Anti-HSV activity of nectin-1-derived peptides targeting HSV gD: an in-silico and in-vitro approach.

Herpes simplex virus (HSV) infections affect a wide range of the global population. The emergence of resistance to the existing anti-HSV therapy highlights the necessity for an innovative strategy. The interaction of HSV gD with its main host receptor nectin-1 is a potential target for new antiviral drugs. The aim of this study was to develop a peptide derived from nectin-1 targeting HSV gD using the in-silico method and evaluate them for anti-HSV activity. Residues 59-133 of the Nectin-1 V-domain constitute the interaction interface with HSV gD. Bioinformatic tools viz., PEP-FOLD3, ClusPro 2.0, HawkDock and Desmond were used to model the peptide and confirm its binding specificity with HSV gD protein. The peptides with potential interactions were custom synthesized and anti-HSV activity was evaluated in vitro against HSV-1 and HSV-2 by CPE inhibition assay. Five peptide sequences were identified as exhibiting good interaction with HSV-gD proteins. Among them, peptide N1 (residues 76-90) offered maximum protection against HSV-1 (66.57%) and HSV-2 (71.12%) infections. Modification of the identified peptide through peptidomimetic approaches may further enhance the activity and stability of the identified peptide.Communicated by Ramaswamy H. Sarma.

A critical review on antiviral peptides derived from viral glycoproteins and host receptors to decoy herpes simplex virus.

The health of the human population has been continuously challenged by viral infections. Herpes simplex virus (HSV) is one of the common causes of illness and can lead to death in immunocompromised patients. Existing anti-HSV therapies are not completely successful in eliminating the infection due to anti-viral drug resistance, ineffectiveness against the latent virus and high toxicity over prolonged use. There is a need to update our knowledge of the current challenges faced in anti-HSV therapeutics and realize the necessity of developing alternative treatment approaches. Protein therapeutics are now being explored as a novel approach due to their high specificity and low toxicity. This review highlights the significance of HSV viral glycoproteins and host receptors in the pathogenesis of HSV infection. Proteins or peptides derived from HSV glycoproteins gC, gB, gD, gH and host cell receptors (HSPG, nectin and HVEM) that act as decoys to inhibit HSV attachment, entry, or fusion have been discussed. Few researchers have tried to improve the efficacy and stability of the identified peptides by modifying them using a peptidomimetic approach. With these efforts, we think developing an alternative treatment option for immunocompromised patients and drug-resistant organisms is not far off.

Evolutionary and in silico guided development of novel peptide analogues for antibacterial activity against ESKAPE pathogens.

According to WHO, to combat the resistant strains, new effective anti-microbial agents are needed on an urgent basis and global researchers should focus their efforts and discovery programs on developing them against antibiotic-resistant pathogens or priority pathogens like ESKAPE. In this context, Cationic antimicrobial peptides (AMPs) are being explored extensively as promising next-generation antimicrobials due to their broad range, fast kinetics and multifunctional role. Despite recent advances, it is still a daunting challenge to identify and design a potent AMP with no cytotoxicity, but with broad specific antimicrobial activity, stability and efficacy under in vivo conditions in a cost-effective and robust manner. In this work, as a proof of concept, we designed novel potent AMPs using artificial intelligence based in silico programs. Shortlisted peptide sequences were synthesized using the fmoc chemistry approach, assessed their antimicrobial activity, cell selectivity, mode of action and in vivo efficacy using a series of experiments. The synthesized peptide analogues demonstrated their antimicrobial activity (MIC in the range of 2.5-80 µM) against bacteria. The identified potential lead molecules showed antibacterial activity in physiological conditions with no signs of cytotoxicity. We further tested the antimicrobial activity of peptide analogues for treating wounds infected with Pseudomonas aeruginosa in the mice burn wound model. In drug-development programs, the identification of lead antimicrobial agents is always challenging and involves screening a large number of molecules which is time-consuming and expensive. This work demonstrates the utility of artificial intelligence based in silico analysis programs in discovering novel antimicrobial agents in an economical, robust way.

