Impact of Calcium Influx on Endoplasmic Reticulum in Excitotoxic Neurons: Role of Chemical Chaperone 4-PBA.

Excessive activation of α-amino-3-hydroxy-5-methyl-4-isoxazole propoinic acid (AMPA) receptors instigates excitotoxicity via enhanced calcium influx in the neurons thus inciting deleterious consequences. Additionally, Endoplasmic Reticulum (ER) is pivotal in maintaining the intracellular calcium balance. Considering this, studying the aftermath of enhanced calcium uptake by neurons and its effect on ER environment can assist in delineating the pathophysiological events incurred by excitotoxicty. The current study was premeditated to decipher the role of ER pertaining to calcium homeostasis in AMPA-induced excitotoxicity. The findings showed, increased intracellular calcium levels (measured by flowcytometry and spectroflourimeter using Fura 2AM) in AMPA excitotoxic animals (male Sprague dawely rats) (intra-hippocampal injection of 10 mM AMPA). Further, ER resident proteins like calnexin, PDI and ERp72 were found to be upregulated, which further modulated the functioning of ER membrane calcium channels viz. IP3R, RyR, and SERCA pump. Altered calcium homeostasis further led to ER stress and deranged the protein folding capacity of ER post AMPA toxicity, which was ascertained by unfolded protein response (UPR) pathway markers such as IRE1α, eIF2α, and ATF6α. Chemical chaperone, 4-phenybutric acid (4-PBA), ameliorated the protein folding capacity and subsequent UPR markers. In addition, modulation of calcium channels and calcium regulating machinery of ER post 4-PBA administration restored the calcium homeostasis. Therefore the study reinforces the significance of ER stress, a debilitating outcome of impaired calcium homeostasis, under AMPA-induced excitotoxicity. Also, employing chaperone-based therapeutic approach to curb ER stress can restore the calcium imbalance in the neuropathological diseases.

Antimicrobial peptides against colorectal cancer-a focused review.

Despite recent advances in the treatment of colorectal cancer (CRC), low patient survival rate due to emergence of drug resistant cancer cells, metastasis and multiple deleterious side effects of chemotherapy, is a cause of public concern globally. To negate these clinical conundrums, search for effective and harmless novel molecular entities for the treatment of CRC is an urgent necessity. Since antimicrobial peptides (AMPs) are part of innate immunity of living beings, it is quite imperative to look for essential attributes of these peptides which may contribute to their effectiveness against carcinogenesis. Once identified, those characteristics can be suitably modified using several synthetic and computational techniques to further enhance their selectivity and pharmacokinetic profiles. Hence, this review analyses scientific reports describing the antiproliferative action of AMPs derived from several sources, particularly focusing on various colon cancer in vitro/in vivo investigations. On perusal of the literature, it appears that AMPs based therapeutics would definitely find special place in CRC therapy in future either alone or as an adjunct to chemotherapy provided some necessary alterations are made in their natural structures to make them more compatible with modern clinical practice. In this context, further in-depth research is warranted in adequate in vivo models.

A review on peptide functionalized graphene derivatives as nanotools for biosensing.

Peptides exhibit unique binding behavior with graphene and its derivatives by forming bonds on its edges and planes. This makes them useful for sensing and imaging applications. This review with (155 refs.) summarizes the advances made in the last decade in the field of peptide-GO bioconjugation, and the use of these conjugates in analytical sciences and imaging. The introduction emphasizes the need for understanding the biotic-abiotic interactions in order to construct controllable peptide-functionalized graphitic material-based nanotools. The next section covers covalent and non-covalent interactions between peptide and oxidized graphene derivatives along with a discussion of the adsorption events during interfacing. We then describe applications of peptide-graphene conjugates in bioassays, with subsections on (a) detection of cancer cells, (b) monitoring protease activity, (c) determination of environmental pollutants and (d) determination of pathogenic microorganisms. The concluding section describes the current status of peptide functionalized graphitic bioconjugates and addresses future perspectives. Graphical abstractSchematic representation depicting biosensing applications of peptide functionalized graphene oxide.

Exploratory data analysis of physicochemical parameters of natural antimicrobial and anticancer peptides: Unraveling the patterns and trends for the rational design of novel peptides.

