Attenuation of Las/Rhl quorum sensing regulated virulence and biofilm formation in Pseudomonas aeruginosa PAO1 by Artocarpesin.

The emergence of multidrug resistance and increased pathogenicity in microorganisms is conferred by the presence of highly synchronized cell density dependent signalling pathway known as quorum sensing (QS). The QS hierarchy is accountable for the secretion of virulence phenotypes, biofilm formation and drug resistance. Hence, targeting the QS phenomenon could be a promising strategy to counteract the bacterial virulence and drug resistance. In the present study, artocarpesin (ACN), a 6-prenylated flavone was investigated for its capability to quench the synthesis of QS regulated virulence factors. From the results, ACN showed significant inhibition of secreted virulence phenotypes such as pyocyanin (80%), rhamnolipid (79%), protease (69%), elastase (84%), alginate (88%) and biofilm formation (88%) in opportunistic pathogen, Pseudomonas aeruginosa PAO1. Further, microscopic observation of biofilm confirmed a significant reduction in biofilm matrix when P. aeruginosa PAO1 was supplemented with ACN at its sub-MIC concentration. Quantitative gene expression studies showed the promising aspects of ACN in down regulation of several QS regulatory genes associated with production of virulence phenotypes. Upon treatment with sub-MIC of ACN, the bacterial colonization in the gut of Caenorhabditis elegans was potentially reduced and the survival rate was greatly improved. The promising QS inhibition activities were further validated through in silico studies, which put an insight into the mechanism of QS inhibition. Thus, ACN could be considered as possible drug candidate targeting chronic microbial infections.

Structural elucidation of ETHR-A and ETHR-B from Plutella xylostella and insight into non-conservative mutations in transmembrane helix-6.

The development of Diamondback moth (DBM) depends on the ecdysis triggering hormone receptor (ETHR); a neuronal membrane G-protein coupled receptor (GPCR) connected to the metamorphosis cascade. Lepidopteran insect DBM is an infamous pest of cruciferous plants. This study examined the full-length coding sequences (CDS) of PxETHR-A and PxETHR-B from the DBM genome. The three-dimensional (3 D) models of both receptors were generated in an inactive state. The behaviour and stability of receptors were examined using molecular dynamics simulations in a lipid membrane system for 300 ns and established a GPCR family-based view. Secondary interactions within receptors were studied to know more about factors contributing to their stability. Multiple sequence alignment revealed conserved features of insect ETHRs those compared to the GPCR family proteins. These features were helpful during the evaluation of the molecular models of both receptors. Side-chain orientation of conserved residues, non-conserved and conserved hydrogen-bond networks (HBN) and hydrophobic clusters were examined in the structures of both receptors. The non-conserved residues L6.35, T6.39, C/S6.43, and L6.48, are present in a conserved position on the transmembrane helix-6 (TM6) of ETHRs. In TM6, PxETHR-A and PxETHR-B differ at positions C/S6.43 and Y/F6.51, both being part of the HBN.Communicated by Ramaswamy H. Sarma.

Alantolactone modulates the production of quorum sensing mediated virulence factors and biofilm formation in Pseudomonas aeruginosa.

Pseudomonas aeruginosa is an opportunistic pathogen in immunocompromised patients and accounts for mortality worldwide. Quorum sensing (QS) and QS mediated biofilm formation of P. aeruginosa increase the severity of infection in the host. New and effective therapeutics are in high demand to eliminate Pseudomonas infections. The current study investigated the quorum quenching and biofilm inhibition properties of alantolactone (ATL) against P. aeruginosa PAO1. The production of key virulence factors and biofilm components were affected in bacteria when treated with sub-MIC of ATL and further validated by qRT-PCR studies. The anti-infective potential of ATL was corroborated in an in vivo model with improved survival of infected Caenorhabditis elegans and reduced bacterial colonization. In silico studies suggested the molecular interactions of ATL to QS proteins as stable. Finally, ATL was explored in the present study to inhibit QS pathways and holds the potential to develop into an effective anti-infective agent against P. aeruginosa.

