Decoding the Structure-Function Relationship of the Muramidase Domain in E. coli O157.H7 Bacteriophage Endolysin: A Potential Building Block for Chimeric Enzybiotics

Bacteriophage endolysins are potential alternatives to conventional antibiotics for treating multidrug-resistant gram-negative bacterial infections. However, their structure-function relationships are poorly understood, hindering their optimization and application. In this study, we focused on the individual functionality of the C-terminal muramidase domain of Gp127, a modular endolysin from E. coli O157:H7 bacteriophage PhaxI. This domain is responsible for the enzymatic activity, whereas the N-terminal domain binds to the bacterial cell wall. Through protein modeling, docking experiments, and molecular dynamics simulations, we investigated the activity, stability, and interactions of the isolated C-terminal domain with its ligand. We also assessed its expression, solubility, toxicity, and lytic activity using the experimental data. Our results revealed that the C-terminal domain exhibits high activity and toxicity when tested individually, and its expression is regulated in different hosts to prevent self-destruction. Furthermore, we validated the muralytic activity of the purified refolded protein by zymography and standardized assays. These findings challenge the need for the N-terminal binding domain to arrange the active site and adjust the gap between crucial residues for peptidoglycan cleavage. Our study shed light on the three-dimensional structure and functionality of muramidase endolysins, thereby enriching the existing knowledge pool and laying a foundation for accurate in silico modeling and the informed design of next-generation enzybiotic treatments.

Enzymatic dual-faced Janus structures based on the hierarchical organic-inorganic hybrid matrix for an effective bioremoval and detoxification of reactive blue-19

A novel, dual-faced, and hierarchical type of Janus hybrid structures (JHSs) was assembled through an in situ growing of lipase@cobalt phosphate sheets on the laccase@copper phosphate sponge-like structures. The chemical and structural information of prepared JHSs was investigated by Scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray diffraction analysis (XRD). The catalytic activity, storage stability, and reusability of JHSs were then investigated. The SEM-EDX analysis clearly confirmed the asymmetric morphology of the fabricated JHSs with two distinct metal distributions. Under optimized synthesis conditions, the prepared JHSs showed 97.8 % and 100 % of laccase and lipase activity, respectively. Compared to the free biocatalysts, the immobilization resulted in ~ a 2-fold increase in laccase and lipase stability at temperatures of >40 °C. The fabricated JHSs maintained 61 % and 90 % of their original laccase and lipase activity upon 12 successive repetition cycles. Up to 80 % of Reactive Blue-19 (RB-19), an anthraquinone-based vinyl sulphone dye, was removed after 5 h treatment with the prepared JHSs (50 % higher than the free forms of laccase and lipase). The dye removal data fitted very well on the pseudo-second-order kinetic model with a rate constant of 0.8 g mg-1 h-1. Following the bioremoval process, bacterial toxicity also decreased by about 70 %. Therefore, the prepared JHSs provide a facile and sustainable approach for the decolorization, biotransformation, and detoxification of RB-19 by integrating enzymatic oxidation and hydrolysis.

Isolation, characterization, and genome analysis of a broad host range Salmonella phage vB_SenS_TUMS_E4: a candidate bacteriophage for biocontrol

Salmonella enteritidis is one of the most important foodborne pathogens that cause numerous outbreaks worldwide. Some strains of Salmonella have become progressively resistant to antibiotics, so they could represent a critical threat to public health and have led to the use of alternative therapeutic approaches like phage therapy. In this study, a lytic phage, vB_SenS_TUMS_E4 (E4), was isolated from poultry effluent and characterized to evaluate its potential and efficacy for bio-controlling S. enteritidis in foods. Transmission electron microscopy revealed that E4 has a siphovirus morphotype, with an isometric head and non-contractile tail. Determining the host range showed that this phage can effectively infect different motile as well as non-motile Salmonella enterica serovars. The biological characteristics of E4 showed that it has a short latent period of about 15 min and a large burst size of 287 PFU/cell, and is also significantly stable in a broad range of pHs and temperatures. The E4 whole genome contains 43,018 bp and encodes 60 coding sequences (CDSs) but no tRNA genes. Bioinformatics analysis revealed that the genome of E4 lacks any genes related to lysogeny behavior, antibiotic resistance, toxins, or virulence factors. The efficacy of phage E4 as a bio-control agent was assessed in various foodstuffs inoculated with S. enteritidis at 4°C and 25°C, and the resulting data indicated that it could eradicate S. enteritidis after a very short time of 15 min. The findings of the present study showed that E4 is a hopeful candidate as a bio-control agent against S. enteritidis and has the potential to be used in various foodstuffs.

Isolation, characterization, and genomic analysis of vB_PaeP_TUMS_P121, a new lytic bacteriophage infecting Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic human pathogen that can cause life-threatening nosocomial infections. The alarming increase in antibiotic resistance has led to an urgent need for alternative therapeutic approaches, such as phage therapy, which has shown promising results in many studies. In this study, P121, a new lytic Pseudomonas phage, was isolated and characterized. Whole-genome sequencing showed that it has a genome of 73,001 bp that contains 91 predicted coding sequences. No genes involved in virulence or lysogeny were found in the genome, thus making it potentially safe for therapeutic applications. Genomic and phylogenetic analysis indicated that P121 is a member of the genus Litunavirus, family Schitoviridae. The present study provides some basic information for further research on treatment of P. aeruginosa infections.

Wound healing and anti-inflammatory effects of bacterial cellulose coated with Pistacia atlantica fruit oil

BACKGROUND

Biological activities of Pistacia atlantica have been investigated for few decades. The fruit oil of the plant has been used for treatment of wounds, inflammation, and other ailments in Traditional Persian Medicine (TPM).

OBJECTIVES

The main objectives of this study were to analyze the chemical composition of Pistacia atlantica fruit oil and to study wound healing and anti-inflammatory effects of oil-absorbed bacterial cellulose in an in vivo burn wound model.

METHOD

Bacterial cellulose membrane was prepared from Kombucha culture and Fourier-transform infrared was used to characterize the bacterial cellulose. Cold press technique was used to obtain Pistacia atlantica fruit oil and the chemical composition was analyzed by gas chromatography. Bacterial cellulose membrane was impregnated with the Pistacia atlantica fruit oil. Pistacia atlantica hydrogel was prepared using specific Carbopol. Burn wound model was used to evaluate in vivo wound healing and anti-inflammatory effects of the wound dressings containing either silver sulfadiazine as positive control, Pistacia atlantica hydrogel or bacterial cellulose membrane coated with the Pistacia atlantica fruit oil. Blank dressing was used as negative control.