Introduction: Peptide-based research has attained new avenues in the antibiotics and cancer drug resistance era. The basis of peptide design research lies in playing with or altering physicochemical parameters. Here in this work, we have done exploratory data analysis (EDA) of physicochemical parameters of antimicrobial peptides (AMPs) and anticancer peptides (ACPs), two promising therapeutics for microbial and cancer drug resistance to deduce patterns and trends. Methods: Briefly, we have captured the natural AMPs and ACPs data from the APD3 database. After cleaning the data manually and by CD-HIT web server, further data analysis has been done using Python-based packages, modlAMP and Pandas. We have extracted the descriptive statistics of 10 physicochemical parameters of AMPs and ACPs to build a comprehensive dataset containing all major parameters. The global analysis of datasets has been done using modlAMP to find the initial patterns in global data. The subsets of AMPs and ACPs were curated based on the length of the peptides and were analyzed by Pandas package to deduce the graphical profile of AMPs and ACPs. Results: EDA of AMPs and ACPs shows selectivity in the length and amino acid compositions. The distribution of physicochemical parameters in defined quartile ranges was observed in the descriptive statistical and graphical analysis. The preferred length range of AMPs and ACPs was found to be 21-30 amino acids, whereas few outliers in each parameter were evident after EDA analysis. Conclusion: The derived patterns from natural AMPs and ACPs can be used for the rational design of novel peptides. The statistical and graphical data distribution findings will help in combining the different parameters for potent design of novel AMPs and ACPs.

DP1, a multifaceted synthetic peptide: Mechanism of action, activity and clinical potential.

AIMS: Microbial infections remain a leading cause of mortality worldwide, with Staphylococcus aureus (S. aureus) being a prominent etiological agent, responsible for causing persistent bacterial infections in humans. It is a nosocomial, opportunistic pathogen, capable to propagate within the bloodstream and withstand therapeutic interventions. In the current study, a novel, indigenously designed synthetic antimicrobial peptide (sAMP) has been evaluated for its antimicrobial potential to inhibit the growth and proliferation of S. aureus. MAIN METHODS: The sAMP, designed peptide (DP1) was evaluated for its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against a panel of pathogenic bacterial strains. Membrane mechanistic studies were performed by measuring membrane conductivity via dielectric spectroscopy and visualizing changes in bacterial membrane structure through field emission scanning electron microscopy (FE-SEM). Further, DP1 was tested for its in vivo antimicrobial potential in an S. aureus-induced systemic infection model. KEY FINDINGS: The results indicated that DP1 has the potential to inhibit the growth and proliferation of a broad spectrum of Gram-positive, Gram-negative and multidrug-resistant (MDR) bacterial strains. Strong bactericidal effect attributed to change in electrical conductivity of the bacterial cells leading to membrane disruption was observed through dielectric spectroscopy and FE-SEM micrographs. Further, in the in vivo murine systemic infection study, 50 % reduction in S. aureus bioburden was observed within 1 day of the administration of DP1. SIGNIFICANCE: The results indicate that DP1 is a multifaceted peptide with potent bactericidal, antioxidant and therapeutic properties. It holds significance as a novel drug candidate to effectively combat S. aureus-mediated systemic infections.

Strategic Approaches to Improvise Peptide Drugs as Next Generation Therapeutics.

In recent years, the occurrence of a wide variety of drug-resistant diseases has led to an increase in interest in alternate therapies. Peptide-based drugs as an alternate therapy hold researchers' attention in various therapeutic fields such as neurology, dermatology, oncology, metabolic diseases, etc. Previously, they had been overlooked by pharmaceutical companies due to certain limitations such as proteolytic degradation, poor membrane permeability, low oral bioavailability, shorter half-life, and poor target specificity. Over the last two decades, these limitations have been countered by introducing various modification strategies such as backbone and side-chain modifications, amino acid substitution, etc. which improve their functionality. This has led to a substantial interest of researchers and pharmaceutical companies, moving the next generation of these therapeutics from fundamental research to the market. Various chemical and computational approaches are aiding the production of more stable and long-lasting peptides guiding the formulation of novel and advanced therapeutic agents. However, there is not a single article that talks about various peptide design approaches i.e., in-silico and in-vitro along with their applications and strategies to improve their efficacy. In this review, we try to bring different aspects of peptide-based therapeutics under one article with a clear focus to cover the missing links in the literature. This review draws emphasis on various in-silico approaches and modification-based peptide design strategies. It also highlights the recent progress made in peptide delivery methods important for their enhanced clinical efficacy. The article would provide a bird's-eye view to researchers aiming to develop peptides with therapeutic applications.

