5a-Cholestan-26-oic acids

SS)-3a,7a,12a-Trihydroxy-5)S-cholestan-26-oic acid 3/8,7a,l 2a-Trihydroxy-5)S-cholestan-26-oic acid 3a,7a,12a-Trihydroxy-5a-cholest-23-en-26-oic acid (25/ )-3a,7a.l2a-Trihydroxy-5/S-cholest-23-en-26-oicacid 3 a,7a. 12 a-T rihydroxy-5j8-cholest-24-en-26-oic acid 3a,7a,24-Trihydroxy-5 8-cholestan-26-oicacid 3a,12a,22-Trihydroxy-5/8-cholestan-26-oicacid 3 a,7a-Dihydroxy-5)8-cholestan-26-oic acid 3 a,7a-Elihydroxy-5j8-cholest-23-en-26-oic acid 3a,7a-Dihydroxy-5y8-choIest-24-en-26-oic acid 3a,7 8-Dihydroxy-5/ -cholestan-26-oic acid 3/8,7/3-Dihydroxy-5/S-cholestan-26-oic acid 3 a. 12 a- Dihydroxy-5/8-cholestan-26-oic acid 3/8,12 a-Dihydroxy-5/8-cholestan-26-oic acid 3a-Hydroxy-5)3-cholestan-26-oic acid 3/8-Hydroxy-5/8-cholestan-26-oic acid 3a,12a-Dihydroxy-7-oxo-5j8-cholestan-26-oic acid 7a,12a-Dihydroxy-3-oxo-5a-cholestan-26-oic acid 7a, 12 a-Dihydroxy-3-oxo-5)6-cholestan-26-oic acid... 

Okuda et al. isolated a higher bile acid from the bile of Iguana iguana [66]. The structure was shown to be 3a,7 ,12a-trihydroxy-5a-cholestan-26-oic acid by lithium aluminum hydride reduction to 27-deoxy-5 -cyprinol [66]. The 5a-C27 bile acid was also partially synthesized from 27-deoxy-5a-cyprinol [67]. 3a,7a,12a-Trihydroxy-5a-cho estan-26-oic acid also occurs in bile of some species of frogs [18,19] and the alligator [68],... 

Three higher bile acids possessing a keto group were detected in the bile of Alligator mississippiensis, and characterized as 7a,12a-dihydroxy-3-oxo-5)8-cholestan-26-oic acid, 3a,12a-dihydroxy-7-oxo-5/3-cholestan-26-oic acid, and 7a,12a-dihy-droxy-3-oxo-5a-cholestan-26-oic acid [68]. Nothing is known about the formation of these bile acids. 

A probable intermediate in the biosynthesis of allocholic acid, 3a,7a, 12a trihydroxy-5a-cholestan-26-oic acid, has been found in the bile of the giant salamander (39). Amimoto (43) obtained allocholic acid and a second radioactive acidic metabolite from bile of the giant salamander after administration of 27-deoxy-5a-cyprinol (3a,7a, 2a, 26-tetrahydroxy-5a-cholestane). The unknown acid was esterified, reduced with LiAlH4, and the product identified as 27-deoxy-5a-cyprinol. Okuda et at. (44) isolated a few crystals (m.p. 227 °C) from the bile of iguana and obtained the same product on reduction of the ester with LiAlH4. 

A trihydroxycholestenoic acid was isolated as a major bile acid from bile of the toad, Bufo vulgaris formosus [70] and was characterized as (25/ )-3a,7a,12o(-trihy-droxy-5/8-cholest-23-en-26-oic acid by oxidation to 23-norcholic acid and hydrogenation to (25/ )-3a,7a,12a-trihydroxy-5j8-cholestan-26-oic acid [71]. The 5a isomer, 3a,7a,12a-trihydroxy-5a-cholest-23-en-26-oic acid, was recently detected as a minor bile acid in toad bile [46]. The bile of Varanus monitor contains as minor constituents 3a,7a,12a-trihydroxy-5j8-cholest-23- and 24-enoic acids [69]. The acid has been synthesized prior to its detection in nature [72]. 

Noma et al. studied minor bile acids of the bullfrog and found 4 different tetrahydroxycholestanoic acids [42]. These were identified as varanic acid, its 5 a isomer, and 3a,7a,12a,26-tetrahydroxy-5a- and 5j8-cholestan-27-oic acids by comparison with synthetic samples [42]. 3a,7a,12a,26-Tetrahydroxy-5 -cholestan-27-oic acid also occurs in bile of the frog, Rana plancyi [19]. 

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