Polypharmacological repurposing approach identifies approved drugs as potential inhibitors of Mycobacterium tuberculosis.

Mycobacterium tuberculosis (M. tb), the causative pathogen of tuberculosis (TB) remains the leading cause of death from single infectious agent. Furthermore, its evolution to multi-drug resistant (MDR) and extremely drug-resistant (XDR) strains necessitate de novo identification of drug-targets/candidates or to repurpose existing drugs against known targets through drug repurposing. Repurposing of drugs has gained traction recently where orphan drugs are exploited for new indications. In the current study, we have combined drug repurposing with polypharmacological targeting approach to modulate structure-function of multiple proteins in M. tb. Based on previously established essentiality of genes in M. tb, four proteins implicated in acceleration of protein folding (PpiB), chaperone assisted protein folding (MoxR1), microbial replication (RipA) and host immune modulation (S-adenosyl dependent methyltransferase, sMTase) were selected. Genetic diversity analyses in target proteins showed accumulation of mutations outside respective substrate/drug binding sites. Using a composite receptor-template based screening method followed by molecular dynamics simulations, we have identified potential candidates from FDA approved drugs database; Anidulafungin (anti-fungal), Azilsartan (anti-hypertensive) and Degarelix (anti-cancer). Isothermal titration calorimetric analyses showed that the drugs can bind with high affinity to target proteins and interfere with known protein-protein interaction of MoxR1 and RipA. Cell based inhibitory assays of these drugs against M. tb (H37Ra) culture indicates their potential to interfere with pathogen growth and replication. Topographic assessment of drug-treated bacteria showed induction of morphological aberrations in M. tb. The approved candidates may also serve as scaffolds for optimization to future anti-mycobacterial agents which can target MDR strains of M. tb.

Fungus mediated synthesis of biogenic palladium catalyst for degradation of azo dye.

Dyes are the coloured substances that are applied on different substrates such as textiles, leather and paper products, etc. Azo dyes release from the industries are toxic and recalcitrant wastewater pollutants, therefore it is necessary to degrade these pollutants from water. In this study, the palladium (0) nanoparticles (PdNPs) were generated through the biological process and exhibited for the catalytic degradation of azo dye. The palladium nanoparticles (PdNPs) were synthesized by using the cell-free approach i.e. extract of fungal strain Rhizopus sp. (SG-01), which significantly degrade the azo dye (methyl orange). The amount of catalyst was optimized by varying the concentration of PdNPs (1 mg/mL to 4 mg/mL) for 10 mL of 50 ppm methyl orange (MO) dye separately. The time dependent study demonstrates the biogenic PdNPs could effectively degrade the methyl orange dye up to 98.7% with minimum concentration (3 mg/mL) of PdNPs within 24 h of reaction. The long-term stability and effective catalytic potential up to five repeated cycles of biogenic PdNPs have good significance for acceleration the degradation of azo dyes. Thus, the use of biogenic palladium nanoparticles for dye degradation as outlined in the present study can provide an alternative and economical method for the synthesis of PdNPs as well as degradation of azo dyes present in wastewater and is helpful to efficiently remediate textile effluent.

Glycosylation of a key cubilin Asn residue results in reduced binding to albumin.

Kidney disease often manifests with an increase in proteinuria, which can result from both glomerular and/or proximal tubule injury. The proximal tubules are the major site of protein and peptide endocytosis of the glomerular filtrate, and cubilin is the proximal tubule brush border membrane glycoprotein receptor that binds filtered albumin and initiates its processing in proximal tubules. Albumin also undergoes multiple modifications depending upon the physiologic state. We previously documented that carbamylated albumin had reduced cubilin binding, but the effects of cubilin modifications on binding albumin remain unclear. Here, we investigate the cubilin-albumin binding interaction to define the impact of cubilin glycosylation and map the key glycosylation sites while also targeting specific changes in a rat model of proteinuria. We identified a key Asn residue, N1285, that when glycosylated reduced albumin binding. In addition, we found a pH-induced conformation change may contribute to ligand release. To further define the albumin-cubilin binding site, we determined the solution structure of cubilin's albumin-binding domain, CUB7,8, using small-angle X-ray scattering and molecular modeling. We combined this information with mass spectrometry crosslinking experiments of CUB7,8 and albumin that provides a model of the key amino acids required for cubilin-albumin binding. Together, our data supports an important role for glycosylation in regulating the cubilin interaction with albumin, which is altered in proteinuria and provides new insight into the binding interface necessary for the cubilin-albumin interaction.

