Synthesis, characterization, and computational evaluation of novel 4-methyl-7-hydroxy coumarin derivatives for potential pharmaceutical applications

 Corresponding author: Dharani Mani. Copyright © 2025 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution Liscense 4.0. Synthesis, characterization, and computational evaluation of novel 4-methyl-7hydroxy coumarin derivatives for potential pharmaceutical applications Dharani Mani 1, *, Rajendran K 2, Rajadevi Ravi 1, Sathya Annadurai 3, Ishwaryalakshmi Suresh 4 and Napolean R 5 1 Assistant professor, Department of Pharmaceutical Chemistry, Thanthai Roever College of Pharmacy, Perambalur621212, Tamil Nadu, India. 2 Professor, Department of Pharmacognosy, J. K. K. Nataraja College of Pharmacy, Kumarapalayam -638138, Tamil Nadu, India. 3 Assistant professor, Department of Pharmacology, Thanthai Roever College of Pharmacy, Perambalur-621212, Tamil Nadu, India. 4 Student, B. Pharm, Thanthai Roever College of Pharmacy, Perambalur -621212, Tamil Nadu, India. 5 Professor, Department of Pharmaceutics, Thanthai Roever College of Pharmacy, Perambalur -621212, Tamil Nadu, India. World Journal of Biology Pharmacy and Health Sciences, 2025, 21(03), 190-205 Publication history: Received on 12 January 2025; revised on 03 March 2025; accepted on 05 March 2025 Article DOI: https://doi.org/10.30574/wjbphs.2025.21.3.0208 Abstract A novel class of molecules has been synthesized and characterized in this study using the Pechmann condensation method. These molecules are derived from 4-methyl-7-hydroxycoumarin, 12-substituted benzaldehyde, and imidazole. As a result of their wide range of applications in various industries, it is believed that these compounds hold significant potential, particularly with regard to pharmaceuticals, cosmetics, and agrochemicals. A wide range of analytical techniques, including IR, 1H NMR, and 13C NMR, were employed to thoroughly characterize the synthesized compounds. Furthermore, computational tools were used to analyze their QSAR parameters in silico. The study found that the designed molecules have desirable properties, including high bioavailability, low blood-brain barrier penetrability, and low toxicity. Multi-software programs were used to test the compounds against enzyme targets, including BIOVIA, PYRX, MOLINSPIRATION, SWISS ADME, and PROTOX II. In addition to providing valuable insight into the compounds' potential efficacy and safety profiles, these computational analyses provide additional information as well. The study emphasizes the reliability of ADMET properties prediction by using multiple computational tools, and this study highlights the promise of the synthesized molecules. Developing new therapeutic agents with diverse applications in the pharmaceutical and related industries may be made possible by the results of the study, potentially contributing to ongoing efforts in drug discovery and development. Keywords: Docking Study; Coumarins Derivatives; Heterocyclic Compounds; Imidazole Derivatives 1. Introduction The study of heterocycles has dominated organic chemistry for more than a century. By the end of the second millennium, there were about 20 million chemicals identified, and more than two-thirds are aromatic in nature, nearly half of which are heterocyclic [1]. The majority of heterocycles are nitrogen-containing, but there are also heterocycles containing oxygen, phosphorus, and selenium. There are numerous natural drugs that are heterocyclic in nature, including papaverine, theobromine, quinine, emetine, and morphine. Many synthetic drugs, including diazepam, chlorpromazine, and metronidazole, also fall into this World Journal of Biology Pharmacy and Health Sciences, 2025, 21(03), 190-205 191 