Luteolin, a promising quorum quencher mitigates virulence factors production in Pseudomonas aeruginosa - In vitro and In vivoapproach.

Pseudomonas aeruginosa (PA) is an opportunistic pathogen that causes healthcare-associated infection and high mortality in immunocompromised patients. It produces several virulence factors through quorum sensing (QS) mechanisms that is essential for subverting host immune system. Even front-line antibiotics are unable to control PA pathogenicity due to the emergence of antibiotic resistance. Luteolin is a naturally derived compound that has proven to be the effective drug to annihilate pathogens through quorum quenching mechanism. In this study, the protective effect of luteolin against the PA-mediated inflammation was demonstrated using zebrafish model. Luteolin protects zebrafish from PA infection and increases their survival rate. It was found that PA-mediated ROS, lipid peroxidation, and apoptosis were also significantly reduced in luteolin-treated zebrafish larvae. Open field test (OFT) reveals that luteolin rescued PA-infected zebrafish from retarded swimming behavior. Furthermore, luteolin increases SOD and CAT levels and decreases LDH and NO levels in PA-infected zebrafish compare to control group. Histological and gene expression analysis reveals that luteolin protects PA-infected zebrafish by decreasing gut inflammation and altering the expression of inflammatory (TNF-α, IL-1ß, IL-6) and antioxidant markers (iNOS, SOD, CAT). Thus, luteolin was found to have dual effect in protecting PA-infected zebrafish by decreasing virulence factors production in PA and stimulating host immune system. This is the first study demonstrating the protective effect of luteolin using animal model. Hence, luteolin could be used as a future therapeutic drug to control multi-drug resistant PA.

Quorum Quenching-Guided Inhibition of Mixed Bacterial Biofilms and Virulence Properties by Protein Derived From Leaves of Carissa carandas.

The inhibition/degradation potential of Carissa carandas proteinaceous leaf extract against mixed bacterial biofilm of Staphylococcus aureus MTCC 96, Escherichia coli MTCC 1304, Pseudomonas aeruginosa MTCC 741, and Klebsiella pneumoniae MTCC 109, responsible for nosocomial infections, was evaluated. Distinct inhibition/degradation of mixed bacterial biofilm by the proteinaceous leaf extract of C. carandas was observed under a microscope, and it was found to be 80%. For mono-species biofilm, the maximum degradation of 70% was observed against S. aureus biofilm. The efficiency of aqueous plant extracts to inhibit the mono-species biofilm was observed in terms of minimum inhibitory concentration (MIC), and the best was found against P. aeruginosa (12.5 µg/ml). The presence of flavonoids, phenols, and tannins in the phytochemical analysis of the plant extract suggests the main reason for the antibiofilm property of C. carandas. From the aqueous extract, protein fraction was precipitated using 70% ammonium sulfate and dialyzed. This fraction was purified by ion-exchange chromatography and found to be stable and active at 10°C (pH 7). The purified fraction showed less than 40% cytotoxicity, which suggests that it can be explored for therapeutic purposes after in-depth testing. In order to investigate the mechanistic action of the biofilm inhibition, the plant protein was tested against Chromobacterium violaceum CV026, and its inhibitory effect confirmed its quorum quenching nature. Based on these experimental analyses, it can be speculated that the isolated plant protein might influence the signaling molecule that leads to the inhibition effect of the mixed bacterial biofilm. Further experimental studies are warranted to validate our current findings.

Interplay between stress and immunity triggers herpes zoster infection in COVID-19 patients: a review.

Coronavirus disease 2019 (COVID-19) is a potential health threat in the highly mobile society of the world. There are also concerns regarding the occurrence of co-infections occurring in COVID-19 patients. Herpes zoster (HZ) is currently being reported as a co-infection in COVID-19 patients. It is a varicella-zoster virus induced viral infection affecting older and immunocompromised individuals. Reactivation of HZ infection in COVID-19 patients are emerging and the mechanism of reactivation is still unknown. The most convincing argument is that increased psychological and immunological stress leads to HZ in COVID-19 patients; this review justifies this argument.

