Significant Bactericidal Activity Research Articles

Antimicrobial properties of multifunctional polypyrrole-cobalt oxide-silver nanocomposite against pathogenic bacteria and parasite.

Conducting polymer based nanocomposites are known to be effective against pathogens. Herein,we report the antimicrobial properties of multifunctional polypyrrole-cobalt oxide-silver nanocomposite (PPy-Co3O4-AgNPs) for the first time. Antibacterial activities were tested against multi-drug-resistant Gram-negative Escherichia coli (E. coli) and Gram-positive methicillin-resistant Staphylococcus aureus (MRSA) bacteria, while antiamoebic effects were assessed against opportunistic protist Acanthamoeba castellanii (A. castellanii). The ternary nanocomposite containing conducting polymer polypyrrole, cobalt oxide, and silver nanoparticles showed potent antimicrobial effects against these pathogens. The antibacterial assay showed that PPy-Co3O4-AgNPs exhibited significant bactericidal activity against neuropathogenic E. coli K1 at only 8 μg/mL as compared to individual components of the nanocomposite, whereas a 70 % inhibition of A. castellanii viability was observed at 50 μg/mL. Moreover, PPy-Co3O4-AgNPs were found to have minimal cytotoxicity against human keratinocytes HaCaT cells in vitro even at higher concentration (50 μg/mL), and also reduced the microbes-mediated cytopathogenicity against host cells. These results demonstrate that PPy-Co3O4-AgNPs hold promise in the development of novel antimicrobial nanomaterials for biomedical applications. •Synthesis of polypyrrole-cobalt oxide-silver (PPy-Co3O4-AgNPs) nanocomposite. •Antimicrobial activity of nanocomposite. •PPy-Co3O4-AgNPs hold promise for biomedical applications.

A Novel Acinetobacter baumannii Bacteriophage Endolysin LysAB54 With High Antibacterial Activity Against Multiple Gram-Negative Microbes.

The rapid spread and emergence of multidrug-resistant Acinetobacter baumannii and other pathogenic Gram-negative bacteria spurred scientists and clinicians to look for alternative therapeutic agents to conventional antibiotics. In the present study, an A. baumannii bacteriophage p54 was isolated and characterized. Morphological and genome analysis revealed that bacteriophage p54 belongs to Myoviridae family with a genome size of 165,813 bps. A novel endolysin, namely LysAB54, showing low similarity with other well-known related endolysins, was cloned, expressed, and characterized from the bacteriophage p54. LysAB54 showed significant bactericidal activity against multidrug-resistant A. baumannii and other Gram-negative bacteria, including Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli, in the absence of outer membrane permeabilizers. Based on all those observations, LysAB54 could represent a potential agent for the treatment of multidrug-resistant Gram-negative superbugs.

Bactericidal silver-doped DLC coatings obtained by pulsed filtered cathodic arc co-deposition

Diamond-like carbon (DLC) coatings have been extensively studied over the last two decades in the field of materials engineering. The addition of effective bactericidal agents like silver suggests the potential application of silver-doped DLC coatings in the biomedical sector. In this paper, DLC coatings containing about 2 at. % Ag were grown on CoCrMo substrates by pulsed filtered cathodic arc co-deposition using pure graphite and silver targets. Morphology, structure and chemical composition of the coatings were characterized by SEM, XPS, XRD, Raman and HRTEM. Wettability and surface free energy were also measured. Mechanical properties were analyzed by means of nanoindentation and Rockwell-C adhesion tests. Corrosion resistance of coated and uncoated samples was determined by potentio-dynamic polarization tests in Hank's solution. Cytotoxicity and antibacterial activity against S. aureus and P. aeruginosa were also studied. For comparative purposes, nitrogen-doped DLC coatings obtained by RF magnetron sputtering were also prepared and characterized. Well-adhered and corrosion resistant Ag-DLC nanostructured coatings of up to 1.5 μm thick and 21 GPa in hardness were obtained. The doping concentration of silver studied in this work seems to be optimal for the preparation of non-cytotoxic coatings with a significant bactericidal activity.