Evolutionarily conserved heat shock protein, HtpX, as an adjunct target against antibiotic-resistant Neisseria gonorrhoeae.

The emergence of multiple drug resistance and extreme drug resistance pathogens necessitates the continuous evaluation of the pathogenic genome to identify conserved molecular targets and their respective inhibitors. In this study, we mapped the global mutational landscape of Neisseria gonorrhoeae (an intracellular pathogen notoriously known to cause the sexually transmitted disease gonorrhoea). We identified highly variable amino acid positions in the antibiotic target genes like the penA, ponA, 23s rRNA, rpoB, gyrA, parC, mtrR and porB. Some variations are directly reported to confer resistance to the currently used front-line drugs like ceftriaxone, cefixime, azithromycin and ciprofloxacin. Further, by whole genome comparison and Shannon entropy analysis, we identified a completely conserved protein HtpX in the drug-resistant as well as susceptible isolates of N. gonorrhoeae (NgHtpX). Comparison with the only available information of Escherichia coli HtpX suggested it to be a transmembrane metalloprotease having a role in stress response. The critical zinc-binding residue of NgHtpX was mapped to E141. By applying composite high throughput screening followed by MD simulations, we identified pemirolast and thalidomide as high-energy binding ligands of NgHtpX. Following cloning and expression of the purified metal-binding domain of NgHtpX (NgHtpXd), its Zn2+ -binding (Kd = 0.4 µM) and drug-binding (pemirolast, Kd = 3.47 µM; and thalidomide, Kd = 1.04 µM) potentials were determined using in-vitro fluorescence quenching experiment. When tested on N. gonorrhoeae cultures, both the ligands imposed a dose-dependent reduction in viability. Overall, our results provide high entropy positions in the targets of presently used antibiotics, which can be further explored to understand the AMR mechanism. Additionally, HtpX and its specific inhibitors identified can be utilised effectively in managing gonococcal infections.

Computational Screening of Neuropilin-1 Unveils Novel Potential Anti-SARS-CoV-2 Therapeutics.

Neuropilin 1 (NRP-1) inhibition has shown promise in reducing the infectivity of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) and preventing the virus entry into nerve tissues, thereby mitigating neurological symptoms in COVID-19 patients. In this study, we employed virtual screening, including molecular docking, Molecular Dynamics (MD) simulation, and Molecular Mechanics-Poisson Boltzmann Surface Area (MM-PBSA) calculations, to identify potential NRP-1 inhibitors. From a compendium of 1930 drug-like natural compounds, we identified five potential leads: CNP0435132, CNP0435311, CNP0424372, CNP0429647, and CNP0427474, displaying robust binding energies of -8.2, -8.1, -10.7, -8.2, and -8.2 kcal/mol, respectively. These compounds demonstrated interactions with critical residues Tyr297, Trp301, Thr316, Asp320, Ser346, Thr349, and Tyr353 located within the b1 subdomain of NRP-1. Furthermore, MD simulations and MM-PBSA calculations affirmed the stability of the complexes formed, with average root mean square deviation, radius of gyration, and solvent accessible surface area values of 0.118 nm, 1.516 nm, and 88.667 nm2 , respectively. Notably, these lead compounds were estimated to penetrate the blood-brain barrier and displayed antiviral properties, with Pa values ranging from 0.414 to 0.779. The antagonistic effects of these lead compounds merit further investigation, as they hold the potential to serve as foundational scaffolds for the development of innovative therapeutics aimed at reducing the neuroinfectivity of SARS-CoV-2.

Adhesions Detection and Staging Classification for Preoperative Assessment of Difficult Laparoscopic Cholecystectomies: A Prospective Case-Control Study.

