Antimicrobial lipids loaded on lectin display reduced MIC, curtail pathogenesis and protect zebrafish from reinfection by immunomodulation.

Antibiotic resistance and re-emergence of highly resistant pathogens is a grave concern everywhere and this has consequences for all kinds of human activities. Herein, we showed that N-palmitoylethanolamine-derived cationic lipid (cN16E) had a lower minimum inhibitory concentration (MIC) against both Gram-positive and Gram-negative bacteria when it was loaded with Butea monosperma seed lectin (BMSL). The analysis using lectin-FITC conjugate labelling indicated that the improved antibacterial activity of BMSL conjugation was due to bacterial cell surface glycan recognition. Live and dead staining experiments revealed that the BMSL-cN16E conjugate (BcN16E) exerts antibacterial activity by damaging the bacterial membrane. BcN16E antimicrobial activity was demonstrated using an infected zebrafish animal model because humans have 70 % genetic similarity to zebrafish. BcN16E therapeutic potential was established successfully by rescuing fish infected with uropathogenic Escherichia coli (UPEC). Remarkably, the rescued infected fish treated with BcN16E prevented reinfection without further therapy, indicating BcN16E immunomodulatory potential. Thus, the study examined the expression of immune-related genes, including tnfα, ifnγ, il-1ß, il-4, il-10, tlr-2, etc. There was a significant elevation in the expression of all these genes compared to control and fish treated with BMSL or cN16E alone. Interestingly, when the rescued zebrafish were reinfected with the same pathogen, the levels of expression of these genes were many folds higher than seen earlier. Radial immune diffusion analyses (RIA) using zebrafish serum revealed antibody production during the initial infection and treatment. Interestingly, reinfected fish had significant immunoprecipitation in RIA, a feature absent in the groups treated with cN16E, BMSL, and control. These results clearly show that the BcN16E complex not only rescued infected zebrafish but also conferred long-lasting protection in terms of immunomodulation that protects against multiple reinfections. The findings support that BcN16E has immense potential as a novel immunostimulant for various biomedical applications.

Weathered polyethylene microplastics induced immunomodulation in zebrafish.

Microplastics are pollutants of emerging concern and the aquatic biota consumes microplastics (MPs), which has a range of toxicological and environmental effects on aquatic organisms that are not the intended targets. The current study looked into how weathered polyethylene (wPE) MPs affected Danio albolineatus immunological and haematological markers. In this experiment, fish of both sexes were placed in control and exposure groups, and they were exposed for 40 d at the sublethal level (1 µg L-1) of fragmented wPE, which contained 1074 ± 52 MPs per litre. Similarly, fish exposed to wPE MPs showed significant modifications in lysozyme, antimicrobial, and antiprotease activity, as well as differential counts. Results of the present study show that the male fish were more susceptible than female fish after 40 d of chronic exposure. Further studies are needed to ascertain how the innate and humoral immune systems of the fish respond to MPs exposure.

Correction: Platinum nanoparticles inhibit bacteria proliferation and rescue zebrafish from bacterial infection.

[This corrects the article DOI: 10.1039/C6RA03732A.].

Hybrid of Metapenaeus dobsoni lectin and platinum nanoparticles exert antimicrobial and immunostimulatory effects to reduce bacterial bioburden in infected Nile tilapia.

A novel antibacterial immunostimulant using Platinum nanoparticles (PtNPs) and lectin from Metapenaeus dobsoni (Md-Lec) was developed. The Md-Lec and PtNPs (Pt-lec) hybrid formed through non-covalent interaction exhibits antimicrobial activity against fish specific pathogens by affecting membrane integrity and producing excess reactive oxygen species. The therapeutic efficacy of Pt-lec was demonstrated through rescuing Aeromonas hydrophila infected Nile Tilapia. Pt-lec prevents the infection spreading and reduces the bacterial bioburden in less than 12 h, and as a result of this the fish were restored to normalcy. To assess immunostimulation, we studied the expression of three different immune related genes, namely LEC, Myd88 and COX-2 in the gills, liver, spleen and kidney of fish under various experimental conditions. Our results showed that Pt-lec treatment appeared to be better when compared to lectin alone in enhancing the expression of Myd88 and COX-2, but LEC was not as expected. These results suggest that Pt-lec has the ability to protect Nile Tilapia against bacterial infection by restricting bacterial bioburden through their direct effects on the bacterial membrane and indirectly through their effects on host immune-related gene expression. This hybrid could have potential "green" application in fish farming in rescuing infected animals when compared to widely and unregulated antibiotics.