Cloning, functional characterization and screening of potential inhibitors for Chilo partellus chitin synthase A using in silico, in vitro and in vivo approaches.

Chitin synthase (CHS) is one of the crucial enzymes that play an essential role in chitin synthesis during the molting process, and it is considered to be the specific target to control insect pests. Currently, there are no potent inhibitors available in the market, which specifically target this enzyme. Pyrimidine nucleoside peptide, nikkomycin Z, binds to nucleotide-binding sites of fungal and insect CHS. But, their mode of action is still fragmentary due to the lack of a 3Dstructure of CHS. Chilo partellus is a severe pest insect of major food crops such as maize and sorghum, in an attempt to target integument expressed cuticular CpCHS. The CpChsA cDNA was cloned, and subsequently, their developmental and tissue-specific expression was studied. The 3D structure of the CHS catalytic domain was modeled, after which natural compounds were screened using a virtual screening workflow and resulted in the identification of five hit molecules. Molecular dynamics simulations were performed to investigate the dynamics and interactions of hits with CpCHS. The obtained results revealed that the compounds kasugamycin, rutin and robinin could act as potent inhibitors of CpCHS. All three molecules were observed to significantly reduce the chitin production as validated using in vitro and in vivo studies. Thus, this study aims to provide a set of novel inhibitor molecules against CpCHS for controlling the pest population. Communicated by Ramaswamy H. Sarma.

Sesamin and sesamolin rescues Caenorhabditis elegans from Pseudomonas aeruginosa infection through the attenuation of quorum sensing regulated virulence factors.

Pseudomonas aeruginosa is an opportunistic pathogen emerging as a public health threat owing to their multidrug resistance profiles. The quorum sensing systems of P. aeruginosa play a pivotal role in the regulation of virulence and act as the target for the development of alternative therapeutics. The study discussed about anti-quorum sensing and antibiofilm properties of lignans (sesamin and sesamolin) found in Sesamum indicum (L.) against P. aeruginosa. The effect of lignans, sesamin and sesamolin on LasR/RhlR mediated virulence factor production, biofilm formation and bacterial motility were studied. To elucidate the mechanism of action of lignans on QS pathways, QS gene expression and in depth in silico analysis were performed. Both the lignans exerted anti-quorum sensing activity at 75 µg/ml without affecting the growth of bacteria. SA and SO exhibited decreased production of virulence factors such as pyocyanin, proteases, elastase and chitinase. The important biofilm constituents of P. aeruginosa including alginate, exopolysaccharides and rhamnolipids were strongly affected by the lignans. Likewise, plausible mechanism of action of lignans were determined through the down regulation of QS regulated gene expression, molecular docking and molecular simulation studies. The in vitro analysis was supported by C. elegans infection model. SA and SO rescued pre-infected worms within 8 days of post infection and reduced the colonization of bacteria inside the intestine due to the anti-infective properties of lignans. The lignans exhibited profound action on Las pathway rather than Rhl which was elucidated through in vitro and in silico assays. In silico pharmacokinetic analysis portrayed the opportunities to employ ligands as potential therapeutics for human use. The deep insights into the anti-QS, anti-biofilm and mechanism of action of lignans can contribute to the development of novel anti-infectives against pseuodmonal infections.

Attenuation of quorum sensing mediated virulence factors production and biofilm formation in Pseudomonas aeruginosa PAO1 by Colletotrichum gloeosporioides HM3.