Background: Laparoscopic cholecystectomy (LC) is the treatment of choice for cholelithiasis; however, there are procedural difficulties in determining preoperative detection of a difficult LC. The current methods using clinical and sonographic variables to identify difficult LCs have limitations to identify gallbladder adhesions which form the most common cause. We present a new method of evaluation using acoustic radiation force impulse (ARFI)-based virtual touch imaging (VTI) for the detection and classification of these patients. Methods: Fifty consecutive patients of cholelithiasis were evaluated preoperatively using conventional scoring system (CSS) and by new adhesion detection and staging (ADS) system, and patients were classified into three classes (I-III) with class I being easy, II and III being moderate-to-high difficulty LCs. Peroperative classification was done based on the difficulty level during surgery after visualization of gallbladder adhesions. The sensitivity, specificity, and area under the curves (AUCs) of both systems were compared. Results: Out of 50 patients, 72% and 54% of patients were in class I by CSS and ADS classification, while 28% and 46% were in class II and III, respectively, and were labeled as difficult LC cases; differences being two classifications were statistically significant (P = 0.02). Sensitivity, specificity, negative predictive value, and accuracy for ADS were 91%, 100%, 93.1%, and 96.0%, and for CSS, 60.9%, 100%, 75%, and 82% with AUCs of 1.0 and 0.63, respectively. Conclusion: ARFI-based VTI accurately detects gallbladder adhesions and can determine the difficult cases of LCs preoperatively using ADS classification and shows higher accuracy than CSS classification, which results in lower operative time and risk of complications.

Energetics of Spike Protein Opening of SARS-CoV-1 and SARS-CoV-2 and Its Variants of Concern: Implications in Host Receptor Scanning and Transmission.

The receptor binding domain(s) (RBD) of spike (S) proteins of SARS-CoV-1 and SARS-CoV-2 (severe acute respiratory syndrome coronavirus) undergoes closed to open transition to engage with host ACE2 receptors. In this study, using multi atomistic (equilibrium) and targeted (non-equilibrium) molecular dynamics simulations, we have compared energetics of RBD opening pathways in full-length (modeled from cryo-EM structures) S proteins of SARS-CoV-1 and SARS-CoV-2. Our data indicate that amino acid variations at the RBD interaction interface can culminate into distinct free energy landscapes of RBD opening in these S proteins. We further report that mutations in the S protein of SARS-CoV-2 variants of concern can reduce the protein-protein interaction affinity of RBD(s) with its neighboring domains and could favor its opening to access ACE2 receptors. The findings can also aid in predicting the impact of future mutations on the rate of S protein opening for rapid host receptor scanning.

Antimicrobial-resistant Neisseria gonorrhoeae can be targeted using inhibitors against evolutionary conservedl-asparaginase.

The emergence of multiple drug-resistant "super gonorrhoea" complicates the management and treatment of Neisseria gonorrhoeae infections due to the progressive accumulation of mutations in the biological targets of frontline antimicrobials. Continuous evaluation and reporting of newer molecular targets and their inhibitors are necessary. Here, we present l-asparaginase of N. gonorrhoeae (NgA) as a new molecular target based on structure-based high-throughput screening, molecular dynamics(MD) simulations, and validation by biophysical, biochemical, and cell viability assays. We observed that the NgA is evolutionarily conserved in both the drug-resistant and susceptible strains of N. gonorrhoeae, indicating its importance in the growth and survival of the pathogen. Three Food and Drug Administration-approved drugs, pemirolast, thalidomide, and decitabine, were identified as potential inhibitors of NgA using high-throughput screening. The binding energies of the drugs with NgA were -20.14, -19.67, and -16.47 kcal/mol, respectively, compared to -6.82 ± 1.46 for enzyme-substrate l-Asn, as obtained through MD simulations. Subsequently, fluorescence quenching and differential scanning calorimetry experiments validated the in silico data. The observance of inhibition of NgA activity at micromolar drug concentrations further strengthened our findings. Conclusive evidence came from the cell viability assays where these drugs were found to impede the growth of N. gonorrhoeae culture effectively. Thus, our study establishes l-asparaginase as a new molecular target against gonococcal infections. From this study, we propose that targeting of NgA can be explored to control N. gonorrhoeae infections in combination therapy.

Berberine Ameliorate Haloperidol and 3-Nitropropionic Acid-Induced Neurotoxicity in Rats.

