Design, Synthesis, Characterization, and Biological Evaluation of Novel Isatin-Based Mannich Derivatives with Antibacterial and Anticancer Activities

Mannich base derivatives have emerged as promising scaffolds in medicinal chemistry due to their structural versatility and broad-spectrum biological activities. This study reports the synthesis and characterization of two novel Mannich base derivatives (S1 and S2) derived from isatin, formaldehyde, and substituted aniline derivatives via a one-pot condensation reaction. The synthesized compounds were confirmed using FTIR and ¹H-NMR spectroscopy, indicating successful β-amino ketone formation. The antimicrobial efficacy of S1 and S2 was assessed against Staphylococcus aureus and Escherichia coli using the cup-plate agar diffusion method at three concentrations. Results revealed dose-dependent inhibition, with S2 showing enhanced activity likely due to its hydroxyl group. Both compounds were tested for cytotoxic capability against MCF-7 human breast cancer cells. S1 showed better anticancer efficacy with a lower IC₅₀ value (~36.9 ppm) than S2 (~41.2 ppm). Both compounds bound well to the oestrogen receptor alpha (PDB ID: 5T92) in molecular docking tests using MOE software. Compound A1 (derived from S2) showed significant hydrogen bonding and π-interactions with critical residues, indicating medicinal potential. Synthesis, spectroscopy, biological tests, and computer docking give a comprehensive knowledge of structure–activity interactions, supporting Mannich derivatives as dual-action medicines. To clinically translate these drugs, mechanistic research and in vivo assessment are needed.