Water-sanitation-health nexus in the Indus-Ganga-Brahmaputra River Basin: need for wastewater surveillance of SARS-CoV-2 for preparedness during the future waves of pandemic.

The Indus-Ganga-Brahmaputra River Basin (IGBRB) is a trans-boundary river basin flowing through four major countries in South Asia viz., India, Pakistan, Bangladesh, and Nepal. Contamination of surface water by untreated or inadequately treated wastewater has been a huge problem for pathogenic microorganisms in economies in transition. Recent studies have reported that sewage surveillance can provide prior information of the outbreak data, because faeces can contain the novel coronavirus (SARS-CoV-2) shed by infected humans. Hence, in this study we geo-spatially mapped the COVID-19 hotspots during the peak time in the first and second wave of pandemic to demonstrate the need and usefulness of wastewater surveillance strategy in IGBRB during ongoing pandemic. Further we discussed the status of sanitation, health and hand-hygiene in the IGBRB along with characterization of the challenges posed by the pandemic in achieving the United Nations Sustainable Development Goals (UN-SDGs). Monthly Geographical Information System (GIS) mapping of COVID-19 hotspots in the IGBRB showed an increase in the spread along the direct sewage discharge points. The social inequalities expose the vulnerabilities of the urban poor in terms of the burden, risks and access to Water, Sanitation, and Hygiene (WASH) needs. Such an evidence-based image of the actual SARS-CoV-2 viral load in the community along the IGBRB can provide valuable insights and recommendations to deal with the future waves of COVID-19 pandemic in this region that can go a long way in achieving the UN-SDGs.

NV14 from serine O-acetyltransferase of cyanobacteria influences the antioxidant enzymes in vitro cells, gene expression against H2 O2 and other responses in vivo zebrafish larval model.

In this study, we have identified a novel peptide NV14 with antioxidative functions from serine O-acetyltransferase (SAT) of Artrospira platensis (Ap). The full sequence of ApSAT and its derived NV14 peptide "NVRIGAGSVVLRDV" (141-154) was characterized using bioinformatics tools. To address the transcriptional activity of ApSAT in response to induce generic oxidative stress, the spirulina culture was exposed to H2 O2 (10 mM). The ApSAT expression was studied using RT-PCR across various time points and it was found that the expression of the ApSAT was significantly upregulated on Day 15. The in vitro cytotoxicity assay against NV14 was performed in human dermal fibroblast cells and human blood leukocytes. Results showed that NV14 treatment was non-cytotoxic to the cells. Besides, in vivo treatment of NV14 in zebrafish larvae did not exhibit the signs of developmental toxicity. Further, the in vitro antioxidant assays enhanced the activity of the antioxidant enzymes, such as SOD and CAT, due to NV14 treatment; and also significantly reduced the MDA levels, while increasing the superoxide radical and H2 O2 scavenging activity. The expression of antioxidant enzyme genes glutathione peroxidase, γ-glutamyl cysteine synthase, and glutathione S-transferase were found to be upregulated in the NV14 peptide pretreated zebrafish larvae when induced with generic oxidative stress, H2 O2 . Overall, the study showed that NV14 peptide possessed potent antioxidant properties, which were demonstrated over both in vitro and in vivo assays. NV14 enhanced the expression of antioxidant enzyme genes at the molecular level, thereby modulating and reversing the cellular antioxidant balance disrupted due to the H2 O2 -induced oxidative stress.

Soil concentrations, compositional profiles, sources and bioavailability of polychlorinated dibenzo dioxins/furans, polychlorinated biphenyls and polycyclic aromatic hydrocarbons in open municipal dumpsites of Chennai city, India.