Berberine due to its antioxidant properties, has been used around the globe significantly to treat several brain disorders. Also, oxidative stress is a pathological hallmark in neurodegenerative diseases like Huntington's disease (HD) and Tardive dyskinesia (TD). Berberine an alkaloid from plants has been reported to have neuroprotective potential in several animal models of neurodegenerative diseases. Hence, this study aims to evaluate the neuroprotective effect of berberine in the animal model of 3-nitropropionic acid (3-NP) induced HD and haloperidol induced tardive dyskinesia with special emphasis on its antioxidant property. The study protocol was divided into 2 phases, first phase involved the administration of 3-NP and berberine at the dose of (25, 50, and 100 mg/kg) intraperitoneally (i.p) and orally (p.o.) respectively for 21 days, and the following parameters (rotarod, narrow beam walk and photoactometer) as a measure of motor activity and striatal and cortical levels of (LPO, GSH, SOD, catalase, and nitrate) evaluated as a measure of oxidative stress were assessed for HD. Similarly in the second phase, TD was induced by using haloperidol, for 21 days and berberine at the dose of (25, 50, and 100 mg/kg) was administered, and both physical and biochemical parameters were assessed as mentioned for the HD study. The resultant data indicated that berberine attenuate 3-NP and haloperidol-induced behavioral changes and improved the antioxidant capcity in rodents. Hence berberine might be a novel therapeutic candidate to manage TD & HD.

Possible Link between Higher Transmissibility of Alpha, Kappa and Delta Variants of SARS-CoV-2 and Increased Structural Stability of Its Spike Protein and hACE2 Affinity.

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) outbreak in December 2019 has caused a global pandemic. The rapid mutation rate in the virus has created alarming situations worldwide and is being attributed to the false negativity in RT-PCR tests. It has also increased the chances of reinfection and immune escape. Recently various lineages namely, B.1.1.7 (Alpha), B.1.617.1 (Kappa), B.1.617.2 (Delta) and B.1.617.3 have caused rapid infection around the globe. To understand the biophysical perspective, we have performed molecular dynamic simulations of four different spikes (receptor binding domain)-hACE2 complexes, namely wildtype (WT), Alpha variant (N501Y spike mutant), Kappa (L452R, E484Q) and Delta (L452R, T478K), and compared their dynamics, binding energy and molecular interactions. Our results show that mutation has caused significant increase in the binding energy between the spike and hACE2 in Alpha and Kappa variants. In the case of Kappa and Delta variants, the mutations at L452R, T478K and E484Q increased the stability and intra-chain interactions in the spike protein, which may change the interaction ability of neutralizing antibodies to these spike variants. Further, we found that the Alpha variant had increased hydrogen interaction with Lys353 of hACE2 and more binding affinity in comparison to WT. The current study provides the biophysical basis for understanding the molecular mechanism and rationale behind the increase in the transmissivity and infectivity of the mutants compared to wild-type SARS-CoV-2.

PGRS Domain of Rv0297 of Mycobacterium tuberculosis Functions in A Calcium Dependent Manner.

Mycobacterium tuberculosis (M.tb), the pathogen causing tuberculosis, is a major threat to human health worldwide. Nearly 10% of M.tb genome encodes for a unique family of PE/PPE/PGRS proteins present exclusively in the genus Mycobacterium. The functions of most of these proteins are yet unexplored. The PGRS domains of these proteins have been hypothesized to consist of Ca2+ binding motifs that help these intrinsically disordered proteins to modulate the host cellular responses. Ca2+ is an important secondary messenger that is involved in the pathogenesis of tuberculosis in diverse ways. This study presents the calcium-dependent function of the PGRS domain of Rv0297 (PE_PGRS5) in M.tb virulence and pathogenesis. Tandem repeat search revealed the presence of repetitive Ca2+ binding motifs in the PGRS domain of the Rv0297 protein (Rv0297PGRS). Molecular Dynamics simulations and fluorescence spectroscopy revealed Ca2+ dependent stabilization of the Rv0297PGRS protein. Calcium stabilized Rv0297PGRS enhances the interaction of Rv0297PGRS with surface localized Toll like receptor 4 (TLR4) of macrophages. The Ca2+ stabilized binding of Rv0297PGRS with the surface receptor of macrophages enhances its downstream consequences in terms of Nitric Oxide (NO) production and cytokine release. Thus, this study points to hitherto unidentified roles of calcium-modulated PE_PGRS proteins in the virulence of M.tb. Understanding the pathogenic potential of Ca2+ dependent PE_PGRS proteins can aid in targeting these proteins for therapeutic interventions.

Plasma Fibrinogen: An Independent Predictor of Pediatric Appendicitis.