RESULTS

FT-IR analysis showed that the structure of the bacterial cellulose corresponded with the standard FT-IR spectrum. The major components of Pistacia atlantica fruit oil constituted linoleic acid (38.1%), oleic acid (36.9%) and stearic acid (3.8%). Histological analysis showed that bacterial cellulose coated with fruit oil significantly decreased the number of neutrophils as a measure of inflammation compared to either negative control or positive control (p < 0.05). Wound closure occurred faster in the treated group with fruit oil-coated bacterial cellulose compared to the other treatments (p < 0.05).

CONCLUSION

The results showed that bacterial cellulose coated with Pistacia atlantica fruit oil can be a potential bio-safe dressing for wound management.

Fabrication of Calcium Sulfate Coated Selenium Nanoparticles and Corresponding In-Vitro Cytotoxicity Effects Against 4T1 Breast Cancer Cell Line

Background: The inhibitory effect of selenium nanoparticles (SeNPs) on cancer cells has been reported in many studies. In this study, the purpose was to compare the in vitro effects of SeNPs and calcium sulfate coated selenium nanoparticles (CaSO4@ SeNPs) on breast cancer cells. Methods: CaSO4@SeNPs and SeNPs were chemically synthesized and characterized with Field Emission Scanning Electron Microscope (FESEM) and energy-dispersive X-ray spectroscopy (EDX). By applying MTT assay, the cytotoxicity effect of both nanomaterials on the 4T1 cancer cells was investigated. Results: While LD50 of SeNPs on 4T1 cancer cells was 80 µg, the LD50 of CaSO4@SeNPs was reported to be only 15 µg. The difference between the inhibition rates obtained for SeNPs and CaSO4@SeNPs was statistically significant (p=0.05). In addition, at higher concentrations (50 µg) of CaSO4@SeNPs, the cytotoxicity was 100% more than SeNPs alone.   Conclusion: According to the result of the present work, it can be concluded that de-coration of SeNPs with calcium sulfate leads to an increase in potency by decreasing the effective dose. This effect can be attributed to activation of intrinsic apoptosis signaling and/or pH regulatory properties of CaSO4@SeNPs. However, further studies are still needed to determine the exact corresponding mechanisms of this synergistic effect.

Comparison of Cytokine Expression in Human PBMCs Stimulated with Normal and Heat-Shocked Lactobacillus plantarum Cell Lysate

Regulation of immune responses is among the beneficial effects of probiotic bacteria on human health. In this study, we aim to investigate the effect of normal and heat-shocked Lactobacillus plantarum PTCC 1058 cell lysate on cytokine expression by human PBMCs. The mid-exponential phase L. plantarum (10⁸ CFU/mL) were used to prepare cell lysate. Isolated PBMCs were stimulated with 100 µg/mL of each normal and heat-shocked L. plantarum cell lysate for 72 h. Non-stimulated PBMCs were also evaluated as negative control. The mRNA expression of IL-6, IL-10, IFN-ɣ, TNF-α, and TGF-β genes was determined by quantitative RT-PCR amplification of total RNA extracted from PBMCs. Both types of cell lysate were able to increase pro-inflammatory cytokines and decrease anti-inflammatory cytokines. However, this effect was significantly stronger in heat-shocked cell lysate-treated PBMCs. Moreover, comparison of IFN-ɣ/IL-10, IFN-ɣ/TGF-β, IL-6/IL-10, IL-6/TGF-β, and TNF-α/IL-10 ratios in both conditions demonstrated that in the heat-shocked group, all of the above ratios were significantly higher than normal lysate treatment (p˂0.001), suggesting that heat-shocked probiotics are a potent inducer of the immune system in comparison to intact probiotics. Regarding these results, it may be possible to develop a new postbiotic product for the stimulation of immune responses of cancer patients or individuals who suffer from an immune defect.

Fabrication of Calcium Sulfate Coated Selenium Nanoparticles and Corresponding In-Vitro Cytotoxicity Effects Against 4T1 Breast Cancer Cell Line

BACKGROUND

The inhibitory effect of selenium nanoparticles (SeNPs) on cancer cells has been reported in many studies. In this study, the purpose was to compare the in vitro effects of SeNPs and calcium sulfate coated selenium nanoparticles (CaSO₄@SeNPs) on breast cancer cells.

METHODS

CaSO₄@SeNPs and SeNPs were chemically synthesized and characterized with Field Emission Scanning Electron Microscope (FESEM) and energy-dispersive X-ray spectroscopy (EDX). By applying MTT assay, the cytotoxicity effect of both nanomaterials on the 4T1 cancer cells was investigated.

RESULTS

While LD₅₀ of SeNPs on 4T1 cancer cells was 80 μg, the LD₅₀ of CaSO₄@SeNPs was reported to be only 15 μg. The difference between the inhibition rates obtained for SeNPs and CaSO₄@SeNPs was statistically significant (p=0.05). In addition, at higher concentrations (50 μg) of CaSO₄@SeNPs, the cytotoxicity was 100% more than SeNPs alone.

CONCLUSION

According to the result of the present work, it can be concluded that decoration of SeNPs with calcium sulfate leads to an increase in potency by decreasing the effective dose. This effect can be attributed to activation of intrinsic apoptosis signaling and/or pH regulatory properties of CaSO₄@SeNPs. However, further studies are still needed to determine the exact corresponding mechanisms of this synergistic effect.

The Toxicity of Synthetic and Biogenic Selenium Nanoparticles on Human Brain Glioblastoma Cell Line: An in vitro Comparison

Background: Brain tumors can be serious and life-threatening when they are treated effectively. Many therapeutic approaches, such as chemotherapy, radiotherapy, and surgery have been used to treat brain tumors. In this regard, selenium supplements have been reported effective.Methods: Selenium Nanoparticles (SeNPs) were produced in two forms of synthetic and biogenic to evaluate their cytotoxicity on brain glioblastoma cell lines. A-172 cell line was cultured in DMEM medium. The cytotoxicity of the synthetic and biogenic SeNP was assessed by MTT assay. Results: There was a significant difference between the group treated with biogenic and synthetic SeNP compared with non-treated cells after 24, 48, and 72 h. Both biogenic and synthetic SeNP increased Bax gene and decreased Bcl-2 gene expression. Conclusion: It seems that biogenic SeNP was more lethal than its synthetic form. Therefore, it should be considered that the method of NP construction may be an important parameter for its bioactivity.