In Vivo Acute Toxicity and Therapeutic Potential of a Synthetic Peptide, DP1 in a Staphylococcus aureus Infected Murine Wound Excision Model.

Bacterial infections at the surgical sites are one of the most prevalent skin infections that impair the healing mechanism. They account for about 20% of all types of infections and lead to approximately 75% of surgical-site infection-associated mortality. Several antibiotics, such as cephalosporins, fluoroquinolones, quinolones, penicillin, sulfonamides, etc., that are used to treat such wound infections not only counter infections but also disrupt the normal flora. Moreover, antibiotics, when used for a prolonged duration, may impair the formation of new blood vessels, delay collagen production, or inhibit the migration of certain cells involved in wound repair, leading to an impaired healing process. Therefore, there is a dire need for alternate therapeutic approaches against such infections. Antimicrobial peptides have gained considerable attention as a promising strategy to counter these pathogens and prevent the spread of infection. Recently, we have reported a designed peptide, DP1, and its broad-spectrum in vitro antimicrobial activity against Gram-positive and Gram-negative bacteria. In the present study, in vivo acute toxicity of DP1 was evaluated and even at a high dose (20 mg/kg body weight) of DP1, a 100% survival of mice was observed. Subsequently, a Staphylococcus aureus-infected murine wound excision model was established to assess the wound healing efficacy of DP1. The study revealed significant wound healing vis-a-vis attenuated S. aureus bioburden at the wound site and also controlled the oxidative stress depicting anti-oxidant activity as well. Healing of the infected wounds was also verified by histopathological examination. Based on the results of this study, it can be concluded that DP1 improves wound resolution despite infections and promotes the healing mechanism. Hence, DP1 holds compelling potential as a novel antimicrobial drug that requires further explorations in clinical platforms.

In silico analysis of genomic landscape of SARS-CoV-2 and its variant of concerns (Delta and Omicron) reveals changes in the coding potential of miRNAs and their target genes.

COVID-19 related morbidities and mortalities are still continued due to the emergence of new variants of SARS-CoV-2. In the last few years, viral miRNAs have been the centre of study to understand the disease pathophysiology. In this work, we aimed to predict the change in coding potential of the viral miRNAs in SARS-CoV-2's VOCs, Delta and Omicron compared to the Reference (Wuhan origin) strain using bioinformatics tools. After ab-intio based screening by the Vmir tool and validation, we retrieved 22, 6, and 6 pre-miRNAs for Reference, Delta, and Omicron. Most of the predicted unique pre-miRNAs of Delta and Omicron were found to be encoded from the terminal and origin of the genomic sequence, respectively. Mature miRNAs identified by MatureBayes from the unique pre-miRNAs were used for target identification using miRDB. A total of 1786, 216, and 143 high-confidence target genes were captured for GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis. The GO and KEGG pathways terms analysis revealed the involvement of Delta miRNAs targeted genes in the pathways such as Human cytomegalovirus infection, Breast cancer, Apoptosis, Neurotrophin signaling, and Axon guidance whereas the Sphingolipid signaling pathway was found for the Omicron. Furthermore, we focussed our analysis on target genes that were validated through GEO's (Gene Expression Omnibus) DEGs (Differentially Expressed Genes) dataset, in which FGL2, TNSF12, OGN, GDF11, and BMP11 target genes were found to be down-regulated by Reference miRNAs and YAE1 and RSU1 by Delta. Few genes were also observed to be validated among in up-regulated gene set of the GEO dataset, in which MMP14, TNFRSF21, SGMS1, and TMEM192 were related to Reference whereas ZEB2 was detected in all three strains. This study thus provides an in-silico based analysis that deciphered the unique pre-miRNAs in Delta and Omicron compared to Reference. However, the findings need future wet lab studies for validation.

Multidrug resistance crisis during COVID-19 pandemic: Role of anti-microbial peptides as next-generation therapeutics.