Several studies have reported the release of halogenated persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) associated with open burning of municipal solid waste. Considering soil as a sink for such organic contaminants, we conducted an in-depth study on the surface soil concentrations of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs), polychlorinated biphenyls (PCBs) and sixteen USEPA enlisted PAHs collected from thirteen zones of the two major municipal dumpsites, Kodungaiyur dumpsite (KDS) and Perungudi dumpsite (PDS) of Chennai city. Indigenous microbes from dumpsite soil samples were isolated and identified based on 16S rRNA sequencing and phylogenetic analysis. Using indigenous microbes, we have elucidated the bioavailability of the targeted organic pollutants for each site.Range of Σ17PCDD/Fs, Σ25PCBs and ∑16PAHs varied between 3.96-612 pg/g (96.0 pg/g; median), ND-182 ng/g (6.35 ng/g; median) and 0.62-3649 ng/g (64.3 ng/g; median), respectively. All the dumpsite samples showed bioavailability for POPs and PAHs. Toxicity equivalent values (TEQs) associated with dioxin-like PCBs and PCDD/Fs from the zones where dumped municipal solid wastes were collected from electronic-waste/IT-corridor/port areas and toxic PAHs from the zone receiving wastes from the industrial corridor of the city were higher than the soil permissible limit prescribed by the World Health Organization.

Anti-mycobacterial activity evaluation of designed peptides: cryptic and database filtering based approach.

Worldwide, TB is one of the deadly airborne diseases, which accounts for 10.4 million deaths annually. Serious toxicity issue, prolonged treatment regimens of the current drugs, rise in multidrug-resistant strains, and the unique defensive mechanism makes the development of novel therapeutic molecules against Mycobacterium tuberculosis (MT) an urgent need. As MT has a lengthy latent phase and unique cell wall architecture, a reasonable approach is needed to find molecules having a different killing mechanism rather than traditional approaches. Host defence peptides (HDPs) will be the most promising alternative, potential therapeutic candidates as they target the microbial membrane in particular and are an essential part of the innate immunity of humans. This works demonstrates the utility of "Database filtering" and three-dimensional (3D) modelling approach in finding novel AMPs with appreciable activity towards MT. Results of this study indicate that peptides with 70% hydrophobicity, but without hydrophobicity patches (> 4 hydrophobic amino acids in series) and charge of + 4 or + 5 are most likely to be good anti-tubercular candidates.

First surveillance of SARS-CoV-2 and organic tracers in community wastewater during post lockdown in Chennai, South India: Methods, occurrence and concurrence.

Surveillance of SARS-CoV-2 and organic tracers (OTs) were conducted in the community wastewater of Chennai city and the suburbs, South India, during partial and post lockdown phases (August-September 2020) as a response to the coronavirus disease 2019 (COVID-19) pandemic. Wastewater samples were collected from four sewage treatment plants (STPs), five sewage pumping stations (SPSs) and at different time intervals from a suburban hospital wastewater (HWW). Four different methods of wastewater concentrations viz., composite (COM), supernatant (SUP), sediment (SED), and syringe filtration (SYR) were subjected to quantitative real time-polymerase chain reaction (qRT-PCR). Unlike HWW, STP inlet, sludge and SPS samples were found with higher loading of SARS-CoV-2 by SED followed by SUP method. Given the higher levels of dissolved and suspended solids in STPs and SPSs over HWW, we suspect that this enveloped virus might exhibit the tendency of higher partitioning in solid phase. Cycle threshold (Ct) values were < 30 in 50% of the HWW samples indicating higher viral load from the COVID-19 infected patients. In the STP outlets, a strict decline of biochemical oxygen demand, >95% removal of caffeine, and absence of viral copies reflect the efficiency of the treatment plants in Chennai city. Among the detected OTs, a combination of maximum dynamic range and high concurrence percentage was observed for caffeine and N1 gene of SARS-CoV-2. Hence, we suggest that caffeine can be used as an indicator for the removal of SARS-CoV-2 by STPs. Our predicted estimated number of cases are in line with the available clinical data from the catchments. Densely distributed population of the Koyambedu catchment could be partly responsible for the high proportion of estimated infected individuals during the study period.