Microplastic contamination in commercial fish species in southern coastal region of India.

Due to its potential impact on food safety and human health, commercial species that have been contaminated with microplastics (MPs) are drawing more attention on a global scale. This study investigated the possibility of MPs contamination in different marine fish species with substantial commercial value that was captured off the south coast of India, from Adyar and Ennore regions. Over the course of six months, from October 2019 to March 2020, 220 fish were examined. It was discovered that the gills and guts had accumulated more numbers of MPs (1115 MPs) of which 68% were fibres and fragments. The commercial fish samples contained an average of 3.2-7.6 MPs per fish. Greater MPs pollution is seen in the Ennore regions. The prevalence of MPs was observed in carnivorous and planktivorous fish collected from both the sites. Fish guts contained the most MPs, according to the data. Pelagic fish accounted for the least amount of MPs, followed by mid- and demersal fish. Four different types of polymers were also identified in the present study: polyethylene, polypropylene, polystyrene, and polyamide. These results clearly showed the degree of microplastic contamination in fish tissues from the south Indian coastal regions of Adyar and Ennore. These results we hope will create a baseline data for MPs contamination in commercial fish species. The presence of MPs in the fish could have detrimental effects both on the environment and human health and thus comprehensive steps are required to prevent plastic pollution of the environment in south India's coastal region.

Biofilm of Klebsiella pneumoniae minimize phagocytosis and cytokine expression by macrophage cell line.

Infectious bacteria in biofilm mode are involved in many persistent infections. Owing to its importance in clinical settings, many in vitro and in vivo studies are being conducted to study the structural and functional properties of biofilms, their drug resistant mechanism and the s urvival mechanism of planktonic and biofilm cells. In this regard, there is not sufficient information on the interaction between Klebsiella biofilm and macrophages. In this study, we have attempted to unravel the interaction between Klebsiella biofilm and macrophages in terms of phagocytic response and cytokine expression. In vitro phagocytosis assays were performed for heat inactivated and live biofilms of K. pneumoniae, together with the expression analysis of TLR2, iNOS, inflammatory cytokines such as IL-ß1, IFN-γ, IL-6, IL-12, IL-4, TNF-α and anti-inflammatory cytokine, IL-10. A phagocytic rate of an average of 15% was observed against both heat inactivated and live biofilms when LPS + IFN-γ activated macrophages were used. This was significantly higher than non-activated macrophages when tested against heat inactivated and live biofilms (average 8%). Heat-inactivated and live biofilms induced similar phagocytic responses and up-regulation of pro-inflammatory genes in macrophages, indirectly conveying that macrophage responses are to some extent dependent on the biofilm matrix.

An insight on 7- ketocholesterol mediated inflammation in atherosclerosis and potential therapeutics.

7-ketocholesterol, a toxic oxidative product of oxysterol is a causative agent of several diseases and disabilities concomitant to aging including cardiovascular diseases like atherosclerosis. Auto-oxidation of cholesterol esters present in low-density lipoprotein (LDL) deposits lead to the formation of oxidized LDL (Ox-LDL) along with its byproducts, namely 7KCh. It is predominantly found in atherosclerotic plaque and also found to be more atherogenic than cholesterol by being cytotoxic, interfering with cellular homeostasis. This makes it a serious threat by being the foremost cause of morbidity and mortality worldwide and is likely to become more serious during forth coming years. It involves in mediating inflammatory mechanisms characterized by the advancement of fibroatheroma plaques. The atherosclerotic lesion is composed of Ox-LDL along with fibrotic mass consisting of immune cells and molecules. Macrophages being the specialized phagocytic cells, contribute to removal of detrimental contents of the lesion along with accumulated lipids leading to alteration of its biology and functionality due to its plasticity. Here, we have explored the known as well as proposed mechanisms involved with 7KCh associated atherogenesis along with potential therapeutic strategies for targeting 7KCh as a diagnostic and target in medicine.

Remediation of textile effluents for water reuse: Decolorization and desalination using Escherichia fergusonii followed by detoxification with activated charcoal.

