5 0-Cyprinol

Murakami, T., et al. 2000. Enhancing effect of 5 a-cyprinol sulfate on mucosal membrane permeability to sodium ampicillin in rats. Eur J Pharm Biopharm 49 111. 

Bile alcohols are polyhydroxy C27 sterols that serve as intermediates in the biosjmthesis of cholic acid and chenodeoxycholic acid from cholesterol (1, 2). Recently several studies have shown that increased amounts of bile alcohols namely 27-nor-5p-cholestane-3a,7a,12a,24, 25-pentol and 5P-cholestane-3a, 7a,12a,25,26-pentol are excreted (as glucuronides in urine of patients with liver diseases such as primary biliary cirrhosis (3), liver cirrhosis (4, 5) and a-antitrypsin deficiency (6). Ichimiya et. al., described the occurrence of 5P-cholestane-3a,7a,12a,26,27-pentol (5P-cyprinol) and 5P-cholestane-3a,7a,... 

Ichimiya, H., Yanagisawa, J. and Nakayama, F. (1984). Significance of bile alcohols in urine of a patient with cholestasis identification of Sp-cholestane-3a,7a,12a,26,27-pentol (5p-bufoI) and 5P-cholestane-3a,7a, 12a,26-tetrol (27-deoxy-5P-cyprinol). Chem. Pham. Bull. 32 2874-2877. 

Cyprinol 5/8-Cholestane-3o,7a,l 2 a,26,27-pentol Several bony fishes some frogs... 

Deoxy-5a-cyprinol 5a-Cholestane-3o,7a,12a,26-tetrol Some fishes some frogs and toads... 

Deoxy-5/8-cyprinol 5/8-Cholestane-3o,7a, 12 a,26-tetrol Some frogs and toads... 

Fig. 2. 5a-Cyprinol sulfate(IV), anhydro-5a-cyprinol(V), 5a-cyprinol(VI) and dehydroanhydro-5a-cyprinol(VII).

Cyprinol sulfate was first found in bile of the eel. Conger myriaster, the principal bile salts of which are taurocholate and taurochenodeoxycholate [26], 5j8-Cyprinol sulfate was later found in the bile of some species of frogs as their principal bile salt [9,18,19,27], and was also detected in bile of some fishes as their minor bile salt [28,29], The structure of 5 8-cyprinol was determined as 5)8-choles-tane-3a,7a,12a,26,27-pentol by direct comparison with the synthetic sample prepared by Hoshita et al. before its isolation from natural sources [30], Partial synthesis of 5)8-cyprinol was also reported by Haslewood and Tammar [29],... 

Deoxy-5a-cyprinol, 5a-cholestane-3a,7a,12a,26-tetrol, has been identified as a minor companion of 5a-cyprinol in the carp bile [31]. This tetrahydroxy-5a-bile alcohol was prepared from anhydro-5a-cyprinol (VII) by lithium aluminum hydride reduction [2], 27-Deoxy-5a-cyprinol also occurs in bile of fishes [32], toads [9,33], and frogs [9]. 

Deoxy-5j8-cyprinol, 5 -choIestane-3o,7a,12a,26-tetrol, is present in some species of frogs [9,19] and toads [9,33]. Two stereoisomers at C-25 of this bile alcohol have been prepared from (257 )- and (25S)-3a,7a,12a-trihydroxy-5)S-cholestan-26-oic acids, respectively [13]. 

In a thorough analysis of solvolyzed material from bullfrog bile. Noma et al. isolated 4 new Cjj bile alcohols along with 5a-ranol, 5)3-ranol, and 5a-cyprinol [41]. Comparison with synthetic samples showed that these were 4 diastereoisomers at C-5 and C-24 of 26-deoxyranol, 27-norcholestane-3a,7a,12a,24-tetrol [41]. The... 

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],... 

Clayton et al. found small amounts of 2 tetrahydroxy C27 bile acids along with a number of C24 bile acids in gastric contents from neonates with high intestinal obstruction [110]. One of the higher bile acids was identified as 3a,7a,12 ,25-tetra-hydroxy-5 -cholestan-26-oic acid another was tentatively identified as 3a,7 ,12a,26-tetrahydroxy-5)8-cholestan-27-oic acid by its reduction with lithium aluminum hydride to 5]3-cyprinol (5j8-cholestane-3 ,7a,12a,26,27-pentol) [110]. 