An antibacterial coated polymer prevents biofilm formation and implant-associated infection

To prevent infections associated with medical implants, various antimicrobial silver-coated implant materials have been developed. However, these materials do not always provide consistent antibacterial effects in vivo despite having dramatic antibacterial effects in vitro, probably because the antibacterial effects involve silver-ion-mediated reactive oxygen species generation. Additionally, the silver application process often requires extremely high temperatures, which damage non-metal implant materials. We recently developed a bacteria-resistant coating consisting of hydroxyapatite film on which ionic silver is immobilized via inositol hexaphosphate chelation, using a series of immersion and drying steps performed at low heat. Here we applied this coating to a polymer, polyetheretherketone (PEEK), and analyzed the properties and antibacterial activity of the coated polymer in vitro and in vivo. The ionic silver coating demonstrated significant bactericidal activity and prevented bacterial biofilm formation in vitro. Bio-imaging of a soft tissue infection mouse model in which a silver-coated PEEK plate was implanted revealed a dramatic absence of bacterial signals 10 days after inoculation. These animals also showed a strong reduction in histological features of infection, compared to the control animals. This innovative coating can be applied to complex structures for clinical use, and could prevent infections associated with a variety of plastic implants.

Chitosan/heparin blends in ionic liquid produce polyelectrolyte complexes that quickly adsorb citrate-capped silver nanoparticles, forming bactericidal composites

We present chitosan (CHT)/heparin (HP) polyelectrolyte complexes (PECs) that quickly adsorb citrate-capped silver nanoparticles (AgNPs). CHT/HP blends in ionic liquid ([HMIm][HSO4]) form durable PECs after precipitation in water. CHT/HP PECs have positive Zeta potentials (higher than +20 mV). They adsorb citrate-capped AgNPs (Zeta potential of - 12.25 mV) synthesized from Turkevich's method. PEC/AgNPs composites are characterized by spectroscopic, thermal, and microscopy analyses. AgNPs on the PEC surfaces are confirmed by transmission electron microscopy. PECs adsorb AgNPs from aqueous suspensions, achieving ≈ 95% of removal (17.18 μg of AgNPs per milligram of PEC) after only 10 min. The pseudo-second-order kinetic model adjusted well to the experimental data. The PECs release approximately 11.80 μg/mg Ag+ (66%) compared to the initial adsorbed AgNPs content (17.18 μg/mg) after 7200 min at pH 2.0. The PECs present low swelling degrees (between 130 and 150%), supporting high stability in water. PEC/AgNPs composites promote significant bactericidal activity toward Staphylococcus aureus and Escherichia coli between 0.25 and 0.5 mg/mL. This study shows a new strategy to create hybrid polysaccharide/AgNPs composites. PECs can stabilize the AgNPs and release Ag+ ions, supporting antimicrobial materials.

Antibacterial activity of melatonin against prime periodontal pathogens: An in vitro study

Aim: Accumulated data make it clear that by introducing large amount of antibiotics into the ecosystem, we have provided an environment conducive to antibiotic resistance and periodontal microbes are no different. Therefore, in the quest of finding a suitable drug as an alternate to antibiotic, we investigated the antibacterial activity of melatonin against predominantly Gram-negative periodontal pathogens in vitro. Melatonin with varied functions has driven its usage enormously; therefore, identifying its action against periodontal pathogens has driven this laboratory investigation. Materials and Methods: American type culture collection (ATCC) strains of Porphyromonas gingivalis, Fusobacterium nucleatum, and Aggregatibacter actinomycetemcomitans were used to determine minimum inhibitory and bactericidal concentrations (MIC and MBC) of melatonin using macro broth dilution method. MIC values were determined at 24, 48, and 72 h and sensitive MIC values were sub-cultured to determine MBC value at 24 h. Qualitative data were obtained and it was recorded as “sensitive” or “resistant” at respective concentrations. Results: When tested over a dilution range of 0.2–100 µg/mL, melatonin significantly inhibited microbial growth. At 48 h, the MIC value against A. actinomycetemcomitans, P. gingivalis, and F. nucleatum was 6.25, 0.8, and ≤0.2 µg/mL, respectively. The MBC value determined at 24 h demonstrated significant bactericidal activity against the pathogens. Conclusion: Melatonin exhibited bactericidal activity against prime periodontal pathogens even at low concentrations in comparison to previously documented evidences suggesting greater potency of the drug. Hence, renewed effort to find and develop new class of drug which can inhibit periodontal pathogens, rather than just improvements on already-existing drugs can potentially prevent the development of resistant strains in periodontal microenvironment.

