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Nicotiana tabacum, or cultivated tobacco, is a perennial herbaceous plant. It is found only in cultivation, where it is the most commonly grown of all plants in the Nicotiana genus, and its leaves are commercially grown in many countries to be processed into tobacco. It grows to heights between 1 to 2 metres. Research is ongoing into its ancestry among wild Nicotiana species, but it is believed to be a hybrid of Nicotiana sylvestris, Nicotiana tomentosiformis, and possibly Nicotiana otophora.
In 1560, Jean Nicot de Villemain brought tobacco seeds and leaves as a "wonder drug" to the French court. In 1586 the botanist Jaques Dalechamps gave the plant the name of Herba nicotiana, which was also adopted by Linné. It was considered a decorative plant at first, then a panacea, before it became a common snuff and tobacco plant. Tobacco arrived in Africa at the beginning of the 17th century. The leaf extract was a popular pest control method up to the beginning of the 20th century. In 1851, the Belgian chemist Jean Stas was the first to prove the use of tobacco extract as a murder poison in the civilised world. The Belgian count Hippolyte Visart de Bocarmé had poisoned his brother-in-law with tobacco leaf extract in order to acquire some urgently needed money. This was the first exact proof of alkaloids in forensic medicine.
N. tabacum is a native of tropical and subtropical America but it is now commercially cultivated worldwide. Other varieties are cultivated as ornamental plants or grow as a weed.
Habitat and ecology
N. tabacum is sensitive to temperature, air, ground humidity and the type of land. Temperatures of 20 to 30°C are best for adequate growth; an atmospheric humidity of 80 to 85% and soil without a high level of nitrogen are also optimal.
Nicotiana tabacum Linné is a robust annual little branched herb up to 2.5m high with large green leaves and long trumpet shaped white-pinkish flowers. All parts are sticky, covered with short viscid-glandular hairs, which exude a yellow secretion containing nicotine.
Very varied in size, the lower leaves are the largest up to 60 cm long, shortly stalked or unstalked, oblonged-elliptic, shortly acuminate at the apex, decurrent at the base, the following leaves decrease in size, the upper one sessile and smallest, oblong- lanceolate or elliptic.
In terminal, many flowered inflorescences, the tube 5–6 cm long, 5mm in diameter, expanded in the lower third (calyx) and upper third (throat), lobes broadly triangular, white-pinkish with pale violet or carmine coloured tips tube yellowish white; calyx with 5narrowly triangular lobes, 1-5-2 cm long.
A capsular ovoid or ellipsoid, surrounded by the persistent calyx and with a short apical beak, about 2 cm long. Seeds are very numerous, very small, ovoid or kidney shaped, brown.
Every part of the plant except the seed contains nicotine, but the concentration is related to different factors such as species, type of land, culture and weather conditions. The concentration of nicotine increases with the age of the plant. Tobacco leaves contain 2 to 8% nicotine combined as malate or citrate. The distribution of the nicotine in the mature plant is widely variable: 64% of the total nicotine exists in the leaves, 18% in the stem, 13% in the root, and 5% in the flowers.
Tobacco contains the following phytochemicals:
Nicotine, Anabasine (an alkaloid similar to the nicotine but less active), Glucosides (tabacinine, tabacine), 2,3,6-Trimethyl-1,4-naphthoquinone, 2-Methylquinone, 2-Napthylamine, Propionic acid, Anatalline, Anthalin, Anethole, Acrolein, Anatabine, Cembrene, Choline, Nicotelline, Nicotianine, Pyrene.
The most prominent phytochemical found in N. tabacum is nicotine. Nicotine binds stereospecifically to acetylcholine receptors at the autonomic ganglia, adrenal medulla, neuromuscular junctions and the brain. As a consequence of the stimulation of nicotinic receptors, possibly located on presynaptic sites, short-term exposure to nicotine results in the activation of several central nervous system neurohumoral pathways, leading to the release of acetylcholine, norepinephrine, dopamine, serotonin, vasopressin, growth hormone, and ACTH.
Most of the effects of nicotine on the central nervous system are due to the direct action on brain receptors, although activation of the brain through afferent nerves of chemoreceptors in the carotid bodies or the lung may also contribute. Nicotine excites nicotinic receptors in the spinal cord, autonomic ganglia, and adrenal medulla, the last of which causes the release of epinephrine. Nicotine evokes the release of catecholamines and facilitates the release of electrical stimulation-evoked neurotransmitters from sympathetic nerves in blood vessels. In experimental preparations, nicotine in low doses causes ganglionic stimulation but in high doses it causes ganglionic blockade after brief stimulation. This biphasic response pattern is observed in the intact organism as well, although the mechanism is far more complex.
