Molecular interaction of difluoroboron curcuminoid and its derivatives with human serum albumin using spectroscopic tools

Difluoroboron curcuminoid (Cur-BF₂) and its Bromo (Br-Cur-BF₂) and Iodo (I-Cur-BF₂) derivatives (reddish orange bio-molecules) were synthesized by modifying 3-diketoas well as feruroyl moieties of naturally occurring curcumin (Cur),a yellow pigment from rhizome of turmeric plant. Cur-BF₂ and its derivatives exhibited excellent photophysical (intense absorption and emission, large extinction coefficients, huge bathochromic shift (~80 nm), fluorescence probes, etc). In consideration of these properties, in the present investigation, the molecular binding interaction between Cur-BF₂, Br-Cur-BF₂ and I-Cur-BF₂ with human serum albumin (HSA),a circulatory protein from humans was investigated systematically by spectroscopic tools like UV–Visible absorption and fluorescence spectroscopy. The binding constants of Cur-BF₂, Br-Cur-BF₂ and I-Cur-BF₂ with HSA were evaluated in the order of 10⁶M^-1. The number of binding sites was estimated as one in HSA for these synthesized bio-molecules.Subsequently, it was observed that these compounds showed static as well as dynamic fluorescence quenching of HSA. Furthermore, the comprehensive studies related to these investigations would be carried out in the future. (author)