The decreasing effectiveness of conventional drugs due to multidrug-resistance is a major challenge for the scientific community, necessitating development of novel antimicrobial agents. In the present era of coronavirus 2 (COVID-19) pandemic, patients are being widely exposed to antimicrobial drugs and hence the problem of multidrug-resistance shall be aggravated in the days to come. Consequently, revisiting the phenomena of multidrug resistance leading to formulation of effective antimicrobial agents is the need of the hour. As a result, this review sheds light on the looming crisis of multidrug resistance in wake of the COVID-19 pandemic. It highlights the problem, significance and approaches for tackling microbial resistance with special emphasis on anti-microbial peptides as next-generation therapeutics against multidrug resistance associated diseases. Antimicrobial peptides exhibit exceptional mechanism of action enabling rapid killing of microbes at low concentration, antibiofilm activity, immunomodulatory properties along with a low tendency for resistance development providing them an edge over conventional antibiotics. The review is unique as it discusses the mode of action, pharmacodynamic properties and application of antimicrobial peptides in areas ranging from therapeutics to agriculture.

Design, characterization and structure-function analysis of novel antimicrobial peptides based on the N-terminal CATH-2 fragment.

The emergence of multidrug resistance coupled with shrinking antibiotic pipelines has increased the demand of antimicrobials with novel mechanisms of action. Therefore, researchers across the globe are striving to develop new antimicrobial substances to alleviate the pressure on conventional antibiotic therapies. Host-Defence Peptides (HDPs) and their derivatives are emerging as effective therapeutic agents against microbial resistance. In this study, five analogs (DP1-5) of the N-terminal (N-15) fragment of CATH-2 were designed based on the delicate balance between various physicochemical properties such as charge, aliphatic character, amphipathicity and hydrophobicity. By means of in-silico and in-vitro studies a novel peptide (DP1) with the sequence "RFGRFLRKILRFLKK" was found to be more effective and less toxic than the N-terminal CATH-2 peptide. Circular dichroism spectroscopy and differential scanning calorimetry were applied for structural insights. Antimicrobial, haemolytic, and cytotoxic activities were also assessed. The resulting peptide was characterized by low cytotoxicity, low haemolytic activity, and efficient anti-microbial activity. Structurally, it displayed strong helical properties irrespective of the solvent environment and was stable in membrane-mimicking environments. Taken together, the data suggests that DP1 can be explored as a promising therapeutic agent with possible clinical applications.

Neuroprotective effects of carbenoxolone against amyloid-beta 1-42 oligomer-induced neuroinflammation and cognitive decline in rats.

The aggregation of Aß plays a major role in the progression of Alzheimer's disease (AD) and induces neuroinflammation, neurodegeneration and cognitive decline. Recent studies have shown that the soluble aggregates of Aß are the major culprits in the development of these aberrations inside the brain. In this study, we investigated the neuroprotective potential of carbenoxolone (Cbx), which has been found to possess anti-inflammatory and nootropic properties. Male SD rats (250-300 g) were divided into the four groups (n = 8 per group): (1) sham control rats injected with vehicles, (2) Aß 1-42 group rats injected i.c.v. with Aß 42 oligomers (10 µl/rat), (3) Aß 1-42+Cbx group rats injected i.c.v. with Aß 42 oligomers (10 µl/rat) and i.p. with carbenoxolone disodium (20 mg/kg body weight) for six-weeks and (4) Cbx group rats injected i.p. with carbenoxolone disodium (20 mg/kg body weight) for six-weeks. Progressive learning and memory deficits were seen through a battery of behavioral tests and a significant increase in the expressions of GFAP and Iba-1 was observed which resulted in the release of pro-inflammatory cytokines post Aß oligomer injection. The levels of BDNF, Bcl-2 and pCREB were decreased while Bax, caspase-3, caspase-9 and cytochrome c levels were induced. Also, neurotransmitter levels were altered and neuronal damage was observed through histopathological studies. After Cbx supplementation, the expressions of GFAP, IBA-1, pro-inflammatory cytokines, iNOS, nNOS and nitric oxide levels were normalized. The expression levels of pro-apoptotic markers were decreased and neurotrophin levels were restored. Also, neurotransmitter levels and neuronal profile were improved and progressive improvements in behavioural performance were observed. Our results demonstrated that Cbx might have prevented the Aß induced neurodegeneration and cognitive decline by inhibiting the neuroinflammation and inducing BDNF/CREB signalling. These findings suggest that Cbx can be explored as a potential therapeutic agent against the progression of AD.

Chemoinformatic Study and In vitro Bioevaluation of Tc-99m-Labeled N-Acetyl Neuraminic Acid in C6 Glioma Cells: Potential Role as a Radionuclide Imaging Probe.

