Supramolecular encapsulation of nanocrystalline Schiff bases into β-cyclodextrin for multifold enrichment of bio-potency

We report the solvent-free green synthesis of two Schiff bases, (E)-2-((2-hydroxy-3-methoxybenzylidene)amino)-4-methylphenol (SL1) and (E)-2-((2-hydroxybenzylidene) amino)-4-methylphenol (SL2), and their inclusion complexes with β-cyclodextrin (β-CD). The encapsulation phenomenon, structural characteristics and hydrolytic stabilities of the SL1, SL2 and their inclusion complexes are determined with a suite of spectroscopic, analytical and crystallographic analyses. Dose and time-dependent cytotoxicity study of SL1-β-CD and SL2-β-CD against two breast cancer cell lines, Michigan Cancer Foundation-7 (MCF-7) and metastatic mammary adenocarcinoma1 (MDA-MB-231), exhibit excellent inhibitory activity with significant non-cytotoxic concentrations and ensure a multifold elevation of bio-potency than the parent Schiff base compounds. The Annexin-V assay determines the efficacy of these inclusion complexes to trigger apoptosis, suggesting that SL2-β-CD possesses better efficacy as an anti-cancer drug. To the best of our knowledge, we, for the first time, report the inclusion of nanocrystalline Schiff bases into β-CD for multifold enrichment of bio-potency.