Benzene-linked bis-amino acids via asymmetric synthesis: CD/UV studies, DNA and serum albumin binding, and MCF-7 cytotoxicity.

A benzene-linked bis-amino acid (compound 4) was synthesized via asymmetric alkylation of a chiral Ni(II)-Schiff base glycine complex and fully characterized. Its interactions with DNA and bovine serum albumin (BSA), as well as its cytotoxicity toward MCF-7 and A549 cancer cells, were evaluated. Circular dichroism titrations indicated moderate affinity for calf thymus DNA (KD ≈ 80 μM) and stronger binding to BSA (KD = 1.27 ± 0.82 μM), accompanied by a decrease in α-helix content from 67.3% to 53.9%. UV-Vis spectra showed non-linear absorbance changes in the 0.1-1.2 μM range, consistent with possible self-association. Docking simulations predicted favorable interactions with both DNA (HDOCK score - 127.58) and BSA (HDOCK score - 128.12). FT-IR measurements supported these interactions, showing a shift of the BSA amide I band from 1643 to 1651 cm-1 together with DNA band variations such as the 1450 → 1443 cm-1 shift and the 1651 → 1597 cm-1 change at higher ligand ratios. Moreover, cytotoxicity assays revealed time-dependent inhibition in cancer cells, with cell viability decreasing to 70-90% at 1.0 mg/mL after 72 h. Overall, these results identify compound 4 as a simple bis-amino-acid scaffold with measurable biomacromolecular binding and antiproliferative activity, further confirmed by real-time monitoring (RTCA), which revealed a pronounced growth-inhibitory effect particularly in MCF-7 cells.