Biological Evaluation of Newly Synthesized Thymol Derivatives: Unveiling Antimicrobial, Anticancer, and Antioxidant Properties

Introduction: Natural products produced by plants have been the backbone for numerous activities such as antimicrobial, antioxidant, and anticancer effects. Thymol, a monoterpenoid phenol, is known for its pharmacological potential, with structural modifications enhancing its biological activity in drug discovery. Methodology: A series of thymol Schiff base derivatives were synthesized and their structures were confirmed by FTIR, NMR (1H & 13C), and MS and also by elemental analysis. The newly prepared compounds were subsequently assessed for their in vitro biological activities, including antimicrobial efficacy against specific microbial strains with the help of tube dilution assay, antioxidant potential through the DPPH assay, and their ability to inhibit the proliferation of the A- 549 cell line using the MTT assay. In silico ADME/Tox profiling, allergenicity prediction, and molecular docking studies were performed using ProTox-II, pkCSM, ChAlPred, and Maestro, respectively. Results: Compound K3 exhibited strong antibacterial activity with MIC values ranging from 0.02 to 0.06 µg/ml, while K13 demonstrated the best antifungal activity (MIC: 0.02 to 0.07 µg/ml). K23 showed superior antioxidant activity (IC50: 9.13 µg/ml) compared to ascorbic acid (11.86 µg/ml). K13 also displayed potent anticancer activity (IC50: 1170.84 nM), surpassing doxorubicin (1290.87 nM). All compounds adhered to Lipinski's rule of five, exhibited favorable bioavailability (score: 0.55), low acute oral toxicity (LD50: 430–2500 mg/kg), good intestinal absorption, moderate BBB permeability, and non-inhibition of CYP3A4. Docking studies revealed strong binding of K13 (–7.117 kcal/mol with 5V5Z) and K3 (–5.96 kcal/mol with 1AJ0), outperforming reference drugs. Discussion: The biological activities of the synthesized thymol derivatives were consistent with in silico predictions, indicating good pharmacokinetic profiles and target binding. Compounds K3, K13, and K23 emerged as multifunctional candidates. Conclusion: The synthesized thymol-based molecules exhibited promising antimicrobial, antioxidant, and anticancer activities, supported by in silico pharmacokinetic and docking data. Compounds K3, K13, and K23 demonstrated the most significant effects, suggesting their potential as lead candidates for further pharmaceutical development.