Molecular Docking, Synthesis of Novel Schiff Base 1, 3-Thiazine Compounds from 3-Methoxy Chalcone and Evaluation of Their Anxiolytic Activity

As they represent a sizable class of naturally occurring and synthetic chemicals with potent biological activity in the pharmaceutical and biological fields, 1, 3 Thiazine heterocycles are of great interest. The goal of this project was to create the Schiff base. 3,-Methoxychalcone derivative of 1,3-thiazine. TLC, IR, 1 HNMR, 13 C NMR, each mass calculation were accustomed to identify the compositions of recently created targeted substances. Using an Elevated plus maze, the test compounds (B1–11) were examined for their ability to reduce anxiety. The most effective CNS medications were B1 and B8 compounds.


INTRODUCTION
Research in organic, pharmaceutical, analytical, and medicinal chemistry has been rapidly exchanged thanks to heterocyclic molecules. In the pharmaceutical industry, the structures of the top 200 branded medications contain heterocyclic fragments in more than 75% of cases. 1 It was discovered that 1,3-thiazines are six-membered heterocyclic rings that include sulfur and nitrogen,is a potential pharmacophore,and are rather stable in other compounds with significant medical applications, for eg, chlormezanone (used a muscle relaxant and as an anxiolytic). 2 Results from studies using thiazine derivative moiety have revealed a variety of biological and pharmacological characteristics, including anticonvulsant, 3 antibacterial, 4 COX-2 inhibitors, 5 NSAID, 6 anticancer, 7-8 antidiabetic, 9 anesthetic, 10 and other actions. Over the world, treating bacterial infections provides a substantial therapeutic challenge. Due to the fact that this tendency has been shifting, it is necessary to design new anxiety medications with distinctive structural properties that can vary from the effects of the current anxiety drugs. Moreover, the thiazine nucleus had a pharmacophore of chlormezanone.which has a key position in anti-anxiety research.In order to obtain a powerful anti-anxiety drug, new 1,3-thiazine derivatives have been synthesised due to the rapid development of anxiety resistance towards existing molecules. The process in the current study uses the synthesis of chalcone to a variety of substituted benzaldehydes and 3-Metoxyacetophenone (Claisen-Schmidt condensation reaction). The starting material for the synthesis of fresh Schiff base thiazines was chalcone derivatives. the synthesized complexes was resolute using the unbolt capillar y system. With a Perkin Elmer 2400 instrument, the IR graphic representation of synthetic substances was captured on potassium bromide discs. Using a Bruker Advance Neo spectrophotometer and 1 H NMR uses tetramethylsilane as an inner degree and 13 CNMR spectra of the produced compounds were captured in CDCl 3 . In ppm (d), all chemical shift values are recorded. In SAIF, P.U., Punjab, India, synthetic substances underwent spectroscopic analysis.
To track the development of the reactions, silica gel G thin-layer chromatography (TLC) was employed, and spots were seen in an iodine chamber. The Elevated plus maze approach will be used to pharmacologically evaluate the target drugs for antianxiety efficacy.

Synthesis of 1-(3-Methoxy-phenyl)-4-methylenehepta-2,5-dien-1-one (chalcone1b for C2)
Equimolar amounts of benzaldehyde and 3-methoxy acetophenone were mixed in pure alcohol (0.02 mol), and 10% NaOH solution (25 mL) was poured in while being stirred dropwise. The action was then permitted to continue for 3-4 h before being stopped overnight. To obtain the outcome, the chemical processing fusion was then submerged in frosty water for a whole night. The final product was created by recrystallizing the crude product from ethanol.

Materials
Thiourea, 3-methoxyacetophenon, sodium hydroxide, and different substituted benzaldehydes were acquired from AB Fine Chemicals for the current study project (Nasik, India). Alprazolam, which was employed as a reference medication, was purchased from Local Market. All of the additional chemicals and solvents were provided by CDH. All of the chemicals were analytical grade and had been cleaned up before usage.

General procedure
The uncorrected melting range of

Synthesis of thiazine compound (C2)
In an ethanolic 10% NaOH solution, chalcone (1b) and thiourea were dissolved in an equimolar amount and 2-3 h of stirring at room hotness. The retort fusion was mixed continuously for 1 h after being refluxed for 4 hours. To get the result, in an ice-water bath, the retort fusion was stand overnight. The obtained product underwent filtering, dried and purified from alcohol to produce the resulting product.