Textile effluents contain high levels of pollutants of different categories like dyes, metal salts, acids, bases and microorganisms. Remediation of textile effluents is often challenging because of its composition, which also varies between dyeing units. In this study, we demonstrate the novel use of a waste-water bacterium, Escherichia fergusonii, in the effective remediation of textile effluents. The bacteria application efficiently caused a reduction of color (98.4%), total dissolved solids (75%), sulphates (87%), bicarbonates (83%), chlorides (64%), calcium (84%), and chemical oxygen demand (81%) of the textile effluents. The bacteria-treated effluents were further disinfected and detoxified by treating with rice husk activated charcoal. After the charcoal treatment, the chemical oxygen demand decreased further by 11.5% and biochemical oxygen demand decreased by 85%. The effluents remediated using the two-step process were subjected to toxicity assays using zebrafish (Danio rerio) model. The textile effluents treated using Escherichia fergusonii, followed by activated charcoal were found to be non-toxic and suitable for reuse for domestic applications. Thus, we present here, a simple, less energy-intensive, economic, two-step process as a complete solution for textile effluent treatment. The results of this investigation can be used to simplify the remediation process of textile effluents in common treatment plants as well as the individual dyeing units.

Amarogentin, a secoiridoid glycoside, activates AMP- activated protein kinase (AMPK) to exert beneficial vasculo-metabolic effects.

INTRODUCTION: AMP-activated protein kinase (AMPK) is a drug target for treatment of metabolic and cardiovascular complications. Extracts of Gentianaceace plants exhibit anti-diabetic and anti-atherosclerotic effects, however, whether their phyto-constitutents activate AMPK remains to be determined. METHODS: Molecular docking of Gentiana lutea constituents was performed with crystal structure of human α2ß1γ1 trimeric AMPK (PDB ID: 4CFE). Binding of Amarogentin (AG) to α2 subunit was confirmed through isothermal titration calorimetry (ITC) and in vitro kinase assays were performed. L6 myotube, HUH7 and endothelial cell cultures were employed to validate in silico and in vitro observations. Lipid lowering and anti-atherosclerotic effects were confirmed in streptozotocin induced diabetic mice via biochemical measurements and through heamatoxylin and eosin, Masson's trichrome and Oil Red O staining. RESULTS: AG interacts with the α2 subunit of AMPK and activates the trimeric kinase with an EC50 value of 277 pM. In cell culture experiments, AG induced phosphorylation of AMPK as well as its downstream targets, acetyl-coA-carboxylase (ACC) and endothelial nitric oxide synthase (eNOS). Additionally, it enhanced glucose uptake in myotubes and blocked TNF-α induced endothelial inflammation. Oral supplementation of AG significantly attenuated diabetes-mediated neointimal thickening, and collagen and lipid deposition in the aorta. It also improved circulating levels of lipids and liver function in diabetic mice. CONCLUSION: In conclusion, AG exerts beneficial vasculo-metabolic effects by activating AMPK. GENERAL SIGNIFICANCE: Amarogentin, a naturally occurring secoiridoid glycoside, is a promising lead for design and synthesis of novel drugs for treatment and management of dyslipidemia and cardiovascular diseases.

Ursolic acid inhibits colistin efflux and curtails colistin resistant Enterobacteriaceae.

Colistin resistance in Enterobacteriaceae especially Klebsiella pneumoniae and Escherichia coli is driving the evolution of pan drug resistant strains. Screening a library of 13 plant nutraceuticals led to the identification of acetyl shikonin and ursolic acid, which exhibited synergy with colistin against extremely drug resistant (XDR) clinical strains of E. coli (U3790) and K. pneumoniae (BC936). Ursolic acid caused a significant colistin MIC reversal of 16-fold in U3790 and 4-fold in BC936 strains. Ursolic acid also potentiated the bactericidal effect of colistin against both U3790 and BC936 by causing ~ 4 to 4.5 log fold decline in CFU of both clinical isolates in a time kill assay. At 2× minimum effective concentration, ursolic acid was non-toxic to zebrafish as evidenced by brain and liver enzyme profiles and by histopathology studies. In combination with colistin, ursolic acid reduced bacterial bioburden of U3790/BC936 by 1-1.58 log fold from the infected muscle tissue of zebrafish. Mechanistic explorations via studies on real time efflux, membrane potential and intracellular accumulation of dansyl chloride tagged colistin revealed that colistin efflux is inhibited by ursolic acid. In addition, ursolic acid also enhanced outer membrane permeability which probably facilitates colistin's attack on outer and inner membranes. Our study shows that ursolic acid synergizes with colistin by inhibiting colistin efflux in Enterobacteriaceae that helps to curtail colistin resistant Enterobacteriaceae.

