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Table 1 Unusual bile salt profiles in reptiles and mammals

From: Evolutionary diversity of bile salts in reptiles and mammals, including analysis of ancient human and extinct giant ground sloth coprolites

Bile salt pattern Examples Comment
5α ('allo') bile acids Lizards, especially Iguania 5α bile acids are generally rare in vertebrates
1α-Hydroxylation Spotted cuscus (Phalanger maculatus) Unusual hydroxylation leads to highly hydrophilic bile acids in this species.
1β-Hydroxylation Feather-tailed glider (Acrobates pygmaeus) Unusual hydroxylation site
6α-Hydroxylation Suidae
Lesser Malay chevrotain (Tragulus javanicus)
Unusual hydroxylation site. Hyocholic acid is only detected in Suidae and the chevrotain.
6β-Hydroxylation Muridae Unusual hydroxylation site
7-Oxo bile acids Queensland koala (Phascolarctos adjustus) Unusual bile salt modification
15α-Hydroxylation Common wombat (Vombatus ursinus) Not seen in other mammals but found in birds
16α-Hydroxylation Snakes Hydroxylation at 16α is common in snakes (Boidae, Cylindrophiidae, Pythonidae, Uropeltidae) and birds but not seen in mammals.
Ursodeoxycholic acid (at > 5%) Ursidae
Caviomorph rodents
Ursodeoxycholic acid is seen in other mammals but only as a small percentage of the bile salt pool.
Δ22 Bile acids Agouti (Dasyprocta punctata)
Mountain paca (Cuniculus taczonowskii)
Pacharana (Dinomys branickii)
Some snakes
This unusual bile acid side-chain modification is seen in a small number of mammals and is also found in some snakes in Colubridae.
22-Hydroxylated C27 bile acids Turtles This type of bile salt is unique to turtles.
23R-Hydroxylation Pinnipeds
Some snakes
23R-Hydroxylation of bile acids is common to Pinnipeds but is not seen in other Carnivora.
100% Bile alcohols Paenungulates, rhinoceroses Profile also seen in lobe-finned fish, jawless fish, some teleost fish, and some amphibians.