Кофеин

Описание

Caffeine is an alkaloid purine belonging to the group of organic compounds called methylxanthines. Pure caffeine is a white, crystalline, bitter-tasting compound. Caffeine is found in a number of plants, principally coffee and tea plants, as well as cola and cacao nuts. In plants, caffeine functions as a natural pesticide to deter insects.

Химические свойства

Caffeine is the alkaloid 1,3,7-trimethylxanthine. It is one of the xanthine derivatives present up to 1.5% in seeds of coffee (Coffea arabica L.) and up to 5% in the leaves of tea (Camelia sinensis). It is a component of the beverages made from these plants. Caffeine is also a component of chocolate (Theobroma cacao) and the cola nut (Cola acuminata Schott and Endel. and related species), the extract of which is used in cola drinks. It is virtually odorless. Caffeine is added to cola-type beverages for its enhancement of flavor. Subtle and subliminal flavors are widely appreciated by consumers and caffeine has a modifying effect on other components of the beverage. The threshold for detecting the presence of caffeine in liquid foods varies depending on the nature of other substances present, but lies close to the level characteristic of currently produced cola-type beverages. The threshold for detection of caffeine in water has been shown to be 0.0095%; in liquid foods, 0.0184%. In one study, panelists could distinguish a solution containing 0.0058% caffeine from the control. The threshold for detecting taste difference between an aqueous solution of caffeine and a water control was also shown to be 0.005% caffeine and to distinguish bitterness, 0.011% caffeine. In aqueous solutions containing threshold and subthreshold concentrations of caffeine, sucrose, citric acid and salt, all compounds depressed the taste intensity of each other.*

Физические свойства

Appearance: odorless silky needle-like crystal or crystal powder with the color of white or a little yellowish green. Solubility: weathering, easily dissolved in water or chloroform and slightly soluble in water, ethanol, or acetone, very slightly dissolved in ether. Melting point: 235–238?°C.

Вхождение

Reported found in coffee and guarana.

История

Runge isolated caff eine from coffee in 1819. Caffeine derives its name from the Kaffa region of Ethiopia. Caffeine comes from the German kaffeine, which in turn is derived from the German word for coffee, kaffee. In 1827, a compound isolated from tea was named theine, but this was eventually shown to be caffeine.

Использование

Caffeine is a bitter, white crystalline xanthine alkaloid that acts as a stimulant drug and a reversible acetylcholinesterase inhibitor. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants. In humans, caffeine acts as a central nervous system stimulant, temporarily warding off drowsiness and restoring alertness. Caffeine is a cardiac and respiratory stimulant; diuretic. Caffeine is toxic at sufficiently high doses.

Показания

This product is included in the Pharmacopoeia of the People’s Republic of China (2015), the British Pharmacopoeia (2017), the United States Pharmacopeia (40), the Japanese Pharmacopoeia (17th ed.), the European Pharmacopoeia (9.0th ed.), the Indian Pharmacopoeia (2010), and the International Pharmacopoeia (5th ed.). Commonly used dosage forms of caffeine include tablet, powder, and injection. Mainly used dosage forms in the market include caffeine citrate tablets, amidopyrine caffeine tablets, amidopyrine caffeine, children acetaminophen aspirin caffeine tablets, ergotamine caffeine tablets, caffeine sodium benzoate injection, cafe bromine agent, etc.

Определение

ChEBI: A trimethylxanthine in which the three methyl groups are located at positions 1, 3, and 7. A purine alkaloid that occurs naturally in tea and coffee.

Общее описание

Odorless white powder or white glistening needles, usually melted together. Bitter taste. Solutions in water are neutral to litmus. Odorless.

Реакции воздуха и воды

Efflorescent in air. Water soluble.

Профиль реактивности

Caffeine may be hygroscopic. Aqueous solutions (1.12 mg/mL) are stable for three weeks at 41° F if protected from light. In normal room lighting and at room temperature, solutions are stable for 3 days. Solutions of Caffeine in water, DMSO, 95% ethanol or acetone should be stable for 24 hours under normal lab conditions. REACTIVITY: Caffeine may react with strong oxidizing agents. Caffeine is also incompatible with iodine, silver salts and tannins. Caffeine is a very weak base. Caffeine is decomposed by strong solutions of caustic alkalis.