AIMS: Appendicitis, in spite of all the diagnostic advances, achieving an accurate and timely diagnosis of this common condition in children remains a challenge. Plasma fibrinogen (FB) is an acute inflammatory mediator and has been proposed and evaluated as an adjunct laboratory marker for improving diagnostic accuracy. The study evaluates the plasma values of Se FB along with other serum markers in pediatric appendicitis patients, to determine their diagnostic accuracy. METHODS: Prospective observational study on 120 patients between the age group of 5 and 12 years. All eligible enrolled cases underwent total leukocyte count (TLC), plasma FB, C reactive protein (CRP), neutrophil-lymphocyte ratio (NLR), absolute neutrophil count (ANC), and erythrocyte sedimentation rate on admission along with pediatric appendicitis score. Final confirmation of diagnosis and allotment of cohort was made by intra operative findings and histopathological confirmation. Two groups were defined: (1) Histopathologically confirmed acute appendicitis-Cases (2) Nonspecific abdominal pain-Controls. Laboratory results were statistically analyzed between the case and the control groups for diagnostic accuracy. RESULTS: Study reflected strong statistical significance in terms of leukocyte count, ANC, NLR, CRP, and FB levels. However, plasma FB (value above 4.02 g/L) had the highest diagnostic accuracy rate of 82.50% compared to other laboratory values (TLC-70.83%, CRP-70.00%). CONCLUSION: Plasma FB has emerged as an accurate diagnostic tool and its diagnostic accuracy is superior to all other laboratory parameter studied (TLC, CRP, NLR, and ANC). Plasma FB values above 4.02 g/L is an independent predictor of appendicitis and can help in reducing negative laparotomy in pediatric age group.

A single-center experience in use of tocilizumab in COVID-19 pneumonia in India.

BACKGROUND: IL-6 receptor antagonist tocilizumab (TCZ) has been used in several reported studies in the treatment of COVID-19 pneumonia and pieces of evidence are still emerging. METHODS: All patients with COVID-19 pneumonia showing features of hyperinflammatory syndrome receiving TCZ at a tertiary care center in India were included in the study and a retrospective descriptive analysis was done. RESULTS: Between May 2020 to August 2020, 21 patients received TCZ out of which 13 survived and 8 died. All non-survivors had longer duration (median 12 days, minimum 9, maximum 15 days compared to median 6 days, minimum 3 and maximum 14 days in survivors) of symptoms and severe disease requiring mechanical ventilation at the time of TCZ administration. Among survivors, 8 patients had severe disease, 3 had moderate disease, and 2 patients had mild disease. Six out of 8 (75%) among non-survivors and 8 out of 13 (62%) among survivors had preexisting medical comorbidities. The non-survivors had higher baseline neutrophil-to-leukocyte ratio (10.5 vs 8.8), serum ferritin (960 ng/ml vs 611 ng/ml), lactate dehydrogenase (795 IU/L vs 954 IU/L), and D-dimer (5900 µg/ml vs 1485 mg/ml) levels. No drug-related serious adverse effect was noted among the patients. CONCLUSION: In a scenario of emerging evidence for the role of TCZ in the management of severe COVID-19, our study provides useful data on its use in the Indian scenario. Deliberate patient selection and timing initiation of TCZ at a crucial stage of the disease may be beneficial in COVID-19 pneumonia with good safety returns.

Effect of encapsulated vitamin E on physical, storage and retention parameters in cookies.

Microencapsulated α-tocopherol and wheat germ oil (WGO) were incorporated as WGO (5.0 ml) in liquid: WGO-L, encapsulated: WGO-E, encapsulated α-tocopherol as E1, E2 and E3 at 2.0, 3.0 and 4.0 g respectively in cookies and evaluated for physical, sensory and shelf life parameters. Spread ratio was decreased, whereas hardness was increased with encapsulated formulations and observed least in WGO-L (40.52 N) formulated cookies. During storage moisture content was observed increased (2.51-4.78%), vitamin E was retained in all formulations except WGO-L and was found maximum in E3 (4.45 mg/100 g) formulated cookies. Formulations brought the peroxide value to nil, free fatty acid development was very less, better antioxidant activity (41.1% maximum), total plate count was observed least in E3 (25 × 102 cfu/g) and good sensory acceptance of cookies up to 4 months of storage. The study concluded that encapsulated vitamin E elevated the antioxidant activity and consequently shelf life and nutritive value of cookies.

Identification and validation of l-asparaginase as a potential metabolic target against Mycobacterium tuberculosis.