Pharmacological importance of TG12 from tachykinin and its toxicological behavior against multidrug-resistant bacteria Klebsiella pneumonia.

Development of antimicrobial drugs against multidrug-resistant (MDR) bacteria is a great focus in recent years. TG12, a short peptide molecule used in this study was screened from tachykinin (Tac) protein of an established teleost Channa striatus (Cs) transcriptome. Tachykinin cDNA has 345 coding sequence, that denotes a protein contained 115 amino acids; in which a short peptide (TG12) was identified at 83-94. Tachykinin mRNA upregulated in C. striatus treated with Aeromonas hydrophila and Escherichia coli lipopolysaccharide (LPS). The mRNA up-regulation was studied using real-time PCR. The up-regulation tachykinin mRNA pattern confirmed the immune involvement of tachykinin in C. striatus during infection. Further, the identified peptide, TG12 was synthesized and its toxicity was demonstrated in hemolytic and cytotoxic assays using human erythrocytes and human dermal fibroblast cells, respectively. The toxicity study exhibited that the toxicity of TG12 was similar to negative control, phosphate buffer saline (PBS). Moreover, the antibiogram of TG12 was active against Klebsiella pneumonia ATCC 27736, a major MDR bacterial pathogen. Further, the antimicrobial activity of TG12 against pathogenic bacteria was screened using minimum inhibitory concentration (MIC) and anti-biofilm assays, altogether TG12 showed potential activity against K. pneumonia. Fluorescence assisted cell sorter flow cytometer analysis (FACS) and field emission scanning electron microscopy (FESEM) was carried on TG12 with K. pneumonia; the results showed that TG12 significantly reduced K. pneumonia viability as well as TG12 disrupt its membrane. In conclusion, TG12 of CsTac is potentially involved in the antibacterial immune mechanisms, which has a prospectus efficiency in pharma industry against MDR strains, especially K. pneumonia.

1,2,3-triazole-thiazole hybrids: Synthesis, in vitro antimicrobial activity and antibiofilm studies.

A new series of triazole-thiazole hybrids were designed, synthesized by the Multi-component reaction approach and evaluated in vitro antimicrobial activity. Most of the tested series of compounds exhibited promising inhibitory activity against the bacterial strains with values in the range of 2.8 to 15.7 µM. The compounds 8i-8l and 8r showed potential-Candida activity against various Candida strains with spectrum values in the range 5.9-14.2 µM. Further, anti-biofilm and toxicity profiles for the potent compounds were also tested, and it was observed that the compounds 8i, 8k, and 8l were found to inhibit the biofilm formation with IC50 values of 6.6, 16.6 and 15.9 µM, respectively against Bacillus subtilis MTCC 121. Besides, 8k and 8l also displayed promising biofilm formation inhibitory activity towards Staphylococcus aureus MTCC 96 with IC50 values of 13.5 and 12.0 µM respectively. In summary, the activity results has emphasized the compounds 8k and 8l as potential leads for further development of antibacterial, anti-Candida, and anti-biofilm agents.

Intracellular ROS scavenging and antioxidant regulation of WL15 from cysteine and glycine-rich protein 2 demonstrated in zebrafish in vivo model.

