a controlled release of 86% over 36 h following zero order kinetics. The anti-microbial activity against common pathogenic Gram −ve and +ve bacteria and yeast increased ~2-fold with a concomitant 4-fold reduction in cytotoxicity assessed using human lung adeno carcinoma (A549) cells. This study demonstrates the affirmative aspects of CS-CBX NPs as a promising antibacterial agent and may facilitate repositioning of the drug for diverse applications.

In Vitro Antibacterial Activities of Various Ethanolic Medicinal Plant Extracts Against Some Human Pathogenic Bacteria

The widespread use of antibiotics often causes increase in the bacterial drugs resistance and causes many side effects in humans. Medical plants have antimicrobial effects against most pathogenic bacteria and can serve as harmless replacement to antibiotics. The aim of this study was to assess the antibacterial effect of five medicinal plant prevailed in Kurdistan region namely; Cinnamon (Cinnamomum cassia (L.) D.Don), Nigella (Nigella sativa L.), Allium (Allium hirtifolium Boiss.), Carrot (Daucus carota L.), and Fennel (Foeniculum vulgare Mill.) against pathogenic Gram positive bacteria (Staphylococcus aureus), and pathogenic Gram negative bacteria (Salmonella typhi and Escherichia coli). The evaluation of antibacterial activity for these plant extracts was carried out using agar-well diffusion method. Results showed that minimum inhibitory concentration (MIC) of A. hirtifolium against tested bacterial isolates were (25 mg/mL), the lowest MIC values for S. aureus were (25 mg/mL) observed with C. cassia, N. sativa and F. vulgare ethanolic extracts and the lowest MIC of D. carota against bacterial isolates were (50 mg/mL), Also, it was observed that S. aureus was more sensitive than S. typhi and E. coli to plant extracts. The ethanol plant extracts had potential antibacterial activities. However, further studies are required to identify the active compounds which could be used for the preparation of new antimicrobial agents and control the bacterial infectious diseases.

Comparative assessment of antimicrobial and antioxidant activity between whole plant and parts of Sphaeranthus\xa0indicus Linn. (Asteraceae)

BackgroundSphaeranthus indicus is an important medicinal plant, which is used to cure various illnesses. The present study is the first investigation of the antimicrobial, antioxidant and phytochemical analysis of Sphaeranthus indicus from Chhattisgarh, India.MethodsThe whole plant and plant parts were extracted with polar and non-polar solvents such as water, methanol, ethyl acetate and hexane to assess various bioactivities. The antimicrobial and antioxidant activities were performed by ager well diffusion method and ferrous reducing capacity, respectively; However free radical scavenging activity was analyzed using DMPD and DPPH scavenging assay. The DMPD and DPPH assay were performed in a time dependent manner. Qualitative and quantitative analysis were performed for the total phytochemicals present in the plant extracts. The total content of phenols, flavonoids and terpenoids was analyzed by colorimetric methods.ResultsEthyl acetate and hexane extract of plant inflorescence and stem exhibited significant antibacterial activity against tested bacterial pathogens. The clinically isolated gram positive pathogenic bacteria responded better as compared to clinically isolated gram negative bacteria as well as pathogenic gram positive and negative bacteria acquired from Microbial Type Culture Collection, India. The leaf and inflorescence exhibited potent antioxidant activity. The polar fraction of leaf methanol extract exhibited the highest reducing power capacity. The aqueous extract of inflorescence exhibited highest inhibition against DMPD and DPPH radicals. The whole plant aqueous extract showed maximum inhibition while aqueous extract of inflorescence exhibited high inhibition among different plant parts. Qualitative phytochemical analysis revealed the presence of terpenoids, phenols, flavonoids, tannins and cardiac glycosides in plant parts. Total terpenoid content was found to be highest in polar fraction of stem methanol extract and ethyl acetate extract of inflorescence. However, total phenol was found to be highest in polar fraction of leaf methanol extract, similarly highest flavonoid content was observed in aqueous extract of leaf.ConclusionThe results suggest that biological activities of plant parts depend on content of active phytochemicals. The inflorescence could be a potential source of antimicrobial and antioxidant compound. Further, investigation pertaining isolation and characterization of active ingredient may provide an insight regarding its phytochemical activity.