PerioVax3, a key antigenic determinant with immunoprotective potential against periodontal pathogen

Treponema (T.) denticola is one of the key etiological agents in the development of periodontitis. The major outer sheath protein (Msp) of T. denticola has been shown to mediate pathogenesis and to facilitate adhesion of T. denticola to mucosal surfaces. This study aimed to find short polypeptides in the amino acid sequence of Msp which may be immunogenic and might elicit protective antisera against T. denticola. The complete msp sequence was divided into six fragments and the corresponding genes were cloned and expressed. Antisera against the polypeptides were raised in rabbits and fragment 3 (F3), hereinafter called PerioVax3 was the most potent fragment of the Msp in terms of yielding high titer antiserum. An adhesion assay was done to examine the inhibitory effects of antisera on the attachment of T. denticola to human gingival fibroblasts (HGFs) and human fibronectin. Antiserum against PerioVax3 significantly inhibited attachment of T. denticola to the substratum. Also, antiserum against PerioVax3 inhibited detachment of HGFs upon T. denticola exposure. To begin examining the clinical relevance of this work, blood samples from 12 sever periodontitis patients were collected and the sera were used in western blotting against the recombinant polypeptides. Periodontitis patient antisera exclusively detected PerioVax3 in western blotting. The data suggest that PerioVax3 carries epitopes that may trigger humoral immunity against T. denticola, which may protect against its adhesion functions. The complexity of periodontitis suggests that PerioVax3 may be considered for testing as a component of an experimental multivalent periodontal vaccine in further preclinical and clinical studies.

Isolation, one-step affinity purification, and characterization of a polyextremotolerant laccase from the halophilic bacterium Aquisalibacillus elongatus and its application in the delignification of sugar beet pulp

The aim of the present work was to study the ability of a halophilic bacterial laccase to efficient delignification in extreme conditions. Here, a highly stable extracellular laccase showing ligninolytic activity from halophilic Aquisalibacillus elongatus is described. The laccase production was strongly influenced by NaCl and CuSO₄ and under optimal conditions reached 4.8UmL^-1. The monomeric enzyme of 75kDa was purified by a synthetic affinity column with 68.2% yield and 99.8-fold purification. The enzyme showed some valuable features viz. stability against a wide range of organic solvents, salts, metals, inhibitors, and surfactants and specificity to a wide spectrum of substrates diverse in structure and redox potential. It retained more than 50% of the original activity at 25-75°C and pH 5.0-10.0. Furthermore, the enzyme was found to be effective in the delignification of sugar beet pulp in an ionic liquid that makes it useful for industrial applications.

Blockage of both the extrinsic and intrinsic pathways of diazinon-induced apoptosis in PaTu cells by magnesium oxide and selenium nanoparticles

Diazinon (DZ) is an organophosphorus insecticide that acts as an acetylcholinesterase inhibitor. It is important to note that it can induce oxidative stress, lipid peroxidation, diabetic disorders, and cytotoxicity. Magnesium oxide (MgO) and selenium nanoparticles (Se NPs) showed promising protection against oxidative stress, lipid peroxidation, cytotoxicity, and diabetic disorders. Therefore, this study was conducted to explore the possible protective mechanisms of MgO and Se NPs against DZ-induced cytotoxicity in PaTu cell line. Cytotoxicity of DZ, in the presence or absence of effective doses of MgO and Se NPs, was determined in human pancreatic cancer cell line (PaTu cells) after 24 hours of exposure by using mitochondrial activity and mitochondrial membrane potential assays. Then, the insulin, proinsulin, and C-peptide release; caspase-3 and -9 activities; and total thiol molecule levels were assessed. Determination of cell viability, including apoptotic and necrotic cells, was assessed via acridine orange/ethidium bromide double staining. Furthermore, expression of 15 genes associated with cell death/apoptosis in various phenomena was examined after 24 hours of contact with DZ and NPs by using real-time polymerase chain reaction. Compared to the individual cases, the group receiving the combination of MgO and Se NPs showed more beneficial effects in reducing the toxicity of DZ. Cotreatment of PaTu cell lines with MgO and Se NPs counteracts the toxicity of DZ on insulin-producing cells.

Biosynthesis of tellurium nanoparticles by Lactobacillus plantarum and the effect of nanoparticle-enriched probiotics on the lipid profiles of mice

Hypercholesterolemia is an important risk factor contributing to atherosclerosis and coronary heart disease. Lactic acid bacteria have attracted much attention regarding their promising effect on serum cholesterol levels. Tellurium (Te) is a rare element that has also gained considerable interest for its biological effects. There have been some recent in vivo reports on the reduction effect of Te on cholesterol content. In this study, Lactobacillus plantarum PTCC 1058 was employed for the intracellular biosynthesis of Te NPs. The UV-visible spectrum of purified NPs showed a peak at 214 nm related to the surface plasmon resonance of the Te NPs. Transmission electron microscopy showed that spherical nanoparticles without aggregation had the average size of 45.7 nm as determined by the laser scattering method. The energy dispersive X-ray pattern confirmed the presence of Te atoms without any impurities. A significant reduction was observed in group which received L. plantarum with or without Te NPs during propylthiouracil and cholesterol diet in compare with the control group which received just propylthiouracil and cholesterol. The levels of triglycerides also remarkably decrease (p<0.05) in mice given L. plantarum with intracellular Te NPs.

Adjuvant Effect of Biogenic Selenium Nanoparticles Improves the Immune Responses and Survival of Mice Receiving 4T1 Cell Antigens as Vaccine in Breast Cancer Murine Model

The modification of tumor-associated antigen-based vaccine to elicit a more robust immune response has been addressed in several ways. In the present work, we aimed to investigate the immunomodulatory effect of selenium nanoparticles as an immunoadjuvant in formulation of a tumor-associated antigen-based vaccine in a preventive form. Fortyfive female inbred BALB/c mice five-to-seven weeks old were used and divided into three groups of test and control, each containing fifteen mice. Group one injected by PBS and used as a control. Group two injected by breast tumor cell lysate alone as vaccine. Group three injected by SeNPs with tumor cell lysate as vaccine. All injections were carried out on day fourteen, twentyone and twentyeight of the study. Tumor induction was done at day thirty. Twenty days after tumor induction serum samples were gathered to measure the cytokine assay. Tumor growth and weight of mice as well as delayed type hyper sensitivity (DTH) response were monitored during the study. Results of the present work showed a significant increase in the level of serum IFN-γ, IL-2, IL-12 and decreased TGF-β in SeNPs/vaccine injected mice as well as lower tumor volume, more potent DTH responses and longer survival rate in comparison to control and tumor lysate vaccine. Taken together, it can be deduced from this work that SeNPs can be considered as an adjuvant in vaccine in triggering robust immune response against breast cancer. But further evaluations are still needed to find the best formula for this agent in antitumor vaccines.

Th1 Immune Response Induction by Biogenic Selenium Nanoparticles in Mice with Breast Cancer: Preliminary Vaccine Model

BACKGROUND

Tumor associated antigens can be viably used to enhance host immune response.

OBJECTIVES

The immunomodulatory effect of biogenic selenium nanoparticles (SeNPs) was compared between treated and untreated mice with crude antigens of 4T1 cells.

