Chemical and oxidative properties of fine particulate matter from near-road traffic sources.

The toxicity associated with the fine particulate matter (PM2.5) has not been well studied, particularly in relation to the emissions from on-road vehicles and other sources in low- and middle-income countries such as India. Thus, a study was conducted to examine the oxidative potential (OP) of PM2.5 at a roadside (RS) site with heavy vehicular traffic and an urban background (BG) site in Mumbai using the dithiothreitol (DTT) assay. Simultaneous gravimetric PM2.5 was measured at both sites and characterized for carbonaceous constituents and water-soluble trace elements and metals. Results depicted higher PM2.5, elemental carbon (EC), and organic carbon (OC) concentrations on the RS than BG (by a factor of 1.7, 4.6, and 1.2, respectively), while BG had higher water-soluble organic carbon (WSOC) levels (by a factor of 1.4) and a higher WSOC to OC ratio (86%), likely due to the dominance of secondary aerosol formation. In contrast, the measured OPDTTv at RS (8.9 ± 5.5 nmol/min/m3) and BG (8.1 ± 6.4 nmol/min/m3) sites were similar. However, OPDTTv at BG was higher during the afternoon, suggesting the influence of photochemical transformation on measured OPDTTv at BG. At RS, OC and redox-active metals (Cu, Zn, Mn, and Fe) were significantly associated with measured OP (p < 0.05), while at BG, WSOC was most strongly associated (p < 0.05). The coefficient of divergence (COD) for PM2.5, its chemical species, and OPDTTv was >0.2, indicating spatial heterogeneity between the sites, and differences in emission sources and toxicity. The estimated hazard index (HI) was not associated with OPDTTv, indicating that current PM2.5 mass regulations may not adequately capture the health effects of PM2.5. The study highlights the need for further studies examining PM2.5 toxicity and developing toxicity-based air quality regulations.

Elucidation of binding mechanism of stigmasterol with human serum albumin: a biophysical and molecular dynamics simulation approach.

In the present study, we have analyzed the interaction of a phytochemical, stigmasterol (Stig), with human serum albumin (HSA) under physiological conditions using fluorescence quenching, circular dichroism and molecular modeling methods. Cytotoxic studies with Stig in mouse macrophages (RAW 246.7) and HeLa cell lines showed anti-inflammatory and anti-cancer properties. Further, the intrinsic fluorescence of HSA was quenched by Stig, which was considered a static quenching mechanism. The site-specific marker experiments revealed that Stig binds to the IIIA subdomain of HSA with a binding constant of KStig=1.8 ± 0.03 × 105 M-1 and free energy of -7.26 ± 0.031 Kcal/mol. The secondary structure of HSA was partially unfolded after binding of Stig, which indicates an alteration in the microenvironment of the protein binding site. Molecular docking experiments found that Stig binds strongly with HSA at the IIIA domain of the hydrophobic pocket with one hydrogen bond. The rigidity of the protein-Stig complex and free energies were analyzed by molecular dynamic simulation (MDS) for 100 ns, where the HSA-Stig was stabilized after 40 ns. MDS studies revealed that HSA does not significantly change the secondary structure when it binds with Stig, which is in agreement with the circular dichroism data. Overall, the results obtained gave qualitative and quantitative insight into the binding interaction between HSA and Stig, which is essential in understanding the latter as a therapeutic molecule.Communicated by Ramaswamy H. Sarma.

Improving the inhibition of ß-amyloid aggregation by withanolide and withanoside derivatives.

Here, we have studied the ameliorative effects of Withania somnifera derivatives (Withanolide A, Withanolide B, Withanoside IV, and Withanoside V) on the fibril formation of amyloid-ß 42 for Alzheimer's disease. We analyzed reduction in the aggregation of ß amyloid protein with these Ashwagandha derivatives by Thioflavin T assay in the oligomeric and fibrillar state. We have tested the cytotoxic activity of these compounds against human SK-N-SH cell line for 48 h, and the IC 50 value found to be 28.61 ± 2.91, 14.84 ± 1.45, 18.76 ± 0.76 and 30.14 ± 2.59 µM, respectively. After the treatment of the cells with half the concentration of IC 50 value, there was a remarkable decrease in the number of apoptotic cells stained by TUNEL assay indicating the DNA damage and also observed significant decrease of reactive oxygen species. Also, the binding and molecular stability of these derivatives with amyloid ß was also studied using bioinformatics tools where these molecules were interacted at LVFFA region which is inhibition site of amyloid-ß1 42. These studies revealed that the Withanolides and Withanosides interact with the hydrophobic core of amyloid-ß 1-42 in the oligomeric stage, preventing further interaction with the monomers and diminishing aggregation.