Synthesis, Characterization and Biocidal Activity of Some Schiff Base Metal(II) Complexes

A Schiff base, 2-[4-(N,N-dimethylamino)benzylidene]benzoic acid has been synthesized by the condensation of 4-(N,N-dimethylamino)benzaldehyde and 2-amino-benzoic acid in 1:1 molar stoichiometry. The Schiff base complexes were synthesized from the chloride salts of Fe(II), Cu(II) and Zn(II) in ethanolic medium and elucidated by infrared spectroscopy, CHN elemental analysis, atomic absorption spectroscopy as well as conductivity and magnetic susceptibility measurements. The solubility and thermal stability were also determined. The metal(II) complexes are coloured solids that are soluble in DMF and DMSO. The melting point of the Schiff base was found to be 177 oC, while the complexes decompose within a temperature range of 202–261 oC suggestive of rather good thermal stability. The molar conductance values were low, indicating non-electrolytic nature of the complexes. Elemental analysis revealed that the stoichiometries of the synthesized complexes are of 1:2 metal-to-ligand ratio. All complexes were hydrated. The spectroscopic and magnetic susceptibility data revealed that the complexes possess four- coordinate distorted square planar stereochemistry, whereas the Schiff base behaves as monoanionic bidentate ligand with the nitrogen atom of the azomethine (C=N) and carboxylate oxygen (COO-) as donor sites. The Schiff base and its corresponding metal(II) complexes were assayed against a number of bacterial and fungal strains to evaluate their inhibitory potentials. All the complexes showed significant bactericidal and fungicidal activities against the tested organisms.

Lincolnenins A-D: Isomeric Bactericidal Bianthracenes from Streptomyces lincolnensis.

Cultivation profiling followed by chemical analysis of Streptomyces lincolnensis yielded four new isomeric bianthracenes, lincolnenins A-D (1-4), with relative stereostructures assigned on the basis of detailed spectroscopic analysis. Lincolnenins A (1) and B (2) exhibit restricted rotation about alternate bianthracene 9-9' and 9-8' bridges, respectively, and exist as single atropisomers, whereas C (3) and D (4) are thermally interconvertible atropisomers sharing a common 8-8' bianthracene bridge. Absolute configurations were assigned to 1-4 on the basis of diagnostic ROESY correlations and ECD calculations, whereas acid-mediated dehydration of 1 led to formation and revision of the absolute configuration of the biosynthetically related known Streptomyces antibiotic, setomimycin (5). Lincolnenin A (1) exhibited significant bactericidal activity against multiple susceptible and drug-resistant Gram-positive pathogens (MIC99 < 2.0 μM), including Mycobacterium tuberculosis H37Ra (MIC99 = 0.9 μM).

Discovery of Natural FabH Inhibitors Using an Immobilized Enzyme Column and Their Antibacterial Activity against Xanthomonas oryzae pv. oryzae.

β-Ketoacyl-acyl carrier protein synthase III (KAS III, FabH) is essential for bacterial fatty acid biosynthesis. Recent studies indicate that FabH can be a potential target for bactericide development. In the present study, an immobilized FabH column was developed and used to screen FabH inhibitors from complex natural product extracts. Combined with HPLC, four secondary metabolites, alternariol (1), altenuisol (2), alterlactone (3), and dehydroaltenusin (4), were site-directed, isolated, and identified from the crude extract of Alternaria alternata ZHJG5. These compounds showed inhibitory activities on FabH of Xanthomonas oryzae pv. oryzae (Xoo) with IC50 values from 29.5 to 74.1 μM and also displayed a varying degree of antibacterial activities against Xoo with minimal inhibitory concentration values from 4 to 64 μg/mL. Molecular modeling was then used to picture how the compounds interact with XooFabH. Two inhibitors, compounds 1 and 3, exhibited significant bactericidal activity against rice bacterial leaf blight with a protective efficiency of 66.2 and 82.5% at the concentration of 200 μg/mL, respectively, suggesting that they could be lead candidates to develop novel bactericides.