MATERIALS AND METHODS

Female inbred BALB/c mice (60) were injected by cancinogenic 4T1 cells causing breast cancer. After 10 days, all tumor bearing mice were divided into 4 groups. Group 1 was daily provided oral PBS and injected by the same buffer after tumor induction and was considered as control. Group 2 received only 100 μg/day SeNPs as an oral supplement for 30 days. Group 3 was only injected with 4T1 cells crude antigens with nil supplementation of SeNPs. Group 4 animals were supplemented 100 μg/day SeNPs for 30 days and simultaneously injected with crude antigens of 4T1 cells. All antigens or PBS injections were introduced at 7, 14 and 28 days following tumor induction. Oral PBS and SeNPs supplementation initiated from the first day of tumor induction and continued up to 30 days. During tumor growth, animal weights and survival rates were monitored and at the end of the study the concentrations of different cytokines and DTH responses were measured.

RESULTS

Data clearly showed that the levels of cellular immunomodulatory components (granzyme B, IL-12, IFN-γ, and IL-2) significantly increased (P < 0.05) in mice treated with both SeNPs and crude antigens of 4T1 cells in comparison to the other groups. In contrast, the levels of TGF-β in these mice decreased.

CONCLUSIONS

Although SeNPs showed a noticeable boosting effect for the immune response in mice bearing tumor exposed to crude antigens of 4T1 cells, further complementary studies seem to be inevitable.

Antimicrobial Activities of Three Medicinal Plants and Investigation of Flavonoids of Tripleurospermum disciforme

Rosa damascena, Tripleurospermum disciforme and Securigera securidaca were used as disinfectant agents and for treatment of some disease in folk medicine of Iran. The antimicrobial effects of different fractions of seeds extract of S. securidaca, petals extract of R. damascena and aerial parts extract of T. disciforme were examined against some gram positive, gram negative and fungi by cup plate diffusion method. The petroleum ether and chloroform fractions of S. securidaca showed antibacterial activities against Staphylococcus aureus and Pseudomonas aeruginosa, while its methanol fraction had no antibacterial effects. R. damascena petals extract demonstrated antibacterial activities against Bacillus cereus, Staphylococcus epidermidis, S. aureus and Pseudomonas aeruginosa. T. disciforme aerial parts extract exhibited antimicrobial effects only against S. aureus and S. epidermidis. None of the fractions had any antifungal activities. Therefore, present study confirmed utility of these plants as disinfectant agents. Six flavonoids were isolated from T. disciforme: Luteolin, Quercetin-7-O-glucoside, Kaempferol, Kaempferol-7-O-glucoside, Apigenin and Apigenin-7-O-glucoside. The flavonoids and the antimicrobial activity of T. disciforme are reported for the first time.

The antimicrobial effects of selenium nanoparticle-enriched probiotics and their fermented broth against Candida albicans

Background

Lactic acid bacteria are considered important probiotics for prevention of some infections. The aim of this work was to investigate the effect of selenium dioxide on the antifungal activity of Lactobacillus plantarum and L. johnsonii against Candida albicans.

Methods

Lactobacillus plantarum and L. johnsonii cells, grown in the presence and absence of selenium dioxide, and their cell-free spent culture media were tested for antifungal activity against C. albicans ATCC 14053 by a hole-plate diffusion method and a time-kill assay.

Results

Both L. plantarum and L. johnsonii reduced selenium dioxide to cell-associated elemental selenium nanoparticles. The cell-free spent culture media, from both Lactobacillus species that had been grown with selenium dioxide for 48 h, showed enhanced antifungal activity against C. albicans. Enhanced antifungal activity of cell biomass against C. albicans was also observed in cultures grown with selenium dioxide.

Conclusions

Selenium dioxide-treated Lactobacillus spp. or their cell-free spent broth inhibited the growth of C. albicans and should be investigated for possible use in anti-Candida probiotic formulations in future.

Sophoraflavanone G from Sophora pachycarpa Enhanced the Antibacterial Activity of Gentamycin against Staphylococcus aureus

In this study the enhancement effect of Sophora pachycarpa roots’ acetone extract on the antibacterial activity of gentamycin was evaluated against Staphylococcus aureus. Disc diffusion and broth dilution methods were used to determine the antibacterial activity of gentamycin in the absence and presence of plant extract and its various fractions separated by TLC. A clinical isolate of S. aureus was used as test strain. The active component of the plant extract involved in enhancement of gentamycin’s activity had Rƒ = 0.72 on a TLC plate. The spectral data (1H NMR, 13C NMR) of this compound revealed that this compound was 5,7,2′,4′-tetrahydroxy-8- lavandulylflavanone (sophoraflavanone G), previously isolated from Sophora exigua. In the presence of 0.03 μg/ mL of sophoraflavanone G the MIC value of gentamycin for S. aureus decreased from 32 to 8 μg/mL (a fourfold decrease). These results signify that the ultra-low concentration of sophoraflavanone G potentiates the antimicrobial action of gentamycin suggesting a possible utilization of this compound in combination therapy against Staphylococcus aureus.

Screening of Medicinal Plant Methanol Extracts for the Synthesis of Gold Nanoparticles by Their Reducing Potential

Development of nontoxic, clean techniques for the synthesis of metal nanoparticles such as gold has attracted increasing attention in recent years. Although many reports have been published about the biogenesis of gold nanoparticles using several plant extracts such as Neem leaf broth (Azadirachta indica), the capacity of a large number of such extracts to form gold nanoparticles has yet to be elucidated. In this research a titrimetric assay was employed for preliminary evaluation of the reducing potential of different medicinal plant extracts. All the extracts were used separately for the synthesis of gold nanoparticles through the reduction of aqueous AuCl4 −. After the screening step, the methanol extracts of Eucalyptus camaldulensis and Pelargonium roseum were selected for further studies. The reducing ability of these extracts was significantly enhanced as compared to Neem leaf broth (Azadirachta indica) which was used as control sample. Transmission electron microscopy, energy-dispersive spectroscopy and visible absorption spectroscopy confirmed the reduction of gold ions to gold nanoparticles. The E. camaldulensis and P. roseum extracts produced gold nanoparticles in the size ranges of 1.25 - 17.5 and 2.5 - 27.5 nm with an average size of 5.5 and 7.5 nm, respectively.

Sophoraflavanone G from Sophora pachycarpa Enhanced the Antibacterial Activity of Gentamycin against Staphylococcus aureus

In this study the enhancement effect of Sophora pachy- carpa roots’ acetone extract on the antibacterial activity of gentamycin was evaluated against Staphylococcus au­reus. Disc diffusion and broth dilution methods were used to determine the antibacterial activity of gentamy­cin in the absence and presence of plant extract and its various fractions separated by TLC. A clinical isolate of S. aureus was used as test strain. The active component of the plant extract involved in enhancement of genta- mycin’s activity had Rf = 0.72 on a TLC plate. The spec­tral data (1H NMR. 13CNMR) of this compound re­vealed that this compound was 5,7,2′,4′-tetrahydroxy-8- lavandulylflavanone (sophoraflavanone G), previously isolated from Sophora exigua. In the presence of 0.03 μg/ mL of sophoraflavanone G the MIC value of gentamy­cin for S. aureus decreased from 32 to 8 μg/mL (a four­fold decrease). These results signify that the ultra-low concentration of sophoraflavanone G potentiates the an­timicrobial action of gentamycin suggesting a possible utilization of this compound in combination therapy against Staphylococcus aureus.

