Vitamins analogs

Hydroxy- and 8-nitro-4-chloroquinazolines have been incorporated into the nucleotide of vitamin B12. These quinazoline-containing vitamin analogs stimulated the growth of cobalamine requiring cultures. ... 

Fluorine has also been introduced stereospecifically at the 3/ positions of la-OH-Da via hydrofluoric acid catalyzed cycloreversion of the 3,5-cyclo vitamin analog which was initially fonned by solvolysis of the 3 3-tosylate [scheme (28)] . ... 

The entire set of stereoisomeric-13-dihydroxy cisftrans vitamin analogs, totalling eight in number, has recently been synthesized from vitamin D3 and epi-vita-min D3 via cyclo vitamin intermediates and Mn02- ally lie hydroxyl epimerization reactions [scheme (33)]. (H. E. Paaren, H. K. Schnoes, and H. F. DeLuca, unpublished results). 

The Observation of Second Order Kinetics to Support a Multistep Displacement Mechanism for a Vitamin Analog 387... 

Vitamin Analogs - The folate analog mettiotrexate is of great value in the treat-... 

Isomerization of double bonds in vitamin D analogs such as calciferol by oxidation and reduction has been carried out via the formation of the tt-allylpalladium complex 334 with PdCl2(PhCN)2 in 70% yield, followed by hydride reduction to afford 335[295],... 

A large number of selenium derivatives such as the selenium analog of vitamin B] have been tested for physiological activity (91). 

In contrast to vitamin K, there has been considerably more activity on fermentative approaches to vitamin (50). The biosynthetic pathway to vitamin K2 is analogous to that of vitamin except that poly(prenylpyrophosphates) are the reactive alkylating agent (51,52). Menaquinones of varying chain lengths from to have been isolated from bacteria. The most common forms are vitamin K2 35, (40) (45) significant amount of K2 20)... 

When the enamine is in conjugation with a carbonyl function, as in a-aminomethylene aldehydes (528,529), ketones (530), or esters (531), a Michael addition is found in vinylogous analogy to the reactions of amides. An application to syntheses in the vitamin A series employed a vinyl lithium compound (532). 

FIGURE 8.18 Dolichol phosphate is an initiation point for the synthesis of carbohydrate polymers in animals. The analogous alcohol in bacterial systems, undecaprenol, also known as bactoprenol, consists of 11 isoprene units. Undecaprenyl phosphate delivers sugars from the cytoplasm for the synthesis of cell wall components such as peptidoglycans, lipopolysaccharides, and glycoproteins. Polyprenyl compounds also serve as the side chains of vitamin K, the ubiquinones, plastoquinones, and tocopherols (such as vitamin E). 

Modification of the oxazole, as in 13 allowed for the formation of vitamin Ba analogs, such as 15 via intermediate pyridine 14. 

The ultraviolet spectrum of vitamin Be, or pyridoxine, measured in aqueous ethanol varies with the composition of the solvent indicating that this compound is in equilibrium with the zwitterion form 38. The equilibrium constant in pure water was obtained by extrapolation. Prior to this, equilibria which involved tautomers of type 39 had been suggested for vitamin Be, but see Section VI,A. In the case of pyridoxal, an additional equilibrium, 40 41, occurs (cf. Section VIII) other pyridoxal analogs have also been studied (Table II). 

Tetronic acids exist predominantly in the dioxo form (32) in solvents of low polarity, while the existence of the monoenol form (33) has been established in other solvents by infrared " and ultraviolet spectral comparisons- and from dipole moment data. " Haynes and Pliramer " have recently reviewed the structure of these compounds [see also reference 28(a)], and the tautomerism of vitamin A (34), which has a related structure, has also been surveyed.- Analogous compounds carrying an amino group in the 3-position are also know n. ... 

Finally, in connection with the investigations on the antineuritic action of homologs and analogs of vitamin Bi, the corresponding seleno compound was also mentioned. However, no details are given on the properties (except mp 203°C) and method of synthesis of this compound. 

This procedure illustrates a broadly applicable method which is essentially that of Roth, Dubs, Gotschi, and Eschenmoser,2 for the synthesis of enolizable /1-dicarbonyl compounds. Although there are various methods for the preparation of /3-dicarbonyl systems,3 the scheme of sulfide contraction widens the spectrum of available methods. The procedure can also be utilized in the synthesis of aza and diaza analogs of /3-dicarbonyl systems. Eschenmoser2 has utilized the method to produce vinylogous amides and amidines in connection with the total synthesis of corrins and vitamin B12.4... 

Ketamine is a cyclohexane human and veterinary injectable anesthetic that is also known by the slang names K, special K, vitamin K, and cat Valium (Bobo and Miller 2002). It is produced in a liquid form or as a white powder and is usually ingested orally or intranasally but is occasionally administered intramuscularly. Ketamine is a phencyclidine (PCP) analog that was first developed in 1962. 

THURNHAM, D I (1994) (3-Carotene, are we misreading the signals in risk groups Some analogies with vitamin C , Proc Nutr Soc, 53, 557-69. 

Bauerfeind, J.C., Carotenoid vitamin A precursors and analogs in foods and feeds, J. Agric. Food Chem., 20, 456, 1972. 

To evalnate whether some foods contain true vitamin B,2 or inactive vitamin B,2 analogs, some vitamin B[2 compoimds were purified and characterized using silica gel 60 TLC [11-15]. An algal health food, spirulina tablets, contained considerable amounts of a vitamin Bjj analog (pseudovitamin Bjj) inactive for humans (Figure 10.6) [11]. 

CF patients with low bone mineral density and low serum vitamin D levels may improve bone health through supplemental vitamin D analogs beyond those found in standard CF vitamins. The optimal dose and analog have not been determined. For ergocalciferol, a minimum of 400 IU and 800 IU... 

Other vitamin D analogs available in the United States include paricalcitol (19-nor-l,25-dihydroxyvitamin D2, Zemplar by Abbott Laboratories, North Chicago, IL) and doxercalciferol (1 -a-hydroxyvitamin D2, Hectoral by Bone Care International, Middleton, WI). Alfacalcidiol (1-a-hydroxyvitamin D3) is only available outside the United States. Paricalcitol has less effect on vitamin D receptors in the intestines, decreasing the effects on... 

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