Deciphering the AChE-binding mechanism with multifunctional tricyclic coumarin anti-Alzheimer's agents using biophysical and bioinformatics approaches and evaluation of their modulating effect on Amyloidogenic peptide assembly.

Investigating the drug-AChE binding mechanism is vital in understanding its cogent use in medical practice against Alzheimer's disease (AD). The production and accumulation of oligomers of ß-amyloid is a central event in the neuropathology of AD. Beside the inhibition of assembly process, modulation of the aggregation process of these proteins towards minimally toxic pathways may be a possible therapeutic strategy for AD. Hence, the present study aims to examine the effect of multifunctional fused tricyclic 7-hydroxy 4-methyl coumarin analogs (HMC1-5) on the self-induced aggregation of ß-amyloid using Thioflavin T (ThT) assay, scanning electron microscopic study, AlamarBlue and immune blotting assays and also the binding mechanism with AChE by fluorescence emission, conformational, molecular docking and molecular dynamic simulation studies under physiological pH 7.4. The ThT assay, FE-SEM study, cell line and western blots establish that the HMC1-5 molecules could irreversibly disrupt preformed Aß42 fibrils, accelerate the aggregates into micro size co-assembled structures, and effectively eliminate the cytotoxicity of Aß1-42. Fluorescence emission studies indicating a strong binding affinity between HMC1-5 and AChE with the binding constants of 1.04 × 105, 3.57 × 104, 1.97 × 104, 3.07 × 104 and 2.95 × 104 M-1, respectively and binding sites number found to be 1. CD studies disclosed a partial unfolding in the secondary structure of AChE upon binding with HMC1-5. Docking analysis inferred that the HMC1-5 were bound through hydrophobic and hydrophilic interactions to the AChE active site. Molecular dynamics simulations emphasized the stability of AChE-HMC1-5 complexes throughout the 100 ns simulations, and the local conformational changes of the residues of AChE validate the stability of complexes. These results provide new and unique complementary approach for modulating the biological effects of the Aß aggregates by coumarin analogs and new insights for further in vivo investigations as novel anti AD agents.

Comparative binding of Swertiamarin with human serum albumin and α-1 glycoprotein and its cytotoxicity against neuroblastoma cells.

Communicated by Ramaswamy H. Sarma.

Unraveling the stability of plasma proteins upon interaction of synthesized uridine products: biophysical and molecular dynamics approach.

Most of the drugs binding to human serum albumin (HSA) are transported to various parts of the body. Here, we have studied the molecular interaction between HSA and synthesized uridine derivatives, 1-[(3R, 4S, 5 R)-2-methyl-3, 4-dihydroxy-5-(hydroxymethyl)oxolan-2-yl]pyrimidine-2,4-dion.)(C-MU); [(2R,3R,4R,5R)-5-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)-3,4-dihydroxy-4-methyl-tetrahydrofuran-2-yl] methyl methyl phosphochloridate (CM-MU) and [(2R,3S,4R,5R)-5-(2,4-dioxopyrimidin-1-yl)-2-methyl-3,4-dihydroxyoxolan-2-yl] methyl dihydrogen phosphate (P-MU). Cytotoxic studies of these synthesized compounds with mouse macrophages (RAW 246.7) and HeLa cells (human cervical cancer cells) and binding mechanism of these uridine derivatives with HSA were performed. Subsequently, fluorescence quenching was observed upon titration of uridine derivatives with HSA via static mode of quenching, and the binding constants (K2-C-MU = 4 ± 0.03 × 104M-1, K5-CM-MU = 1.95 ± 0.03 × 104 M-1 and K5-P-MU =1.56 ± 0.03 × 104 M-1) were found to be in sync with the computational results. Further, molecular displacement and molecular docking data revealed that all the derivatives are binding in the subdomain IIA and IIB regions of HSA. The protein secondary structure of complexes was determined by circular dichroism, indicating partial unfolding of the protein upon addition of the uridine derivatives. Furthermore, atomic force microscopy data reveal the change in topology upon binding of 2-C-MU, 5-CM-MU and 5-P-MU with HSA, indicating change in the microenvironment around tryptophan region. Additionally, cytotoxicity studies on HeLa and Raw Cell lines suggested that these molecules have significant anti-proliferative and anti-inflammatory properties. Hence, the study may be of help for development of new drugs based on uridine derivatives which may be helpful for combating various potential diseases.Communicated by Ramaswamy H. Sarma.

Spectroscopic evaluation of synthesized 5ß-dihydrocortisol and 5ß-dihydrocortisol acetate binding mechanism with human serum albumin and their role in anticancer activity.