Signal dependent microbial communication in Pseudomonas aeruginosa PAO1 is a typical phenomenon mediated by acyl homo-serine lactone molecules that helps in developing biofilm and enhance antibiotic resistance. Microbial sources provide insight to the hidden treasure of secondary metabolites, and these structurally diversified chemical motifs can be used as antimicrobial and anti-infective agents. In the present study, endophytic fungus, Colletotrichum gloeosporioides HM3 isolated from Carica papaya leaves was explored for anti-infective potential against P. aeruginosa PAO1. The crude extract of C. gloeosporioides HM3 displayed bacteriostatic effect on P. aeruginosa PAO1 growth at 750 µg/ml concentration. A significant decline was observed in the production of quorum sensing regulated virulence factors, i.e. 56.32%, 62.54%, and 66.67% of pyocyanin, chitinase, and elastase enzyme, respectively. A drastic reduction in pathogenic determinant behaviour after treatment with crude extract of C. gloeosporioides HM3 i.e. EPS, rhamnolipid, and HCN production was noted. Light microscopy and CLSM analysis revealed that fungal extract treatment has reduced bacterial ability to form dense biofilm architecture. In silico analysis demonstrated the binding efficiency of bioactive compound, 4-(2,3-dimethoxybenzylidene)-3-methyl-1-(4-nitrophenyl)-2-pyrazolin-5-one, which is equipotent to the natural ligand and displayed a docking score of -5.436 kcal/mol with QS transcriptional regulator (LasR). Whereas the compound Acetamide, n-[tetrahydro-3-(phenylmethyl) thieno [3,4-d]thiazol-2 (3 h)-ylidene]-, s,s-dioxide exhibits a docking score of -4.088 kcal/mol (LasR) and -1.868 kcal/mol (RhlR) with cognate receptor proteins. Henceforth, the research report suggests C. gloeosporioides HM3 derived metabolites could be considered as a potential inhibitors of QS regulated virulence factors and biofilm production in P. aeruginosa PAO1.

In silico Binding Profile Analysis and In vitro Investigation on Chitin Synthase Substrate and Inhibitors from Maize Stem Borer, Chilo partellus.

INTRODUCTION: Insect growth and metamorphosis are strictly dependent on the structural changes that occur in chitin containing tissues and organs. Chitin synthase catalyzes chitin polymerization by ß-(1, 4) glycosidic linkage of N-acetyl-D-glucosamine (GlcNAc) monomers; the major component of insect cuticles. Targeting this enzyme could be a promising strategy to control insect pests while avoiding adverse effects on coexisting populations. Nikkomycin Z and polyoxins are commercially available fungal inhibitors known to bind to the nucleotide-binding sites of insects and fungal chitin synthase. But the binding mode of chitin synthase has not been explored to date as its structure is not available yet. METHODS: To understand the structural features of the Chilo partellus chitin synthase enzyme (CpCHS), the three-dimensional (3D) structure of the CpCHS catalytic domain was modeled using ROBETTA webserver. The obtained model was used to investigate the binding mode of its substrate, uridine diphosphate-N-acetyl-D-glucosamine (UDP-GlcNAc), and inhibitors (nikkomycin Z and polyoxins) by molecular docking approach using Schrödinger Suite-Maestro v9.2. The docked complexes were further investigated for their interaction stability by performing molecular dynamics (MD) simulations using GROMACS v5.1.2. RESULTS: Our study highlighted the significance of various interactions made by CHS residues present in the Walker-B loop and donor-binding motifs with the substrate (UDP-GlcNAc), and GEDR motif with an acceptor (GlcNAc). Also, the interactions of the QRRRW motif while forming chitin polymer were explored. We observed that the inhibitors exhibited good binding affinity with these motifs, indicated by their docking and binding affinity scores. CONCLUSION: In vitro analysis suggested that nikkomycin Z showed higher inhibition of chitin synthase activity at a concentration of 2.5 µg.L-1. Our study provided insights into the crucial interactions of chitin synthase while designing inhibitors against insect pests.

Inhibition of quorum sensing-associated virulence factors and biofilm formation in Pseudomonas aeruginosa PAO1 by Mycoleptodiscus indicus PUTY1.

Pseudomonas aeruginosa is the second most emerging multidrug-resistant, opportunistic pathogen after Acinetobacter baumannii that poses a threat in nursing homes, hospitals, and patients who need devices such as ventilators and blood catheters. Its ability to form quorum sensing-regulated virulence factors and biofilm makes it more resistant to top most therapeutic agents such as carbapenems and next-generation antibiotics. In the current study, we studied the quorum quenching potential of secondary metabolites of Mycoleptodiscus indicus PUTY1 strain. In vitro observation showed a mitigation in virulence factors such as rhamnolipids, protease, elastase pyocyanin, exopolysaccharides, and hydrogen cyanide gas. Furthermore, a significant reduction in the motility such as swimming, swarming, twitching, and inhibition in biofilm formation by Pseudomonas aeruginosa PAO1 was observed. Results of in vitro studies were further confirmed by in silico studies through docking and molecular dynamic simulation of GC-MS-detected compounds of Mycoleptodiscus indicus employing LasR and RhlR proteins. Both in vitro and in silico observations indicate a new alternative approach for combating virulence of Pseudomonas aeruginosa by targeting its protein receptors LasR and RhlR. Graphical abstract.

