Role of Metabolic Activation in Elemicin-Induced Cellular Toxicity

Elemicin, an alkenylbenzene constituent of natural oils of several plant species, is widely distributed in food, dietary supplements, and medicinal plants. 1'-Hydroxylation is known to cause metabolic activation of alkenylbenzenes leading to their potential toxicity. The aim of this study was to explore the relationship between elemicin metabolism and its toxicity through comparing the metabolic maps between elemicin and 1'-hydroxyelemicin. Elemicin was transformed into a reactive metabolite of 1'-hydroxyelemicin, which was subsequently conjugated with cysteine (Cys) and N-acetylcysteine (NAC). Administration of NAC could significantly ameliorate the elemicin- and 1'-hydroxyelemicin-induced cytotoxicity of HepG2 cells, while depletion of Cys with diethyl maleate (DEM) increased cytotoxicity. Recombinant human CYP screening and CYP inhibition experiments revealed that multiple CYPs, notably CYP1A1, CYP1A2, and CYP3A4, were responsible for the metabolic activation of elemicin. This study revealed that metabolic activation plays a critical role in elemicin cytotoxicity.