Oleanolic acid oxime derivatives and their conjugates with aspirin modulate the NF-κB-mediated transcription in HepG2 hepatoma cells

The aim of this study was to evaluate the effect of new oleanolic acid oxime (OAO) derivatives and their conjugates with aspirin (ASP) on the expression and activation of NF-kappa B in human hepatoma HepG2 cells. OAO derivatives showed a stronger cytotoxic effect against HepG2 cells compared with their conjugates with aspirin. Moreover, conjugation of OAO with ASP led to enhanced downregulation of NF-kappa B expression and activation. Among the hybrids with ASP, compounds: 19, 3-(2-acetoxy)benzoyloxyiminoolean-12-en-28-oic acid morpholide and 13, 3-(2-acetoxy)benzoyloxyiminoolean-12-en-28-oic acid methyl ester, differing, respectively, in morpholide and methyl ester groups at the C-17 position of oleanolic acid (OA) molecule were the most efficient. COX-2 transcript and protein levels were also diminished after treatment with these compounds. The results of this study indicate that the new derivatives of OAO and particularly their conjugates with ASP, downregulate the expression of COX-2 in HepG2 cells by modulating the NF-kappa B signaling pathway and suggest their potential application in the prevention of liver inflammation and cancer.