Phomopsis tersa as Inhibitor of Quorum Sensing System and Biofilm Forming Ability of Pseudomonas aeruginosa.

Endophytic fungi provide rich reservoir for novel antimicrobial compounds. An endophytic fungus, from Carica papaya plant identified as Phomopsis tersa, was investigated for attenuating the quorum sensing mediated pathogenicity of Pseudomonas aeruginosa PAO1. Crude extract of P. tersa was found to reduce the production of redox-active pigments-pyocyanin and pyoverdine in P. aeruginosa PAO1 by 92.46% and 71.55%, respectively at sub-MIC concentration of 900 µg/mL. In addition, the crude extract was also able to inhibit the expression of virulence factors involved in biofilm formation: exopolysaccharide (72.21%) and alginate (72.50%). Secretion of cell-lytic enzymes was also found to be reduced: chitinase by 79.73% and elastase by 74.30%. 3-Isobutylhexahydropyrrolo[1,2-a]pyrazine-1,4-dione identified from GC-MS analysis, displayed favorable molecular interactions with P. aeruginosa transcriptional regulators, LasR and RhlR with good docking scores of - 6.873 kJ/mol and - 6.257 kJ/mol, respectively. The study thus reveals the potential use of P. tersa for discovering drugs against infectious pathogens.

Inhibition of Microbial Quorum Sensing Mediated Virulence Factors by Pestalotiopsis sydowiana.

Quorum sensing (QS)-mediated infections cause severe diseases in human beings. The control of infectious diseases by inhibiting QS using antipathogenic drugs is a promising approach as antibiotics are proving inefficient in treating these diseases. Marine fungal (Pestalotiopsis sydowiana PPR) extract was found to possess effective antipathogenic characteristics. The minimum inhibitory concentration (MIC) of the fungal extract against test pathogen Pseudomonas aeruginosa PAO1 was 1,000 µg/ml. Sub-MIC concentrations (250 and 500 µg/ml) of fungal extract reduced QS-regulated virulence phenotypes such as the production of pyocyanin, chitinase, protease, elastase, and staphylolytic activity in P. aeruginosa PAO1 by 84.15%, 73.15%, 67.37%, 62.37%, and 33.65%, respectively. Moreover, it also reduced the production of exopolysaccharides (74.99%), rhamnolipids (68.01%), and alginate (54.98%), and inhibited the biofilm formation of the bacteria by 90.54%. In silico analysis revealed that the metabolite of P. sydowiana PPR binds to the bacterial QS receptor proteins (LasR and RhlR) similar to their respective natural signaling molecules. Cyclo(-Leu-Pro) (CLP) and 4-Hydroxyphenylacetamide (4-HPA) were identified as potent bioactive compounds among the metabolites of P. sydowiana PPR using in silico approaches. The MIC values of CLP and 4-HPA against P. aeruginosa PAO1 were determined as 250 and 125 µg/ml, respectively. All the antivirulence assays were conducted at sub-MIC concentrations of CLP (125 µg/ml) and 4-HPA (62.5 µg/ml), which resulted in marked reduction in all the investigated virulence factors. This was further supported by gene expression studies. The findings suggest that the metabolites of P. sydowiana PPR can be employed as promising QS inhibitors that target pathogenic bacteria.

Peruvoside targets apoptosis and autophagy through MAPK Wnt/ß-catenin and PI3K/AKT/mTOR signaling pathways in human cancers.

