Nicotiana rustica Tobacco alkaloids

Synonyms Nicotiana tabacum (cultivated tobacco) Nicotiana rustica Methylpyridylpyrrolidine Description Tobacco products contain dried tobacco leaves, which are used to take advantage of the psychoactive effects of the alkaloid nicotine. Snuff has a pH of 7.8-8.1. Cigarettes are acidic. Chewing tobacco has alkali added and is basic Chemical Formula C10H14N2 (nicotine)... 

Nicotine is one of the principal constituents of tobacco. It occurs in the dried leaves of Nicotiana tabacum and Nicotiana rustica to the extent of 2-8%. Exposure risk to this alkaloid arises from smoking, chewing. 

Nicotine belongs to the Solanaceae (nightshade family) alkaloids. It is the principal alkaloid of tobacco, but occurs also as a trace component in Acacia, Sedum, Erythroxylum, Equisetum and Lycopodium species. The two economically most important tobacco species are Nicotiana tabacum (Virginia tobacco), which grows up to 3 metres in height, has reddish flowers and lancet-shaped, pointed leaves, and the 1.2-metre high Nicotiana rustica species (known in South America as Mapacho and in Vietnam as Thuoc Lao), with greenish-yellow flowers and egg-shaped leaves (Fig. 5.204). 

Nicotine is formed mainly in the roots and transported to the leaves to be stored there. The nicotine content in the different tobacco varieties ranges from 0.3 to 7 or even 9 % (Nicotiana rustica) of dry weight. In so-called nicotine-free tobaccos, the alkaloid is enzymatically demethylated, which reduces the nicotine content to below 0.1 %. [532]... 

Similar results have been published for other Solanaceae alkaloids, namely, those of the tropane group. Heine (1942) grafted Datura scions upon Nicotiana rustica and found that nicotine accumulated instead of tropane alkaloids. This finding was confirmed by Hills et al, (1946) with Nicotiana-Duboisia grafts. The tobacco scion on Duboisia root was found to accumulate tropane alkaloids. Surprisingly, the tobacco scion accumulated both hyoscine and the unesterified tropine. In all grafts between plants... 

Nicotinoids. Nicotine from tobacco was one of the earliest insecticides and was recommended for use in 1763 as a tea for the destruction of aphids (1,20). Nicotine [54-11 -3], L-l-methyl-2-(3 -pyridyl)pyrrolidine (1) (bp 247°C, d 1.009), is found in the leaves of Nicotiana tobacum and N. rustica (Solanaceae) in amounts ranging from 2 to 14%, and also is found in Duboisia hopwoodii and in Aesclepias syriaca. It occurs as the principal alkaloid along with small amounts of 12 other alkaloids of which nomicotine [494-97-3], 2-(3,-pyridyl)pyrrolidine (2) (bp 270°C, d 1.07 g/mL), and anabasine [494-52-0], l-2-(3 -pyridyl)piperidiae (3) (bp 281°C, d 1.048), are of insecticidal importance (see Alkaloids). Nomicotine occurs as both the D and L forms, the former in D. hopn oodii and the latter commonly predominating in Nicotiana. Anabasine is the chief alkaloid of Anabasis aphylla, where it occurs from 1—2% in the shoots and is found to ca 1% in Nicotianaglauca. 

Nicotine, an alkaloid, is extracted from leaves of tobacco plants (Nicotiana tabacum and Nic-otiana rustica). It is used in home gardens and greenhouses for control of sucking insects such as leafhoppers, aphids, scales, thrips, and whiteflies. However, the use of nicotine is rapidly declining and is being replaced by newer synthetic insecticides because of its comparatively high mammalian toxicity. Its oral LD50 in rats is 55 mg/kg. 

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. 

These alkaloids were mostly found in crude nicotine obtained commercially by treating the leaves of cultivated tobacco Nicotiana tabacum L. and sometimes N. rustica L.) with an aqueous solution of an alkali and distilling with steam (265). The total nicotine content of the tobacco plant is distributed as follows flowers, 5%, stems 18%, roots 13%, and leaves 64% (266). There is considerable variation in the nicotine content of different varieties of tobacco, but there is a close parallelism in the plant between nicotine and citric acid. Nicotine in the plant, however, is not always combined with an organic acid. The glucoside tabacilin yields glucose, nicotine, and other substances (267) when hydrolyzed while the tobacco glucoside tabacin yields nicotine when treated with alkalis (268). 

The main alkaloid of different cultivars of commercial tobacco species Nicotiana tabacum and N. rustica, Solanaceae) is nicotine, (S)-l-methyl-2-(pyrid-3-yl)pyrrolidone or (S)-3-(l-methylpyrrolidin-2-yl)pyridine, 10-7. Nicotine is also present in small quantities in other plants (about 24 species of 12 plant families), but especially in plants of the nightshade family, which also includes potatoes, tomatoes and eggplants (aubergines). Biosynthesis of nicotine takes place in the roots of plants, from where nicotine is transported to the aerial parts, especially to the leaves. 

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