Interaction of oleanolic acid and its derivatives with bovine serum albumin by spectrofluorimetry

Oleanolic acid was chemically modified to improve its interaction with bovine serum albumin, thus to increase the mutual binding ability. As a lead compound, oleanolic acid reacted with Jones-reagent, then methyl iodide and finally hydroxylamine to obtain four different derivatives. Their structures were confirmed by IR and ¹H NMR analysis. The interaction between these derivatives and bovine serum albumin and the effect of temperature and trace metal ions as Cu²⁺ and Co²⁺ on the interaction were investigated by fluorescence spectroscopy. All these derivatives exhibited improvement of the interaction compared with oleanolic acid with 16 times stronger for OA₂. The interaction also increased with the presence of trace metal ions as Cu²⁺and Co²⁺. These results indicate that chemical modification can improve the interaction of oleanolic acid with bovine serum albumin.