Exploring the interaction of tepotinib with calf thymus DNA using molecular dynamics simulation and multispectroscopic techniques.

In recent times, there has been a surge in the discovery of drugs that directly interact with DNA, influencing gene expression. As a result, understanding how biomolecules interact with DNA has become a major area of research. One such drug is Tepotinib (TPT), an FDA-approved anti-cancer medication known as a MET tyrosine kinase inhibitor, used in chemotherapy for metastatic non-small cell lung cancer (NSCLC) with MET exon 14 skipping alterations. In our study, we adopted both biophysical and in-silico methods to investigate the binding relationship of TPT and ctDNA. The absorption spectra of ctDNA exhibited a hypochromic effect when titrated with TPT and the binding constant of TPT-ctDNA complex was calculated, Ka = 9.91 × 104 M-1. By computing bimolecular enhancement constant (KB) and thermodynamic enhancement constant (KD) in fluorometric investigations, it was found that the fluorescence enhancement is a result of a static process involving the ctDNA-TPT complex formation in the ground state, as opposed to a dynamic process. The displacement assay results further supported this finding, showing that TPT exhibits a binding preference for minor groove of ct-DNA and was also demonstrated by KI quenching and CD spectroscopy. The molecular docking and molecular dynamic simulations validated TPT's groove binding nature and binding pattern with ctDNA, respectively. Thus, the results of our present investigation offer valuable insights into the interaction between TPT and ctDNA. It is evident that TPT, as an anti-cancer medication, binds to the minor groove of ctDNA.

Discovery of Quinolinone Hybrids as Dual Inhibitors of Acetylcholinesterase and Aß Aggregation for Alzheimer's Disease Therapy.

The development of multitargeted therapeutics has evolved as a promising strategy to identify efficient therapeutics for neurological disorders. We report herein new quinolinone hybrids as dual inhibitors of acetylcholinesterase (AChE) and Aß aggregation that function as multitargeted ligands for Alzheimer's disease. The quinoline hybrids (AM1-AM16) were screened for their ability to inhibit AChE, BACE1, amyloid fibrillation, α-syn aggregation, and tau aggregation. Among the tested compounds, AM5 and AM10 inhibited AChE activity by more than 80% at single-dose screening and possessed a remarkable ability to inhibit the fibrillation of Aß42 oligomers at 10 µM. In addition, dose-dependent screening of AM5 and AM10 was performed, giving half-maximal AChE inhibitory concentration (IC50) values of 1.29 ± 0.13 and 1.72 ± 0.18 µM, respectively. In addition, AM5 and AM10 demonstrated concentration-dependent inhibitory profiles for the aggregation of Aß42 oligomers with estimated IC50 values of 4.93 ± 0.8 and 1.42 ± 0.3 µM, respectively. Moreover, the neuroprotective properties of the lead compounds AM5 and AM10 were determined in SH-SY5Y cells incubated with Aß oligomers. This work would enable future research efforts aiming at the structural optimization of AM5 and AM10 to develop potent dual inhibitors of AChE and amyloid aggregation. Furthermore, the in vivo assay confirmed the antioxidant activity of compounds AM5 and AM10 through increasing GSH, CAT, and SOD activities that are responsible for scavenging the ROS and restoring its normal level. Blood investigation illustrated the protective activity of the two compounds against lead-induced neurotoxicity through retaining hematological and liver enzymes near normal levels. Finally, immunohistochemistry investigation revealed the inhibitory activity of ß-amyloid (Aß) aggregation.

Identification of new oxospiro chromane quinoline-carboxylate antimalarials that arrest parasite growth at ring stage.

Malaria still threatens half the globe population despite successful Artemisinin-based combination therapy. One of the reasons for our inability to eradicate malaria is the emergence of resistance to current antimalarials. Thus, there is a need to develop new antimalarials targeting Plasmodium proteins. The present study reported the design and synthesis of 4, 6 and 7-substituted quinoline-3-carboxylates 9(a-o) and carboxylic acids 10(a-b) for the inhibition of Plasmodium N-Myristoyltransferases (NMTs) using computational biology tools followed by chemical synthesis and functional analysis. The designed compounds exhibited a glide score of -9.241 to -6.960 kcal/mol for PvNMT and -7.538 kcal/mol for PfNMT model proteins. Development of the synthesized compounds was established via NMR, HRMS and single crystal X-ray diffraction study. The synthesized compounds were evaluated for their in vitro antimalarial efficacy against CQ-sensitive Pf3D7 and CQ-resistant PfINDO lines followed by cell toxicity evaluation. In silico results highlighted the compound ethyl 6-methyl-4-(naphthalen-2-yloxy)quinoline-3-carboxylate (9a) as a promising inhibitor with a glide score of -9.084 kcal/mol for PvNMT and -6.975 kcal/mol for PfNMT with IC50 values of 6.58 µM for Pf3D7 line. Furthermore, compounds 9n and 9o exhibited excellent anti-plasmodial activity (Pf3D7 IC50 = 3.96, 6.71 µM, and PfINDO IC50 = 6.38, 2.8 µM, respectively). The conformational stability of 9a with the active site of the target protein was analyzed through MD simulation and was found concordance with in vitro results. Thus, our study provides scaffolds for the development of potent antimalarials targeting both Plasmodium vivax and Plasmodium falciparum.Communicated by Ramaswamy H. Sarma.