Multidrug-resistant Mycobacterium tuberculosis (Mtb) has emerged as a major health challenge, necessitating the search for new molecular targets. A secretory amidohydrolase, l-asparaginase of Mtb (MtA), originally implicated in nitrogen assimilation and neutralization of acidic microenvironment inside human alveolar macrophages, has been proposed as a crucial metabolic enzyme. To investigate whether this enzyme could serve as a potential drug target, it was studied for structural details and active site-specific inhibitors were tested on cultured Mycobacterial strain. The structural details of MtA obtained through comparative modeling and molecular dynamics simulations provided insights about the orchestration of an alternate reaction mechanism at the active site. This was contrary to the critical Tyr flipping mechanism reported in other asparaginases. We report the novel finding of Tyr to Val replacement in catalytic triad I along with the structural reorganization of a ß-hairpin loop upon substrate binding in MtA active site. Further, 5 MtA-specific, active-site-based inhibitors were obtained by following a rigorous differential screening protocol. When tested on Mycobacterium culture, 3 of these, M3 (ZINC 4740895), M26 (ZINC 33535), and doxorubicin showed promising results with inhibitory concentrations (IC 50 ) of 431, 100, and 56 µM, respectively. Based on our findings and considering stark differences with human asparaginase, we project MtA as a promising molecular target against which the selected inhibitors may be used to counteract Mtb infection effectively.

Genetic modification in Malaysia and India: current regulatory framework and the special case of non-transformative RNAi in agriculture.

Recent developments in modern biotechnology such as the use of RNA interference (RNAi) have broadened the scope of crop genetic modification. RNAi strategies have led to significant achievements in crop protection against biotic and abiotic stresses, modification of plant traits, and yield improvement. As RNAi-derived varieties of crops become more useful in the field, it is important to examine the capacity of current regulatory systems to deal with such varieties, and to determine if changes are needed to improve the existing frameworks. We review the biosafety frameworks from the perspective of developing countries that are increasingly involved in modern biotechnology research, including RNAi applications, and make some recommendations. Malaysia and India have approved laws regulating living modified organisms and products thereof, highlighting that the use of any genetically modified step requires regulatory scrutiny. In view of production methods for exogenously applied double-stranded RNAs and potential risks from the resulting double-stranded RNA-based products, we argue that a process-based system may be inappropriate for the non-transformative RNAi technology. We here propose that the current legislation needs rewording to take account of the non-transgenic RNAi technology, and discuss the best alternative for regulatory systems in India and Malaysia in comparison with the existing frameworks in other countries.

The Gelsolin Pathogenic D187N Mutant Exhibits Altered Conformational Stability and Forms Amyloidogenic Oligomers.

Gelsolin is an actin-severing protein that attains an open functional conformation in the presence of Ca2+ or low pH. Mutations (D187N/Y) in the second domain of gelsolin trigger the proteolytic pathway producing amyloidogenic fragments that form the pathological hallmark of gelsolin amyloidosis and lattice corneal dystrophy type 2 (LCD2). Here, we show that the D187N mutant gelsolin in a Ca2+ depleted, low pH-activated, open conformation could assemble into amyloidogenic oligomers without necessarily undergoing the specific proteolytic step. Although both wild-type (WT) and mutant proteins exhibit closely overlapping globular shapes at physiological conditions, the latter exhibits subjugated actin depolymerization, loss of thermodynamic stability, and folding cooperativity. Mutant gelsolin displayed aberrant conformational unwinding and formed structural conformers with high associative properties at low pH conditions. A SAXS intensity profile and Guinier analysis of these conformers showed the formation of unusual, higher order aggregates. Extended incubation at low pH resulted in the formation of thioflavin T and Congo red positive, ß-sheet rich aggregates with a fibrillar, amyloid-like morphology visible under electron and atomic force microscopy. Mass spectrometric analysis of disaggregated end-stage fibrils displayed peptide fragments encompassing the entire protein sequence, indicating the involvement of full length mutant gelsolin in fibril formation. Atomistic and REMD simulations indicated a larger increase in solvent accessibility and loss of fold architecture in mutant gelsolin at low pH as compared to WT gelsolin. Our findings support the existence of a secondary oligomerization-dependent aggregation pathway associated with gelsolin amyloidosis and can pave the way for better therapeutic strategies.

Arjunolic acid, a peroxisome proliferator-activated receptor α agonist, regresses cardiac fibrosis by inhibiting non-canonical TGF-ß signaling.