In vitro Photodynamic Therapy of Polymicrobial Biofilms Commonly Associated With Otitis Media

Otitis media (OM) is a prevalent pediatric infection characterized by painful inflammation of the middle ear. There are more than 700 million cases of OM diagnosed globally each year, with 50% of affected children under 5 years of age. Further, OM is the most common reason for children to receive antibiotic treatment in developed countries. The most recent work on this dynamic disease indicates that biofilms and polymicrobial infections play a role in recurrent OM and chronic OM, which are difficult to eradicate using standard antibiotic protocols. Antimicrobial photodynamic therapy (aPDT) is a promising new strategy for the treatment of resistant bacteria and persistent biofilms which lead to chronic infections. While PDT continues to be successfully used for oncological, dermatological, and dental applications, our work focuses on the efficacy of aPDT as it relates to otopathogens responsible for OM. Previous studies from our laboratory and others have shown that non-typeable Haemophilus influenzae, Streptococcus pneumoniae and Moraxella catarrhalis, the three most common otopathogens, are susceptible to different forms of aPDT. However, many cases of OM involve multiple bacteria and to date no one has investigated the efficacy of this technology on these complex polymicrobial biofilms. We treated polymicrobial biofilms of the three most common otopathogens with the photosensitizer Chlorin e6 (Ce6) and a continuous wave 405 ± 10 nm light emitted diode. Our data show significant bactericidal activity on polymicrobial biofilms associated with OM. These studies indicate that aPDT warrants further analysis as a possible treatment for OM and our results provide the foundation for future studies designed to identify the optimal aPDT parameters for polymicrobial biofilm-associated infections of the middle ear.

Effects of aqueous and ethanolic leaf extracts from drumstick tree (Moringa oleifera) on gilthead seabream (Sparus aurata L.) leucocytes, and their cytotoxic, antitumor, bactericidal and antioxidant activities

Aqueous and ethanolic extracts of drumstick, Moringa oleifera, leaves were evaluated in vitro to ascertain their principal active components and determine their immunostimulant, cytotoxic, antitumoral, bactericidal and antioxidant activities. Phytochemical screening of M. oleifera leaf extracts showed a greater abundance of phenolic and cyanogenic glycosides in aqueous than in ethanolic extracts, characterized by several flavonoids, condensed tannins and saponins. No significant effects on gilthead seabream (Sparus aurata) head-kidney leucocyte activities (phagocytic ability and capacity, respiratory burst and peroxidase) were detected after incubation for 24 h with different concentrations (0.001/1 mg mL−1) of either extract. In addition, the aqueous extract showed a marked cytotoxic effect on both SAF-1 (at doses above 0.01 mg mL−1) and PLHC-1 (at doses above 0.25 mg mL−1) cell lines. The ethanolic extract improved the viability of SAF-1 cells and decreased the viability of PLHC-1 cells when used at higher concentrations. Both the ethanolic and, particularly, the aqueous extracts showed significant bactericidal activity on pathogenic Vibrio anguillarum and Photobacterium damselae strains. The antiradical activity of M. oleifera, as determined by the ABTS assay, increased in a linear dose-response with increasing extract concentrations. The results as a whole for the cytotoxic, bactericidal and antioxidant activities of M. oleifera leaf extracts point to their possible use as additives in functional diets for farmed fish.

Enhanced Antimicrobial Activity of N-Terminal Derivatives of a Novel Brevinin-1 Peptide from The Skin Secretion of Odorrana schmackeri.

Antimicrobial peptides (AMPs) are promising therapeutic alternatives compared to conventional antibiotics for the treatment of drug-resistant bacterial infections. However, the application of the overwhelming majority of AMPs is limited because of the high toxicity and high manufacturing costs. Amphibian skin secretion has been proven to be a promising source for the discovery and development of novel AMPs. Herein, we discovered a novel AMP from the skin secretion of Odorrana schmackeri, and designed the analogues by altering the key factors, including conformation, net charge and amphipathicity, to generate short AMPs with enhanced therapeutic efficacy. All the peptides were chemically synthesised, followed by evaluating their biological activity, stability and cytotoxicity. OSd, OSe and OSf exhibited broad-spectrum antibacterial effects, especially OSf, which presented the highest therapeutic index for the tested bacteria. Moreover, these peptides displayed good stability. The results from scanning electron microscopy and transmission electron microscopy studies, indicated that brevinin-OS, OSd, OSe and OSf possessed rapid bactericidal ability by disturbing membrane permeability and causing the release of cytoplasmic contents. In addition, OSd, OSe and OSf dramatically decreased the mortality of waxworms acutely infected with MRSA. Taken together, these data suggested that a balance between positive charge, degrees of α-helicity and hydrophobicity, is necessary for maintaining antimicrobial activity, and these data successfully contributed to the design of short AMPs with significant bactericidal activity and cell selectivity.