BACKGROUND: To date, the use of sialic acid that are reported to be elevated during malignancy has been largely unexplored for tumor imaging. The purpose of the present study was to study the modeled stable conformers of n-acetyl neuraminic acid (Neu5Ac) and its radiolabeled conjugate (Tc-99m-Neu5Ac) through computational chemistry approach and its in-vitro bioevaluation in rat C6 cell lines. MATERIALS AND METHODS: The Neu5Ac was radiolabeled with Tc-99m using stannous reduction method and the radiochemical purity of Tc-99m-Neu5Ac was determined by instant thin layer chromatography. A Cheminformatic study of Tc-99m-Neu5Ac was performed by using Marvin application of ChemAxon. Glioma cancer cells were taken to evaluate the cytotoxicity and binding efficacy of Tc-99m-Neu5Ac. RESULTS: Cheminformatic studies exhibited that the most stable conformer of Tc-99m-Neu5Ac is 15 kcal/mol more stable energetically over least stable conformer. The radiochemical yield of Tc-99m labeled Neu5Ac was observed to be greater than 90%. Further, the radiolabeled complex (Tc-99m-Neu5Ac)exhibited specificity for C6 glioma with time and concentration dependent cytotoxicity. CONCLUSION: In conclusion, Tc-99m-Neu5Ac has the potential to be exploited as an in-vivo radionuclide probe for tumor imaging.

Maintenance of Amyloid-beta Homeostasis by Carbenoxolone Post Aß-42 Oligomer Injection in Rat Brain.

The equilibrium between cerebral production and clearance of Aß is maintained either by the active removal through blood-brain barrier or by the uptake and degradation through ubiquitin-proteasome system (UPS) and autophagy. The dysfunction of UPS and dysregulation of molecular chaperones such as heat shock proteins (HSPs) is well correlated with the progression of Alzheimer's disease (AD). Therefore, the restoration of heat shock system and UPS appears to be an effective approach to maintain the Aß homeostasis. The alteration in the Aß homeostasis was induced by a single bilateral intrahippocampal injection of Aß 42 oligomers (10 µl/rat) into the dorsal hippocampus of the rat brain. Cbx (carbenoxolone), a HSP inducer and Aß 42 aggregation inhibitor, was tested (20 mg/kg body weight, i.p. for six-weeks) against the altered Aß homeostasis in the rat brain. Aß 42 oligomers downregulated the expression of HSPs and co-treatment with Cbx prevented this decline. Cbx was able to restore the UPS function post Aß 42 oligomer injection. Aß 42 oligomers induced upregulation of the expression levels of APP, BACE-1 and Tau was also normalized after the co-treatment with Cbx. A significant decrease in the thioflavin-T and Aß positive deposits in different regions of the rat brain was observed after Cbx co-treatment. Thus, the present study projects Cbx as a potential candidate for the maintenance of Aß homeostasis through inhibition of amyloid aggregation and restoration of the functioning of molecular chaperones and UPS system in the progression of AD.

Green synthesis of peptide functionalized reduced graphene oxide (rGO) nano bioconjugate with enhanced antibacterial activity.

Bioengineered nanoconjugates have enormous potential as a multifunctional platform for biomedical applications. Conjugation between biotic and abiotic materials enables formulation of nanoconjugates with enhanced physico-chemical properties, increased stability and ability to overcome the inherent shortcomings of individual materials. In this study, we report the preparation and biophysical characterization of an antibacterial system formulated by functionalizing reduced graphene oxide (rGO) with an antimicrobial peptide via covalent as well as non-covalent interaction mechanisms. Environmentally benign synthesis approach was adopted for the formation of rGO, using L-ascorbic acid as a reducing agent. Covalently conjugated peptide-graphitic conjugate displayed improved antibacterial efficacy against Escherichia coli with considerably low cytotoxic activity towards erythrocytes in comparison to self-assembled conjugate and rGO alone. The studies described herein are highly significant in the field of biomaterials and aims to open new avenues of research focusing on a plethora of applications as a prospective non-toxic substitute to conventional antibacterial approaches.

Genome-wide computational prediction of miRNAs in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) revealed target genes involved in pulmonary vasculature and antiviral innate immunity.