Two matrix metalloproteinase inhibitors from scrophularia striata boiss

Many species belonging to the Scrophularia genus have been used since ancient times as folk remedies for many medical conditions such as scrofulas, scabies, tumors, eczema, psoriasis, inflammations. The aim of this study was to characterize the matrix metalloproteinases (MMPs) inhibitor compounds of the Scrophularia striata extract by bio-guide fractionation. The aerial parts of S. striata were collected and different extracts were sequentially prepared with increasingly polar solvents. The MMPs inhibitory activity of the crude extract and its fractions were evaluated by the Zymoanalysis method. The pure compounds were purified from the active fraction by chromatography methods. Chemical structures were deduced by nuclear magnetic resonance and mass spectrometry. Two active compounds (acteoside and nepitrin) were identified by bio-guide fractionation. The inhibitory effects of nepitrin and acteoside at 20 µg/mL were about 56 and 18 percent, respectivly. The inhibitory effects of acteoside at 80 µg/mL were increased to about 73 percent. In summary, the results suggest that nepitrin effectively inhibited MMPs inhibitory activity at low concentrations, whereas acteoside showed inhibition at high concentrations.

Antioxidant and cytotoxic effect of biologically synthesized selenium nanoparticles in comparison to selenium dioxide

The present study was designed to evaluate antioxidant and cytotoxic effect of selenium nanoparticles (Se NPs) biosynthesized by a newly isolated marine bacterial strain Bacillus sp. MSh-1. An organic-aqueous partitioning system was applied for purification of the biogenic Se NPs and the purified Se NPs were then investigated for antioxidant activity using DPPH scavenging activity and reducing power assay. Cytotoxic effect of the biogenic Se NPs and selenium dioxide (SeO2) on MCF-7 cell line was assesed by MTT assay. Tranmission electron micrograph (TEM) of the purified Se NPs showed individual and spherical nanostructure in size range of about 80-220nm. The obtained results showed that, at the same concentration of 200μg/mL, Se NPs and SeO2 represented scavenging activity of 23.1±3.4% and 13.2±3.1%, respectively. However, the data obtained from reducing power assay revealed higher electron-donating activity of SeO2 compared to Se NPs. Higher IC50 of the Se NPs (41.5±0.9μg/mL) compared to SeO2 (6.7±0.8μg/mL) confirmed lower cytotoxicity of the biogenic Se NPs on MCF-7 cell line.

Inhibition of Nitrofurantoin Reduction by Menthol Leads to Enhanced Antimicrobial Activity

Nitrofurantoin is a nitroaromatic compound used for the treatment of urinary tract infections. Nitrofurantoin activity is regulated by a nitroreduction process. It is first reduced by bacterial nitroreductases to active short-life intermediates, which are further converted to non-toxic molecules, which negatively affect its antibacterial activity. In this study we have shown that resistant strains of Klebsiella sp. inactivate the bactericidal activity of nitrofurantoin. Also we demonstrated a synergistic effect between menthol and nitrofurantoin bactericidal activities against nitrofurantoin susceptible Enterobacteriaceae.

Efficacy of biogenic selenium nanoparticles against Leishmania major: in vitro and in vivo studies

PROJECT

This study investigated the in vitro and in vivo effectiveness of biogenic selenium nanoparticles (Se NPs), biosynthesized by Bacillus sp. MSh-1, against Leishmania major (MRHO/IR/75/ER).

PROCEDURE

The 3-(4,5-dimethylthiozol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay was used to evaluate the cytotoxicity effects of the biogenic Se NPs against both promastigote and amastigote forms of L. major. In a separate in vivo experiment, we also determined the preventive and therapeutic effects of biogenic Se NPs in BALB/c mice following subcutaneous infected with L. major.

RESULTS

The MTT assays showed that the highest toxicity occurred after 72 h against both promastigote and amastigote forms of L. major. The cytotoxicity of Se NPs was higher at all incubation times (24, 48, and 72 h) against the promastigote than the amastigote form (p<0.05). The 50% inhibitory concentrations (IC50) of the Se NPs were 1.62±0.6 and 4.4±0.6 μg ml(-1) against the promastigote and amastigote forms, respectively, after a 72-h incubation period. Apoptosis assays showed DNA fragmentation in promastigotes treated with Se NPs. In an animal challenge, prophylactic doses of biogenic Se NPs delayed the development of localized cutaneous lesions. Moreover, daily administration of Se NPs (5 or 10 mg kg(-1) day(-1)) in similarly infected BALB/c mice that had not received prophylactic doses of Se NPs also abolished the localized lesions after 14 days.

CONCLUSION

Based on these in vitro and in vivo studies, biogenic Se NPs can be considered as a novel therapeutic agent for treatment of the localized lesions typical of cutaneous leishmaniasis.

Isolation, characterization and complete genome sequence of PhaxI: a phage of Escherichia coli O157 : H7

Bacteriophages are considered as promising biological agents for the control of infectious diseases. Sequencing of their genomes can ascertain the absence of antibiotic resistance, toxin or virulence genes. The anti-O157 : H7 coliphage, PhaxI, was isolated from a sewage sample in Iran. Morphological studies by transmission electron microscopy showed that it has an icosahedral capsid of 85-86 nm and a contractile tail of 115×15 nm. PhaxI contains dsDNA composed of 156 628 nt with a G+C content of 44.5 mol% that encodes 209 putative proteins. In MS analysis of phage particles, 92 structural proteins were identified. PhaxI lyses Escherichia coli O157 : H7 in Luria-Bertani medium and milk, has an eclipse period of 20 min and a latent period of 40 min, and has a burst size of about 420 particles per cell. PhaxI is a member of the genus 'Viunalikevirus' of the family Myoviridae and is specific for E. coli O157 : H7.

Selenium nanoparticle-enriched Lactobacillus brevis causes more efficient immune responses in vivo and reduces the liver metastasis in metastatic form of mouse breast cancer

BACKGROUND AND THE PURPOSE OF THE STUDY

Selenium enriched Lactobacillus has been reported as an immunostimulatory agent which can be used to increase the life span of cancer bearing animals. Lactic acid bacteria can reduce selenium ions to elemental selenium nanoparticles (SeNPs) and deposit them in intracellular spaces. In this strategy two known immunostimulators, lactic acid bacteria (LAB) and SeNPs, are concomitantly administered for enhancing of immune responses in cancer bearing mice.

