તમાકુ (અંગ્રેજી:Tobacco, Cultivated Tobacco; વૈજ્ઞાનિક નામ: Nicotiana tabacum) એક બહુવર્ષાયુ વનસ્પતિ છે, જે છોડ સ્વરૂપે જોવા મળે છે.  નિકોશિયાના ટેબેકમ તરિકે વર્ગિકૃત કરવામાં આવેલી આ વનસ્પતિના છોડ ફક્ત ખેતીમાં જ જોવા મળે છે, અને નિકોશિયાના પ્રજાતિની બધીજ જાતીઓમાં સૌથી વધુ વવાતી આ જાતી છે. ઘણા બધા દેશોમાં તેને તેના પાન કે જે તમાકુ તરિકે વપરાય છે તેના માટે ઉગાડવામાં આવે છે. તેનો છોડ ૧થી ૨ મીટર જેટલો ઉંચો થાય છે.

ઇતિહાસ
In their first voyage to the New World, Christopher Columbus and his expedition were introduced to a plant whose smoke was called tobacco by the natives of Hispaniola.

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.

ભૌગોલિક વિખિરણ
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.

નિવાસ
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.

વાનસ્પતિક વર્ણન
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.

પુષ્પ
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.

ઉપયોગી અંગો
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.

રસાયણો

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.

ફાર્માકોલોજીકલ અસરો
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.
તમાકુ સેવનની અસરો

    તમાકુ તમારા શરીરના વિવિધ ભાગો, જેવા કે મુખ, ગળું, ફેફસા, જઠર, મૂત્રપિંડ, મૂત્રાશય, વગેરેના કેન્સર માટે જવાબદાર છે.

સમર્થનરૂપ તથ્યો

    વિશ્વમાં મુખ કેન્સરના સૌથી વધારે કિસ્સાઓ ભારતમાં છે અને તેનુ કારણ છે તમાકુ.
    ભારતમાં પુરુષોના કેન્સરમાં તમાકુનો ફાળો 56.4 ટકા અને સ્ત્રીઓના કેન્સરમાં 44.9 ટકા છે.
    90 ટકા કરતા વધારે ફેફસાના કેન્સર અને ફેફસાના અન્ય રોગો ધૂમ્રપાનને કારણે થાય છે.

    તમાકુ હ્રદય અને રક્તવાહિનીઓના રોગ, હાર્ટ એટેક, છાતીમાં દુખાવો, હ્રદયરોગથી અચાનક મૃત્યુ, સ્ટ્રોક (બ્રેઇન એટેક), પેરિફેરલ વાસ્ક્યુલર રોગ (પગનું ગેંગ્રીન)

લોકવૈદુ

Tobacco has been used as an antispasmodic, a diuretic, an emetic, an expectorant, a sedative, and a sialagogue, and in homeopathy.

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. They are used externally in the treatment of rheumatic swelling, skin diseases and scorpion stings. The plant should be used with great caution, when taken internally it is addictive. The active ingredients can also be absorbed through the skin. Wet tobacco leaves can be applied to stings in order to relieve the pain. They are also a certain cure for painful piles. A homeopathic remedy is made from the dried leaves. It 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.

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.

પોષણ મૂલ્ય

Edible Parts: Leaves. Edible Uses: Egg.
A protein 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

અન્ય ઉપયોગો

All parts of the plant contain nicotine, which has been 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 have been dried and chewed as an intoxicant. The dried leaves are also used as snuff or smoked. This is the main species that is used to make cigarettes and cigars. A drying oil is obtained from the seed.

લણણી પછીની પ્રક્રિયા

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.

ઝાંખી

સંદર્ભ
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

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