Author Correction: Jacalin capped platinum nanoparticles confer persistent immunity against multiple Aeromonas infection in zebrafish.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Jacalin capped platinum nanoparticles confer persistent immunity against multiple Aeromonas infection in zebrafish.

Bacterial resistance is a major clinical problem, which is compounded by both a lack of new antibiotics and emergence of multi- and extremely-drug resistant microbes. In this context, non-toxic nanoparticles could play an important role in conferring protection against bacterial infections and in this study we have made an attempt to show the usefulness of jacalin capped platinum nanoparticles in protecting zebrafish against multiple infections with Aeromonas hydrophila. Our results also indicate that use of nanoparticles promotes adaptive immune response against the pathogen, so much so that zebrafish is able to survive repetitive infection even after twenty one days of being treated with jacalin-capped platinum nanoparticles. This is significant given that platinum salt is not antibacterial and jacalin is non-immunogenic. Our study for the first time reveals a novel mechanism of action of nanoparticles, which could form an alternate antibacterial strategy with minimal bacterial resistance.

Exploration of Antifungal and Immunomodulatory Potentials of a Furanone Derivative to Rescue Disseminated Cryptococosis in Mice.

Cryptococcus neoformans infection is quite complex with both host-pathogen interaction and host immune profile determining disease progress and therapeutic outcome. Hence in the present study, the potential utility of (E)-5-benzylidenedihydrofuran-2(3 H)-one (compound-6) was explored as an effective anticryptococcal compound with immunomodulatory potential. The efficacy of compound-6 in pulmonary cryptococosis model using H99 strain was investigated. The effective dose was found to provide 100% survival, with a significant reduction of yeast burden in lungs and brain. The biodistribution analysis provided evidence for the presence of higher concentration of compound-6 in major organs including lungs and brain. In addition, compound-6 treated mice had significantly higher expression of IL-6, IL-4 and IFN-γ in lung and brain. Similarly, elevated expression of TNF-α, IL-ß1 and IL-12 were observed in lungs, suggesting the protective host response against C. neoformans. The reduction and clearance of fungal load in systemic organs and mouse survival are notable results to confirm the ability of compound-6 to treat cryptococcosis. In conclusion, the low molecular weight (174 Da), lipophilicity, its ability to cross blood brain barrier, and facilitating modulation of cytokine expression are the added advantages of compound-6 to combat against disseminated cryptococosis.

ASK2 Bioactive Compound Inhibits MDR Klebsiella pneumoniae by Antibiofilm Activity, Modulating Macrophage Cytokines and Opsonophagocytosis.

The emergence and spread of pathogens harboring extended spectrum beta-lactamase (ESBL) like carbapenem resistant Gram negative bacteria are the major emerging threat to public health. Of particular concern Klebsiella pneumoniae carbapenamase- producing strains have been recorded worldwide. Catheter associated urinary tract infections (CAUTI) caused by K. pneumoniae are significantly associated with morbidity and mortality. Hence the present work was aimed to develop a strategy for addressing these issues through an innovative approach of antibiofilm and immunomodulation. These two independent activities were analyzed in a Streptomyces derived ASK2 bioactive compound. While analysing the effect of sub-minimum inhibitory concentrations (sub-MICs), 0.5x of Minimum Inhibitory Concentration (MIC) was found to be more effective in preventing biofilm formation on coverslip and silicone catheter. The minimum biofilm eradication concentration (MBEC) was found to be 15-fold higher MIC with eradication of 75% of 3 day old biofilm. Apart from its antibiofilm potential, ASK2 also acts as an opsonin and enhances phagocytic response of macrophages against multidrug resistant K. pneumoniae. In addition, ASK2 resulted in elevated levels of nitric oxide generation by the macrophages and has a stimulating effect on IL-12, IFN-γ, and TNF-α proinflammatory cytokines. The opsonic role of ASK2 and its potential in modulating proinflammatory cytokines secreted by macrophages implies the importance of ASK2 in modulating cellular immune response of macrophages against MDR K. pneumoniae. The present study proposes ASK2 as a promising candidate for treating MDR K. pneumoniae infections with its dual properties of antibiofilm and immunomodulatory activities.

Bioactive Molecule from Streptomyces sp. Mitigates MDR Klebsiella pneumoniae in Zebrafish Infection Model.