METHODS

Forty five female inbred BALB/c mice were divided into three groups of tests and control, each containing 15 mice. Test mice were orally administered with SeNP-enriched Lactobacillus brevis or Lactobacillus brevis alone for 3 weeks before tumor induction. After that the administration was followed in three cycles of seven days on/three days off. Control group received phosphate buffer saline (PBS) at same condition. During the study the tumor growth was monitored using caliper method. At the end of study the spleen cell culture was carried out for both NK cytotoxicity assay and cytokines measurement. Delayed type hypersensitivity (DTH) responses were also assayed after 72h of tumor antigen recall. Serum lactate dehydrogenase (LDH) and alkaline phosphatase (ALP) levels were measured, the livers of mice were removed and prepared for histopathological analysis.

RESULTS

High level of IFN-γ and IL-17 besides the significant raised in NK cytotoxicity and DTH responses were observed in SeNP-enriched L. brevis administered mice and the extended life span and decrease in the tumor metastasis to liver were also recorded in this group compared to the control mice or L.brevis alone administered mice.

CONCLUSION

Our results suggested that the better prognosis could be achieved by oral administration of SeNP-enriched L. brevis in highly metastatic breast cancer mice model.

Sub-inhibitory concentration of biogenic selenium nanoparticles lacks post antifungal effect for Aspergillus niger and Candida albicans and stimulates the growth of Aspergillus niger

BACKGROUND

The antifungal activity of selenium nanoparticles (Se NPs) prepared by Klebsiella pneumoniae has been reported previously for different fungi. In the present study, freshly prepared Se NPs produced by K. pneumoniae were purified and characterized by transmission electron microscopy and Energy-Dispersive X-ray spectroscopy (EDS) and its post antifungal effects for two fungi were evaluated.

MATERIALS AND METHODS

The minimum inhibitory concentrations (MICs) of Se NPs, determined by serial dilution were 250 µg/ml for Aspergillus niger and 2,000 µg/ml for Candida albicans. The effect of exposure of A. niger and C. albicans to Se NPs on later growth was evaluated by incubating the fungi for 1 hour at 25 °C in media containing 0, 1, 2 and 4 x MIC of Se NPs and diluting the cultures 100 times with Se free medium. The kinetics of growth of the fungi in control cultures and in non-toxic Se NPs concentration of, 0.01 × MIC, 0.02 × MIC or 0.04 × MIC were measured.

RESULTS

The exposure of A. niger and C. albicans to 2 and 4 x MIC of Se NPs stimulated the growth of both fungi in the absence of toxic concentrations of Se. The strongest stimulation was observed for A. niger.

CONCLUSION

It is concluded that exposure to high concentration of the Se NPs did not have any post-inhibitory effect on A. niger and C. albicans and that trace amounts of this element promoted growth of both fungi in a dose- dependent-manner. The role of nanoparticles serving as needed trace elements and development of microorganism tolerance to nanoparticles should not be dismissed while considering therapeutic potential.

Acute and subacute toxicity of novel biogenic selenium nanoparticles in mice

CONTEXT

In the present investigation, acute and subacute toxicity of the biogenic Se nanoparticles (Se NPs) has been reported.

OBJECTIVE

To characterize the Se NPs produced by a bacterium species and to evaluate their toxicity and impact on clinical chemistry and hematological parameters of NMRI mice.

MATERIALS AND METHODS

The Se NPs were prepared by Bacillus sp. MSh-1 in a culture medium containing SeO(2) (1.26 mM) and their physiochemical properties investigated using TEM, XRD and FT-IR. The LD(50) of Se NPs and SeO(2) were determined and the subacute toxicity evaluated by orally administration of 0, 2.5, 5, 10 and 20 mg kg(-1) of Se NPs to male mice for 14 consecutive days. Parameters of blood cells, AST, ALT, ALP, creatinine, BUN, cholesterol, bilirubin, triglyceride and CPK were experimentally measured.

RESULTS

The XRD and TEM analyses showed that the spherical NPs were amorphous, in the size range of 80-220 nm. The toxicological evaluation showed that the LD(50) values of SeO(2) and Se NPs were 7.3 and 198.1 mg kg(-1), respectively. No biochemical changes were observed from the administration of 2.5, 5 and 10 mg kg(-1) of Se NPs, but a dose of 20 mg kg(-1) was accompanied with signs of toxicity including lower body weight and changes in clinical chemistry and hematological parameters.

CONCLUSION

The biogenic Se NPs were less toxic than synthetic Se NPs and much less (26-fold) toxic than the SeO(2), which demonstrates the important role of Bacillus sp. MSh-1 in conversion of a highly toxic Se compound to the less toxic Se NPs.

Effect of Oral Supplementation of Biogenic Selenium Nanoparticles on White Blood Cell Profile of BALB/c Mice and Mice Exposed to X-ray Radiation

BACKGROUND

Radiation therapy is an effective method used for treatment of many types of cancers. However, this method can cause unwanted side effects such as bone marrow suppression. In this study, the effect of oral administration of biogenic selenium nanoparticles (SeNPs) on total and differentiated white cells profile of BALB/c mice exposed to X-ray radiation was investigated and compared with non-irradiated mice.

METHODS

Sixty female BALB/c mice between six to eight weeks olds were divided into 4 test and control groups in two categories of normal and irradiated mice. In normal mice SeNPs administration was started from the day 0 and followed for a month. Irradiated mice were divided into three groups and were exposed to doses of 2, 4 and 8 Gy. After 72 hr of irradiation, the SeNPs treatment was started and continued for a month. Total and differentiated blood cells counts of both irradiated and non-irradiated groups were monitored during 30 days and the obtained results were compared. Also, the deposition of Se in different tissues and blood serum of normal mice was determined in normal mice after 30 days period of supplementation.

RESULTS

In normal mice an increase in the count of neutrophils was observed after 30 days of supplementation. In irradiated mice, SeNPs supplementation led to increase in both lymphocytes and neutrophils counts especially in mice exposed to 2 and 4 Gys radiation.

CONCLUSION

Radiotherapy is categorized as an invasive method which can cause tissue damage and suppress the host immune defense. A restore of lymphocytes which was observed after SeNPs supplementation in irradiated mice can be highly interesting and provide cellular immunity against malignant diseases or other bacterial or fungal infections after radiotherapy.

