Trigonelline, Nicotinic Acid

Trigonelline (N-methylnicotinic acid) is present in green coffee up to 0.6% and is 50% decomposed during roasting. The degradation products include nicotinic acid, pyridine, 3-methyl pyridine, nicotinic acid methyl ester, and a number of other compounds. 

Acetaldehyde, methanethiol, propanal, methyl-propanal, 2-/3-methylbutanal, 2,3-butandione, 

2- methyl-3-furanthiol, 2-furfurylthiol, 2-/3-methyl-butyric acid, methional, 2,3,5-trimethylthiazole, trimethylpyrazine, 3-mercapto-3-methyl-l-butanol, 

3- isopropylpyrazine, 5-ethyl-2, 4-dimethylthiazole, 2-ethyl-3, 5-dimethylpyrazine, phenylacetaldehyde, 2-ethenyl-3, 5-dimethylpyrazine, Unalool, 

3- diethyl-5-methylpyrazine, 3,4-dimethyl-2-cyclopentenol-l-one, guaiacol, 4-hydroxy-2, 5-dimethyl-3(2H)-furanone, 3-isobutyl-2-methoxy-pyrazine, 2-ethenyl-3-ethyl-5-methylpyrazine, 6,7-dihydro-5-methyl-5H-cyclopentapyrazine, (E)-2-nonenal, 5-ethyl-4-hydroxy-2-methyl-3(2H)-furanone, 3-hydroxy-4,5-dimethyl-2(5H)-fuianone, 

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Main components 25-45% mucilage, protein, 25-30% fatty oil, traces of an unpleasant smelling essential oil, choline, trigonelline (nicotinic acid-N-methyl betaine), diosgenin and other sterols ]102, 103]. 

Casal S., Oliveira M., Alves M.R. and Ferreira M.A. (2000a) Discriminate analysis of roasted coffee varieties for trigonelline, nicotinic acid and caffeine content. J. Agric. Food Chem. 48 (8), 3420—4. 

Stennert A. and Maier H.G. (1996) Trigonelline in coffee. III. Calculation of the degree of roast by the trigonelline/ nicotinic acid ratio. New GC method for nicotinic acid. Z. Lebensm. Unters. Forsch. 202, 45-7. 

Lang R, Yagar EF, Eggers R, Hofmann T. Quantitative investigation of trigonelline, nicotinic acid, and nicotinamide in foods, urine, and plasma by means of LC—MS/MS and stable isotope dilution analysis. J Agri Food Chem 2008 56 11114-21. 

When trigonelline is heated in closed tubes with baryta water at 120°, it gives rise to methylamine, whilst similar treatment with hydrochloric acid at 260° furnishes methyl chloride and nicotinic acid (pyridine-3-carboxylic acid), indicating that it is the methylbetaine of nicotinic acid. 

Hantzsch prepared this betaine by treating nicotinic acid methiodide with silver hydroxide and. lahns subsequently identified trigonelline with Hantzsch s synthetic base. 

Trigonelline appears to exert no marked physiological action. Ackermann first observed that nicotinic acid administered to dogs appears in the urine as trigonelline. 

Trigonelline is present in green coffee (1 %),15 but it is rapidly decomposed on roasting so that only about 0.1% trigonelline is present in a deeply roasted coffee.161 The products of trigonelline breakdown are evident in roasted coffee and include nicotinic acid and its methylester, pyridine, and p-picoline (Figure 17).3... 

Robusta coffee has undesirable flavor agents that can be masked by the addition of L-aspartyl-L-phenylalaninemethyl ester.218 The methylxanthine stimulant properties of coffee can be antagonized by spraying freshly roasted coffee beans with nicotinamide and nicotinic acid,219 quinolinic acid, or trigonelline.220... 

N.A. Protein, linoleic, oleic, linolenic and palmitic acids, trigonelline, choline, coumarin, nicotinic acid.100117175 Reduce total cholesterol and triglycerides without affecting the HDL, reduce blood sugar. 

In general, niacin is widespread in foodstuffs (93,94). Cereals, seeds, meat, and fish are good food sources of niacin. The niacin content of coffee beans is primarily a product of the roasting process, which converts trigonelline (1-methylnicotinic acid) to nicotinic acid (95). 

Seeds contain the alkaloid, trigonelline (0.38%, methyl betaine of nicotinic acid). It yields nicotinic acid on heating with hydrochloric acid at 260-270°C. 

Dry fenugreek contains trigonelline during roasting two-thirds of trigonelline is converted into niacin or nicotinic acid. Nicotinic acid is almost absent in the former. It is reported that fermentation increases both free and total niacin. 

Decarboxylations occurred also in the LukeS reduction of the methyl betaines of picolinic and nicotinic acids. Thus, both homarine (87) and trigonelline (88) afforded a mixture of l-methyl-3-piperideine and 1-methylpiperidine.91... 

Figure 8.3. Metabolites of nicotinamide and nicotinic acid. Nicotinamide deamidase (nicotinamidase), EC 3.5.1.19 nicotinamide Af-methyltransferase, EC 2.1.1.1 aldehyde dehydrogenase, EC 1.1.1.1. Relative molecular masses (Mr) nicotinamide, 123.1 nicotinic acid, 122.1 nicotinamide JV-oxide, 139.1 Af -methyl nicotinamide, 139.1 trigonelline, 137.1 nicotinuric acid, 179.2 and methyl pyridone carboxamides, 154.1.

Nicotinic acid can be conjugated with glycine to form nicotinuric acid (nicotinoyl-glycine), or may be methylated to trigonelline (AT -methyl nicotinic... 

The relation of many of the simpler alkaloids to the aromatic amino acids is obvious. For example, germinating barley contains (241), besides tyrosine and tyramine, A -methyltyramine, JViV -dimethyltyramine (hordenine), and the trimethylammonium derivative (candicine). In this simple case the. AT-methylated derivatives are known to be derivable from isotopically labeled tyramine (538) and the methyl groups are known to arise from methionine by transmethylation (540, 586). Similarly AT-methyl derivatives of phenylethylamine, 3,4-dihydroxyphenylethylamine, and 3,4,5-trihy-droxyphenylethylamine are well known alkaloids (cf. review, 701). N-Methylated derivatives of tryptamine and hydroxytryptamine equally occur for example, eserine has an obvious relation to 5-hydroxy tryptamine. Methylated derivatives of metabolites of the aromatic amino acids also occur, for example, trigonelline (67), which is the betaine of nicotinic acid, and damascenine is probably similarly related to hydroxyanthranilic acid. 

Trigonelline is biogenetically derived from nicotinic acid by an enzymatic methylation, at the expense of the methyl group coming from methionine (Poisson, 1979). 

Viani and Horman (1974, 1976) (who also quoted Teply et al, 1945) identified nicotinic acid in the non-volatile fraction of the thermal fragmentation of trigonelline (see Section 2.1.1.2). 

Pinner s formulation of nicotine received support from the discovery that the nicotyrine (3 -pyridyl-N-methyl-2-pyrrole) formed by the oxidation of nicotine with silver oxide is accompanied by a small quantity of N-methylpyrrolidine (357), and from the methylation of nicotine which gives rise to two isomeric quaternary methiodides (358). One of these, nicotine isomethiodide, yields a quaternary hydroxide which on oxidation with potassium permanganate produces trigonelline, the methylbetaine of nicotinic acid. Nicotine isomethiodide, therefore, has a quaternary pyridine nitrogen, C6H4N CH3I C4H7N CH3 while nicotine methiodide has... 

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