Covalent Modification of Phosphatidylethanolamine by Benzyl Isothiocyanate and the Resultant Generation of Ethanolamine Adduct as Its Metabolite

• Published in: Chemical research in toxicology Vol. 32; no. 4; pp. 638 - 644
• Main Authors: Nakamura, Toshiyuki, Hirakawa, Miho, Nakamura, Yoshimasa, Ishisaka, Akari, Kitamoto, Noritoshi, Murakami, Akira, Kato, Yoji
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 15.04.2019
• Subjects: Animals; Ethanolamine - analysis; Ethanolamine - metabolism; Isothiocyanates - analysis; Isothiocyanates - metabolism; Liposomes - chemistry; Liposomes - metabolism; Mice; Molecular Structure; Phosphatidylethanolamines - analysis; Phosphatidylethanolamines - metabolism; RAW 264.7 Cells
• ISSN: 0893-228X; 1520-5010
• DOI: 10.1021/acs.chemrestox.8b00331

Benzyl isothiocyanate (BITC), a dietary isothiocyanate (ITC) derived from cruciferous vegetables, has anticancer properties. It is believed that the ITC moiety (−NCS) that reacts predominantly with thiol compounds plays a central role in triggering the activities resulting from these properties. Recent studies have demonstrated that ITCs also covalently modify amino moieties in a protein. In this study, we examined the chemical reaction between BITC and the aminophospholipid, phosphatidylethanolamine (PE), in the cell membrane or lipoprotein particle. To detect the BITC-modified PE, the bond between ethanolamine (EA) and phosphatidic acid in PE was cleaved using phospholipase D to form the BITC–EA adduct, which was then measured. BITC–EA was detected from the BITC-treated unilamellar liposome and low-density lipoprotein even with only a few micromoles of BITC treatment, suggesting that BITC might react with not only a thiol/amino group of a protein but also an amino moiety of an aminophospholipid. Moreover, after incorporating BITC–PE included in the liposomes into the cultured cells or after direct exposure of BITC to the cells, free BITC–EA was excreted and accumulated in the medium in a time-dependent manner. It indicates that an intracellular enzyme catalyzes the cleavage of BITC–PE to produce BITC–EA. Because the ITC–amine adduct is stable, the ITC–EA adduct could be a promising indicator of ITC exposure in vivo.