category. Diazinon and paraquat are both pesticides and herbicides that contain heterocycles, as are dyes like mauveine and luminophores like acridine orange. There are a number of therapeutic properties associated with synthetic heterocycles, including antibacterial, antifungal, antiviral, and antiparasitic properties. Additionally, they can reduce inflammation, provide analgesia, counter convulsive activity, and fight cancer [2]. A class of organic compounds known as Coumarins was widely distributed in nature and is readily synthesized. Food and cosmetics, liquid crystal displays, pharmaceuticals, insecticides, rodenticides, and inks, paints, and synthetic rubber use them as fixatives, odor masking agents, and insecticides [3] In addition to antibacterial, anti-inflammatory, antioxidant, anticoagulant, anticancer, and anti-HIV properties, coumarin derivatives show a wide range of therapeutic applications [4,5]. Over the years, numerous synthesis methods have been developed to meet the demand for these versatile compounds [6]. Some of the most well-known methods are Pechmann condensation, Knoevenagel, Perkin, Witting, and Reformatsky reactions, and flash vacuum pyrolysis or carbon suboxide methods. A simple method for synthesis of 4-substituted coumarins, the Pechmann reaction, uses simple and inexpensive starting materials, i.e., phenols and β-ketoesters. [7] There have been several heterogeneous solid acid catalysts recently, including Nafion-H, zeolite H-BEA, montmorillonite clays, ionic liquids, Nafion resin/silica nanocomposites, and silica supported by chloric acid (HCIO4). Pechmann condensation has been replaced by mesoporous zirconium phosphate (m-ZrP), cellulose sulfuric acid, ZrOCL2.8H20/SiO2, and others. As a catalyst for pechmann condensation, concentrated sulfuric acid forms coumarin (2H-1-benzopyran-2-one). In contrast, millemole quantities of the reactants are required for microwave irradiation to accelerate these reactions several-fold and improve product yields [8,9]. Using insilico tools, even before their practical synthesis, drugs can be predicted as drug candidates and their ADMET profiles can be built, thereby minimizing the costs incurred during the synthesis, preclinical, and clinical testing phases [10]. It was critical to have quality experimental data under the database for a tool to predict ADMET accurately. The purpose of docking a molecule is to determine whether there is an affinity between the ligands and their targets. The docking study was conducted using Auto Dock Vina through PyRx[11]. Figure 1 Structure of coumarins Figure 2 Schematic illustration of docking a small molecule ligand (green) to a protein target (black) producing a stable complex 2. Methodology 2.1. In-silico studies of designed compounds To optimize lead molecules in drug development, computer-based simulations are essential. It is imperative that the formulation (potency, selectivity, and pharmacokinetics), as well as absorption, distribution, metabolism, and excretion (ADME) of a drug, as well as toxicity assessment must all be optimized before clinical trials. According to Lipinski et al., World Drug Index physicochemical properties can help predict oral bioavailability. A combination of Swiss ADME and World Journal of Biology Pharmacy and Health Sciences, 2025, 21(03), 190-205 192 PreADMET software was used in this study to assess ADME properties, while ProTox II software was used to assess toxicity. 2.2. ADME Prediction Several in vitro methods are used to assess intestinal absorption, including Caco2-cell and MDCK cell models. HIA and skin permeability models, along with Caco2-cell and MDCK assays, assist in identifying potential oral and transdermal drug candidates. A distribution analysis includes the penetration of the BBB for CNS drug delivery as well as the binding of plasma protein for disposition and effectiveness. Resilient back-propagation neural networks are used for building QSAR models using genetic approximations. 