Protection of cisplatin-induced spermatotoxicity, DNA damage and chromatin abnormality by selenium nano-particles

Cisplatin (CIS), an anticancer alkylating agent, induces DNA adducts and effectively cross links the DNA strands and so affects spermatozoa as a male reproductive toxicant. The present study investigated the cellular/biochemical mechanisms underlying possible protective effect of selenium nano-particles (Nano-Se) as an established strong antioxidant with more bioavailability and less toxicity, on reproductive toxicity of CIS by assessment of sperm characteristics, sperm DNA integrity, chromatin quality and spermatogenic disorders. To determine the role of oxidative stress (OS) in the pathogenesis of CIS gonadotoxicity, the level of lipid peroxidation (LPO), antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) and peroxynitrite (ONOO) as a marker of nitrosative stress (NS) and testosterone (T) concentration as a biomarker of testicular function were measured in the blood and testes. Thirty-two male Wistar rats were equally divided into four groups. A single IP dose of CIS (7 mg/kg) and protective dose of Nano-Se (2 mg/kg/day) were administered alone or in combination. The CIS-exposed rats showed a significant increase in testicular and serum LPO and ONOO level, along with a significant decrease in enzymatic antioxidants levels, diminished serum T concentration and abnormal histologic findings with impaired sperm quality associated with increased DNA damage and decreased chromatin quality. Coadministration of Nano-Se significantly improved the serum T, sperm quality, and spermatogenesis and reduced CIS-induced free radical toxic stress and spermatic DNA damage. In conclusion, the current study demonstrated that Nano-Se may be useful to prevent CIS-induced gonadotoxicity through its antioxidant potential.

The use of artificial neural networks for optimizing polydispersity index (PDI) in nanoprecipitation process of acetaminophen in microfluidic devices

Artificial neural networks (ANNs) were used in this study to determine factors that control the polydispersity index (PDI) in an acetaminophen nanosuspension which was prepared using nanoprecipitation in microfluidic devices. The PDI of prepared formulations was measured by dynamic light scattering. Afterwards, the ANNs were applied to model the data. Four independent variables, namely, surfactant concentration, solvent temperature, and flow rate of solvent and antisolvent were considered as input variables, and the PDI of acetaminophen nanosuspension was taken as the output variable. The response surfaces, generated as 3D graphs after modeling, were used to survey the interactions happening between the input variables and the output variable. Comparison of the response surfaces indicated that the antisolvent flow rate and the solvent temperature have reverse effect on the PDI, whereas solvent flow rate has direct relation with PDI. Also, the effect of the concentration of the surfactant on the PDI was found to be indirect and less influential. Overall, it was found that minimum PDI may be obtained at high values of antisolvent flow rate and solvent temperature, while the solvent flow rate should be kept to a minimum.

The immunostimulatory effect of biogenic selenium nanoparticles on the 4T1 breast cancer model: an in vivo study

Selenium salts as well as elemental selenium nanoparticles are attracting the attention of researchers due to their excellent biological properties. The aim of the present work was to study immunomodulation by applying elemental Se NPs to stimulate the immune response of mice bearing 4 T1 breast cancer tumors. Six- to 8-week-old female inbred BALB/c mice were divided into two groups of test and control, each containing 15 mice. Every day, for 2 weeks prior to tumor induction, selenium nanoparticles were orally administered to the mice at a dose of 100 μg/day. Then, 1 × 10(6) cells from a 4 T1 cell line were injected subcutaneously to each mouse. Oral nanoparticle administration was continued daily for 3 weeks after tumor induction. Different immunological parameters were then evaluated including cytokine level, delayed type hypersensitivity (DTH) response as well as tumor growth and the survival rates in all treated or nontreated animals. The production of Th1 cytokines, such as IFN-γ and IL-12, in spleen cell culture was increased in the test mice-administered selenium nanoparticles. The DTH response of test mice also showed a significant increase when compared to the control mice. The survival rate was notably higher for the selenium nanoparticle-treated mice compared to the control mice. Our results suggest that selenium nanoparticle administration can result in considerable induction of the Th1 platform of immune response through the elevation of IFN-γ and IL-12 and may be a cause for better prognosis in mice with tumors.

The preventive oral supplementation of a selenium nanoparticle-enriched probiotic increases the immune response and lifespan of 4T1 breast cancer bearing mice

The immunomodulatory effects of lactic acid bacteria have been demonstrated previously. In this study, a Lactobacillus plantarum strain was selected and enriched with selenium nanoparticles for use as a new immunomodulating agent in a breast cancer murine model. 30 female inbred BALB/c mice were equally divided into a test group and a control group. For 2 weeks prior to tumor induction, each mouse received a daily oral administration of 2.5×108 CFU/ml of L. plantarum enriched with selenium nanoparticles (SeNPs), and then 1×106 4T1 cells were injected subcutaneously. After tumor induction, daily SeNP administration was repeated for 3 cycles of 7 days on/3 days off. Immunological parameters such as levels of cytokines, NK cell activity, tumor growth, and mouse survival were evaluated. The production of the pro-inflammatory cytokines IFN-γ, TNF-α, and IL-2 in spleen cell cultures was increased in test mice administered SeNP-enriched L. plantarum. The test mice also showed significant increases in NK cell activity. The tumor volumes of treated mice were decreased and their survival rate notably increased when compared to mice that received L. plantarum alone or control mice. Administration of SeNP-enriched L. plantarum can induce an efficient immune response through the elevation of the pro-inflammatory cytokines IFN-γ, TNF-α and IL-2 levels and increased NK cell activity. Therefore, this treatment may result in better cancer prognosis.

Derivation of Adipocytes from Human Endometrial Stem Cells (EnSCs)

BACKGROUND

Due to increasing clinical demand for adipose tissue, a suitable cell for reconstructive adipose tissue constructs is needed. In this study, we investigated the ability of Human Endometrial-derived stem cells (EnSCs) as a new source of mesenchymal stem cells to differentiate into adipocytes. EnSCs are the abundant and easy available source with no immunological response, for cell replacement therapy.

METHODS

Single-cell suspensions of EnSCs were obtained from endometrial tissues from 10 women experiencing normal menstrual cycles, and were cultured at clonal density (10 cells/cm (2) ) or limiting dilution. Endometrial mesenchymal stem cell markers were examined flow cytometry. These cells were treated with adipogenic-inducing medium for 28 days. The adipogenic differentiation of the EnSC was assessed by cellular morphology and further confirmed by Oil Red O staining and RT-PCR. The BM-MSC differentiated into adipocytes in the presence of adipogenic stimuli for 3 weeks.

RESULTS

The flow cytometric analysis showed that the cells were positive for CD90, CD105, CD146 and were negative for CD31, CD34.We showed that the key adipocytes marker PPARa was expressed in mRNA level after 28 days post treatment (PT).

CONCLUSION

According to our finding, it can be concluded that EnSCs represent a useful in vitro model for human adipogenesis, and provide opportunities to study the stages prior to commitment to the adipocyte lineage.

Amelioration of experimental colitis by a novel nanoselenium-silymarin mixture

BACKGROUND

Silymarin has intracellular antioxidant property and inhibits activation of nuclear factor-κB (NF-κB) in low concentrations and reduces tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6 levels, cyclooxygenase (COX), and angiogenesis. Selenium is one of the necessary trace element nutrients for human and animals. Selenium nanoparticles (nano-Se) have more bioavailability with less toxicity.