At very low doses, similar to those seen during cigarette smoking, the cardiovascular effects appear to be mediated by the central nervous system, either through the activation of chemoreceptor afferent pathways or by direct effects on the brain stem. The net result is sympathetic neural discharge, with an increase in blood pressure and heart rate. At higher doses, nicotine may act directly on the peripheral nervous system, producing ganglionic stimulation and the release of adrenal catecholamines. At extremely high doses, nicotine produces hypotension and slowing of the heart rate, mediated by either peripheral ganglionic blockade, vagal afferent nerve stimulation, or direct depressor effects mediated by action on the brain.
Tobacco has a long history of use by medical herbalists as a relaxant, though since it is a highly addictive drug it is seldom employed internally or externally at present. The leaves act as antispasmodics, discutients, diuretics, emetics, expectorants, irritants, sedatives and sialagogues. Wet tobacco leaves are applied externally in the treatment of rheumatic swelling, skin diseases and stings, as the active ingredients can be absorbed through the skin. They are also a certain cure for painful piles. A homeopathic remedy made from the dried leaves is used in the treatment of nausea and travel sickness. Some other activities reported for Nicotiana tabacum are: Analgesic activity, anesthetic activity, angiogenesis inhibition, antibacterial activity, anti convulsant activities, anti estrogenic effect, antifungal activity, antiglaucomic activity, antioxidant activity, antistress effect, antiviral activity, aromatase inhibition, arrhythmogenic effect, carcinogenic activity, bronchoconstrictor activity, bupivacaine kinetics,
The regions that have histories of use of the plant include:
- Brazil: Leaves are heated and the juice is squeezed out, mixed with ash from bark of Theobroma subircanum or other Theobroma species to make an intoxicating snuff. The leaf juice is taken orally to induce vomiting and narcosis.
- Colombia: Fresh leaf is used as poultice over boils and infected wounds; the leaves are crushed with oil from palms and used as hair treatment to prevent baldness.
- Cuba: Extract of the leaf is taken orally to treat dysmenorrheal.
- East Africa: Dried leaves of Nicotiana tabacum and Securinega virosa are mixed into a paste and used externally to destroy worms in sores.
- Ecuador: Leaf juice is used for indisposition, chills and snake bites and to treat pulmonary ailments.
- Fiji: Fresh root is taken orally for asthma and indigestion; fresh root is applied ophthalmically as drops for bloodshot eyes and other problems; seed is taken orally for rheumatism and to treat hoarsness.
- Guatemala: Leaves are applied externally by adults for myasis, headache and wounds; hot water extract of the dried leaf is applied externally for ring worms, fungal diseases of the skin, wounds, ulcers, bruises, sores, mouth lesions, stomartitis and mucosa; leaf is orally taken for kidney diseases.
- Haiti: Decoction of dried leaf is taken orally for bronchitis and pneumonia.
- India: Juice of Securinega leucopyrus is mixed with the dried leaves of Nicotiana tabacum and applied externally for parasites; Fresh leaves are mixed with corn-cob or Amorphophallus paeonifolium to treat asthma.
- Iran: Infusion of the dried leaf is applied externally as an insect repellent; ointments made from crushed leaves are used for baldness, dermatitis and infectious ulceration and as a pediculicide.
- Mexico (Southeastern): Among the Ancient Maya, Nicotiana was considered a sacred plant, closely associated with deities of earth and sky, and used for both visionary and therapeutic ends. The contemporary Tzeltal and Tzotzil Maya of Highland Chiapas (Mexico) are bearers of this ethnobotanical inheritance, preserving a rich and varied tradition of Nicotiana use and folklore. The entire tobacco plant is viewed as a primordial medicine and a powerful botanical ‘‘helper’’ or ‘‘protector.’’ Depending on the condition to be treated, whole Nicotiana leaves used are used alone or in combination with other herbs in the preparation of various medicinal plasters and teas. In its most common form, fresh or ‘‘green’’ leaves are ground with slaked lime to produce an intoxicating oral snuff that serves as both a protective and therapeutic agent.