2.3. ProTox II The ProTox II virtual lab was designed to predict toxicities of small molecules, a critical part of drug design and development. It offers speed and reduces the requirement for animal experiments thanks to its computational estimations. As a result of the incorporation of fragment propensities, similarity, and machine learning, ProTox II predicts acute toxicity, hepatotoxicity, cytotoxicity, carcinogenesis, mutagenesis, immunotoxicity, Tox21 pathways, and toxicity targets. 2.4. Molecular docking PyRx software was used in this study to conduct docking studies. This study focused on the active site of COX (PDB ID: 6F86). In order to analyze docking, RCSB's protein structure was obtained. [11, 12] 2.4.1. Scheme of Work Figure 3 Work Scheme World Journal of Biology Pharmacy and Health Sciences, 2025, 21(03), 190-205 193 2.5. Synthesis procedures 2.5.1. Step: 1 Synthesis of 4-Methyl-7Hydroxy Coumarin Nine ml of concentrated sulphuric acid were chilled and placed into a suitable container to start the synthesis process. 2.2 grams of resorcinol powder were gently added to chilled sulfuric acid with continuous mechanical stirring. Temperatures must not exceed 10 degrees Celsius during this process. To facilitate the condensation reaction, stirring is continued for 30 to 40 minutes. In order to separate the product, the resulting mixture is carefully transferred into a container filled with crushed ice water. After the separated product has been filtered using suction, it is thoroughly rinsed with cold water to remove any impurities. 2.5.2. Step:2 Condensation of product Using an ethanol solution containing a catalytic amount of potassium hydroxide (KOH) (0.1 ml), a mixture containing acetyl coumarin and the corresponding aromatic aldehyde (5 mmol) was prepared. A one-hour irradiation was then performed on the prepared mixture. 2.5.3. Step: 3 Final Product formation (Substituted Imidazole coumarins) Sodium hydroxide (0.045 mol, 0.40 g), coumarin (4-methyl-7-hydroxy-8-acetyl) (0.01 mol), as well as thiourea (0.015 mol, 0.96 g) were meticulously mixed in a small quantity of water. Irradiating the resulting mixture for approximately 30 minutes initiated the condensation process. Cooling the mixture until it acquired a dark-yellow hue was followed by a reduction in temperature. Afterwards, ethanol solvent was used to perform recrystallization. 2.5.4. Characterisation of Synthesized compounds A variety of spectroscopy techniques were used to characterize the synthesized compounds, including FT-IR, 1H-NMR, 13C-NMR, and MASS Spectroscopy. 3. Results and discussion 3.1. In-silico modelling Table 1 Substituted Chemical Constituents S.n o Chemical constituents Structure Smiles 1 Imidazole substituted 2hydroxybenzaldehyd e 4-methyl -7hydroxy coumarin O O CH 3 O OH OH O NH N O=Cc1c(ccc(c1O)c1ccccc1CCC(=O)c1c(O)ccc2c1OC(=O)CC2C)C1C =NCN1 2 Imidazole substituted 2,3dihydroxybenzaldeh yde 4-methyl -7hydroxy coumarin O O CH 3 O OH O NH N OH OH O=Cc1cc(c(O)c(O)c1C1C=NCN1)c1ccccc1CCC(=O)c1c(O)ccc2c1OC (=O)CC2C World Journal of Biology Pharmacy and Health Sciences, 2025, 21(03), 190-205 194 3 Imidazole orthochloro benzaldehyde 4methyl -7-hydroxy coumarin O O CH3 O OH O NH NCl O=Cc1cc(c(Cl)cc1C1C=NCN1)c1ccccc1CCC(=O)c1c(O)ccc2c1OC(= O)CC2C 4 Imidazole substituted parachlorobenzaldeh yde 4-methyl -7hydroxy coumarin O O CH3 O OH O NH NCl O=Cc1cc(c(Cl)cc1C1C=NCN1)c1ccccc1CCC(=O)c1c(O)ccc2c1OC(= O)CC2C 5 Imidazole 4methylbenzaldehyde 4-methyl -7-hydroxy coumarin O O