AIM: To investigate the cytotoxic effect of Peruvoside and mechanism of action in human cancers. MAIN METHODS: Cell viability was measured by MTT assay and the cell cycle arrest was identified by FACS. Real-time qPCR and western blotting studies were performed to identify important gene and protein expressions in the different pathways leading to apoptosis. Immunofluorescence was performed to understand protein localization and molecular docking studies were performed to identify protein-ligand interactions. KEY FINDINGS: Peruvoside showed significant anti-proliferative activities against human breast, lung, and liver cancer cells in dose-dependent manner. The anti-cancer mechanism was further confirmed by DNA damage and cell cycle arrest at the G0/G1 phase. Dysregulation of Wnt/ß-catenin signaling with Peruvoside treatment resulted in inhibition of cyclin D1 and c-Myc also observed in this study. Furthermore, we identified that Peruvoside can inhibit autophagy by PI3K/AKT/mTOR signaling and through downregulating MEK1. Moreover, Peruvoside has the ability to modulate the expressions of key proteins from the cell cycle, MAPK, NF-kB, and JAK-STAT signaling. In silico studies revealed that Peruvoside has the ability to interact with crucial proteins from different biochemical signaling pathways. SIGNIFICANCE: Our results demonstrated that Peruvoside has the ability to inhibit cancer cell proliferation by modulating the expression of various key proteins involved in cell cycle arrest, apoptosis, and autophagic cell death. Clinical data generated from the present study might provide a novel impetus for targeting several human cancers. Conclusively, our findings suggest that the Peruvoside possesses a broad spectrum of anticancer activity in breast, lung, and liver cancers, which provides an impetus for further investigation of the anticancer potentiality of this biomolecule.

Anti-quorum sensing and antibiofilm activities of Blastobotrys parvus PPR3 against Pseudomonas aeruginosa PAO1.

The bacterial cell communication also termed as Quorum sensing (QS) system was involved in the expression of several virulence traits during Pseudomonas infection. The attenuating of this bacterial cell communication system is an attractive approach for the management of bacterial infections without the complication of resistance development. In this respect, the marine environment has gained significant attention due to its biodiversity and as a source of novel bioactive compounds. The present study aimed to screening effective QS inhibitors from marine associated fungal species for QS inhibitors. Twelve morphologically distinct fungal isolates were isolated from the wood of Avicennia marina from marine ecosystem. The anti-QS potential of fungal crude extract from was investigated in biosensor strain and test bacterium, Chromobacterium violaceum and Pseudomonas aeruginosa PAO1, respectively. Promising anti-QS activity was observed in the crude extract of one of the fungal isolate and identified by molecular characterization using internal transcribed spacer (ITS) region as Blastobotrys parvus PPR3. The anti-virulence and antibiofilm effects of ethyl acetate fractions from PPR3 against P. aeruginosa PAO1 were evaluated. The fungal metabolites responsible for the anti-QS activity of fungal crude extract was identified using gas chromatography-mass spectrometry (GC-MS). Furthermore, molecular docking studies were performed to understand the interaction of bioactive compounds with as receptors of P. aeruginosa PAO1. The crude extract of PPR3 showed reduction in different virulence traits of P. aeruginosa PAO1 such as production of pyocyanin, elastase, protease, chitinase, swimming and swarming motility, biofilm formation, exopolysaccharide production and alginate production at different sub-MIC concentrations. Interaction of bioactive metabolites with LasR and RhlR receptors of P. aeruginosa PAO1 was reported. The findings of the present study suggested that metabolites of B. parvus PPR3 interfere with QS system of P. aeruginosa PAO1 and alters the production of virulence factors.

Molecular cloning, gene expression analysis, and in silico characterization of UDP-N-acetylglucosamine pyrophosphorylase from Bombyx mori.

