N6-Isopentenyladenosine, an isoprenoid cytokinin endowed with biological activity cytotoxicity against MDA-MB-231 breast cancer cell line and interaction with bovine serum albumin

N6-isopentenyladenosine (iPA) is a member of the cytokinin family of plant hormones that regulate plant cell growth and differentiation and is present in mammalian cells in a free form as a mononucleotide in cytoplasm or tRNA-bound. The cytotoxicity effect of iPA on MDA-MB-231 cells was measured by the SRB assay and the results showed that iPA could inhibit cell growth in a dose- and time-dependent manner with an IC50 value of 6.2 ?mol/L at 72 h after the drug was added into the culture. The interaction of BSA with iPA was studied in aqueous solution at physiological conditions, using constant protein concentration of 10-5 M and various drug contents of 10-5 M – 2.5 x 10-7 M. UV-vis spectroscopic method was used to determine iPA binding mode, the binding constant and the effects of iPA complexation on protein secondary structure. The spectroscopic results showed that iPA is located along the polypeptide chains with overall affinity constant of KiPA=4.9 x 104 M-1.