Stability of the Aß42 Peptide in Mixed Solutions of Denaturants and Proline.

Amyloid ß-peptide (Aß) is responsible for the neuronal damage and death of a patient with Alzheimer's disease (AD). Aß42 oligomeric forms are dominant neurotoxins and are related to neurodegeneration. Their different forms are related to various pathological conditions in the brain. We investigated Aß42 peptides in different environments of proline, urea, and GdmCl solutions (in pure and mixed binary forms) through atomistic molecular dynamics simulations. Preferential exclusion from the protein surface and facile formation of a large number of weak molecular interactions are the driving forces for the osmolyte's action. We have focused on these interactions between peptide monomers and pure/mixed osmolytes and denaturants. Urea, as usual, denatures the peptide strongly compared to the GdmCl by accumulation around the peptide. GdmCl shows lesser build-up around protein in contrast to urea but is involved in destabilizing the salt bridge formation of Asp23 and Lys28. Proline as an osmolyte protects the peptide from aggregation when mixed with urea and GdmCl solutions. In mixed solutions of two denaturants and osmolyte plus denaturant, the peptide shows enhanced stability as compared to pure denaturant urea solution. The enhanced stability of peptides in proline may be attributed to its exclusion from the peptide surface and favoring salt bridge formation.

In silico studies of the human IAPP in the presence of osmolytes.

The human islet amyloid polypeptide or amylin is secreted along with insulin by pancreatic islets. Under the drastic environmental conditions, amylin can aggregate to form amyloid fibrils. This amyloid plaque of hIAPP in the pancreatic cells is the cause of type II diabetes. Early stages of amylin aggregates are more cytotoxic than the matured fibrils. Here, we have used the all-atom molecular dynamic simulation to see the effect of water, TMAO, urea and urea/TMAO having ratio 2:1 of different concentrations on the amylin protein. Our study suggest that the amylin protein forms ß-sheets in its monomeric form and may cause the aggregation of protein through the residue 13-17 and the C-terminal region. α-Helical content of protein increases with an increase in TMAO concentration by decreasing the SASA value of protein, increase in intramolecular hydrogen bonds and on making the short-range hydrophobic interactions. Electrostatic potential surfaces show that hydrophobic groups are buried and normalised configurational entropy of backbone, and side-chain atoms is lesser in the presence of TMAO, whereas opposite behaviour is obtained in the case of urea. Counteraction effect of TMAO using Kast model towards urea is also observed in ternary solution of urea/TMAO.

Effect of TMAO and Urea on Dimers and Tetramers of Amyloidogenic Heptapeptides (23FGAILSS29).

Human islet amyloid polypeptide (hIAPP) (1-37) is an intrinsically disordered protein that is released with insulin by ß-cells found in the pancreas. Under certain environmental conditions, hIAPP can aggregate, which leads to ß-cell death. FGAILSS (23-29) residues of the hIAPP protein form ß sheets, which may be toxic species in type 2 diabetes (T2D) patients. All-atom molecular dynamics (MD) simulations have been used to analyze the effect of two distinct types of osmolytes trimethylamine N-oxide (TMAO) and urea on two and four FGAILSS heptapeptides. TMAO leads the individual peptide toward an extended conformation with a higher radius of gyration and favors the formation of antiparallel ß-sheets with an increase in its concentration. However, urea mostly shows compaction of individual peptides except at 4.0 M in the case of a tetramer but does not show aggregation behavior as a whole. TMAO leads both the dimer and tetramer toward the native state with an increase in its concentration. Moreover, both the dimer and tetramer show irregular behavior in urea. The tetramer in 4.0 M urea shows the maximum fraction of native contacts due to the formation of antiparallel ß-sheets. This formation of antiparallel ß-sheets favors the aggregation of peptides. TMAO forms a smaller number of hydrogen bonds with peptides as compared to urea as the exclusion of TMAO and accumulation of urea around the peptides have occurred in the first solvation shell (FSS). Principal component analysis (PCA) results suggest that the minima in the free energy landscape (FEL) plot are homogeneous for a particular conformation in TMAO with smaller basins, while in urea, the dimer shows minima mostly for extended conformations. For a 4.0 M urea concentration, the tetramer shows the minimum for antiparallel ß-sheets, which indicates the aggregation behavior of the tetramer, and for a higher concentration, it shows minima with wider basins of extended conformations.