The present study was aimed to explore the molecular and structural features of UDP-N-acetylglucosamine pyrophosphorylase of Bombyx mori (BmUAP), an essential enzyme for chitin synthesis in insects. The BmUAP cDNA sequence was cloned and expression profiles were monitored during the molting and feeding stages of silkworm larvae. The effect of 20-hydroxyecdysone (20E) on BmUAP expression, and on silkworm molting was studied, which revealed that 20E regulates its expression. Multiple sequence alignment of various pyrophosphorylases revealed that the residues N223, G290, N327, and K407 of human UAP (PDB ID: 1JV1) were found to be highly conserved in BmUAP and all other eukaryotic UAPs considered for the study. Phylogenetic analysis inferred that the UAPs possess discrete variations in primary structure among different insect Orders while sharing good identity between species of the Order. The structure of BmUAP was predicted and its interactions with uridine triphosphate, N-acetylglucosamine-1-phosphate, and UDP-N-acetylglucosamine were analyzed. Virtual screening with a library of natural compounds resulted in five potential hits with good binding affinities. On further analysis, these five hits were found to be mimicking substrate and product, in inducing conformational changes in the active site. This work provides crucial information on molecular interactions and structural dynamics of insect UAPs.

Synthesis and biological evaluation of flavone-8-acrylamide derivatives as potential multi-target-directed anti Alzheimer agents and investigation of binding mechanism with acetylcholinesterase.

In a search for novel multifunctional anti-Alzheimer agents, a congeneric set of seventeen flavone-8-acrylamide derivatives (8a─q) were synthesized and evaluated for their cholinesterase inhibitory, antioxidant, neuroprotective and modulation of Aß aggregation activities. The target compounds showed effective and selective inhibitory activity against the AChE over BuChE. In addition, the target compounds also showed moderate anti-oxidant activity and strong neuroprotective capacities, and accelerated dosage-dependently the Aß aggregation. Also, we presented here a complete study on the interaction of 8a, 8d, 8e, 8h and 8i with AChE. Through fluorescence emission studies, the binding sites number found to be 1, binding constants were calculated as 2.04 × 104, 2.22 × 104, 1.18 × 104, 9.8 × 103 and 3.2 × 104 M-1 and free energy change as -5.83, -5.91, -5.51, -5.41 and -6.12 kcal M-1 at 25 °C which were well agreed with the computational calculations indicating a strong binding affinity of flavones and AChE. Furthermore, the CD studies revealed that the secondary structure of AChE became partly unfolded upon binding with 8a, 8d, 8e, 8h and 8i.

Mosloflavone attenuates the quorum sensing controlled virulence phenotypes and biofilm formation in Pseudomonas aeruginosa PAO1: In vitro, in vivo and in silico approach.

Quorum sensing (QS) is the cell density dependent communication network which coordinates the production of pathogenic determinants in majority of pathogenic bacteria. Pseudomonas aeruginosa causes hospital-acquired infections by virtue of its well-defined QS network. As the QS regulatory network in P. aeruginosa regulates the virulence determinants and antibiotic resistance, attenuating the QS system seems to be influential in developing next-generation anti-infective agents. In the current study, the QS attenuation potential of a flavonoid, mosloflavone was investigated against P. aeruginosa virulence and biofilm formation. Mosloflavone inhibited the pyocyanin production, LasB elastase and chitinase by 59.52 ±â€¯2.74, 35.90 ±â€¯4.34 and 61.18 ±â€¯5.52% respectively. The QS regulated biofilm formation and development was also reduced when supplemented with sub-MIC of mosloflavone. The gene expression studies of mosloflavone using RT-PCR depicted its ability to down-regulate the expression levels of QS regulated virulence genes such as lasI (60.64%), lasR (91.70%), rhlI (57.30%), chiC (90.20%), rhlA (47.87%), rhlR (21.55%), lasB (37.80%), phzM (42.40%), toxA (61.00%), aprA (58.4%), exoS (78.01%), algD (46.60%) and pelA (50.45%). The down-regulation of QS virulence phenotypes by mosloflavone could be attributed to its binding affinity with the QS regulatory proteins, LasR and RhlR by competitively inhibiting the binding of natural autoinducers as evidenced from simulation studies. Mosloflavone also exhibited promising potential in controlling bacterial infection in Caenorhabditis elegans model system, in vivo. The anti-biofilm and anti-QS potential of mosloflavone in the current study illustrated the candidature of mosloflavone as a promising biocide.

Pharmacophore-based virtual screening approach for identification of potent natural modulatory compounds of human Toll-like receptor 7.