Antibacterial, Cytotoxicity and Larvicidal Activity of Green Synthesized Selenium Nanoparticles Using Penicillium corylophilum

Anopheles mosquitoes became one of the biggest problems threaten human life through causing malaria disease. Hereby, Selenium nanoparticles (Se-NPs) as anti-victor malaria were fabricated for the first time through Penicillium corylophilum in presence of ascorbic acid as a reducing agent. Antibacterial versus pathogenic Gram +Ve and Gram −Ve bacteria, as well, in vitro cytotoxicity against two types of cell lines (normal Wi 38 and cancer Caco-2) were explored prolonging with their larvicidal activity towards Anopheles stephensi mosquitoes. Se-NPs is characterized by UV–Vis spectroscopy, FT-IR, TEM, EDX, XRD, DLS. Results affirmed the ability of Penicillium corylophilum to build up Se-NPs in spherical shape with average size 29.1–48.9 nm. In addition, Se-NPs exhibited broad spectrum activity against pathogenic Gram +Ve and Gram −Ve bacteria, while the results obtained from cytotoxicity evaluation signified clearly that, alteration occurred in the cells was represented as loss of their typical shape, partial or complete loss of monolayer, granulation, shrinking or cell rounding with IC50 value of 171.8 and 104.3 ppm Wi 38 and Caco-2 cell lines respectively, which revealing the high toxicity of Se-NPs towards cancer cells compared with normal cells. However, Se-NPs displayed larvicidal activity against causative malaria vector Anopheles stephensi.

Theoretical and spectroscopic evidence on a new triphenyltin(IV) 3,5-dinitrosalicylhydroxamate complex: synthesis, structural characterization, and biological screening

The triphenyltin(IV) complex of composition [Ph3Sn(3,5-(NO2)2C6H2(OH)CONHO)] (1) has been synthesized by the reaction of Ph3SnCl with potassium 3,5-dinitrosalicylhydroxamate [3,5-(NO2)2C6H2(OH)CONHOK] and characterized by physicochemical studies, spectroscopic techniques (IR, 1H 13C, and 119Sn NMR), and mass spectrometry. The electrochemical behavior of ligand and 1 have been studied by cyclic voltammetry. The thermal behavior of 1 has been studied by thermogravimetric techniques (TGA, DTG, and DTA) and various kinetic parameters have been calculated. The optimized geometry of 1 was computed by the DFT method using B3LYP/631-G* set. The vibrational frequencies, 1H and 13C NMR spectra have been computed and compared with the experimental data. The global descriptors have been calculated. The various thermodynamic parameters, Gibbs free energy (G), enthalpy (H), entropy (S), bond energy (E), constant heat volume capacity (Cv), internal energy (U), and dipole moment (µ) have been calculated. The in vitro antimicrobial activity assay against pathogenic gram-(−) bacteria viz. Salmonella typhi, Escherichia coli; gram-(+) bacteria Bacillus cereus and Staphylococcus aureus; and fungi Fusarium sambucinum and Rhizoctona solani by MIC method; the in vitro cytotoxicity on human muscle rhabdomyosarcoma (RD) by MTT method and the antioxidant potential by DPPH free radical scavenging showed higher inhibitory effect of 1 than ligand.

A wide spectrum of antibacterial activity of secondary metabolites from Bacillus amyloliquefaciens ELI149

A highly potent secondary metabolites-producing Bacillus strain was isolated from Mexican soil (Puebla State), together with other fifty strains. The fifty-one strains were subjected for metabolites extraction and evaluated as antibacterial against several bacteria. The active metabolites of these strains were extracted using amberlite XAD16 absorbent resin. The antibacterial activity of crude extracts of all strains was performed by disk diffusion method against some pathogenic gram positive and gram-negative bacteria. Among all Bacillus strains tested, the most potent strain ELI149 (NRB) was selected for molecular characterization. The nucleotide sequence of the 16S rRNA gene (1.5 Kb) of this strain evidenced a 94% similarity with Bacillus amyloliquefaciens strain IIHR-Ba-2, which showed the highest inhibition against the most bacteria probed even greater inhibition than the standard antibiotic. In conclusion, secondary metabolites extracted from Bacillus amyloliquefaciens strain are highly potent as antibiotic against the most bacteria probed. Identification of which metabolites extracted from amberlite are the responsible of the bacteria growth inhibition will be a challenge.

