Table 1.

Major types of biochemical reactions relevant to detoxification. The examples of enzymes and, in particular, of reactions are for illustration only; the list is not meant to be complete. Based on (Hoffmann and Maser, 2007; Josephy et al., 2005; Parkinson and Ogilvie, 2008; Zimniak, 2006).

Process	Enzyme	Common acronym	Example reactions
Oxidation	cytochrome P450	CYP	Hydroxylation of aromatic rings; hydroxylation of steroids
	alcohol dehydrogenase	ADH	Conversion of ethanol to acetaldehyde
	aldehyde dehydrogenase	ALDH	Conversion of acetaldehyde to acetic acid
	peroxidase		Oxidation of an organic, e.g., glutathione, or inorganic compound with concomitant reduction of an organic hydroperoxide or of H2O2
Reduction	aldo-keto reductase	AKR	Reduction of aldehydes, e.g., aldoses or 4-HNE, to alcohols
	short chain dehydrogenase/reductase	SDR	Reduction of keto group in doxorubicin; conversion of cortisone to cortisol
Hydrolysis	epoxide hydrolase		Conversion of naphthalene epoxide to naphthalene Diol
Conjugation of nucleophiles	UDP-glucuronosyltransferase	UGT	Glucuronidation of naphthol (on hydroxyl group), of aniline (on amino group), of thiophenol (on sulfhydryl group), of bilirubin (on carboxyl group)
	sulfotransferase	SULT	Sulfonation (sulfation) of phenols and aliphatic alcohols
	methyltransferase		Methylation of hydroxyl group in L-DOPA; of imidazole nitrogen in histamine
	acetyltransferase		Acetylation of aromatic amines and of substituted hydrazine
Conjugation of electrophiles	glutathione transferase	GST	Glutathione conjugation at electrophilic carbon atom in: 1-chloro-2,4-dinitrobenzene (halogen displacement), 4-HNE (Michael addition), epoxide (ring opening)