Antimicrobial Photodynamic Therapy with Chlorin e6 Is Bactericidal against Biofilms of the Primary Human Otopathogens.

Moraxella catarrhalis, Streptococcus pneumoniae, and nontypeable Haemophilus influenzae (NTHi) are ubiquitous upper respiratory opportunistic pathogens. Together, these three microbes are the most common causative bacterial agents of pediatric otitis media (OM) and have therefore been characterized as the primary human otopathogens. OM is the most prevalent bacterial infection in children and the primary reason for antibiotic administration in this population. Moreover, biofilm formation has been confirmed as a primary mechanism of chronic and recurrent OM disease. As bacterial biofilms are inherently metabolically recalcitrant to most antibiotics and these complex structures also present a significant challenge to the immune system, there is a clear need to identify novel antimicrobial approaches to treat OM infections. In this study, we evaluated the potential efficacy of antibacterial photodynamic therapy (aPDT) with the photosensitizer chlorin e6 (Ce6) against planktonic as well as biofilm-associated M. catarrhalis, S. pneumoniae, and NTHi. Our data indicate aPDT with Ce6 elicits significant bactericidal activity against both planktonic cultures and established biofilms formed by the three major otopathogens (with an efficacy of ≥99.9% loss of viability). Notably, the implementation of a novel, dual-treatment aPDT protocol resulted in this disinfectant effect on biofilm-associated bacteria and, importantly, inhibited bacterial regrowth 24 h posttreatment. Taken together, these data suggest this novel Ce6-aPDT treatment may be a powerful and innovative therapeutic strategy to effectively treat and eradicate bacterial OM infections and, significantly, prevent the development of recurrent disease.IMPORTANCE Otitis media (OM), or middle ear disease, is the most prevalent bacterial infection in children and the primary reason for antibiotic use and surgical intervention in the pediatric population. Biofilm formation by the major bacterial otopathogens, Moraxella catarrhalis, Streptococcus pneumoniae, and nontypeable Haemophilus influenzae, has been shown to occur within the middle ears of OM patients and is a key factor in the development of recurrent disease, which may result in hearing impairment and developmental delays. Bacterial biofilms are inherently impervious to most antibiotics and present a significant challenge to the immune system. In this study, we demonstrate that antimicrobial photodynamic therapy (aPDT) using the photosensitizer chlorin e6 elicits significant bactericidal activity versus planktonic and biofilm-associated otopathogens and supports further analyses of this novel, efficacious, and promising technology as an adjunctive treatment for acute and recurrent OM.

Effect of bacterial nanocellulose binding on the bactericidal activity of bovine lactoferrin

Bovine lactoferrin (bLF) has been extensively described as a wide spectrum antimicrobial protein. bLF bactericidal activity has been mainly attributed to two different mechanisms: environmental iron depletion and cell membrane destabilization. Due to its antimicrobial properties, bLF has been included in the formulation nutraceutical food products and edible active packages. This work comprises the experimental evidence of the requirement of bLF unrestricted mobility (“free bLF”) to effectively perform its bactericidal action. To assess the unrestricted and restricted bLF activity, a nontoxic matrix of bacterial nanocellulose (BNC) was used as carrier, and as an anchoring scaffold, respectively. Therefore, BNC was functionalized with bLF through two different methodologies: (i) bLF was embedded within the three-dimensional structure of BNC and; (ii) bLF was covalently bounded to the nanofibrils of BNC. bLF efficiency was tested against two bacteria isolated from clinical specimens, Escherichia coli and Staphylococcus aureus. bLF concentration after covalent binding to BNC was two-fold higher in comparison to the embedding method. Nevertheless, only the embedded bLF exhibited a significant bactericidal activity, due to bLF ability to permeate the BNC matrix and execute its bactericidal action.

Antibacterial Activity of Four Plant Extracts Extracted from Traditional Chinese Medicinal Plants against Listeria monocytogenes, Escherichia coli, and Salmonella enterica subsp. enterica serovar Enteritidis.

