Nicotinoyl esters

Unavailable Niacin in Cereals Chemical analysis reveals niacin in cereals (largely in the bran), but this is biologically unavailable, because it is bound as niacytin - nicotinoyl esters to a variety of macromolecules ranging between Mr 1,500 to 17,000. In wheat bran, 60% is esterified to polysaccharides, and the remainder to polypeptides and glycopeptides (Mason et al., 1973). In calculation of niacin intakes, it is conventional to ignore the niacin content of cereals completely. 

Nicotinic acid (hut not nicotinamide) causes a marked vasodilatation, with flushing, burning, and itching of the skin. Very large single doses of nicotinic acid may cause sufficient vasodilatation to lead to hypotension after the administration of 1 to 3 g of nicotinic acid daily for several days, the effect wears off to a considerable extent. A number of nicotinoyl esters have been developed to permit sensitive patients to benefit from the hypoUpidemic effect of... 

Members of the Celastraceae family produce a wide variety of macrocyclic sesquiterpene pyridine alkaloids, which will be discussed below. In addition, various nicotinoyl esters of the base sesquiterpene structure p-dihydroagarofuran are produced, such as in the cangorins [160], wilforcidine [161], triptofordinines [162], and related compounds [163]. 

Chemical analysis reveals niacin in cereals (largely in the bran), but this is biologically unavailable, as it is bound as niacytin - nicotinoyl esters to polysaccharides, polypeptides and glycopeptides. 

Syntheses of naphthyridone derivatives follow the same procedures as those of quinolones, except that substituted 2-aminopyridines (Gould-Jacobs modification) or substituted nicotinic ester/nicotinoyl chloride are used instead of anilines or o-halobenzoic acid derivatives. Most of the recently introduced quinolone antibacterials possess bicyclic or chiral amino moieties at the C-7 position, which result in the formation of enantiomeric mixtures. In general, one of the enantiomers is the active isomer, therefore the stereospecific synthesis and enantiomeric purity of these amino moieties before proceeding to the final step of nucleophilic substitution at the C-7 position of quinolone is of prime importance. The enantiomeric purity of other quinolones such as ofloxacin (a racemic mixture) plays a major role in the improvement of the antibacterial efficacy and pharmacokinetics of these enan-... 

Most recently, Baltzer and co-workers have incorporated a lysine-bound nicotinamide into a more complex peptide scaffold [75]. This approach takes advantage of the augmented reactivity of a lysine residue contained in a helix-turn-helix scaffold (as described previously [76]). An adjacent histidine is able to selectively catalyze the formation of an amide bond between activated esters and the lysine c-amino group under aqueous conditions. Thus, reaction of the 42-residue peptide LA-42 withp-nitrophenyl hT-methylnicotinate in an aqueous solution at pH 5.9 yields the nicotinoyl-functionalized peptide (Fig. 27). 

Nicotine Nicotine, l-methyl-2-(3-piridyl)pirrolidine (13.1.27), is an alkaloid that is isolated from the plant Nicotiana (Nicotiana tabacum, Nicotiam rustica, and others) and can be synthesized in varions ways [33-36]. In particular, it is proposed to proceed from nicotinic acid ethyl ester, which is condensed with iV-methylpyrrolidone, giving l-methyl-2-nicotinoyl pyrrolidone-2 (13.1.23). Acidic hydrolysis of this compound leads to an opening of the pyrrolidine ring giving the intermediate (13.1.24), which under the reaction conditions is decarboxylated to the /-aminoketone (13.1.25). The carbonyl group is reduced to an alcohol and the resnlting prodnct (13.1.26) undergoes dehydration to nicotine (13.1.27). 

With the help of chiral auxiliary substitutent, the pyridine derivatives can be diastereoselectively hydrogenated. In 2000, Hegedus group reported a diastereose lective heterogeneous hydrogenation of N nicotinoyl (S) proline methyl ester 43 with up to 94% de and complete conversion [49]. However, this result was not reproducible and the maximum de was corrected to 30% (Scheme 10.36). 

M+-C6H5NO), and the IR spectrum showed carbonyl bands at 1710 and 1680 cm-1 for unsaturated ester and lactam moieties. The H NMR spectrum showed the signals that corresponded to strychnovoline (64), except that the signal for H-6 was shifted downfield from 4.06 ppm to 5.46 ppm, suggesting that it was esterified, and this unit was identified from the XH NMR spectrum as a nicotinoyl moiety. The structure 66 for the isolate, and its absolute configuration, were confirmed through semisynthesis (see Section III.G) (39). 

N-acetyl tyrosyl-2-amino-pyridinamide or N-nicotinoyl tyrosyl benzyl ester... 

N-nicotinoyl tyrosyl benzyl ester Indole or 2-amino-5,6-dimethylbenzimidazole N-methacryloyl L-Ser, N-methacryloyl L-Asp, N-methacryloyl L-His, N-methacryloyl L-Cys, N-methacryloyl S-Ala, 4-vinyl phenol, HEMA and/or MAA EDMA Co(II)Cl2 poly(glycidyl methacrylate-EDMA) MeOH 4-VPy EDMA CH2Cl2... 

Alcohols can be derivatized to nicotinates, equivalent to picolinyl esters of fatty acids. A preliminary study involving GC-MS of the nicotinoyl derivative of l,3-di(9,10-methyleneoctadecanoyl)glycerol showed a prominent odd-numbered ion due to fragmentation through the ring of one of the... 

The a-keto ester XI-6S was synthesized in good yields by treating 3-nicotinoyl chloride with a Wittig reagent. Treatment of the oxime of... 

The main form of this vitamin in foods of plant origin is nicotinic acid. Plants contain a number of nicotinic acid derivatives, such as N-(fl-D-glucopyranosyl)nicotinic acid (5-66), the ester 1-0-nicotinoyl-fl-D-glucopyranose and other nicotinoyl derivatives of glucose. 

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