Antioxidant peptides are naturally present in food, especially in fishes, and are considered to contain rich source of various bioactive compounds that are structurally heterogeneous. This study aims to identify and characterize the antioxidant property of the WL15 peptide, derived from Cysteine and glycine-rich protein 2 (CSRP2) identified from the transcriptome of a freshwater food fish, Channa striatus. C. striatus is already studied to contain high levels of amino acids and fatty acids, besides traditionally known for its pharmacological benefits in the Southeast Asian region. In our study, in vitro analysis of WL15 peptide exhibited strong free radical scavenging activity in 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), superoxide anion radical and hydrogen peroxide (H2O2) scavenging assay. Further, to evaluate the cytotoxicity and dose-response, the Human dermal fibroblast (HDF) cells were used. Results showed that the treatment of HDF cells with varying concentrations (10, 20, 30, 40 and 50 µM) of WL15 peptide was not cytotoxic. However, the treatment concentrations showed enhanced antioxidant properties by significantly inhibiting the levels of free radicals. For in vivo assessment, we have used zebrafish larvae for evaluating the developmental toxicity and for determining the antioxidant property of the WL15 peptide. Zebrafish embryos were treated with the WL15 peptide from 4 h of post-fertilization (hpf) to 96 hpf covering the embryo-larval developmental period. At the end of the exposure period, the larvae were exposed to H2O2 (1 mM) for inducing generic oxidative stress. The exposure of WL15 peptide during the embryo-larval period showed no developmental toxicity even in higher concentrations of the peptide. Besides, the WL15 peptide considerably decreased the intracellular reactive oxygen species (ROS) levels induced by H2O2 exposure. WL15 peptide also inhibited the H2O2-induced caspase 3-dependent apoptotic response in zebrafish larvae was observed using the whole-mount immunofluorescence staining. Overall results from our study showed that the pre-treatment of WL15 (50 µM) in the H2O2-exposed zebrafish larvae, attenuated the expression of activated caspase 3 expressions, reduced Malondialdehyde (MDA) levels, and enhanced antioxidant enzymes, including superoxide dismutase (SOD) and catalase (CAT). The gene expression of antioxidant enzymes such as glutathione S-transferase (GST), glutathione peroxide (GPx) and γ-glutamyl cysteine synthetase (GCS) was found to be upregulated. In conclusion, it can be conceived that pre-treatment with WL15 could mitigate H2O2-induced oxidative injury by elevating the activity and expression of antioxidant enzymes, thereby decreasing MDA levels and cellular apoptosis by enhancing the antioxidant response, demonstrated by the in vitro and in vivo experiments.

TL15 of Arthrospira platensis sulfite reductase scavenges free radicals demonstrated in oxidant induced larval zebrafish (Danio rerio) model.

The antioxidant role of sulfite reductase (SiR) derived from Arthrospira platensis (Ap) was identified through a short peptide, TL15. The study showed that the expression of ApSiR was highly expressed on day ten due to sulfur deprived stress in Ap culture. TL15 peptide exhibited strong antioxidant activity when evaluated using antioxidant assays in a concentration ranging from 7.8 and 125 µM. Further, the cytotoxicity of TL15 peptide was investigated, even at the higher concentration (250 µM), TL15 did not exhibit any toxicity, when tested in vitro using human leucocytes. Moreover, a potential reduction in reactive oxygen species (ROS) production was observed due to the treatment of TL15 peptide (>15.6 µM) to H2O2 exposed leucocytes. For the in vivo assessment of TL15 toxicity and antioxidant ability, experiments were performed in zebrafish (Danio rerio) larvae to analyse the developmental toxicity of TL15 peptide. Results showed that, exposure to TL15 peptide in tested concentrations ranging from 10, 20, 40, and 80 µM, did not affect the development and physiological parameters of the zebrafish embryo/larvae such as morphology, survival, hatching and heart rate. Fluorescent assay was performed using DCFH-DA (2,7-dichlorodihydrofluorescein diacetate) to examine the production of intracellular reactive oxygen species (ROS) in zebrafish treated with TL15 peptide during the embryo-larval stages. Fluorescent images showed that pre-treatment with TL15 peptide to attenuate the H2O2 induced ROS levels in the zebrafish larvae in a dose-dependent manner. Further to uncover the underlying biochemical and antioxidant mechanism, the enzyme activity of superoxide dismutase (SOD), catalase (CAT) and lipid peroxidation (LPO) levels were studied in zebrafish larvae. TL15 pre-treated groups showed enhanced antioxidant enzyme activity, while the hydrogen peroxide (H2O2) exposed larvae showed significantly diminished activity. Overall results from the study revealed that, TL15 act as a potential antioxidant molecule with dose-specific antioxidant property. Thus, TL15 peptide could be an effective and promising source for biopharmaceutical applications.

