Muricholic acid
Muricholic acids are a group of bile acids found as some of the main forms in mice, which gives them their name, and at low concentrations in other species.
The two principal forms, α- and β-muricholic acids, differ from the primary bile acids found in humans, cholic acid and chenodeoxycholic acid, by both having a hydroxyl group at the 6-position in the β-configuration. The orientation of the hydroxyl group at the 7-position defines whether they are α- or β-muricholic acid. Muricholic acids are detectable at low concentrations in human urine.
The three major bile acids in germ-free mice are cholic acid, α-muricholic, and β-muricholic acids. In conventional mice with a normal microbiome, ω-muricholic acid, and various sulfated forms are also found. Conjugation with taurine, or with glycine takes place in the liver before secretion.
The enzyme responsible for the 6-hydroxylation reactions forming muricholates in mice is the cytochrome P450 Cyp2c70. This produces α-muricholic acid from chenodeoxycholic acid, and β-muricholic acid from ursodeoxycholic acid.
Tauromuricholic acids were shown to be potent antagonists of the bile acid receptor farnesoid X receptor.