The current outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in China threatened humankind worldwide. The coronaviruses contains the largest RNA genome among all other known RNA viruses, therefore the disease etiology can be understood by analyzing the genome sequence of SARS-CoV-2. In this study, we used an ab-intio based computational tool VMir to scan the complete genome of SARS-CoV-2 to predict pre-miRNAs. The potential pre-miRNAs were identified by ViralMir and mature miRNAs were recognized by Mature Bayes. Additionally, predicted mature miRNAs were analysed against human genome by miRDB server to retrieve target genes. Besides that we also retrieved GO (Gene Ontology) terms for pathways, functions and cellular components. We predicted 26 mature miRNAs from genome of SARS-CoV-2 that targets human genes involved in pathways like EGF receptor signaling, apoptosis signaling, VEGF signaling, FGF receptor signaling. Gene enrichment tool analysis and substantial literature evidences suggests role of genes like BMPR2 and p53 in pulmonary vasculature and antiviral innate immunity respectively. Our findings may help research community to understand virus pathogenesis.

Carbenoxolone Reverses the Amyloid Beta 1-42 Oligomer-Induced Oxidative Damage and Anxiety-Related Behavior in Rats.

The characteristic feature of Alzheimer's disease (AD) is the deposition of amyloid beta inside the brain mainly consisting of Aß 40 and 42 aggregates. Soluble aggregates of Aß 42 are reported to be more toxic and exert their neurotoxicity by the induction of oxidative damage and cognitive deficits such as anxiety-like behavior. These alterations emerge due to the induction of gap junction communication through increased activity and expression of connexins such as connexin43 (Cx43) leading to the release of small neurotoxic molecules. In the present study, single intracerebroventricular (icv) injection of Aß 42 oligomers (10 µl/rat) was used to induce oxidative damage and anxiety-related behavior in rats. Carbenoxolone (Cbx), a gap junction blocker, was tested (20 mg/kg body weight, i.p., for 6 weeks) against these alterations. Cbx supplementation reversed the Aß 42 oligomer-induced alterations in the antioxidant defense system. The levels ROS, lipid peroxidation, and protein carbonyls were normalized with Cbx co-treatment leading to the decreased DNA fragmentation and pyknosis in different regions of the rat brain. Cbx induced the anxiolytic behavior and ameliorated the cognitive decline in rats post Aß 42 oligomer injection. The increased expression of Cx43 post Aß 42 oligomer injection was also reduced with Cbx supplementation, which might have inhibited the release of small neurotoxic molecules. Our results showed that Cbx prevents the Aß 42 oligomer-induced oxidative damage and anxiety-like behavior partly by blocking the gap junction communication, which suggests that the therapeutic potential of Cbx may be explored in the progression of AD.

Construction and design of single stranded collagen-like structure.

Polytheonamide B, a 48 residue long highly cytotoxic polypeptide extracted from marine sponges contains amino acids of alternate chirality and the N-terminal region is rich in t-Leu residues. The aim of this study is to analyze the effect of these alternate chiralities and conformational behavior of various model peptides containing t-Leu, in order to explore their role in designing bioactive peptides that shall offer advantages comparable to polytheonamide B, while circumventing its limitations. The conformational behavior of various peptides constructed from t-Leu of the form Ac-(L/D-X-L/D-Y)n-NHMe, where X = Gly/Ala/Leu and Y = t-Leu has been studied and compared with the corresponding peptides containing Leu residue. The results show that the helix driving capacity of L and D forms of t-Leu is less than that of Leu residue. In poly t-Leu peptides, the population of collagen/inverse collagen-type structures or right/left handed-helical structures for L and D forms respectively is found to be chain length-dependent. The stability of the helical structures is increased by -2 kcal per residue over the collagen-type structure in poly t-Leu peptides with chain length greater than five residues. Molecular view of peptides in collagen-type structure shows that the bulky side chains of t-Leu residues mask the NH moieties of the peptide bond, while the carbonyl groups lying along the helical groove are accessible to the small solvent molecules. Molecular model building suggests that one ethylene glycol molecule interacts by forming hydrogen bonds with carbonyl groups of two adjacent t-Leu residues. To the best of our knowledge, this is the first study of its own kind on the construction of a single-strand collagen/inverse collagen-type structure using unusual amino acid residues. Such synthetic collagen mimetic peptides shall exhibit specific affinity to natural collagen under controlled thermal conditions (heat or laser treatment) and hence can be explored as a new targeting method to attach therapeutic drugs to collagens in the living tissues and to biomaterials that incorporate natural collagens.

Inhibition of Alzheimer's amyloid-beta aggregation in-vitro by carbenoxolone: Insight into mechanism of action.