Innate immune function of serine/threonine-protein kinase from Macrobrachium rosenbergii in response to host-pathogen interactions.

The occurrences of multiple drug-resistant strains have been relentlessly increasing in recent years. The aquaculture industry has encountered major disease outbreaks and crucially affected by this situation. The usage of non-specific chemicals and antibiotics expedites the stimulation of resistant strains. Triggering the natural defense mechanism would provide an effective and safest way of protecting the host system. Hence, we have investigated the innate immune function of serine/threonine-protein kinase (STPK) in Macrobrachium rosenbergii (Mr). The in-silico protein analysis resulted in the identification of cationic antimicrobial peptide, MrSL-19, with interesting properties from STPK of M. rosenbergii. Antimicrobial assay, FACS and SEM analysis demonstrated that the peptide potentially inhibits Staphylococcus aureus by interacting with its membrane. The toxic study on MrSL-19 demonstrated that the peptide is not toxic against HEK293 cells as well as human erythrocytes. This investigation showed the significant innate immune property of an efficient cationic antimicrobial peptide, MrSL-19 of STPK from M. rosenbergii.

Peroxiredoxin of Arthrospira platensis derived short molecule YT12 influences antioxidant and anticancer activity.

This study demonstrates both the antioxidant and anticancer potential of the novel short molecule YT12 derived from peroxiredoxin (Prx) of spirulina, Arthrospira platensis (Ap). ApPrx showed significant reduction in reactive oxygen species (ROS) against hydrogen peroxide (H2 O2 ) stress. The complementary DNA sequence of ApPrx contained 706 nucleotides and its coding region possessed 546 nucleotides between position 115 and 660. Real-time quantitative reverse transcription polymerase chain reaction analysis confirmed the messenger RNA expression of ApPrx due to H2 O2 exposure in spirulina cells at regular intervals, in which the highest expression was noticed on Day 20. Cytotoxicity assay was performed using human peripheral blood mononuclear cells, and revealed that at 10 µM, the YT12 did not exhibit any notable toxicity. Furthermore, ROS scavenging activity of YT12 was performed using DCF-DA assay, in which YT12 scavenged a significant amount of ROS at 25 µM in H2 O2 -treated blood leukocytes. The intracellular ROS in human colon adenocarcinoma cells (HT-29) was regulated by oxidative stress, where the YT12 scavenges ROS in HT-29 cells at 12.5 µM. Findings show that YT12 peptide has anticancer activity, when treated against HT-29 cells. Through the MTT assay, YT12 showed vital cytotoxicity against HT-29 cells. These finding suggested that YT12 is a potent antioxidant molecule which defends ROS against oxidative stress and plays a role in redox balance.

CxxC Zinc Finger Protein Derived Peptide, MF18 Functions Against Biofilm Formation.

The major threat in modern medicine was biofilm forming bacterial related infections and they were highly tolerant to conventional antibiotics and a boundless demand for new drugs. In this regard, antimicrobial peptide (AMP) have been considered as potential alternative agents to conventional antibiotics. In this study, we have reported a CxxC zinc finger protein derived peptide, MF18 and its various biological role including activity against biofilm forming bacteria. Zinc finger protein are important in regulation of several cellular processes and wide range of molecular functions. The CxxC zinc finger protein identified from the cDNA library of a teleost fish; further it was characterised using various online bioinformatics programs. During the in-silico analysis, an AMP named MF18 was identified from the CxxC zinc finger protein, then it was synthesised for further biological activity studies. The antimicrobial activity of MF18 was confirmed against the biofilm clinical isolates such as Staphylococcus aureus and Escherichia coli. The MIC of the antimicrobial peptide at the concentration of 320 µM was observed against these two biofilm bacteria. The mechanism of the peptides was determined using bacteria on its membrane permeabilization ability by scanning electron microscopy. It is exhibited that the MF18 potentially influenced in damaging the morphology of the bacteria. The toxicity of MF18 against the continuous cell line (RAW 264.7) was demonstrated by MTT assay and also using peripheral red blood cells by haemolytic assay; both assays showed that the peptide have no toxicity on the cells at lower concentration. Overall, the study showed the potential therapeutic application of the peptide in pharma industry.