Cardiac hypertrophy and associated heart fibrosis remain a major cause of death worldwide. Phytochemicals have gained attention as alternative therapeutics for managing cardiovascular diseases. These include the extract from the plant Terminalia arjuna, which is a popular cardioprotectant and may prevent or slow progression of pathological hypertrophy to heart failure. Here, we investigated the mode of action of a principal bioactive T. arjuna compound, arjunolic acid (AA), in ameliorating hemodynamic load-induced cardiac fibrosis and identified its intracellular target. Our data revealed that AA significantly represses collagen expression and improves cardiac function during hypertrophy. We found that AA binds to and stabilizes the ligand-binding domain of peroxisome proliferator-activated receptor α (PPARα) and increases its expression during cardiac hypertrophy. PPARα knockdown during AA treatment in hypertrophy samples, including angiotensin II-treated adult cardiac fibroblasts and renal artery-ligated rat heart, suggests that AA-driven cardioprotection primarily arises from PPARα agonism. Moreover, AA-induced PPARα up-regulation leads to repression of TGF-ß signaling, specifically by inhibiting TGF-ß-activated kinase1 (TAK1) phosphorylation. We observed that PPARα directly interacts with TAK1, predominantly via PPARα N-terminal transactivation domain (AF-1) thereby masking the TAK1 kinase domain. The AA-induced PPARα-bound TAK1 level thereby shows inverse correlation with the phosphorylation level of TAK1 and subsequent reduction in p38 MAPK and NF-κBp65 activation, ultimately culminating in amelioration of excess collagen synthesis in cardiac hypertrophy. In conclusion, our findings unravel the mechanism of AA action in regressing hypertrophy-associated cardiac fibrosis by assigning a role of AA as a PPARα agonist that inactivates non-canonical TGF-ß signaling.

Modulation of prion polymerization and toxicity by rationally designed peptidomimetics.

Misfolding and aggregation of cellular prion protein is associated with a large array of neurological disorders commonly called the transmissible spongiform encephalopathies. Designing inhibitors against prions has remained a daunting task owing to limited information about mechanism(s) of their pathogenic self-assembly. Here, we explore the anti-prion properties of a combinatorial library of bispidine-based peptidomimetics (BPMs) that conjugate amino acids with hydrophobic and aromatic side chains. Keeping the bispidine unit unaltered, a series of structurally diverse BPMs were synthesized and tested for their prion-modulating properties. Administration of Leu- and Trp-BPMs delayed and completely inhibited the amyloidogenic conversion of human prion protein (HuPrP), respectively. We found that each BPM induced the HuPrP to form unique oligomeric nanostructures differing in their biophysical properties, cellular toxicities and response to conformation-specific antibodies. While Leu-BPMs were found to stabilize the oligomers, Trp-BPMs effected transient oligomerization, resulting in the formation of non-toxic, non-fibrillar aggregates. Yet another aromatic residue, Phe, however, accelerated the aggregation process in HuPrP. Molecular insights obtained through MD (molecular dynamics) simulations suggested that each BPM differently engages a conserved Tyr 169 residue at the α2-ß2 loop of HuPrP and affects the stability of α2 and α3 helices. Our results demonstrate that this new class of molecules having chemical scaffolds conjugating hydrophobic/aromatic residues could effectively modulate prion aggregation and toxicity.

Optimizing microencapsulation of α-tocopherol with pectin and sodium alginate.

α-Tocopherol is a well-known fat-soluble antioxidant and is widely used in the food industry for stabilizing free radicals. Incorporation and stability of it into food is another challenge as directly added α-tocopherol is prone to inactivation by food constituents. This study was aimed at optimizing conditions for encapsulation of α-tocopherol using combination of sodium alginate (0.5, 1.0, 1.5 and 2.0%) as primary wall material and pectin (2.0%) as filler. The optimum conditions were selected on the basis of encapsulation efficiency, shape, size, bulk density, yield and swelling index with syringe method. The encapsulation efficiency of α-tocopherol in microencapsules produced under optimal conditions was 52.91% using sodium alginate 1.5% w/v and pectin 2.0% w/v. α-Tocopherol was encapsulated with encapsulator using standard conditions and was compared with syringe method. The encapsulation efficiency was found more (55.97%) in microencapsules prepared with encapsulator and 52.11% in microencapsules prepared with syringe.