The emergence and spread of multi-drug resistant (MDR) especially carbapenem-resistant Klebsiella pneumoniae is a major emerging threat to public health, leading to excess in mortality rate as high as 50-86%. MDR K. pneumoniae manifests all broad mechanisms of drug resistance, hence development of new drugs to treat MDR K. pneumoniae infection has become a more relevant question in the scientific community. In the present study a potential Streptomyces sp. ASK2 was isolated from rhizosphere soil of medicinal plant. The multistep HPLC purification identified the active principle exhibiting antagonistic activity against MDR K. pneumoniae. The purified compound was found to be an aromatic compound with aliphatic side chain molecule having a molecular weight of 444.43 Da. FT-IR showed the presence of OH and C=O as functional groups. The bioactive compound was further evaluated for drug induced toxicity and efficacy in adult zebrafish infection model. As this is the first study on K. pneumoniae - zebrafish model, the infectious doses to manifest sub-clinical and clinical infection were optimized. Furthermore, the virulence of K. pneumoniae in planktonic and biofilm state was studied in zebrafish. The MTT assay of ex vivo culture of zebrafish liver reveals non-toxic nature of the proposed ASK2 compound at an effective dose. Moreover, significant increase in survival rate of infected zebrafish suggests that ASK2 compound from a new strain of Streptomyces sp. was potent in mitigating MDR K. pneumoniae infection.

Purification and characterisation of a pronase-inducible lectin isolated from human serum.

A new lectin was purified to electrophoretic homogeneity from pronase treated human serum by a single-step of affinity chromatography on concanavalin A-Sepharose 4B. The isolated lectin agglutinated five types of vertebrate RBC, with highest titer against hen RBC. This activity was independent of divalent cations, insensitive to EDTA and specific to mannosamine, glucosamine as well as galactosamine. Purified lectin gave a single symmetrical peak in its native form with a molecular mass estimate of 6kDa in FPLC analysis and 6.5kDa by MALDI-TOF MS. SDS-PAGE analysis of the lectin revealed that it is a homo-oligomer of a 3kDa subunit protein. Isolated lectin did possess both, hemagglutinating and phenoloxidase activities, but did not exhibit any antibacterial or antifungal activities. In addition, this lectin could oxidize all nine different phenolic substrates tested, with hydroquinone proving to be the best among them. Phenoloxidase inhibitors namely, phenylthiourea and tropolone inhibited this oxidation activity.

Hyperglycemia-Induced Oxidative-Nitrosative Stress Induces Inflammation and Neurodegeneration via Augmented Tuberous Sclerosis Complex-2 (TSC-2) Activation in Neuronal Cells.

Diabetes is a systemic disease mainly characterized by chronic hyperglycemia and with extensive and long-lasting spiteful complications in central nervous systems (CNS). Astrocytes play an important role in the defense mechanism of CNS, with great ability of withstanding accumulation of toxic substances. Apart from functional disorders, hyperglycemia leads to slow progressive structural abnormalities in the CNS through oxidative stress pathways. However, the molecular mechanism by which neurons die under oxidative stress induced by high glucose (HG) remains largely unclear. Here, we report that HG-induced inflammation and neurodegeneration in brain tissues, brain astrocytes (C6), and pheochromocytoma (PC-12) cells are cultured in HG conditions. Our results show that the increases in phosphorylation of Akt and ERK1/2MAPK are associated with increased accumulations of reactive oxygen species (ROS) in neuronal cells, which simultaneously enhanced phosphorylations of tuberous sclerosis complex-2 (TSC-2) and mammalian target of rapamycin (mTOR) in the diabetic brain and in HG-exposed neuronal cells. Pharmacologic inhibition of Akt or ERK1/2 or siRNA-mediated gene silencing of TSC-2 suppressed the strong downregulation of TSC-2-mTOR activation. Findings of this study also demonstrate that HG resulted in phosphorylation of NF-κB, coinciding with the increased production of inflammatory mediators and activation of neurodegenerative markers. Pretreatment of cells with antioxidants, phosphoinositide3-kinase (PI3-K)/Akt, and ERK1/2 inhibitors significantly reduced HG-induced TSC-2 phosphorylation and restored NF-κB protein expression leading to decreased production of inflammatory mediators and neurodegenerative markers. These results illustrate that ROS functions as a key signaling component in the regulatory pathway induced by elevated glucose in neuronal cell activation leading to inflammation and neurodegeneration.

Effect of surfactant in mitigating cadmium oxide nanoparticle toxicity: Implications for mitigating cadmium toxicity in environment.