Flexible Hierarchical Wraps Repel Drug-Resistant Gram-Negative and Positive Bacteria.

Healthcare acquired infections are a major human health problem, and are becoming increasingly troublesome with the emergence of drug resistant bacteria. Engineered surfaces that reduce the adhesion, proliferation, and spread of bacteria have promise as a mean of preventing infections and reducing the use of antibiotics. To address this need, we created a flexible plastic wrap that combines a hierarchical wrinkled structure with chemical functionalization to reduce bacterial adhesion, biofilm formation, and the transfer of bacteria through an intermediate surface. These hierarchical wraps were effective for reducing biofilm formation of World Health Organization-designated priority pathogens Gram positive methicillin-resistant Staphylococcus aureus (MRSA) and Gram negative Pseudomonas aeruginosa by 87 and 84%, respectively. In addition, these surfaces remain free of bacteria after being touched by a contaminated surface with Gram negative E. coli. We showed that these properties are the result of broad liquid repellency of the engineered surfaces and the presence of reduced anchor points for bacterial adhesion on the hierarchical structure. Such wraps are fabricated using scalable bottom-up techniques and form an effective cover on a variety of complex objects, making them superior to top-down and substrate-specific surface modification methods.

4-Chloromercuribenzoic acid enhances carbapenem sensitivity among pathogenic Gram negative bacteria by altering blaVIM, adeB and ompC expression

BackgroundRapid global dissemination of carbapenem resistant Gram negative bacteria (CRGNB) is supposed to be clinically most alarming. Since, p-chloromercuribenzoic acid (pCMB) is a well known metallo-beta-lactamase inhibitor; evaluation of its bactericidal and carbapenem resistance reversing potential would be important. MethodsIn this study, bactericidal and meropenem resistance reversing potential of pCMB was investigated against CRGNB by MIC determination, checkerboard assay, time-kill assay and cellular viability assay. Effect of pCMB on cellular morphology was visualized by Scanning Electron Microscopy. Further, quantitative Real Time-PCR was performed to evaluate effects of pCMB on clinically relevant metallo-beta-lactamases, major efflux pumps and outer membrane proteins expression. ResultspCMB exhibited at least four fold reduced MIC value (2–256μg/ml) than that of meropenem against CRGNB. Moreover, pCMB exhibited synergism with meropenem against 86.06% of CRGNB. MIC of pCMB (16−32μg/ml) could kill upto 99.96% bacteria within 6−8h of dosing. pCMB exerted bactericidal activity by severely disrupting cell wall integrity. Reversal of carbapenemase property of CRGNB by pCMB might have developed through alteration of blaVIM, acrB, mexB and ompk36 expression. ConclusionsHence, the current study identified pCMB as a potential bactericidal agent which enhanced meropenem sensitivity by altering blaVIM, acrB, mexB and ompk36 expression.

Biosynthesis of Silver Nanoparticles from Melia azedarach: Enhancement of Antibacterial, Wound Healing, Antidiabetic and Antioxidant Activities.

