Table 1.

Phase I metabolism (non-cytochrome P450) in rodent and human fetal livers. ¹

Enzyme	Mouse	Rat	Human	References
Alcohol Dehydrogenases
Adh1	↓(M)			[3]
Adh4	↓(M)			[3]
Adh5	↓(M)			[3]
Adh6-ps1	↓(M)			[3]
Adh7	↓(M)			[3]
Aldo-Keto Reductases
Akr1	↓(M)			[3]
Akr7	↓(M)			[3]
Aldehyde Dehydrogenases
Aldh1	↓(M)			[2,3]
Aldh2	↓(M)			[2,3]
Aldh3a2	↓(M)			[2,3]
Aldh4a1	↓(M)			[2,3]
Aldh6a1	↓(M)			[2,3]
Aldh7a1	↓(M)			[2,3]
Carboxylesterases
Ces		↓(A)		[7]
Ces1/CES1	↓(M)		↓(M,P,A)	[3,8]
Ces2/CES2	↓(M)		↓(M)	[3,8]
Ces3	↓(M)			[3]
Flavin-Containing Monooxygenases
Fmo1/FMO1	↓(M)↔(P)		↑(M,P)	[3–6]
Fmo2	↓(M)			[3]
Fmo3/FMO3	↓(M,P)		↓(M)	[3–5]
Fmo4/FMO4	↔(M)		↔(M)	[3,5]
Fmo5	↓(M,P)			[3,4]

¹Expression or activity compared to adult liver levels. mRNA expression (M), protein expression (P), and activity (A) are noted; ↑ denotes up-regulation; ↓ denotes down-regulation; and ↔ denotes no change. Human orthologs are indicated only for isoforms with human data.