As shown in Fig. 3, the initial reaction in the conversion of S S-cholestane-3a,7a,12a-triol (VIII) to cholic acid is 26-hydroxylation, forming 27-deoxy-5j8-cyprinol (5j8-cholestane-3a,7a,12a,26-tetrol) (IX). The in vitro formation from the triol (VIII) and the in vitro conversion of tribydroxy-S S-cholestanoic acid (X) of 27-deoxy-5 -cyprinol (IX) were demonstrated before the detection of this tetrol in nature [132]. 

Chimaerol, S S-bufol, 5j8-cyprinol, and scymnol are the 24-, 25-, and 27-hy-droxylated, and 24,27-dihydroxylated derivatives of 27-deoxy-5j8-cyprinol (IX), respectively. It is possible that these naturally occurring bile alcohols could be intermediates in alternative pathways for the formation of choUc acid (XIV) from 27-deoxy-5)8-cyprinol (IX). To test this possibility, these cholestanepolyols were labeled with tritium and given to guinea pigs or rats with a biliary fistula [133-136]. Of the tested bile alcohols, 5)3-chimaerol and 5 -cyprinol were converted efficiently to cholic acid [135,136]. However, these results do not provide conclusive evidence for alternative pathways of cholic acid formation since the conversion of these bile alcohols to cholic acid may merely reflect a lack of specificity of the enzyme systems involved in the conversion of 27-deoxy-5/8-cyprinol (IX) to cholic acid (XIV) via trihydroxy-5)3-cholestanoic acid (XII). 

The major bile salt of the carp, Cyprinm carpio, is 5a-cyprinol sulfate [21]. When [4- C]cholesterol was injected intraperitoneally into the carp, radioactive 5a-cyprinol was isolated from gallbladder bile [148]. It has been shown that the initial step in the major pathway for the formation of 5a-cyprinol (VI) from cholesterol (XV) is the 7a-hydroxylation of cholesterol to form cholest-5-ene-3j8,7a-diol (XVI) [149] (Fig. 4). It has also been shown that the double bond is isomerized to the A position before being reduced [150]. These in vivo studies suggest that until the intermediary formation of a A compound, presumably 7 ,12a-dihydroxycholest-4-en-3-one (XVII), the sequence of reactions in the biosynthesis of 5 -cyprinol (VI) in the carp is the same as that in the conversion of cholesterol (XV) to cholic acid (XIV) in mammals. 7a,12a-Dihydroxycholest-4-en-3-one (XVII) was found to be converted into 5a-cholestane-3a,7a,12a-triol (XVIII) by the microsomal fraction of carp hver fortified with NADPH [151]. The conversion of the triol (XVIII) to 5a-cyprinol (VI) via 27-deoxy-5a-cyprinol (XIX) was also established. The 26-hydroxylation of the triol (XVIII) was catalyzed by the microsomal fraction fortified with NADPH, and the 27-hydroxylation of 27-deoxy-5a-cyprinol (XIX) was catalyzed by the mitochondrial fraction fortified with NADPH [151]. 

In the in vivo studies with labeled cholesterol [33] as well as mevalonate [157], the label was incorporated into the minor bile acids of the toad, cholic acid (XIV) and 3a,7a,12a-trihydroxy-5y3-cholestan-26-oic acid (X). In contrast, the major bile acids, 3a,7 ,12 -trihydroxy-5/3-cholest-22-ene-24-carboxylic acid and 3a,7a,12a-trihy-droxy-5)8-cholest-23-en-26-oic acid, did not become labeled and their biochemical origin is still obscure. The formation of labeled cholic acid and trihydroxy-5j8-cholestanoic acid suggests that in the toad 27-deoxy-5j8-cyprinol (VIII) is converted to cholic acid (XIV) via the C27 bile acid (X) by the same pathway as that in mammals. 

The formation of 27-deoxy-5a-cyprinol and 5a-cyprinol in the carp has been shown by Hoshita (121) and Masui et al. (178) to involve 26(27)-hydroxylation of 5a-cholestane-3a,7a,12a-triol, catalyzed by the microsomal fraction fortified with NADPH, followed by 26(27)-hydroxylation of 27-deoxy-5a-cyprinol, catalyzed by the mitochondrial fraction fortified with NADPH. 