PurposeGlobal demand for novel, biocompatible, eco-friendly resources to fight diseases inspired this study. We investigated plants used in traditional medicine systems and utilized nanotechnology to synthesize, evaluate, and enhance potential applications in nanomedicine.MethodsAqueous leaf extract from Melia azedarach (MA) was utilized for bio-synthesis of silver nanoparticles (MA-AgNPs). Reaction conditions were optimized for high yield and colloidal stability was evaluated using UV-Vis spectroscopy. MA-AgNPs were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Standard methods were used to analyze the antibacterial, wound healing, antidiabetic, antioxidant, and cytotoxic activities.ResultsThe formation of MA-AgNPs at room temperature was confirmed by stable brown colloidal solution with maximum absorbance at 420 nm (UV-Vis Spectroscopy). MA-AgNPs were spherical (SEM), uniformly dispersed, 14–20 nm in diameter (TEM), and crystalline in nature (XRD). Presence of elemental silver was confirmed by peak at 3 KeV (EDX). FTIR data revealed the presence of functional groups which indicate phyto-constituents (polyphenols, flavonoids, and terpenoids) may have acted as the reducing and capping agents. MA-AgNPs (1000 µg/mL) showed larger zone of inhibition than MA-extract in the disk diffusion assay for human pathogenic gram positive bacteria, Bacillus cereus (34 mm) and gram negative, Escherichia coli (37 mm), thus confirming their higher antibacterial activity. The cell scratch assay on human dermal fibroblast cells revealed potential wound healing activity. The MA-AgNPs (400 µg/mL) demonstrated high antidiabetic efficacy as measured by α-amylase (85.75%) and α-glucosidase (80.33%) inhibition assays and antioxidant activity as analyzed by DPPH (63.83%) and ABTS (63.61%) radical scavenging assays. Toxic effect of MA-AgNPs against human chang liver cells (CCL-13) as determined by MTS assay, optical microscopic and CMFDA dye methods was insignificant.ConclusionThis sustainable, green synthesis of AgNPs is a competitive alternative to conventional methods and will play a significant role in biomedical applications of Melia azedarach.

Antimicrobial effect, electronic and structural correlation of nano-filled Tin Bismuth metal alloys for biomedical applications

In this work silver vanadate (AgVO3) nano-rods were successfully synthesized using chemical precipitation route and doped in hypo (Sn 99%- Bi 1% ) and hyper (Sn 3%- Bi 97% ) -eutectic tin-bismuth (Sn-Bi) alloy. Nanostructured metal alloy was synthesized using powder compact metallurgy technique as a new low cost and time-consuming route. Effects of the AgVO3 nano-rods content on the band structure of (Sn-Bi) alloy has been investigated through electronic transition studied via ATR ultraviolet/visible spectrophotometric and Hall Effect measurements. Antimicrobial studies for pathogenic Gram negative as well as Gram positive bacteria were also investigated and correlated to the analyzed electronic and optical properties. The work a debate avenue for probability controllingthe microbial growth and to correlate electronic properties of (Sn-Bi) alloy along with their antimicrobial properties.

MOLECULAR EPIDEMIOLOGY OF METALLO BETA LACTAMASES IN ACINETOBACTER BAUMANNII AT A TERTIARY CARE HOSPITAL

Background: Carbapenem resistance mediated by metallo beta lactamases (MBL) in Acinetobacter baumannii is a global challenge due to its rapid spread and limited therapeutic options.
 Objective: To determine the prevalence of MBL in A. baumannii isolates in hospitalized patients by both phenotypic and genotypic methods.
 Materials and Methods: The clinical samples were collected from inpatients and subcultured on routine culture media for growth. Identification of bacteria along with antimicrobial sensitivity testing was done by VITEK -2 Compact (bioMerieux). Antibiotics that were not tested by VITEK-2 were tested manually by Kirby-Bauer disk diffusion method according to CLSI 2017 and EUCAST 2016 guidelines. The isolates which were resistant to carbapenem (imipenem and/ or meropenem) were tested by phenotypic (imipenem-EDTA combined disk method) and genotypic method for presence of common metallo beta lactamases genes (blaIMP, blaNDM, blaGIM, blaVIM, blaSPM and blaSIM).
 Results: 84 non duplicate A.baumannii were isolated out of 947 pathogenic gram negative isolates. Majority (47.6%) of isolates were obtained from tracheostomy/endotracheal/bronchoalveolar lavage (TT/ET/BAL) followed by sputum (21.4%). None of the isolates were found to be resistant to colistin and tigecycline. 73 (86.9%) isolates were found to be carbapenem resistant, among these 60 (82.2%) were found to be MBL positive by phenotypic and 32 (43.2%) by genotypic method. MBL genes detected were blaNDM (39.7%), blaGIM (2.7%) and blaVIM (1.4%). None of the isolates were positive for blaIMP, blaSPM and blaSIM.
 Conclusion: The prevalence of MBL in carbapenem resistant isolates of A.baumannii was 87.7%. blaNDM was the most common gene detected. No significant difference was found in the ability of phenotypic and genotypic methods for MBL detection. The resistance rate of the A.baumannii is high for most antibiotics except for polymyxins (E&B) and tigecycline.
 Key words: Metallo beta Lactamases, Acinetobacter baumannii, Carbapenem.

