Nicotiana alkaloids

NT436 Hutchinson, C. R., M. T. S. Hsia, and R. A. Carver. Biosynthetic studies with C02 secondary plant metabolites. Nicotiana alkaloids. 1. Initial experiments. J Am Chem Soc 1976 98 6006. 

This allows an aldol-type reaction with the A-methylpyrrolinium cation, and finally dehydrogenation of the dihydropyridine ring back to a pyridine gives nicotine. Nornicotine is derived by oxidative demethylation of nicotine. Anaba-sine is produced from nicotinic acid and lysine via the A1 -piperidinium cation in an essentially analogous manner (Figure 6.32). A subtle anomaly has been exposed in that a further Nicotiana alkaloid anatabine appears to be derived by... 

Tropane alkaloids Coca alkaloids Nicotiana alkaloids... 

Nicotiana alkaloids, which serve as chemical defence compounds, are synthesized in the roots and are transported to other plant organs, such as aerial parts, via the xylem. These alkaloids accumulate in vacuoles. PMT and A622 oxidoreductase are strongly expressed in the endodermis and outer cortex cells of tobacco root tips and to a lesser degree in other parts of the cortex and parenchyma cells surrounding the xylem (Shoji et ah, 2002). The localization of nicotine biosynthesis in the parenchyma cells surrounding the xylem may aid the loading of the xylem with nicotine. 

The family Solanaceae is one of the important and interesting plant families. It may be classified into four groups based on their usefulness and chemical composition of alkaloids contained (1) Nicotiana spp. such as N. tabacum and N. rustica, which provide tobacco and contain nicotiana alkaloids such as nicotine and nomicotine (2) Hyoscyamus, Scopolia, Atropa, and Datura species, which are pharmacologically important and contain tropane alkaloids such as hyocyamine, scopolamine, and tropine (3) Solanum spp., which are sometimes the starting material for production of synthetic steroids for medical uses and which contain solanum alkaloids and (4) Capsicum, Solanum, and Lycoper-sicum species, which serve as foods and are alkaloid-free. 

Nicotiana Alkaloids.—Experiments with C02 have also been used in consideration of the origin of the pyridine ring of nicotine (27) and correlated with similar work on the pyrrolidine ring of this alkaloid. When Nicotiana glutinosa... 

Pinidine and Coniine Nicotiana Alkaloids yV-Methylpelletierine Lycopodium Alkaloids Lyduraceae Alkaloids Pyrrolizidine Group Tropane and Pyrrolidine Alkaloids Quinoline and Acridme Alkaloids Benzodiazepine Alkaloids Tylophora Alkaloids Cactus Alkaloids Ephedrine... 

The various Nicotiana species, particularly N. rustica, N. tabacum, N. sylvestris and N. glauca, contain different Nicotiana alkaloids in various proportions. The most important of these alkaloids are nicotine (1), nornicotine (2) and anabasine... 

B04. Bush, L.P. and M.W. Crowe Nicotiana alkaloids in Toxicants of plant origin, edited by P.R. Cheeke, CRC Press, Inc. Boca Raton, FL (1989) pp. 87-107. 17B22. 

Applications of n.m.r. spectroscopy to structural elucidation of Nicotiana alkaloids have been reviewed. 

Approximately 40-60 mg of nicotine (43) is a lethal dose for an adult human the LD50 i.v. in mouse is 0.3 mg/kg (Wink, 1993). This base is the main pharmacologically active component of tobacco smoke and probably is responsible for the addictive nature of cigarettes. The pharmacology of nicotine and other Nicotiana alkaloids has been reviewed (Fodor and Colasanti, 1985). Nicotine mimics acetylcholine and activates acetylcholine receptors (Wink, 1993). 

Anabasine a Nicotiana alkaloid, M, 162.2. It is isolated in the L-form, primarily from Nicotiana glau-ca and the asiatic Anabasis aphylla, being the most abundant alkaloid in both of these species. In other tobacco species it is only a secondary alkaloid. Its physiological effects are similar to those of nicotine, and like nicotine, it is used as an insecticide. For biosynthesis, see Nicotiana alkaloids. 

Nicotine chief representative of the Nicotiana alkaloids (see). Oxidative degradation of N. produces nicotinic acid. N. is present in all parts of the tobacco plant (Nicotiana), being biosynthesized in the roots of the plant, then transported to the aerial parts. De-... 

Pyridine alkaloids a group of alkaloids containing the pyridine ring system, which occur in various unrelated plants, and as metabolic products of microorganisms. Important examples are Nicotiana alkaloids (see), Areca alkaloids (see), Gentiana alkaloids (see), and Valeriana alkaloids (see). They are biosynthesized either from nicotinic acid, or as products of terpene synthesis. 

Lysine has also a role in the biosynthesis of Nicotiana alkaloids, e.g., anabasine, in which beside nicotinic acid, the precursor of pyridine ring, lysine formed the piperidine core. 

Panter KE, Keeler K (1990) Conium, Lupinus, Nicotiana alkaloids fetal effects and the potential for residues in milk. Vet Hum Toxicol 32 89-93... 

The Nicotiana alkaloids, nicotine and anabasine, are products of a fusion of nicotinic acid with a heterocyclic compound originating from ornithine or lysine. In case ornithine is the precursor, the second ring in the Nicotiana alkaloid will have four carbon atoms but when originating from lysine it will contain five carbons (see Figure 2.6b). 

Table 2.2. Inheritance of Ability to Store Nicotiana Alkaloids ...

The starting material for the synthesis of the lupin alkaloids is the amino acid lysine, which is first decarboxylated to give its biogenic amine cadaverine. Two units of cadaverine are then joined via a still hypothetical intermediate to give lupinin. Addition of another cadaverine unit to lupinin gives sparteine, which then can be oxidized to lupanin and, further, to hydroxylupanin. The C skeleton of the quinolizidine alkaloids is derived entirely from lysine. We shall now consider two further groups of alkaloids, the nicotiana alkaloids and the tropane alkaloids, which derive only a part of their C skeleton from the aliphatic amino acids ornithine or lysine. 

The most important nicotiana alkaloids (tobacco alkaloids) are nicotine, nornicotine, and anabasine (Fig. 122). Nicotine and nornicotine are the chief alkaloids of Nicotiana tabacum, and anabasine of Nicotiana glauca. Both nicotine and nornicotine consist of a pyridine ring to which a pyrrolidine ring is attached. In the case of nicotine this pyrrolidine ring bears a methyl group on its ring-N. Anabasine also consists of a pyridine... 

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