Toll-like receptor 7 (TLR7) is a transmembrane glycoprotein playing very crucial role in the signaling pathways involved in innate immunity and has been demonstrated to be useful in fighting against infectious disease by recognizing viral ssRNA & specific small molecule agonists. In order to find novel human TLR7 (hTLR7) modulators, computational ligand-based pharmacophore modeling approach was used to identify the molecular chemical features required for the modulation of hTLR7 protein. A training set of 20 TLR7 agonists with their known experimental activity was used to create pharmacophore model using 3D-QSAR pharmacophore generation (HypoGen algorithm) module in Discovery Studio. The best developed hypothesis consists of four pharmacophoric features namely, one hydrogen bond donor (HBD), one ring aromatic (RA), and two hydrophobic (HY) character. The developed hypothesis was then validated by different methods such as cost analysis, test set method, and Fischer's test method for consistency. Hence, this validated model was further employed for screening of natural hit compounds from InterBioScreen Natural product database, consisting of more than 60,000 natural compounds and derivatives. The screened hit compounds were subsequently filtered by Lipinski's rule of 5, ADME and toxicity parameters and molecular docking studies to remove the false positive rates. Finally, molecular docking analysis led to identification of the (3a'S,6a'R)-3'-(3,4-dihydroxybenzyl)-5'-(3,4-dimethoxyphenethyl)-5-ethyl-3',3a'-dihydro-2'H-spiro[indoline-3,1'-pyrrolo[3,4-c]pyrrole]-2,4',6'(5'H,6a'H)-trione (Compound ID: STOCK1N-65837) as potent hTLR7 modulator due to its better docking score and molecular interactions compared to other compounds. The result of virtual screening was further validated using molecular dynamics (MD) simulation analysis. Thus, a 30 ns MD simulation analysis revealed high stability and effective binding of STOCK1N-65837 within the binding site of hTLR7. Therefore, the present study provides confidence for the utility of the selected chemical feature based pharmacophore model to design novel TLR7 modulators with desired biological activity.

Screening and analysis of acetyl-cholinesterase (AChE) inhibitors in the context of Alzheimer's disease.

Acetyl-cholinesterase enzyme (AChE) is a known target for identifying potential inhibitors against Alzheimer diseases (AD). Therefore, it is of interest to screen AChE with the CNS-BBB database. An AChE enzyme is a member of hydrolase family is activated by acetylcholine (ACh), so, targeting the AChE enzyme with the potential inhibitor may block the binding of the ACh. In this study we carried out virtual screening of drug-like molecules from Chemical Diversity Database particularly CNS-BBB compounds, to identify potential inhibitors using Glide docking program. Top ranking ten compounds, which have lower Glide Score when compared to known drugs (Tacrine and Galantamine) for AChE. For top three molecules MD simulation was carried out and calculated binding free energy. We report the best binding compounds with AChE compared to known drugs (Taine and Galantamine) for AD. We further document the salient features of their molecular interaction with the known target. Three molecules (1-benzyl-3-(2- hydroxyethyl)-N-[2-(3-pyridyl)ethyl]-3-pyrrolidinecarboxamide, N-{3[benzyl(methyl)amino]propyl}-1,5-dimethyl-4-oxo-4,5-dihydro- 1H-pyrrolo[3,2-c]quinoline-2-carboxamide, and 6-chloro-N-[2-(diethylamino)-2-phenylethyl]-4-oxo-4H-chromene-2-carboxamide) have -196.36, -204.27, -214.40 kJ/mol, binding free energy values respectively which are much lower than values calculated for the reference ligands Tacrine and Galantamine having -119.65 and -142.18 kJ/mol respectively. Thus these molecules can be very novel potential inhibitors against AChE involved in Alzheimer's disease.

Aspergillus ochraceopetaliformis SSP13 modulates quorum sensing regulated virulence and biofilm formation in Pseudomonas aeruginosa PAO1.

