Ethoxyquin: An Antioxidant Used in Animal Feed

Table 3

Metabolite/degradation products of EQ detected in different organisms.

	EQ metabolite/degradation product	Organism
	1,2-Dihydro-6-hydroxy-2,2,4-trimethylquinoline sulphate	Rats^1
	1,2-Dihydro-6-hydroxy-2,2,4-trimethylquinoline glucuronide	Mice^1
	1,2,3,4-Tetrahydro-3,6-dihydroxy-4-metylene-2,2-dimethylquinoline sulphate	Rats^1
	1,2-Dihydro-6-ethoxy-8-hydroxy-2,2,4-trimethylquinoline glucuronide	Rats^1; Mice^1
	8-(S-glutathionyl)-2,2,4-trimethylquinol-6-one	Rats^1; Mice^1
	1,2,3,4-Tetrahydro-6-ethoxy-3-hydroxy-4-(S-glutathionyl)-2,2,4-trimethylquinoline	Rats^1; Mice^1
	2,6-Dihydro-2,2,4-trimethyl-6-quinolone (quinone imine (QI))	Rats^1; Atlantic salmon^2
	6-Hydroxy-2,2,4-trimethyl-1,2-dihydroquinoline (deethylated EQ (DEQ))	Atlantic salmon^2
	1,8′-Di(1,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline) or 6,6′-diethoxy-2,2,2′,2′,4,4′-hexamethyl-1′,2′-dihydro-2H-1,8′-biquinoline (ethoxyquin dimer (EQDM)); *Instead of the hydrogen atom there is a methyl group, it gives methyl C-N ethoxyquin dimer,; 6,6′-Diethoxy-1′,2,2,2′,2′,4,4′-heptamethyl-1′,2′-dihydro-2H-1,8′-biquinoline	Atlantic salmon^2; Pears^3,4
	N-N Ethoxyquin dimer,; 1,1′-di(1,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline) or; 6,6′-diethoxy-2,2,2′,2′,4,4′-hexamethyl-2H,2′H-1,1′-biquinoline	Pears^3,4
	6-Ethoxy-1,2,2,4-tetramethyl-1,2-dihydroquinoline,; methylethoxyquin (MEQ)	Pears^3,4
	6-Ethoxy-2,4-dimethylquinoline, dehydrodemethylethoxyquin (DHMEQ)	Pears^3,4
	6-Ethoxy-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline, dihydroethoxyquin (DHEQ)	Pears^3,4
	6-Ethoxy-2,4-dimethyl-1,2-dihydroquinoline,; demethylethoxyquin (DMEQ)	Pears^3,4

Glu: glucuronide, G: glutathione, Et: ethyl group (C₂H₅).
¹Burka et al. [21], 2Berdikova Bohne et al. [26], ³Gupta and Boobis [14], ⁴JMPR [25].