The State of Vitamin A in the Liver of the Rat

Gray, Edward LeB.; Cawley, John D.

doi:10.1093/jn/23.3.301

Cited by 12 publications

(3 citation statements)

References 13 publications

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“…with respect to esterification and this seems to agree with the findings of Pollard & Bieri (1960), but not with those of High et al (1956). Gray & Cawley (1942) had implied the presence of both hydrolytic and synthetic activities for vitamin A esters in the small intestine and our studies have demonstrated that these activities are present not only in the lumen, but also in the muscles and mucosae of the small intestine of rats. Rapid hydrolysis of vitamin A esters and esterification of the free vitamin A can be demonstrated with the mucosal-cell homogenates, as well as with the soluble enzymes prepared from the acetone-dried mucosae.…”

Section: Na3aso3mentioning

confidence: 70%

“…The fatty acid-specificity experiments have indicated that the esterification of vitamin A by the mucosal enzymes takes place with fatty acids containing more than 10 carbon atoms without any preference for chain length or unsaturation of the acid. Gray & Cawley (1942) have suggested that in rat liver vitamin A is probably stored as its palmitate. More recent work has shown that after feeding of vitamin A acetate the vitamin appears in the muscles of the small intestine as its higher ester (Mahadevan et al 1959).…”

Section: Discussion the Work Ofmentioning

confidence: 99%

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Studies on vitamin A esterase. 4. The hydrolysis and synthesis of vitamin A esters by rat intestinal mucosae

Mahadevan

Murthy

Krishnamurthy

et al. 1961

Biochemical Journal

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The formation of this compound involves hydrolysis of an acetoxy group and subsequent lactonization, as well as removal of the side chain. The same compound is formed on hydrolysis of cephalosporin Cc. 4. Hydrolysis of cephalosporin CA (pyridine) in dilute acid yields the nucleus of cephalosporin CA (pyridine). This nucleus is also formed when 7aminocephalosporanic acid reacts with aqueous pyridine. We are indebted to Mrs M. Loveridge, Miss M. Arber and Miss 0. Breitenmoser for skilful technical assistance. We wish to thank the Lilly Research Laboratories and Merck Sharp and Dohme Inc. for gifts of 6-aminopenicillanic acid, and Dr M. R. Pollock for purified penicillinase.

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Section: Na3aso3mentioning

confidence: 70%

Section: Discussion the Work Ofmentioning

confidence: 99%

Studies on vitamin A esterase. 4. The hydrolysis and synthesis of vitamin A esters by rat intestinal mucosae

Mahadevan

Murthy

Krishnamurthy

et al. 1961

Biochemical Journal

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“…In this part of the work it was essential that the plasma samples examined should be free from vitamin A ester in transit. Ester is present during active absorption, for the free vitamin A liberated in the alimentary tract by intestinal enzymes is resynthesized to ester during passage through the gut wall (Gray & Cawley, 1942) and it is this esterified vitamin A in transport to the liver which, superimposed on the normal vitamin A alcohol content of the plasma, gives rise to the typical tolerance curve.…”

Section: Rate Of Absorption Of Large Doses Of Vitamin Amentioning

confidence: 99%

Studies in vitamin A

Glover

Goodwin

Morton

1947

Biochemical Journal

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South african fish products. Part XXVI. Application of the fitelson method of “squalene” determination to some marine oils

Karnovsky

Rapsōn

1947

J. Chem. Technol. Biotechnol.

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estimated as calcium pectate and of extraneous ash, it will be seen that this object is best achieved (results of Experiments VIII and XII) by the process of first submitting the crude pectin extract to dialysis followed by precipitation by alcohol at a concentration of 70%. It will be noted, however, that in none of the experiments did the material estimated as calcium pectate reach a higher value than 7574 of the total solid matter.The problems relating to the nature of the residual 25'% of " ballast " material, and to its possible bearing on the gel forming properties of the pectin, are under investigation. It was demonstrated in all the experiments that this ballast material waS reduced more by precipitation than by dialysis, the ash, on the other hand, was removed more completely by dialysis than by precipitation. The value of ionic exchange bases for the purpose of removing ash is rather doubtful ; dialysis experiments demonstrated clearly that a small quantity of inorganic matter is combined with the pectin, while esperiments XIV and XV show that this combined ash may be removed, at least to a large extent, by the exchange bases. This removal is desirable if the inorganic matter is a fortuitous contamination of the pectin due to the method of extraction, but undesirable if it is a normal constituent in the sense that the methoxy groups are normal; in this connection it is noteworthy that the authors have examined many pectins from a wide range of fruits and vegetables which have been extracted under conditions which would render contamination with metallic ions unlikely, and in all cases have found a residual ash after dialysis.It will be noted that in none of the experiments which may be considered as having given maximum purification (namely, I and VIII, XI1 and XIV);did the sum of the saponification value, and free and combined acidic groups equal the theoretical value of 20.5% ; Hinton' found values ranging from 16.2% to 20.2% with an average value of 18.5% for a wide range of pectins, figures which are in good agreement with those reported. It would appear that a criterion of the purity of a pectin is the approach of this figure to the theoretical value of 20.5y0 (the fange 16.2% to 20.2% being regarded as satisfactory), combmed with an increase of the calcium pectate to a maximum. The copper reducingjpower;of the] pectin is of little value as a measure of thelpurification ; the values obtained are in agreement with those obtained by Hinton for the iodine reducing values (which ranged between 2.5% and 23'3%). Conclusion(a) Experiments carried out on the purification of crude Pectin solutions showed that dialysis followed by precipitation from aqueous solution by alcohol (70%) gave a pectin of the highest pectin content (determined as calcium pectate).(b) The process reduced the ash content to a minimum value of the order of 2-4% of the calcium pectatc value which, it is concluded, represents inorganic ions combined with some of the un-esterified carboxyl groups of the pectin.(c) Further reduction of t...

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The State of Vitamin A in the Liver of the Rat

Cited by 12 publications

References 13 publications

Studies on vitamin A esterase. 4. The hydrolysis and synthesis of vitamin A esters by rat intestinal mucosae

Studies on vitamin A esterase. 4. The hydrolysis and synthesis of vitamin A esters by rat intestinal mucosae

Studies in vitamin A

South african fish products. Part XXVI. Application of the fitelson method of “squalene” determination to some marine oils

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