Pseudomonas aeruginosa is an opportunistic nosocomial pathogen causing the majority of acute and persistent infections in human beings. The ability to form biofilm adds a new dimension to its resistance to conventional therapeutic agents. In the present study, down-regulation of quorum sensing regulated virulence and biofilm development resulting from exposure to Aspergillus ochraceopetaliformis SSP13 extract was investigated. The in vitro results inferred impairment in the production of LasA protease, LasB elastase, chitinase, pyocyanin, exopolysaccharides and rhamnolipids. In addition, motility and biofilm formation by P. aeruginosa PAO1 was significantly altered. The in vitro results were further supported by molecular docking studies of the metabolites obtained from GC-MS analysis depicting the quorum sensing attenuation by targeting the receptor proteins LasR and RhlR. The in vitro and in silico studies suggested new avenues for the development of bioactive metabolites from A. ochraceopetaliformis SSP13 extract as potential anti-infective agents.

Attenuation of quorum sensing regulated virulence and biofilm development in Pseudomonas aeruginosa PAO1 by Diaporthe phaseolorum SSP12.

In recent years, Pseudomonas aeruginosa PAO1 emerged as the significant pathogenic microorganism in majority of the hospital-acquired infections due to its resistance to the conventional antibiotics by virtue of its highly organized quorum sensing and associated biofilm formation. In the present study, quorum sensing attenuation potential of Diaporthe phaseolorum SSP12 extract was investigated against P. aeruginosa PAO1 amply supported by molecular docking studies. D. phaseolorum SSP12 extract significantly inhibited the production of LasI/R mediated LasA protease, LasB elastase and chitinase with 66.52 ±â€¯5.41, 71.26 ±â€¯4.58 and 61.16 ±â€¯4.28% of inhibition respectively at a concentration of 750 µg mL-1. In addition, RhlI/R mediated production of pyocyanin, exopolysaccharides and rhamnolipids were also down-regulated by 74.71 ±â€¯3.97, 66.41 ±â€¯3.62 and 63.75 ±â€¯3.76% respectively on treatment with sub-MIC concentration of D. phaseolorum SSP12. The light, fluorescence and confocal laser scanning microscopic (CLSM) analysis confirmed the significant disruption in biofilm formation. The presence of bioactive constituents such as phenyl ethylalcohol, 2, 4-di-tert-butylphenol, fenaclon, 1, 4-phenylenediacetic acid, and benzyl hydrazine in D. phaseolorum SSP12 extract was evident from Gas chromatography-mass spectrophotometric (GC-MS) analysis. From the in silico molecular docking studies, fenaclon and 2, 4-di-tert-butylphenol competitively binds to QS receptors LasR and RhlR and alters the binding of its cognate ligands and modulates the expression of virulence phenotypes. The promising anti quorum sensing efficacy of D. phaseolorum SSP12 extract suggested new avenues for development of anti-infective drugs from fungal derived metabolites to counteract the problems associated with conventional antibiotic therapies.

Identifying novel small molecule antagonists for mLST8 protein using computational approaches.

Mammalian lethal with SEC13 protein 8 (mLST8), is an indispensable protein subunit of mammalian target of rapamycin (mTOR) signaling pathway that interacts with the kinase domain of mTOR protein, thereby stabilizing its active site. Experimental studies reported the over expression of mLST8 in human colon and prostate cancers by activation of both mTORC1/2 complexes and subsequent downstream substrates leading to tumor progression. Considering its role, targeting mLST8 protein would be a therapeutic approach against tumor progression in colon and prostate cancers. Hence, using in silico structure based drug design approach, the comparative binding patterns of 1,1'-binapthyl-2,2'diol (BINOL), 1-(2-carboxynaphth-1yl)-2-naphthoic acid (SCF-12) and their analogs in the cavity of mLST8 were explored. ADME and binding energy calculations led to the identification of five compounds with favorable Glide (G) scores and implicated the importance of Asn132 and Gln225 as key binding residues. Molecular dynamics (MD) simulations and free energy landscape (FEL) approaches helped in elucidating the binding mechanism and suggested the possibility of ligands 1-3 namely, ZINC01765622, ZINC62723702 and ZINC02576980 to be promising antagonists for mLST8. Thus, this study substantiates the prospect of targeting mLST8 protein using potent hits which could hinder tumor progression in colon and prostate cancers.