CH3 O OH O NH N CH3 O=Cc1cc(c(C)cc1C1C=NCN1)c1ccccc1CCC(=O)c1c(O)ccc2c1OC(= O)CC2C 6 Imidazole substituted 2methylbenzaldehyde 4-methyl -7-hydroxy coumarin O O CH3 O OH O NH N CH3 O=Cc1c(ccc(c1C)c1ccccc1CCC(=O)c1c(O)ccc2c1OC(=O)CC2C)C1C =NCN1 7 Imidazole substituted 4hydroxybenzaldehyd e 4-methyl -7hydroxy coumarin O O CH 3 O OH O NH NOH O=Cc1cc(c(O)cc1C1C=NCN1)c1ccccc1CCC(=O)c1c(O)ccc2c1OC(= O)CC2C World Journal of Biology Pharmacy and Health Sciences, 2025, 21(03), 190-205 195 Table 2 MOLINSPIRATION of designed Compounds Compound MilogP TPSA Å N Atom Molecular Weight No. of violation No Of rotatable bonds Volume 4A 2.44 125.29 37 498.54 0 7 440.23 4B 2.15 135.52 38 446.67 0 7 448.25 4C 3.34 105.07 38 478.27 0 7 445.75 4D 3.34 105.07 38 478.27 0 7 445.75 4E 3.11 105.07 37 496.56 0 7 448.78 4F 3.11 105.07 37 496.56 0 7 448.78 4G 2.44 125.29 37 498.54 0 7 440.23 Table 3 SWISS ADME Results Compound No Lipinski Ghose Veber Egan Muegge Bioavailability score GI absorption BBB permeation P-gp substrate Log kP cm/s Synthetic accessibility score 4A Yes No Yes Yes Yes 0.55 High No Yes -6.56 cm/s 4.80 4B Yes No Yes Yes Yes 0.55 Low No Yes -7.31 cm/s 4.94 4C Yes No Yes Yes Yes 0.55 Low No Yes -7.31 cm/s 4.94 4D Yes No Yes Yes Yes 0.55 High No Yes -6.37 cm/s 4.79 4E Yes No Yes Yes Yes 0.55 High No Yes -6.37 cm/s 4.79 4F Yes No Yes Yes Yes 0.55 High No Yes -6.43 cm/s 4.84 4G Yes No Yes Yes Yes 0.55 High No Yes -6.56 cm/s 4.80 Table 4 PROTOXII Analysis Compound No Predicted LD50 mg/kg Predicted toxicity class Carcinogenicity Hepatotoxicity Mutagenicity Cytotoxicity 4A 5000mg/kg 4 Inactive 0.72 Inactive 0.50 Inactive 0.59 Inactive 0.64 4B 5000mg/kg 4 Inactive 0.72 Inactive 0.51 Inactive 0.57 Inactive 0.64 World Journal of Biology Pharmacy and Health Sciences, 2025, 21(03), 190-205 196 4C 5000mg/kg 4 Inactive 0.72 Inactive Inactive Inactive 4D 5000mg/kg 4 Inactive 0.72 Inactive Inactive Inactive 4E 4000mg/kg 4 Inactive 0.72 Inactive 0.50 Inactive 0.59 Inactive 0.63 4F 4800mg/kg 4 Inactive 0.72 Inactive 0.50 Inactive 0.59 Inactive 0.64 4G 5000mg/kg 4 Inactive 0.72 Inactive 0.50 Inactive 0.59 Inactive 0.64 Table 5 Ligand Against Target Enzyme COX I S. NO Compound No Docking score Kcal/mol Amino acid interaction with Distance 1 4A -9 ARG76-3.074 THR165-2.42 ASP73-2.22 ASP49-4.536 PRO79-4.93 2 4B -8.8 ASN46-2.94 GLY77-2.56 ASP49-2.54 GLU50-2.04 3 4C -8.1 ARG76-2.77 THR165-2.34 ASN46-2.48 ASP49-4.55 4 4D -8.8 ARG76-2.78 THR:165-2.32 ASN46-2.68 5 4E -9.1 ARG76-3.074 THR165-2.42 ASP73-2.22 ASP49-4.536 PRO79-4.93 6 4F -8.2 ARG76-3.074 THR165-2.42 ASP73-2.22 ASP49-4.536 PRO79-4.93 7 4G -9.3 ARG76-3.074 THR165-2.42 ASP73-2.22 World Journal of Biology Pharmacy and Health Sciences, 2025, 21(03), 190-205 197 ASP49-4.536 PRO79-4.93 Comp 4A Comp 4B Comp 4C Comp 4D Figure 4 Molecular docking (Ligand against Target Enzyme) 3.2. Spectral Characterisation Figure 5 a IR Spectra for Compound 4A World Journal of Biology Pharmacy and Health Sciences, 2025, 21(03), 190-205 198 Figure 5 b IR Spectra for Compound 4B Figure 5 c IR Spectra of Compound 4C Figure 5 d IR Spectra of Compound 4D World Journal of Biology Pharmacy and Health Sciences, 2025, 21(03), 190-205 205 [13] Khan IA, Kulkarni MV, Gopal M, Shahabuddin MS, Sun CM. Synthesis and biological evaluation of novel angularly fused polycyclic coumarins. Bioorg Med Chem Lett 2005; 15(15): 3584-7. [14] Grant SS, Hung DT. Persistent bacterial infections, antibiotic tolerance, and the oxidative stress response. Virulence 2013; 4(4): 273-83. [15] Kim JS, Heo P, Yang TJ, Lee KS, Jin YS, Kim SK, et al. [No title available]. [16] Dandriyal J, Singla R, Kumar M, Jaitak V. Recent developments of C-4 substituted coumarin derivatives as anticancer agents. Eur J Med Chem 2016; 119: 141-68.