Antimicrobial Activity Of Silver Nanoparticles Synthesized with Extract of Tomato plant Against Bacterial and Fungal Pathogens

Objective: Silver nanoparticles (AgNPs) have a wide range of applications. Environmental-friendly synthesis methods for these nanoparticles are more preferable due to their various advantages. This study aimed to synthesize AgNPs using the extract of the tomato plant in an easy and economical way. and testing this AgNPs against some human pathogens.Methods: Silver nanoparticles were synthesized using aqueous silver nitrate and reducing tomato plant extract. The characterization of AgNPs was determined by ultraviolet-visible spectrophotometry (UV-Vis), X-ray crystallography (XRD) Scanning electron microscopy (SEM), Fourier transform infrared Spectroscopy (FT-IR), energy dispersive X-ray spectrum (EDAX), thermogravimetric - differential thermal analysis (TGA-DTA) data. The effects of the particles on pathogenic microorganisms were determined by minimum inhibition concentration (MIC).Results: These data, with a maximum absorbance of 450.51 nm, in the spherical view, with the peaks and values of 111o, 200o, 220o and 311o (38.08, 44.28, 64.42 and 77.34), AgNPs showed a cubic crystal structure and, using the Debye-Scherrer equation, it was determined that they had a crystal size of 21.11 nm AgNPs had an antimicrobial activity on hospital pathogens gram negative, gram positive and Candida albicans yeast. Conclusion: We found that these particles showed antimicrobial activity on various microorganisms even at very high concentrations. As a solution to the antimicrobial search, it can be developed in medical industry.

Leishmanicidal and antimicrobial activity of primin and primin-containing extracts from Miconia willdenowii

As a part of an ongoing bioprospective project, searching for potential medicinal plants from the Brazilian Atlantic Forest, Miconia willdenowii was selected for its potential leishmanicidal and antimicrobial activities. The crude ethanolic extract of M. willdenowii showed an inhibition of 99.7% of the promastigote forms of Leishmania amazonensis at the concentration of 80 μg/mL. Further investigation of its antimicrobial activity against pathogenic fungi and Gram positive and negative bacteria, revealed a significant antimicrobial activity. A bioguided study with its liquid-liquid partition fractions revealed the hexane fraction (Hex) as the most active against Leishmania, inhibiting 99.2% and 46.9% of the protozoan at concentrations of 40 and 20 μg/mL, respectively. Hex also showed significant antimicrobial activity against Staphylococcus aureus and Candida krusei with IC50 of 15.6 and 62.5 μg/mL, respectively. Purification of Hex led to the isolation of 2-methoxy-6-pentyl-benzoquinone (1, also known as primin) as the active metabolite, probably responsible for the observed antimicrobial and anti-leishmania effects. Primin (1) disclosed leishmanicidal activity (IC50 = 1.25 μM), showing higher potency than the standard drug amphotericin B (IC50 = 5.08 μM), with additional antifungal effects against all tested fungi species. Compound 1 also showed significant activity against S. aureus (IC50 = 8.94 μM), showing a comparable potency with the reference drug chloramphenicol (IC50 = 6.19 μM), but with a potential cytotoxicity towards peripheral human blood mononuclear cells (CC50 = 255.15 μM). Here in, the antimicrobial and anti-L. amazonensis effects of M. willdenowii are reported for the first time, as well as Primin (1) as its probable bioactive metabolite.

