Biophysical Interactions of Novel Oleic Acid Conjugate and its Anticancer Potential in HeLa Cells

Novel conjugate 2,6-Diisopropylphenol-Oleic acid (2,6P-OLA) has shown potent anticancer activity on various cancer cell lines (Khan et al. Lipids 47:973-986, 2012). In the present study, the protein-or/ and DNA-binding property of 2,6P-OLA was evaluated that could predict its potential toxic effect, in vitro. Preferential structural stability and interaction mechanism of 2,6P-OLA to human serum albumin (HSA) and calf thymus DNA (CT-DNA) was used as model molecules, employing fluorescence spectroscopy (FS) and circular dichroism (CD) methods. The binding and apoptotic activities of conjugate were determined on bacterial recombinant DNA, pBR322 and human cancer cell line, HeLa, respectively. FS studies showed a strong conjugate binding affinity to HSA with overall binding constant of K = 7.66 (±0.03) × 10(2) M(-1). Higher concentration induced detectable changes in the CD spectrum of HSA. The conjugate complexation altered HSA secondary conformation by an increase in α-helices and decrease in β-sheets. Flourescence quenching studies with CT-DNA exhibited K = 1.215 × 10(2) L mol(-1) where 2,6P-OLA efficiently displaced the ethidium bromide (EtBr) bound DNA indicating its strong competition with EtBr for intercalation. Similarly, 2,6P-OLA was able to partially bind pBR322, resulting in decrease the intensity of EtBr gradually. The conjugate significantly reduced survival of HeLa cells. Morphological studies revealed altered cell morphology, suggesting apoptotic death of HeLa cells. Overall, our data shows that 2,6P-OLA bind well with both HSA and DNA and possessed anticancer activities.