Design, microwave-assisted Knoevenagel synthesis of benzothiazolyl-benzylidene spiroheterocycles: In silico and in vitro evaluation of anticancer, antioxidant, and antimicrobial activities

Spiroheterocycles incorporating benzothiazole and benzylidene scaffolds are recognized for their broad pharmacological potential, particularly in anticancer and antimicrobial applications. However, the development of efficient synthetic routes and the identification of potent derivatives remain key challenges. This study aimed to synthesize a new series of benzothiazolyl-benzylidene spiroheterocycles and to evaluate their anticancer, antioxidant, antimicrobial, and in silico pharmacokinetic properties. Compounds ( 3a-e and 4a-e ) were synthesized via microwave-assisted organic synthesis (MAOS) using 2-aminobenzothiazole, cyclic ketones, and aromatic aldehydes through a Knoevenagel condensation. Structural characterization was performed using IR, 1 H NMR, 13 C NMR, and mass spectrometry. In vitro anticancer activity was assessed against MCF-7 cells, alongside antioxidant and antimicrobial assays. Molecular docking against the 3EQM protein and molecular dynamics simulations were conducted to evaluate binding and stability, while ADME-Tox predictions assessed pharmacokinetic properties. In vitro evaluations revealed significant anticancer activity against MCF-7 cells with spiro intermediate B emerging as the most promising candidate (IC 50 = 0.86 µM), and 3e shows excellent potency (IC 50 = 1.83 µM). Antioxidant potency was highest in compound A and 3b , whereas antifungal and antibacterial assessments show 4e and A as potent, respectively. In silico molecular docking against the 3EQM protein and molecular dynamics simulations revealed favourable binding conformations and stability. ADME-Tox profiling demonstrated drug-likeness, good oral bioavailability, and CNS accessibility. The synthesized benzothiazolyl-benzylidene spiroheterocycles exhibit promising bioactivity, with compounds B , 3e , A , and 4e emerging as strong therapeutic candidates. The efficient microwave-assisted synthesis of Benzothiazolyl-benzylidene spiroheterocycles ( 3a-e and 4a-e ). Among these, 3e showed the strongest anticancer activity against the breast cancer (MCF-7) cell line. Molecular docking and 100 ns molecular dynamics simulations confirmed the stable binding of the active compounds to protein 3EQM, supporting their bioactivity. All the synthesized compounds were analysed for the antioxidant activity using the DPPH radical assay and anti-microbial potency using the Kirby-Bauer disk diffusion method. • Microwave synthesis gave high-yield benzothiazolyl spiroheterocycles ( 3a–e, 4a–e ) through Knoevenagel reaction. • Compound B showed strongest anticancer activity (0.86 µM); 3e , 3c and 4b were also potent • Compound A showed strong antioxidant/antibacterial effects; 4e was most active antifunga • Docking and MD confirmed stable binding of B , 3e , 3c and 4b with protein 3EQM, supporting their bioactivity. • ADME-Tox profiling indicated good drug-likeness, oral bioavailability, and CNS accessibility.