Green synthesis of silver nanoparticles using Combretum erythrophyllum leaves and its antibacterial activities

A simple, green, cost effective and environmentally benign method for the synthesis of silver nanoparticles (Ag-NPs) using aqueous extract of Combretum erythrophyllum plant leaves as both the reducing and capping agents is herein reported for the first time. The as-prepared Ag-NPs were characterised using Ultraviolet–Visible (UV–Vis) absorption spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and dynamic light scattering (DLS) techniques. TEM image showed that the particles are spherical in shape, and well dispersed with the average particle diameter of 13.62 nm. The as- synthesised Ag-NPs showed efficient antibacterial activities against pathogenic Gram- positive Staphylococcus aureus (ATCC 25923) &Staphylococcus epidermidis (ATCC 12228), and Gram-negative Escherichia coli (ATCC 10536) &Proteus vulgaris (33420). Compared to the streptomycin drug, which was ineffective against S. epidermidis, the as-synthesised Ag-NPs were effective against S. epidermidis and other Staphylococcus species that are implicated in different dermatological infections.

Identification and structural analysis of the tripartite \u03b1-pore forming toxin of Aeromonas hydrophila

The alpha helical CytolysinA family of pore forming toxins (α-PFT) contains single, two, and three component members. Structures of the single component Eschericia coli ClyA and the two component Yersinia enterolytica YaxAB show both undergo conformational changes from soluble to pore forms, and oligomerization to produce the active pore. Here we identify tripartite α-PFTs in pathogenic Gram negative bacteria, including Aeromonas hydrophila (AhlABC). We show that the AhlABC toxin requires all three components for maximal cell lysis. We present structures of pore components which describe a bi-fold hinge mechanism for soluble to pore transition in AhlB and a contrasting tetrameric assembly employed by soluble AhlC to hide their hydrophobic membrane associated residues. We propose a model of pore assembly where the AhlC tetramer dissociates, binds a single membrane leaflet, recruits AhlB promoting soluble to pore transition, prior to AhlA binding to form the active hydrophilic lined pore.

Association of Carbapenem and Colistin Resistance in Pathogenic Gram Negative Bacteria

Association of Carbapenem and Colistin Resistance in Pathogenic Gram Negative Bacteria

Isolation and characterization of sophorolipid producing yeast from fruit waste for application as antibacterial agent

The present study was primarily emphasized on isolation of yeast from diverse samples and screening for potential biosurfactant producer. Yeast isolates AH16, AH23, AH46 and AH62 showed effective oil displacement activity and were confirmed to be potential biosurfactant producers. Among them, maximum yield of 4.23 g/l of crude biosurfactant was extracted from isolate AH62 within 96 h of fermentation which also showed effective emulsification activity of 76.4 ± 0.38% when tested against diesel. It could further decrease the surface tension of water from 72 to 31.4 ± 0.38 mN/m and was hence selected for subsequent study. The isolate was identified as Candida sp. AH62 through phylogenetic analysis. Characterization of extracted biosurfactant using thin layer chromatography (TLC), Fourier transform infrared spectroscopy (FTIR), high performance liquid chromatography (HPLC), gas chromatography (GC) and liquid chromatography–tandem mass spectrometry (LC–MS/MS) revealed sophorolipid to exist as a heterogeneous mixture of lactonic and acidic forms. The isolated sophorolipids showed potential antibacterial activity towards pathogenic Gram negative and Gram positive bacteria.