AIMS

To investigate the combination effect of silymarin and nano-Se on inhibition of NF-κB, proinflammatory cytokines, and oxidative stress biomarkers in the experimental colitis.

METHODS

Trinitrobenzene sulfonic acid (TNBS) was used to induce colitis. After TNBS instillation, rats were distributed into six groups, containing silymarin and nano-Se alone or in combination, dexamethasone, negative control with no treatment and the last one was normal sham rats. All drugs were administered for 7 days. Colon samples were scored macroscopically and microscopically. The levels of activated NF-κB, IL-1β, TNF-α, myeloperoxidase (MPO), lipid peroxidation, protein carbonyl (PC), and the antioxidant power of the colon homogenates were determined.

RESULT

A significant decrease in NF-κB activity in treated groups was observed. The levels of TNF-α, IL-1β, MPO, lipid peroxidation, and PC were reduced and an improvement in antioxidant power of treated groups was seen. Combination of silymarin and nano-Se were more effective than each one alone in improvement of NF-κB, TNF-α, antioxidant power, and lipid peroxidation values, although this difference was not significant in other factors.

CONCLUSION

Co-administration of silymarin and nano-Se with a good antioxidant profile and inhibition of NF-κB is a possible candidate for better management of inflammatory bowel disease.

Purification and biochemical characterization of extracellular laccase from the ascomycete Paraconiothyrium variabile

An extracellular laccase-producing ascomycete was isolated from soil and identified as Paraconiothyrium variabile using rDNA sequence analysis. Typical laccase substrates including 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS), 2,6-dimethoxyphenol (DMP), and guaiacol were oxidized by the purified enzyme (designated as PvL). The molecular mass of PvL was 84 kDa and it showed a pI value of 4.2. The enzyme acted optimally at pH 4.8 and exhibited an optimum temperature of 50 °C. Using ABTS, PvL represented Km and Vmax of 203 μM and 40 μmol min(-1) mg(-1), respectively. After 24 h incubation at pH 4.8 and 4 °C, 80% of the initial activity of PvL remained. The enzyme was inhibited by Fe2+, Hg2+, and Mn2+, but induced by Cu2+. EDTA (10 mM), 1,4-dithiothreitol (DTT) (0.1 mM), and NaN3 (10 mM) were found to completely inhibit PvL. Sixty-eight percent of Malachite green was decolorized by 4 U/mL of PvL after 15 min incubation at 30 °C.

An Enhancing Effect of Gold Nanoparticles on the Lethal Action of 2450 MHz Electromagnetic Radiation in Microwave Oven

Today, there is an increasing interest in the use of metal nanoparticles in health sciences. Amongst all nanoparticles, the gold nanoparticles have been known to kill the cancer cells under hyperthermic condition by near-infrared frequency electromagnetic waves. On the other hand, although there are different physiochemical methods for disinfection of microbial pollution, however applications of irradiated gold nanoparticles against microorganisms have not yet been investigated. In this study, gold nanoparticles were prepared using D-glucose and characterized (particle size <26 nm). In the next step, the enhancing effect of the non toxic level of gold nanoparticles (50 µg/mL) on the antimicrobial activity of 2450 MHz electromagnetic radiation generated at a microwave oven operated at low power (100 W), was investigated by time-kill course assay against Staphylococcus aureus (S.aureus) ATCC 29737. The results showed that application of gold nanoparticles can enhance the lethal effect of low power microwave in a very short exposure time (5 s).

Cytotoxic Activities of Silver Nanoparticles and Silver Ions in Parent and Tamoxifen-Resistant T47D Human Breast Cancer Cells and Their Combination Effects with Tamoxifen against Resistant Cells

Studies on biomedical applications of nanoparticles are growing with a rapid pace. In medicine, nanoparticles may be the solution for multi-drug-resistance which is still a major drawback in chemotherapy of cancer. In the present study, we investigated the potential cytotoxic effect of silver nanoparticles (Ag NPs) and silver ions (Ag(+)) in both parent and tamoxifen-resistant T47D cells in presence and absence of tamoxifen. Ag NPs were synthesized (< 28 nm) and MTT assay was carried out. The associated IC(50) values were found to be: 6.31 µg/ml for Ag NPs/parent cells, 37.06 µg/ml for Ag NPs/tamoxifen-resistant cells, 33.06 µg/ml for Ag(+)/parent cells and 10.10 µg/ml for Ag(+)/resistant cells. As a separate experiment, the effect of subinhibitory concentrations of Ag NPs and Ag(+) on the proliferation of tamoxifen-resistant cells was evaluated at non-toxic concentrations of tamoxifen. Our results suggested that in non-cytotoxic concentrations of silver nanomaterials and tamoxifen, the combinations of Ag(+)-tamoxifen and Ag NPs-tamoxifen are still cytotoxic. This finding may be of great potential benefit in chemotherapy of breast cancer; since much lower doses of tamoxifen may be needed to produce the same cytotoxic effect and side effects will be reduced.

Biosynthesis of selenium nanoparticles using Klebsiella pneumoniae and their recovery by a simple sterilization process

The use of biologically derived metal nanoparticles for various proposes is going to be an issue of considerable importance; thus, appropriate methods should be developed and tested for the biological synthesis and recovery of these nanoparticles from bacterial cells. In this research study, a strain of Klebsiella pneumoniae was tested for its ability to synthesize elemental selenium nanoparticles from selenium chloride. A broth of Klebsiella pneumoniae culture containing selenium nanoparticles was subjected to sterilization at 121(o)C and 17 psi for 20 minutes. Released selenium nanoparticles ranged in size from 100 to 550 nm, with an average size of 245 nm. Our study also showed that no chemical changes occurred in selenium nanoparticles during the wet heat sterilization process. Therefore, the wet heat sterilization process can be used successfully to recover elemental selenium from bacterial cells.

Post-antibacterial effect of thymol

The antibacterial activity of thymol has been well established and reported in the scientific literature. Continued suppression of bacterial growth following limited exposure to antimicrobial compounds at different concentrations greater than or equal to the minimum inhibitory concentration level (MIC) and at concentrations less than the MIC can be used as an indicator of biological activity, and are respectively referred to as a post-antibacterial effect (PAE) and a post-antibiotic sub-MIC effect (PA-SME). In this study, the PAE and the PA-SME of thymol against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus cereus were investigated. A spectrophotometric method was used to determine the PAE and the PA-SME of thymol against the selected test strains. Thymol exhibited a considerable PAE and PA-SME at MIC and sub-MIC concentrations against test strains. The greatest duration of both the PAE and the PA-SME was observed for thymol against E. coli and P. aeruginosa. The PAE and PA-SME times for E. coli were 12 and 8 h, respectively, and for P. aeruginosa were 11 and 7.5 h, respectively. The duration of the PAE and PA-SME observed for S. aureus and B. cereus was shorter than for Gram-negative strains.