Our study focus on the biological importance of synthesized 5ß-dihydrocortisol (Dhc) and 5ß-dihydrocortisol acetate (DhcA) molecules, the cytotoxic study was performed on breast cancer cell line (MCF-7) normal human embryonic kidney cell line (HEK293), the IC50 values for MCF-7 cells were 28 and 25 µM, respectively, whereas no toxicity in terms of cell viability was observed with HEK293 cell line. Further experiment proved that Dhc and DhcA induced 35.6 and 37.7% early apoptotic cells and 2.5, 2.9% late apoptotic cells, respectively, morphological observation of cell death through TUNEL assay revealed that Dhc and DhcA induced apoptosis in MCF-7 cells. The complexes of HSA-Dhc and HSA-DhcA were observed as static quenching, and the binding constants (K) was 4.7 ± .03 × 104 M-1 and 3.9 ± .05 × 104 M-1, and their binding free energies were found to be -6.4 and -6.16 kcal/mol, respectively. The displacement studies confirmed that lidocaine 1.4 ± .05 × 104 M-1 replaced Dhc, and phenylbutazone 1.5 ± .05 × 104 M-1 replaced by DhcA, which explains domain I and domain II are the binding sites for Dhc and DhcA. Further, FT-IR, synchronous spectroscopy, and CD results revealed that the secondary structure of HSA was altered in the presence of Dhc and DhcA. Furthermore, the atomic force microscopy and transmission electron microscopy showed that the dimensions like height and molecular size of the HSA-Dhc and HSA-DhcA complex were larger compared to HSA alone. Detailed analysis through molecular dynamics simulations also supported greater stability of HSA-Dhc and HSA-DhcA complexes, and root-mean-square-fluctuation interpreted the binding site of Dhc as domain IB and domain IIA for DhcA. This information is valuable for further development of steroid derivative with improved pharmacological significance as novel anti-cancer drugs.

Elucidating the active interaction mechanism of phytochemicals withanolide and withanoside derivatives with human serum albumin.

Withania somnifera (Ashwagandha) is an efficient medicinal plant known in Ayurveda and Chinese medicine since ancient times, whose extracts are consumed orally as food supplement or as a health tonic owing to its several restorative properties for various CNS disorders, inflammation, tumour, stress, rheumatism etc. In this study, we have analyzed the binding interaction of four derivatives of Withania somnifera (Withanolide A, Withanolide B, Withanoside IV and Withanoside V) with HSA because of their important pharmacological properties. To unravel the binding between derivatives of Withania somnifera and HSA, fluorescence spectroscopy was used. Binding studies were further studied by molecular docking and dynamics and results confirmed greater stability upon binding of derivatives with HSA. Circular dichroism data illustrated change in the secondary structure of protein upon interaction with these derivatives, particularly the helical structure was increased and ß-sheets and random coils were decreased. Furthermore, morphological and topological changes were observed using AFM and TEM upon binding of ligands with HSA indicating that HSA-withnoside/withanolide complexes were formed. All the results cumulatively demonstrate strong binding of withanosides and withanolides derivatives with serum albumin, which should further be explored to study the pharmacokinetics and pharmacodynamics of these derivatives.

A comparative evaluation of dental caries status and salivary properties of children aged 5-14 years undergoing treatment for acute lymphoblastic leukemia, type I diabetes mellitus, and asthma - In vivo.

BACKGROUND: The subjective sensation of dry mouth, xerostomia, is a well-recognized problem in adults, however, relatively little attention has been paid to this issue in children. Xerostomia commonly occurs as an adverse effect of drugs in asthma and leukemia, which alter the composition and flow of saliva and systemic diseases, including diabetes. It decreases the oral pH and significantly increases the development of plaque and dental caries. AIM: This study aims to evaluate and compare the dental caries status and salivary properties of children aged 5-14 years undergoing treatment for acute lymphoblastic leukemia, type 1 diabetes mellitus, and asthma - in vivo. MATERIALS AND METHODS: The study was divided into two parts: Part I: Oral examination was performed and dental caries status Decayed, Missing, Filled Teeth/ decayed, extraction, filled teeth (DMFT/deft) was noted and Part II: Salivary analysis was performed by GC Saliva-Check BUFFER kit to check for hydration, viscosity, pH of saliva, salivary flow, and buffering capacity. STATISTICAL ANALYSIS: All statistical analysis was performed using the SPSS 21 statistical software version. Inferential statistics were performed using Chi-square test and ANOVA. Post hoc pairwise comparison was done using Post hoc Tukey's test. RESULTS: The prevalence of mean DMFT/deft with regard to salivary properties was highest in leukemic patients followed in descending order by diabetic and asthmatic patients. CONCLUSIONS: Leukemic patients had significantly higher caries and decreased salivary properties while asthmatic patients showed the least caries prevalence and best salivary properties.