The worldwide ethnobotanical use of four investigated plants indicates antibacterial properties. The aim of this study was to screen and determine significant antibacterial activity of four plant extracts in vitro and in a poultry digest model. Using broth microdilution, the concentrations at which four plant extracts inhibited Listeria monocytogenes, Salmonella enteritidis, and Escherichia coli over 24 h was determined. Agrimonia pilosa Ledeb, Iris domestica (L.) Goldblatt and Mabb, Anemone chinensis Bunge, and Smilax glabra Roxb all exhibited a minimum inhibitory concentration (MIC) of 62.5 mg/L and a minimum bactericidal concentration (MBC) of 500 mg/L against one pathogen. A. pilosa Ledeb was the most effective against L. monocytogenes and E. coli with the exception of S. enteritidis, for which A. chinensis Bunge was the most effective. Time–kills of A. pilosa Ledeb and A. chinensis Bunge against L. monocytogenes, E. coli and S. enteritidis incubated in poultry cecum were used to determine bactericidal activity of these plant extracts. A. chinensis Bunge, significantly reduced S. enteritidis by ≥ 99.99% within 6 h. A. pilosa Ledeb exhibited effective significant bactericidal activity within 4 h against L. monocytogenes and E. coli. This paper highlights the potential of these plant extracts to control pathogens commonly found in the poultry gastrointestinal tract.

Biosynthesis, characterization, bactericidal and sporicidal activity of silver nanoparticles using the leaves extract of Litchi chinensis

Biosynthesis of silver nanoparticles (AgNPs) using plant extracts has become a promising alternative to the conventional chemical synthesis approach. In this study, cost-effective synthesis of AgNPs was attempted using leaves extract of Litchi chinensis. Bio-reduction reaction for the synthesis of NPs was checked by confirming the presence of AgNPs in solution by UV-vis spectrophotometry and with further characterization by fourier-transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). Surface plasmon resonance (SPR) band showed absorption peak at 422 nm indicating the formation of AgNPs, and FTIR spectra confirmed the presence of biological molecules involved in AgNPs synthesis. TEM analysis revealed the spherical shape of AgNPs with particle size distribution in a range of 5–15 nm. Further, the biosynthesized AgNPs showed significant bactericidal and sporicidal activity against model spore former Bacillus subtilis. AgNPs at concentrations ranging from 25 to 100 µg/mL showed bactericidal activity with inhibition zone ranging from 4–19 mm and sporicidal activity at 100–200 µg/mL in a range of 4.46–61.6% with an exposure time of 2–8 h. These findings exhibit distinctive potential of biogenic AgNPs for their efficient use in developing novel bactericidal and sporicidal agent against spore forming bacilli.

Review on calcium- and magnesium-based silicates for bone tissue engineering applications.

Bone is a self-engineered structural component of the human body with multifaceted mechanical strength, which provides indomitable support to the effective functioning of the human body. It is indispensable to find a suitable biomaterial for substituting the bone as the bone substitute material requirement is very high due to the rate of bone fracture and infection lead to osteoporosis in human beings increases rapidly. It is not an easy task to design a material with good apatite deposition ability, a faster rate of dissolution, superior resorbability, high mechanical strength, and significant bactericidal activity. Since the synthetic hydroxyapatite was not able to achieve the dahlite phase of hydroxyapatite (natural bone mineral phase), silicates emerged as an alternate biomaterial to meet the need for bone graft substitutes. All silicates do not exhibit the properties required for bone graft substitutes, as their composition and methodology adopted for the synthesis are different. Calcium, magnesium, and silicon play a major role in the formation of bone mineral and their metabolism during bone formation. In this review, the relationship between composition and activity of calcium, magnesium-based silicates have been discussed along with the future scope of these materials for hard tissue engineering applications.

Antibacterial, Antibiofilm and Anticancer Activity of Biologically Synthesized Silver Nanoparticles Using Seed Extract of Nigella sativa

