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Xanthine formula

Caffeine Caffeine [l,3,7-trimethyl-l//-purine-2,6(3/7,7//)-dione], molecular formula C8H10N4O2, is a xanthine (purine) alkaloid, found mainly in tea leaves Camellia sinensis) and coffee beans (Coffea arabica). Caffeine is sometimes called guaranine when found in guarana (Paullinia cupana), mateine when found in mate (Ilex paraguariensis) and theine when found in tea. Caffeine is found in a number of other plants, where it acts as a natural pesticide. It is odourless white needles or powder. Apart from its presence in the tea and coffee that we drink regularly, caffeine is also an ingredient of a number of soft drinks. [Pg.300]

Caffeine, also known as theine, or methyltheobromine, 1,2,7-trimethyl xanthine (see structural formula in accompanying diagram), white, fleecy or long, flexible crystals. Caffeine effloresces in air and commences losing water at 80 C. Soluble in chloroform, slightly soluble in water and alcohol, very slightly soluble in ether, mp 236.8°C, odorless, bitter taste. Solutions are neutral to litmus paper. [Pg.50]

The heteroaromatic betaines, [l,3,4]thiadiazolo[3,2-a]pyrimidine-5,7-diones (753), which are isoconjugate with methylated xanthines, are in the same way as the latter found to be inhibitors of cyclic AMP phosphodiesterase (78JPS1762). The N-/3-D-ribofuranosyl nucleoside (754) inhibits the synthesis of RNA and DNA but not of protein. The primary blockade is in the synthesis of purine nucleotides (79MI42902). RNA synthesis is also inhibited by [l,3,4]thiadiazolo[3,2-a]pyrimidines of structure (755). The activity is attributed to the chemical reactivity at C-2 leading to reactions with an SH or OH group in RNA polymerase (80ABC1923). Compounds with the 7-oxo formula (756) are claimed to be useful as immune enhancers (78GEP2712932). [Pg.748]

Fig. 15.2 a -d. Formulas of some modified bases occurring naturally in transfer RNA s. a Hypo-xanthine, a guanine derivative lacking the 2-amino group b dihydrouracil and c 4-thiouracil, two derivatives of uracil d 1-methyladenine, a positively charged derivative of adenine... [Pg.234]

In the early attempts to identify the nitrogenous bases of desoxy-ribosenucleic acid, some confusion arose for two reasons. At first, the products obtained by hydrolysis of nucleoprotein were studied, and there was no assurance that any particular base came from the nucleic acid rather than from the protein. Then, when the nucleic acid itself became available, the hydrolytic agents at first employed were sufficiently drastic to cause some deamination of the amino-purines (with the production of some xanthine and hypoxanthine) and some demethylation of thymine to uracil. In 1874, Piccard isolated guanine (and h3T>oxanthine) from sperm nuclein. Kossel and Neumann discovered in the hydrolysate of thymus nucleic acid two new pyrimidine bases which they named thy-mine and cytosine but they assigned incorrect empirical formulas to them. In 1894, they correctly described thymine as CsHgOjNs, but cytosine was not purified and characterized till much later. " " Levene now analyzed a series of nucleic acids from a variety of sources and found " that they all contained guanine and adenine. By mild hydrolysis of thymus nucleic acid, Steudel obtained guanine and adenine as the sole purine bases and demonstrated that they occur in equi-molecular proportions. Levene and Mandel confirmed this result and showed that the two purine bases and the two pyrimidine bases (thymine and cytosine) all occur in thymus nucleic acid in equimolecular proportions. [Pg.237]

Therapeutic Function Xanthine oxidase inhibitor gout therapy Chemical Name 1 H-pyrazolo[3,4-d] pyrlmidin4-ol Common Name -Structural Formula ... [Pg.42]

Only six of the approximately 600 naturally occurring carotenoids [6] have so far been produced industrially these are three symmetrical C4o-carotenoids, p,p-carotene (3), cantha-xanthin (380), and astaxanthin (403), and three apo-p-carotenoids, ethyl 8 -apo-p-caroten-8 -oate (7), 8 -apo-p-caroten-8 -al (482) and the C33-ketone citranaxanthin (466). Table 1 gives the structural formulae of these pigments and their main applications. [Pg.259]

In researches based on those of Hill and Mabery, he arrived at the formula (6) above for xanthine. Fischer s formulae for the purine derivates were taught to and memorised by students for thirteen years. With the exception of Medi-cus s formula for uric acid they are all incorrect. [Pg.829]

Esculetin, umbeUiferone (7-hydroxycoumarin) and 7-hydroxy-4-methyl coumarin are strong xanthine oxidase inhibitors (Chang and Chiang 1995). The structure of 7-hydroxy coumarin plays a very important role in xanthine oxidase inhibition, the 6-hydroxy group present in the molecule of 7-hydroxy coumarin, e.g. esculetin enhanced the activity, whereas substitution by the 6-methoxy group, e.g. scopoletin (formula [47]), reduced the inhibitory effect. (Chang and Chiang 1995). [Pg.480]

Marcet discovered in a urinary calculus a substance which he called xanthic oxide, since it was soluble in alkalis and on evaporation with nitric acid gave a yellow substance. Its correct formula, C5H4O2N4, was first found by Wohler and Liebig, and since it contains one atom of oxygen less than uric acid, Berzelius called it urous acid (Harnige Saure). It is now called xanthine it can be obtained by reducing uric acid with sodium amalgam and is colourless when pure. ... [Pg.791]

Purines and pyrimidines are planar, aromatic, heterocyclic ring systems which absorb ultraviolet light. Formulas (V) and (VI) depict the two tautomeric forms of the purine xanthine which are in equilibrium with one another. Purines and pyrimidines exist predominantly in the keto form in aqueous solution (la). [Pg.462]


See other pages where Xanthine formula is mentioned: [Pg.450]    [Pg.16]    [Pg.351]    [Pg.237]    [Pg.713]    [Pg.334]    [Pg.778]    [Pg.828]    [Pg.829]    [Pg.95]    [Pg.317]    [Pg.484]    [Pg.101]    [Pg.181]    [Pg.400]    [Pg.425]    [Pg.932]    [Pg.707]   
See also in sourсe #XX -- [ Pg.392 ]




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