Trans-vitamin

After stirring for 2 hours at room temperature, the mass of vitamin A acid has crystallized out. It is sharply filtered off by suction and washed with a little ice-cold isopropanol. From the filtrate, a further small amount of mainly all trans vitamin A acid crystallizes out upon the addition of water. The filter cake is suspended in 600 parts of water and stirred for 4 hours at room temperature it is filtered by suction and the product washed with water. It is dried in vacuo at 40° to 50°C and 115 parts of vitamin A acid are obtained. The melting point lies between 146° and 159°C. 

The mixture of the all trans and mainly 9,10-cis vitamin A acid may be separated by fractional crystallization from ethanol. All trans vitamin A acid has a melting point of 180° to 182°C and 9,10-cis vitamin A acid, which crystallized in the form of pale yellow fine needles collected into clusters, has a melting point of 189° to 190°C. 

AOAC official method 992.27. Trans-vitamin K, (phylloquinone) in ready-to-feed milk-based infant formula. Liquid chromatographic method. In MP Bueno, ed. Official Methods of Analysis of AOAC International. 16th ed. Arlington, VA AOAC International, 1995, p. 50-6-50-8. 

J Boldingh, HR Cama, FD Collins, RA Morton, NT Gridgeman, O Isler, M Kofler, RJ Taylor, AS Welland, T Bradbury. Pure all-trans vitamin A acetate and the assessment of vitamin A potency by spectrophotometry. Nature 168 598, 1951. 

It is well-known that plants do not synthesize vitamin A. Also, animals can only synthesize vitamin A from p-carotene or carotenoids in which one-half of the molecule is like p-carotene. In nature, the vitamin A precursor comes either from plants or microorganisms. The most common sources of vitamin A in citrus are a- and p-carotenes and p-cryptoxanthin. In addition to the above name carotenoids, p-apo-8 -carotenal in citrus peel could be a source of provitamin A. However, the peel is not usually consumed. Provitamin A compounds are cleaved to form vitamin A aldehyde in the intestine by p-carotene 15,15 -oxygenase (Figure 4) (54). Aldehyde reductase reduces the aldehyde to the all trans-vitamin A. p-Carotene is cleaved between the 15,15 carbon... 

Figure 7.2.16 Comparison of continuous-flow 1H NMR spectra of all-trans vitamin A acetate, recorded (a) during an HPLC-NMR separation, and (b) during an SFC-NMR separation...

This polyene has 11 conjugated n bonds, with X = 450 nm. Carotene can be cleaved enzymatically into two units of a -trans- vitamin A, which is a polyene with five conjugated n bonds ... 

The mixture of reaction product and triphenylphospbine oxide (16), which mixture is gelatinous owing to the alkali metal salt formed, enters an extraction column e, in which the desired reaction product, after acidification with sulfuric acid, is extracted, in counter-current, by hydrocarbons. In a second column, the hydrocarbon extract is washed, also continuously, with aqueous alcohol in order to remove the last residues of triphenylphosphine oxide (16). After concentration, under mild conditions, of the hydrocarbon extract, the all-trans vitamin A acetate (9) formed in the reaction crystallizes out and is separated off. The cis isomer, which does not crystallize, remains in the mother liquor and can be converted, according to one of the above-mentioned techniques, into the all-trans compound. 

MYVPACK OLEOVITAMIN A OPHTHALAMIN PREPALIN RETINOL aU-trans RETINOL RETRO-VITAMIN A TESTAVOL VAFLOL VI-ALPHA VITAMIN A1 VITAMIN A1 ALCOHOL aU-trans-VITAMIN A ALCOHOL VITAVEL-A VITPEX VOGAN VOGAN-NEU... 

RETINOL ACETATE RETINYL ACETATE all-trans-RETINYL ACETATE trans-VITAMIN A ACETATE VITAMIN A ALCOHOL ACETATE... 

Ergosterol undergoes similar changes although with the 7,8 unsaturation already present ring B opening occurs facilely with the result that in addition to vitamin 03, lumisterol, tachysterol and the 5,6-trans vitamin are formed. 

R 2625 Retinoic acid, all trans (vitamin A acid) Ligands for both the retinoic acid recepte (RAR) and the retinoid X receptor (RXR) that act as transcription factors to regulate the growth and differentiation of normal and malignant cells. 

Curiously the 5E-lsomer, the so-called trans-vltamln D that is easily obtained from I2 catalyzed "thermal" Isomerization of vitamin D (75), could not be traced in the irradiation mixtures (11a, 74). Mennet-Bouvier concludes to the occurrence of trans-vitamin D In mixtures obtained upon short-term Irradiation (12). Bakker report that the trans isomer is formed by heating of the primary photoproducts, the vinylcyclobutenes (11a). 

Much of the stereochemical uncertainties associated with the configuration of dihydrovitamin D and dihydrotachysterol have been resolved by recent studies By reacting cis- and trans-vitamin D2 with 9-borobicyclononane followed by a basic peroxide workup, the stereoisomeric lOS and IQR 19-hydroxymethyl dihydro-deriv-atives were obtained in good yields. Tosylation of the 19-alcohol produced the inter-... 

Synonyms Anti-infective vitamin Antixerophthalmic vitamin Axerophthol 3,7-Dimethyl-9-(2,6,6-trimethyl-1-cyclohexen-1-yl)-2,4,6,8-nonatretraen-1-ol Oleovitamin A all-trans-Retinol Retrovitamin A Vitamin A Vitamin A alcohol all-trans-Vitamin A alcohol Classification Organic compd. 

CAS 127-47-9 EINECS/ELINCS 204-844-2 Synonyms Acetic acid, retinyl ester Retinol acetate all-trans-Retinyl acetate Vitamin A acetate trans-Vitamin A acetate Vitamin A alcohol acetate Definition Ester of retinol and acetic acid Empiricai C22H32O2... 

Vitamin A alcohol. See Retinol Vitamin A alcohol acetate. See Retinyl acetate all-trans-Vitamin A alcohol. See Retinol Vitamin Be. See Folic acid Vitamin BX. See p-Aminobenzoic acid Vitamin Bs, calcium salt. See Calcium D-pantothenate... 

Vitamin A has four such double bonds therefore, 32 different geometrical isomers are possible. Only those four isomers that exist in nature will be considered here. The trans form (see Fig. 4-33) is the most stable form, so most natural compounds contain mainly trans vitamin A. However, it is possible to con-... 

Fig. 4.18 The rhodopsin cycle. The bleaching of rhodopsin yields all-trans retinene (now more currently indicated as retinal), which must be isomerized to neoretinene b before it can regenerate the visual pigment. Alternatively, having been reduced to all trans vitamin A, the latter in turn must be isomerized to neovitamin Ab before it takes part in rhodopsin synthesis. Rod vision thus depends on the continuous stereoisomerization of all-trans retinene or vitamin A, or on the continuous replacement of these substances by new supplies of vitamin Ab from external sources (adapted from [196, 197])...

Cook KK, Mitchell GV, Grundel E, Rader Jl. HPLC analysis for trans-vitamin Ki and dlhydro-vitamin Kj in margarines and margarine-like products using C30 stahonary phase. Food Chem 1999 67 79—88. 

Vitamin A, and more recently retinoic acid (all-trans vitamin A acid) has long been used either systemically or topically in the treatment of keratinizing... 

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