Secondary bile acids and the biliary epithelia: The good and the bad

Table 1 Some physico-chemical features of the most relevant primary and secondary bile acids in human bile

	Hydroxil groups number and position	Solubility in water (protonated form, µM)1	Critical micellar concentration (sodium salt, mM)1	Hydrophobicity index (taurine conjugated)2
Primary bile acids
Cholic acid	3 (3, 7, 12)	273	13	0
Chenodeoxycholic acid	2 (3, 7)	27	9	0.46
Secondary bile acids
Deoxycholic acid	2 (3, 12)	28	10	0.59
Lithocholic acid	1 (3)	0.05	0.9	1
Ursodeoxycolic acid	2 (3, 7)	0.9	19	-0.47

¹Values assessed in water as reported by Hofmann et al[44].

²Cholic acid and Lithocholic acid were assumed to have (by definition) a value of 0 and 1 respectively[8].