BACKGROUND: The major hallmark of Alzheimer's disease (AD) is the formation of amyloid aggregates, which are formed due to improper folding of proteins leading to the aggregation of amyloid beta (Aß) 42 peptide. Inhibition of Aß 42 aggregation using a drug such as carbenoxolone (Cbx), which has already been stated as neuroprotective, appears to be an effective approach against AD. OBJECTIVE: The present study was designed to investigate the anti-fibrillation activity of Cbx against the Aß 42 aggregation. METHODS: The aggregation of Aß 42 peptide was observed by performing in-vitro studies and the propensity of aggregation of Aß 42 peptide was evaluated by the prediction of binding sites and amyloidogenic regions. The binding of Cbx in these binding sites was predicted by computational studies. RESULTS: Thioflavin-T (Th-T assay), congo red assay and circular dichroism (CD) analysis suggested significant inhibition of Aß 42 aggregation by Cbx. The propensity of aggregation of Aß 42 peptide was evaluated by the prediction of binding sites and amyloidogenic regions. The mechanism of anti-fibrillation activity of Cbx was elucidated by molecular docking and simulation studies and has been predicted to interact with amyloidogenic residues of Aß 42 peptides as well as fibrils. Cbx also interacts with residues involved in the stabilization of the oligomeric structure. CONCLUSION: These results project Cbx as a suitable candidate for the inhibition of Aß 42 aggregation and the therapeutic potential of Cbx against AD can further be studied using in-vivo experiments.

Alzheimer's disease like pathology induced six weeks after aggregated amyloid-beta injection in rats: increased oxidative stress and impaired long-term memory with anxiety-like behavior.

OBJECTIVES: Amyloid-beta (Aß) peptide deposition into insoluble plaques is a pathological hallmark of Alzheimer's disease (AD), but soluble oligomeric Aß is considered to be more potent and has been hypothesized to directly impair learning and memory. Also, evidences from some clinical studies indicated that Aß oligomer formation is the major cause for early AD onset. However, the biochemical mechanism involved in the oligomer-induced toxicity is not very well addressed. So, thise present study was undertaken to study the effects of single intracerebroventricular (icv) injection of protofibrillar Aß 1-42 on the behavioral and biochemical profile in rats. METHODS: Rats were divided into two groups (n = 8 per group): (1) sham control group and (2) Aß 1-42 injected group. A single dose of protofibrillar Aß 1-42 (5 ul) through icv injection was bilaterally administered into the dorsal hippocampus, while sham control animals were administered with 5 µl of vehicle. RESULTS: The results demonstrated that the protofibrillar Aß significantly inhibited long-term memory retention and increased anxiety levels as shown by the behavioral studies. The amyloid deposits were present inside the brain even six weeks after injection as confirmed by thioflavin-T staining and the neurodegeneration induced by these deposits was confirmed by Nissl's staining in hippocampal and cortical regions. The amyloid aggregates induced reactive oxygen species (ROS) production, acetylcholinesterase activity, nitrite levels, lipid peroxidation, and inhibited antioxidant enzyme activity in hippocampus, cortex, and striatum regions of rat brain after six weeks. DISCUSSION: The present study indicated that protofibrillar Aß 1-42 injection altered long term memory, induced anxiety-like behavior and also developed Alzheimer's disease like pathology in rats.

Construction and conformational behavior of peptoids with cis-amide bond geometry: design of a peptoid with alternate φ, ψ values of inverse PP-II/PP-II and PP-I structures.

In peptoids due to the absence of amide protons, the backbone is devoid of hydrogen bond donor, linked by tertiary amide, which can be iso-energetic between cis and trans-amide bond geometry. The peptoids can be realized with cis amide bond if the side chain of ith residue can engage the carbonyl group of ith-1 residue in CH--O interactions. Simulations studies both in water and DMSO have been carried out. The peptoid Ac-(N(tle))(7) -NMe(2) can adopt degenerate conformations with alternate φ, ψ values of inverse PP-I and PP-I type structure's, or vice versa in water. In DMSO, Ac-(N(tle))(7)-NMe(2) also adopts inverse PP-I type structure. Like polyproline, molecule adopting a rigid structure can be used as molecular markers or spacers in biological studies.The peptoid Ac-(N(ala)-N(tle))(3)-NMe(2) with alternate trans and cis amide bond geometry for N(ala) and N(tle) residue corresponding to inverse PP-II/PP-II type and for N(tle) residue of PP-I type.