N-(naphthalen-1-yl(phenyl)carbamothioyl)-3-nitrobenzamide against Methicillin-resistant Staphylococcus aureus (MRSA) isolates: Thermal kinetics, theoretical and molecular docking studies

• Aroylthioureas are considered antibacterial agents . • MRSA is a major health problem. • The novel aroylthiourea was highly effective against MRSA isolates. In this study, the thiourea derivative N-(naphthalen-1-yl(phenyl)carbamothioyl)-3-nitrobenzamide ligand (HL) was synthesized and structurally characterized using FT-IR and 1 H NMR spectrometers. The thermal properties of HL were analyzed using a Thermal Gravimetry/Differential Thermal Gravimetry/Differential Thermal Analysis (TG/DTG/DTA) system. Kinetic parameters were calculated using the Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) methods, with activation energies ( E a ) determined as 170.71–87.92 kJ mole -1 (FWO) and 166.40–83.71 kJ mole -1 (KAS) for each decomposition stage. Quantum chemical calculations were conducted via Density Functional Theory (DFT) at the B3LYP/6–311G(d,p) level of theory using the Gaussian 09 program package. The antimicrobial efficacy of HL against Methicillin-resistant Staphylococcus aureus (MRSA) isolates was also investigated. Minimum inhibitory concentration (MIC) values were calculated as follows: ≤0.25 µg/mL for 7 isolates, 0.5 µg/mL for 30 isolates, 1 µg/mL for 57 isolates, 2 µg/mL for 28 isolates, 4 µg/mL for 7 isolates, 8 µg/mL for 11 isolates, 64 µg/mL for 3 isolates, 128 µg/mL for 1 isolate, and 256 µg/mL for 6 isolates. The variation in antimicrobial activity may be attributed to the resistance mechanisms of individual isolates. The high efficacy of HL, particularly against MRSA isolates, suggests its potential as a drug precursor for treating S. aureus-related infections. Molecular docking studies revealed binding scores with MRSA proteins (1MWR, 1MWS, 1MWT, 1VQQ, and 6H5O) ranging from -8.1 to -9.8 kcal/mole, further demonstrating HL's reactivity against MRSA proteins.