Cadmium (Cd), classified as human carcinogen, is an extremely toxic heavy metal pollutant, and there is an increasing environmental concern for cadmium exposure through anthropogenic sources including cigarette smoke. Though Cd based nanoparticles such as cadmium oxide (CdO) are being widely used in a variety of clinical and industrial applications, the toxicity of CdO nanoparticles has not been well characterized. Herein we report the toxicity of CdO nanoparticles employing zebrafish as a model. Two different CdO nanoparticles were prepared, calcination of Cd(OH)2 without any organic molecule (CdO-1) and calcination of Cd-citrate coordination polymer (CdO-2), to evaluate and compare the toxicity of these two different CdO nanoparticles. Results show that zebrafish exposed to CdO-2 nanoparticles expressed reduced toxicity as judged by lower oxidative stress levels, rescue of liver carboxylesterases and reduction in metallothionein activity compared to CdO-1 nanoparticles. Histopathological observations also support our contention that CdO-1 nanoparticles showed higher toxicity relative to CdO-2 nanoparticles. The organic unit of Cd-citrate coordination polymer might have converted into carbon during calcination that might have covered the surface of CdO nanoparticles. This carbon surface coverage can control the release of Cd2+ ions in CdO-2 compared to non-covered CdO-1 nanoparticles and hence mitigate the toxicity in the case of CdO-2. This was supported by atomic absorption spectrophotometer analyses of Cd2+ ions release from CdO-1 and CdO-2 nanoparticles. Thus the present study clearly demonstrates the toxicity of CdO nanoparticles in an aquatic animal and also indicates that the toxicity could be substantially reduced by carbon coverage. This could have important implications in terms of anthropogenic release and environmental pollution caused by Cd and human exposure to Cd2+ from sources such as cigarette smoke.

Dithiazole thione derivative as competitive NorA efflux pump inhibitor to curtail multi drug resistant clinical isolate of MRSA in a zebrafish infection model.

Multi drug resistant (MDR) pathogens pose a serious threat to public health since they can easily render most potent drugs ineffective. Efflux pump inhibitors (EPI) can be used to counter the MDR phenotypes arising due to increased efflux. In the present study, a series of dithiazole thione derivatives were synthesized and checked for its antibacterial and efflux pump inhibitory (EPI) activity. Among 10 dithiazole thione derivatives, real-time efflux studies revealed that seven compounds were potent EPIs relative to CCCP. Zebrafish toxicity studies identified four non-toxic putative EPIs. Both DTT3 and DTT9 perturbed membrane potential and DTT6 was haemolytic. Among DTT6 and DTT10, the latter was less toxic as evidenced by histopathology studies. Since DTT10 was non-haemolytic, did not affect the membrane potential, and was least toxic, it was chosen further for in vivo study, wherein DTT10 potentiated effect of ciprofloxacin against clinical strain of MRSA and reduced bacterial burden in muscle and skin tissue of infected zebrafish by ~ 1.7 and 2.5 log fold respectively. Gene expression profiling of major efflux transport proteins by qPCR revealed that clinical isolate of MRSA, in the absence of antibiotic, upregulated NorA, NorB and MepA pump, whereas it downregulates NorC and MgrA relative to wild-type strain of Staphylococcus aureus. In vitro studies with NorA mutant strains and substrate profiling revealed that at higher concentrations DTT10 is likely to function as a competitive inhibitor of NorA efflux protein in S. aureus, whereas at lower concentrations it might inhibit ciprofloxacin efflux through NorB and MepA as implied by docking studies. A novel non-toxic, non-haemolytic dithiazole thione derivative (DTT10) was identified as a potent competitive inhibitor of NorA efflux pump in S. aureus using in silico, in vitro and in vivo studies. This study also underscores the importance of using zebrafish infection model to screen and evaluate putative EPI for mitigating MDR strains of S. aureus.

Future prospects of antibacterial metal nanoparticles as enzyme inhibitor.

Nanoparticles are being widely used as antibacterial agents with metal nanoparticles emerging as the most efficient antibacterial agents. There have been many studies which have reported the mechanism of antibacterial activity of nanoparticles on bacteria. In this review we aim to emphasize on all the possible mechanisms which are involved in the antibacterial activity of nanoparticles and also to understand their mode of action and role as bacterial enzyme inhibitor by comparing their antibacterial mechanism to that of antibiotics with enzyme inhibition as a major mechanism. With the emergence of widespread antibiotic resistance, nanoparticles offer a better alternative to our conventional arsenal of antibiotics. Once the biological safety of these nanoparticles is addressed, these nanoparticles can be of great medical importance in our fight against bacterial infections.