- United States: Extract of N. tabacum is taken orally to treat tiredness, ward off diseases, and quiet fear.
- Tanzania: Leaves of Nicotiana tabacum are placed in the vagina to stimulate labor.
A protein of the White–Brown Complex subfamily can be extracted from the leaves. It is an odourless, tasteless white powder and can be added to cereal grains, vegetables, soft drinks and other foods. It can be whipped like egg whites, liquefied or gelled and can take on the flavour and texture of a variety of foods. It is 99.5% protein, contains no salt, fat or cholesterol. It is currently being tested as a low calorie substitute for mayonnaise and whipped cream
All parts of the plant contain nicotine, which can be extracted and used as an insecticide. The dried leaves can also be used; they remain effective for 6 months after drying. The juice of the leaves can be rubbed on the body as an insect repellent. The leaves can be dried and chewed as an intoxicant. The dried leaves are also used as snuff or are smoked. This is the main species that is used to make cigarettes, cigars, and other smokable tobacco preparations. A drying oil is obtained from the seed.
Curing and aging
After tobacco is harvested, it is cured (dried), and then aged to improve its flavor. There are four common methods of curing tobacco: air curing, fire curing, flue curing, and sun curing. The curing method used depends on the type of tobacco and its intended use. Air-cured tobacco is sheltered from wind and sun in a well-ventilated barn, where it air dries for six to eight weeks. Air-cured tobacco is low in sugar, which gives the tobacco smoke a light, sweet flavor, and high in nicotine. Cigar and burley tobaccos are air cured.
In fire curing, smoke from a low-burning fire on the barn floor permeates the leaves. This gives the leaves a distinctive smoky aroma and flavor. Fire curing takes three to ten weeks and produces a tobacco low in sugar and high in nicotine. Pipe tobacco, chewing tobacco, and snuff are fire cured.
Flue-cured tobacco is kept in an enclosed barn heated by flues (pipes) of hot air, but the tobacco is not directly exposed to smoke. This method produces cigarette tobacco that is high in sugar and has medium to high levels of nicotine. It is the fastest method of curing, requiring about a week. Virginia tobacco that has been flue cured is also called bright tobacco, because flue curing turns its leaves gold, orange, or yellow.
Sun-cured tobacco dries uncovered in the sun. This method is used in Greece, Turkey, and other Mediterranean countries to produce oriental tobacco. Sun-cured tobacco is low in sugar and nicotine and is used in cigarettes.
Once the tobacco is cured, workers tie it into small bundles of about 20 leaves, called hands, or use a machine to make large blocks, called bales. The hands or bales are carefully aged for one to three years to improve flavor and reduce bitterness.
- Tobacco BY-2 cells - Cell suspension line made of N. tabacum cultivar, used in plant science research.
- Medicinal Plants of the world, By Ivan A. Ross
- Poisonous plants, Dr Julia Higa de Landoni Seccion Toxicologia
- Hospital de Clinicas "José de San Martin" Cordoba 2351, 1120 Capital, Argentina
- African Ethnobotany: Poisons and Drugs: Chemistry, Pharmacology, Toxicology by Hans Dieter Neuwinger
- Nan Ren and Michael P. Timko (August 2001). "AFLP analysis of genetic polymorphism and evolutionary relationships among cultivated and wild Nicotiana species". Genome 44 (4): 559–571. DOI:10.1139/gen-44-4-559. PMID 11550889. http://article.pubs.nrc-cnrc.gc.ca/ppv/RPViewDoc?_handler_=HandleInitialGet&journal=gen&volume=44&calyLang=fra&articleFile=g01-060.pdf.
- Wennig, Robert (April 2009). "Back to the roots of modern analytical toxicology: Jean Servais Stas and the Bocarmé murder case". Drug Test Anal (England) 1 (4): 153–5. DOI:10.1002/dta.32. PMID 20355192.
- Groark, Kevin P. 2010. The Angel in the Gourd: Ritual, Therapeutic, and Protective Uses of Tobacco (Nicotiana tabacum) among the Tzeltal and Tzotzil Maya of Chiapas, Mexico. Journal of Ethnobiology 30(1):5-30 (http://usc.academia.edu/KevinGroark/Papers/316651/The_Angel_in_the_Gourd_Ritual_Therapeutic_and_Protective_Uses_of_Tobacco_Nicotiana_tabacum_among_the_Tzeltal_and_Tzotzil_Maya_of_Chiapas_Mexico)