Silver nanoparticle (AgNP) based approaches using plant materials have been accepted as biomedical applications. The current study aimed to test the antibacterial, antibiofilm, and anticancer activity of silver nanoparticles synthesized by seed extract of Nigella sativa (Ns) as stabilizing and reducing agents. Characterization was done through UV–visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electronic microscopy (SEM), and transmission electronic microscopy (TEM) analyses. UV-Vis spectroscopy showed a specific silver plasmon peak at 400 nm and a quick color change was observed in the bio-reaction medium. Electron microscopic images of Ns-AgNPs identified as spherical in shape with varied size ranged between 8 and 80 nm and zeta potential analysis evidenced the particles stability and polydisperity. Antibiofilm activity of Ns-AgNPs was evident as at 12.5 µg/mL Ns-AgNps restricted the biofilm formation by 88.42% for Enterococcus faecalis, 84.92% for E. coli, 81.86% for Klebsiella pneumonia, 82.84% for Staphylococcus aureus, and 49.9% for Pseudomonas aeruginosa, respectively. Furthermore, biologically synthesized AgNPs showed the significant bacteriostatic and bactericidal activity. Even the lowest concentration of Ns-AgNps restricted the highest rate of inhibition against S. aureus (6.5 and 15 µg/mL) and E. faecalis (6.5 and 15 µg/mL). Antimicrobial activity of S. aureus and E. fecalis was more prominent than E. coli (15 and 30 µg/mL), K. pneumonia (15 and 30 µg/mL) and P. aeruginosa (30 and 60 µg/mL) respectively. Moreover, Ns-AgNPs revealed significant cytotoxic ability and substantially killed human breast cancer cell (HCC-712) viability. The results of current study advocate that Ns-AgNps may be considered as a potential option in biomedical applications, alternative therapy, designing anti-biofilm agents, treating multi drug resistance bacterial infection, and anti-cancer therapy.

Enhanced Bactericidal Effects of Pyrazinamide Toward Mycobacterium smegmatis and Mycobacterium tuberculosis upon Conjugation to a {Au(I)-triphenylphosphine}+ Moiety.

As part of the quest for new gold drugs, we have explored the efficacy of three gold complexes derived from the tuberculosis drug pyrazinamide (PZA), namely, the gold(I) complex [Au(PPh3)(PZA)]OTf (1, OTf = trifluoromethanesulfonate) and two gold(III) complexes [Au(PZA)Cl2] (2) and [Au(PZO)Cl2] (3, PZO = pyrazinoic acid, the metabolic product of PZA) against two mycobacteria, Mycobacterium tuberculosis and Mycobacterium smegmatis. Only complex 1 with the {Au(PPh3)}+ moiety exhibits significant bactericidal activity against both strains. In the presence of thiols, 1 gives rise to free PZA and {Au(PPh3)}-thiol polymeric species. A combination of PZA and the {Au(PPh3)}-thiol polymeric species appears to lead to enhanced efficacy of 1 against M. tuberculosis.

Influence of probiotic complex on productive performance and metabolism in growing pigs

Topicality. To date, an extensive scientific and practical material has been accumulated to study the effectiveness of probiotic feed additives in the feeding of farm animals. Some mechanisms of their action on the animal body have been studied, positive effects have been established, which are expressed in improving the microbial balance of the intestine, increasing the protective properties of the body, and realizing the productive qualities of animals. It is necessary to study the effectiveness of the use of probiotic complexes in comparison with the action of antibiotic-containing drugs.Methodology. It was studied the probiotic complex of Enzymsporin containing a consortium of bacteria of the genus Bacillus (Bacillus subtilis VKM B-2998 D, Bacillus licheniformis VKM B-2999 D, Bacillus subtilis VKM B-3057D) at least 5x109 CFU/g was studied in comparison with antibiotic-containing drug Virginiamycin in feeding fattened young pigs. The studies were carried out on four groups (30 heads in each group) of growing pigs in the conditions of LLC “Bryansk meat processing plant” and in the laboratories of L.K. Ernst Federal Science Center for Animal Husbandry. The duration of the experiment was 113 days.Results. During the studies, the control group of animals received compound feeds without probiotic additives, while the animals of the 2nd and 3rd experimental groups received compound feed with the addition of probiotic complex in an amount of 0.5 and 1.0 kg/t, the 4th experimental group of pigs received compound feed with the addition of antibiotic-containing drug Virginiamycin 250 g/t. By the end of the study, the live weight and average daily increments of experimental animals increased by 5.0; 6.0; 10.02 and 5.8; 6.5; 12.2% (p &lt; 0.001), respectively, compared with the control. Biochemical, morphological, immunological blood indices corresponded to physiological norms, the inclusion in the feed of pigs fed different levels of probiotic complex has led to a significant increase lysozyme, bactericidal and phagocytic activity of blood in animals 2nd and 3rd groups during rearing. Additional profit for the period of research was in the experimental groups of fattened young pigs +705,0; +849,0 and 1440.0 rubles/ head, accordingly, in comparison with the control, which indicates the effective use of not only antibiotic-containing drugs in feeding pigs, but also suggests the effective use of probiotics instead of antibiotic-containing feed preparations.