General Procedure Synthesis Schiff base of Thiazine derivatives (B1-B11)
The volume was lowered by up to 25% after an equimolar mixture of substituted benzaldehyde and thiazine derivative (C2) were dissolved in Glacial acetic acid. In order to produce the desired result, The mixture for the reaction was left overnight. The end product was obtained by filtering, washing, and recrystallizing the resultant precipitate from ethanol, and the reaction's completeness was verified by TLC.

Molecular Modeling Studies
Studies on the separated chemicals' molecular docking, the isolated compounds (B1-B11) were docked with the target protein Human Gamma-aminobutyric Acid (GABAA) (PDB ID: 4COF) in this work. Using Auto Dock Vina4.2 (MGLtools 1.5.7), It was determined through molecular docking studies how the test medicines would likely bind to the targeted anxiolytic proteins. 11 Binding force (kcal per mol), bond lengths of hydrogen and a graphic demonstration of feasible modeling locations are among the results of the docking computation. ChemDraw 16.0 were worn to display the arrangements of the products (B1-B11) in the suitable 2D inclinations. ChemDraw3D extreme was worn to reduce the power of the compounds/ligands. When the energy of the ligand molecules was decreased, AutoDock Vina was used to run the docking simulation. Using the protein data database, the receptor protein molecules' crystal structures were discovered (PDB file). The intricate synchronizes of the arrangements, which contained hydrated particles and other grains are what gave rise to the better resolution. A protein preparation technique with default settings was used to prepare the proteins. 12 With Auto Processing of intention Protein wallet Auto Dock 4.2, the object protein wallet was created via departure the correlated deposit (eradicate hydrated atom and coaspects) with the protein wallet (MGL tools 1.5.7). The visual punter boundary software was altered such that the lattice box for the molecular modeling simulation, which has a dimension of 60, 60, 64, and 0.377 points, encompasses the macromolecule's region of interest. Using the docking technique of AutoDock Vina, It was calculated how much energy the protein and ligand might potentially bind with. PyMOL and Discovery Studio Visualizer choose the configurations with the least favourable attaching energies among the intention molecule of proteins and chemicals in order to study the dealings between the intention Protein and molecule. The interrelating deposits and H-bonds are revealed as stick displayed, although the drug is represented by different colors.   Table  2 provides a summary of the elevated plus maze method results.

Molecular model
Human Gamma-Aminobutyr ic acid (GABAA) (PDB ID:4COF) was the subject of a molecular docking investigation of target compounds (B1-B11) in relation to the reference medication Alprazolam. The target molecules (B1-B11) had lower docking scores on human gammaaminobutyric acid, indicating that they could have more effective anxiolytic actions. B8, B1, B4, B9, and B2 were among the produced compounds that were most effective because they had the lowest docking scores for the human gamma-aminobutyric acid (GABAA) receptor.

Pharmacology
At a quantity of 5 mg per kg i.p., the elevated plus maze procedure was employed to assess the anxiolytic effects. Table 2 exhibits the anxiolytic activity results. Alprazolam was used as a common medication. B8 showed a significant amount of anxiolytic activity, whereas B1 showed the least amount. The findings indicated that the activity response was producing outcomes comparable to those of the docking research.

CONCLUSION
Novel Schiff bases thiazine derivatives (B1-B11) were synthesized by first creating 1-(3-Methoxy-phenyl)-4-methylene-hepta-2, 5-dien-1-one (chalcones 1b) using a stirring Claisen-Schmidt Condensation reaction between benzaldehyde and 3-methoxy acetophenone compound 1b was exposed to a continuous stirring and reflux cyclization procedure to produce thiazine compound (C2).In glacial acetic acid and ethyl alcohol, the compound C2 interacted with several substituted benzaldehydes to produce a Schiff base of derivatives of thiazine. According to experimental data, compound B8, whose benzaldehyde ring has one bromo group in 3-position has a notable effect. Overall, the 4COF enzyme is inhibited by the substance B8, which is a powerful antianxiety molecule for the treatment of anxiety, which may be related to the outcome of molecular docking. Alprazolam (LEU, PHE) and B8 (2D Image 8) (LEU, PHE) interaction residues for the 4COF receptor are identical, according to the research of docking results with regard to residues involved in amino acid interactions. The similarity between the interaction residues for alprazolam and B1 (2D Image 1) (LEU, PHE) for the 4COF receptor was also found.