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  • Formation of hepatic DNA adducts by methyleugenol in mouse models: drastic decrease by Sult1a1 knockout and strong increase by transgenic human SULT1A1/2.

Formation of hepatic DNA adducts by methyleugenol in mouse models: drastic decrease by Sult1a1 knockout and strong increase by transgenic human SULT1A1/2.

Carcinogenesis (2013-12-10)
Kristin Herrmann, Wolfram Engst, Walter Meinl, Simone Florian, Alexander T Cartus, Dieter Schrenk, Klaus Erich Appel, Tobias Nolden, Heinz Himmelbauer, Hansruedi Glatt
ABSTRACT

Methyleugenol--a natural constituent of herbs and spices--is hepatocarcinogenic in rodent models. It can form DNA adducts after side-chain hydroxylation and sulfation. We previously demonstrated that human sulfotransferases (SULTs) 1A1 and 1A2 as well as mouse Sult1a1, expressed in Salmonella target strains, are able to activate 1'-hydroxymethyleugenol (1'-OH-ME) and 3'-hydroxymethylisoeugenol (3'-OH-MIE) to mutagens. Now we investigated the role of these enzymes in the formation of hepatic DNA adducts by methyleugenol in the mouse in vivo. We used FVB/N mice [wild-type (wt)] and genetically modified strains in this background: Sult1a1 knockout (ko), transgenic for human SULT1A1/2 (tg) and the combination of both modifications (ko-tg). Methyleugenol (50mg/kg body mass) formed 23, 735, 3770 and 4500 N (2)-(trans-methylisoeugenol-3'-yl)-2'-deoxyguanosine adducts per 10(8) 2'-deoxyribonucleosides (dN) in ko, wt, ko-tg and tg mice, respectively. The corresponding values for an equimolar dose of 1'-OH-ME were 12, 1490, 12 400 and 13 300 per 10(8) dN. Similar relative levels were observed for the minor adduct, N (6)-(trans-methylisoeugenol-3'-yl)-2'-deoxyadenosine. Thus, the adduct formation by both compounds was nearly completely dependent on the presence of SULT1A enzymes, with human SULT1A1/2 producing stronger effects than mouse Sult1a1. Moreover, a dose of 0.05 mg/kg methyleugenol (one-fourth of the estimated average daily exposure of humans) was sufficient to form detectable adducts in humanized (ko-tg) mice. Although 3'-OH-MIE was equally mutagenic to 1'-OH-ME in Salmonella strains expressing human SULT1A1 or 1A2, it only formed 0.14% of hepatic adducts in ko-tg mice compared with an equimolar dose of 1'-OH-ME, suggesting an important role of detoxifying pathways for this isomer in vivo.

MATERIALS
Product Number
Brand
Product Description

Supelco
Methyl eugenol, analytical standard
Eugenol, European Pharmacopoeia (EP) Reference Standard
Supelco
Eugenol, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
Eugenol, ReagentPlus®, 99%
Sigma-Aldrich
Eugenol, natural, ≥98%, FG
Sigma-Aldrich
Eugenol, ≥98%, FCC, FG
Supelco
Eugenol, PESTANAL®, analytical standard
Sigma-Aldrich
Methyl eugenol, ≥98%, FCC
Sigma-Aldrich
4-Allyl-1,2-dimethoxybenzene, 99%
Supelco
Eugenol, certified reference material, TraceCERT®, Manufactured by: Sigma-Aldrich Production GmbH, Switzerland