Arthrospira platensis transglutaminase derived antioxidant peptide-packed electrospun chitosan/ poly (vinyl alcohol) nanofibrous mat accelerates wound healing, in vitro, via inducing mouse embryonic fibroblast proliferation.

In this present study, we have carried out the antioxidant function of transglutaminase (TG) identified from Arthrospira platensis (Ap) transcriptome. The antioxidant peptide ML11 (MLRSIGIPARL) has been predicted from the transglutaminase core domain and the peptide's free radical scavenging potential was evaluated and it shows that it functions on a dose dependent manner. The ML11 peptide cell toxicity was analysed in the human blood leucocytes which resulted no cytotoxic activity in any of the cell population. Moreover, the nanofibre mat encapsulated with antioxidant peptide ML11 was prepared by electrospinning technique. The antioxidant peptide ML11 encapsulated mat showed increase in fibre diameter compared to the chitosan polyvinyl alcohol blended mat. The change in the crystalline behaviour of both chitosan and polyvinyl alcohol polymer to the amorphous nature was determined by X-ray diffraction at the broad band between 20 and 30° (2θ°). FTIR revealed the functional groups which present in the polymer as well as the interaction between their components of chitosan (CS) and polyvinyl alcohol (PVA). The fibre retains the antioxidant activity due to the peptide encapsulated by scavenging the intracellular ROS that was confirmed by flowcytometry and fluorescence microscopy. The ML11 peptide encapsulated mat showed no cytotoxicity in the NIH-3T3 mouse embryonic fibroblast cells. Also, ML11 peptide encapsulated fibre showed potential wound healing activity in NIH-3T3 cells. Taken altogether, the study indicates that the wound healing potential of the ML11 peptide encapsulated nano fibre mat may be used as biopharmaceutical drug.

M. tuberculosis class II apurinic/ apyrimidinic-endonuclease/3'-5' exonuclease (XthA) engages with NAD+-dependent DNA ligase A (LigA) to counter futile cleavage and ligation cycles in base excision repair.

Class-II AP-endonuclease (XthA) and NAD+-dependent DNA ligase (LigA) are involved in initial and terminal stages of bacterial DNA base excision repair (BER), respectively. XthA acts on abasic sites of damaged DNA to create nicks with 3'OH and 5'-deoxyribose phosphate (5'-dRP) moieties. Co-immunoprecipitation using mycobacterial cell-lysate, identified MtbLigA-MtbXthA complex formation. Pull-down experiments using purified wild-type, and domain-deleted MtbLigA mutants show that LigA-XthA interactions are mediated by the BRCT-domain of LigA. Small-Angle-X-ray scattering, 15N/1H-HSQC chemical shift perturbation experiments and mutational analysis identified the BRCT-domain region that interacts with a novel 104DGQPSWSGKP113 motif on XthA for complex-formation. Isothermal-titration calorimetry experiments show that a synthetic peptide with this sequence interacts with MtbLigA and disrupts XthA-LigA interactions. In vitro assays involving DNA substrate and product analogs show that LigA can efficiently reseal 3'OH and 5'dRP DNA termini created by XthA at abasic sites. Assays and SAXS experiments performed in the presence and absence of DNA, show that XthA inhibits LigA by specifically engaging with the latter's BRCT-domain to prevent it from encircling substrate DNA. Overall, the study suggests a coordinating function for XthA whereby it engages initially with LigA to prevent the undesirable consequences of futile cleavage and ligation cycles that might derail bacterial BER.