Comparative study on antimicrobial activity of commercial and extracted chitin and chitosan from Marsupenaeus japonicus shells

Chitin was extracted from the skeleton of Marsupenaeus japonicus shrimp shell waste with a yield of 27.7% of the net weight through three steps namely; deproteinization, decolourization and demineralization. After deacetylation process of extracted chitin, chitosan was produced and represented 55.1% of the extracted chitin. Scanning electron microscope and Fourier Transform Infrared spectroscopy (FTIR) analyses were conducted to characterize the obtained chitin and chitosan. The FTIR analysis revealed different absorption bands within 4000-400 cm-1 range; by comparison these bands were found to be similar to those of commercial chitin and chitosan and confirmed partial deacetylation in the produced chitosan. Moreover, the antimicrobial activity of commercial and extracted chitin and chitosan were examined against different pathogenic Gram positive, Gram negative bacteria and fungi using agar well diffusion test. Results showed that there was no significant difference p < 0.05 in the antimicrobial activity of the extracted compounds and commercial ones against test pathogens as the extracted compounds recorded inhibition zones ranged from 12 to 23 mm in diameter while the commercial compounds recorded inhibition zones of diameters ranged from 12 to 22 mm only; with Staphylococcus aureus ATCC 25923 being the most affected microbe with inhibition zone of 23 mm produced by extracted chitin, while the lowest zone of inhibition was recorded against Enterococcus faecalis ATCC 29212 with only 12 mm by commercial and extracted chitosan.

Synthesis, structural and antimicrobial studies of half-sandwich ruthenium, rhodium and iridium complexes containing nitrogen donor Schiff-base ligands

Synthesis, characterization and antibacterial activity of p-cymene ruthenium, Cp*rhodium and Cp*iridium metal complexes containing pyridyl azine Schiff base ligands have been described. All the complexes have been characterized by various spectroscopic techniques. Molecular structure of complexes 1, 2, 5, 6 and 8 have been obtained by single crystal X-ray diffraction analyses. Spectral studies revealed that ligand L1 bound to metals as neutral mono dentate N donor whereas ligand L2 and L3 revealed the formation of bi dentate NN′ cationic complexes. In vitro antibacterial activity of the complexes was evaluated by the agar well diffusion method using human pathogenic Gram positive bacteria Staphylococcus aureus and Gram-negative bacteria viz., Escherichia coli and Klebsiella pneumonia. Complexes 2–4 does not show any activity against the selected bacteria whereas complexes 1, 5–9 possesses moderate antimicrobial activity and they are more active than the free ligands. The potent activities of the complexes may arise from the coordination, which tends to make metal complexes act as more controlling and potent antimicrobial agents, thus hindering the growth of microorganisms.

Callus mediated biosynthesis and antibacterial activities of zinc oxide nanoparticles from Viola canescens: an important Himalayan medicinal herb

The plant mediated synthesis of metallic nanoparticles is preferred over chemical and physical methods owing to their easy synthesis, simplicity, eco-friendliness, stability and developed as lucrative field of green nanotechnology. Use of calli in place of other plant organ avoids the mass collection of plant from their wild habitat and offers the synthesis of nanoparticles for all those plants which are critically endangered or are not available throughout the year. In the present study, an alternative and novel protocol has been developed for the biosynthesis of Zinc Oxide nanoparticles (ZnO NPs) using in vitro culture technique of plant tissue culture as a basic platform for the plant material. Thus the present work aimed to synthesized ZnO NPs using the calli of Viola canescens (Banafsha) and study anti-microbial activity of synthesized nanoparticles. The calli were generated from the leaf and petiole explants, using the auxin (2,4-D and NAA) and cytokinin (Kn). Interaction of callus extract with Zinc nitrate hexahydarate extract for the bio-reduction of Zinc nitrate hexahydarate to its nanoparticles showed potency of calli to reduce Zinc nitrate to its nanosizes. The confirmation for the synthesis of the nanoparticles was done by UV–visible analysis followed by characterization of synthesized nanoparticles with XRD, FTIR and SEM techniques. X-ray diffraction analysis showed that nanoparticles exhibited the crystalline nature with wurtzite hexagonal shape and average size was less than 09 nm. FTIR revealed the presence of biomolecules which act as reduction and capping agent for the synthesis of ZnO NPs. Antibacterial activity of the synthesized nanoparticles against four different pathogenic (gram positive and gram negative) strains showed clear zone of inhibitions that confirm the potency of nanoparticles as an antibacterial agent. The present work explored the potential of the callus as bio-reduction material for nanoparticles synthesis.