The bile salts found in vertebrates classified below the level of the reptiles are unique in that they are mostly sulfate esters of polyhydric alcohols. The bile alcohols, such as scymnol (24,25-oxido-3a,7a,12a,26-tetra-hydroxycoprostane), ranol (3a,la, 12a,24,26-pentahydroxy-27-norcholestane), and cyprinol (3a,7a,12a,26,27-pentahydroxycholestane), are discussed in a recent review by Hoshita and Kazuno (53) and in Chapter 2 by Matschiner (this volume). 

In the carp, chub, and related fishes, 5a-cyprinol is a principal bile alcohol (220). It also occurs in the lungfish and in the coelacanth, where it is accompanied by its 3/9-epimer, latimerol. The characterization of 5a-cyprinol was accomplished by Hoshita et al. (221) and by Anderson et al. (222)... 

Cyprinol has been obtained from the frog (Rana nigromaculata) (224), the eel (Conger myriaster) (225), the sturgeon, and the paddlefish (223). Hoshita, Kouchi, and Kazuno (226) prepared this compound before its isolation from natural sources. It has also recently been prepared by Haslewood and Tammar (223). 

The ancient bony fish, the coelacanth, has bile that contains little if any bile acid and has as its principal bile alcohol the compound shown above, which is latimerol. Latimerol was isolated and characterized by Anderson and Haslewood (227). It occurs along with its 3a-epimer, 5a-cyprinol. 

This alcohol has been isolated from the bile of the carp (228). It may be the alcohol isolated much earlier from the toad Bufo vulgaris japonica) by Makino (229) and named tetrahydroxybufostane (194). 27-Deoxy-5a-cyprinol was prepared from anhydrocyprinol by Hoshita (230). Its 5,3-epimer may be an expected intermediate in the formation of trihydroxycoprostanic acid, but the alcohol has not been widely found. Both the 5 - and 5 -epimers of 27-deoxycyprinol were formed in toads given C-cholesterol (194). 

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. 

Hoshita et al. (39) reported the synthesis of this acid from anhydro-5a-cyprinol (26,27-epoxy-3o ,7a,12a-trihydroxy-5a-cholestane) (XV) as shown in Fig. 10. Kallner (66) and Ziller, Mitra, and Elliott (68,40) prepared the ester as described under A, 2 and A, 3 respectively. 

To ascertain whether cholesterol is a precursor of 5a-cyprinol, Hoshita (133) administered C-cholesterol intraperitoneally to carp, in which 5a-cyprinol is the principal biliary sterol (134). After 12 days bile was collected from the gallbladder, and radioactive 5a-cyprinol corresponding to 0.14% of the administered sterol was recovered from bile. To ascertain whether choles-tanol or 7a-hydroxycholesterol was a precursor of 5a-cyprinol in this species Hoshita (58) administered these tritiated sterols intraperitoneally to carp and studied the distribution of in biliary constituents. From cholestanol-5,6- H, 1.1% of the biliary remained in the neutral fraction, of which 5a-cyprinol and 27-deoxy-5a-cyprinol were the major and minor constituents ( 22 1). Allocholic acid was the only radioactive component identified in the acid fraction. Two weeks after similar injection of 7a-hydroxycholesterol-7/S- H into carp, 17.6% of the radioactivity was recovered in bile, 86.5% of which was present in the neutral fraction and 6.3 % in the acid fraction. 5a-Cyprinol and 27-deoxy-5a-cyprinol ( 9 1) retained most of the tritium in the former fraction, whereas allocholic and cholic acids each retained ( 1.5 1) in the acid fraction. Thus, carp liver enzymes convert 7a-hydroxy-cholesterol to 5a sterols and to the 5/9- and 5a-C24 acids. Normally carp bile contains more cholic than allocholic acid. 

Masui et al. (136) have shown that carp liver microsomes contain the necessary 5a-reductase and a 26-hydroxylase to convert 7a,12a-dihydroxy-cholest-4-en-3-one (XXXVI) to 27-deoxy-5a-cyprinol when fortified with NADPH, and that a mitochondrial enzyme system requiring NADPH converts the latter 5a-sterol to 5a-cyprinol. They suggested that the microsomal system hydroxylated one of the terminal methyl groups in a stereospecific form (25 -form), and the mitochondrial system hydroxylated the 25a-form. 

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