Опасность

One grain or more is toxic, 200 μg/m L has been found to inhibit activity of the enzyme DNA polymerase. Use in soft drinks not to exceed 0.02%. Questionable carcinogen.

Угроза здоровью

Caffeine is a stimulant of the central nervoussystem. It eliminates fatigue and drowsiness. However, high doses cause gastrointestinal motility, restlessness, sleeplessness,nervousness, and tremor. Acute poisoningeffects include nausea, vomiting, headache,excitability, tremor, and sometimes, convulsive coma. Other symptoms may be respiratory depression, muscle contraction, distortedperception, and hallucination. Ingestion of15–20 g may be fatal to humans.
LD50 value, oral (mice): 127 mg/kg
LD50 value, oral (rabbits): 224 mg/kg
Animal studies indicate that caffeine athigh doses produces adverse reproductiveeffects, causing developmental abnormalities. It tested negative in the histidine reversion–Ames and TRP reversion tests.

Пожароопасность

Flash point data for Caffeine are not available; however, Caffeine is probably combustible.

Биологическая активность

Central nervous system stimulant. Antagonist at A 1 and A 2A adenosine receptors and inhibitor of cyclic nucleotide phosphodiesterases. Mobilises calcium from intracellular stores and inhibits benzodiazepine binding to GABA receptors.

Клиническое использование

The commonly used clinical preparations include caffeine sodium benzoate and ergotamine caffeine. The preparation of caffeine sodium benzoate (injection) is constituted of 0.12?g/ml of caffeine, 0.13?g/ml of sodium benzoate, and cafe bromine mixture (oral liquid). Clinically, it can be used for migraine headaches, cerebral artery dilated headache, or headache caused by histamine. However, it is invalid in the prevention of headaches. The adverse reactions include nausea, vomiting, abdominal pain, and fatigue. Other common symptoms include numbness and tingling of the hands, toes, and face and swelling of the foot and lower limb. Overdose causes severe poisoning, mental disorder, ataxia, convulsions, gray chills of the hand and foot, sensory disturbance, and even death due to coma and respiratory paralysis. Caffeine citrate preparation, including injection and oral solution, is the only internationally approved drug for the treatment of premature infant apnea.

Профиль безопасности

A human poison by ingestion. An experimental poison by ingestion, subcutaneous, intraperitoneal, intramuscular, rectal, and intravenous routes. Human systemic effects: ataxia, blood pressure elevation, change in heart rate, changes in tubules, convulsions or effect on seizure threshold, dtarrhea, distorted perceptions, hallucinations, hypermotility, muscle contraction, musculoskeletal tumors, nausea or vomiting, toxic psychosis, tremors. A human teratogen causing developmental abnormalities of the craniofacial and musculoskeletal systems, pregnancy termination (abortion), and stillbirth. Human maternal effects include an unspecified effect on labor or chddbirth. Human mutation data reported. An experimental teratogen. Other experimental reproductive effects. Questionable carcinogen with experimental carcinogenic data. Large doses (above 1.0 g> cause palpitation, excitement, insomnia, dtzziness, headache, and vomiting. Continued excessive use of caffeine in tea or coffee may lead to digestive disturbances, constipation, palpitations, shortness of breath, and depressed mental states. It is also implicated in cardiac disorders under those condttions. When heated to decomposition it emits toxic fumes of NOx

Экологическая судьба

Caffeine can have profound effects on the cardiovascular system. At least four mechanisms have been proposed for the pro-arrhythmic potential of caffeine in overdose. First, caffeine increases circulating catecholamines. Second, caffeine inhibits phosphodiesterase. Increased circulating catecholamines after caffeine overdose increase b1-receptor stimulation. Stimulation of b1-receptors increases intracellular cAMP by G protein stimulation of adenylate cyclase. The activity of cAMP is prolonged due to its decreased metabolism as phosphodiesterase is inhibited by caffeine. Subsequently, b1-receptor effects are exaggerated and tachydysrhythmias are induced. Third, caffeine increases myocardial intracellular calcium. Caffeine both induces release of calcium from the sarcoplasmic reticulumand blocks calcium’s reuptake into the sarcoplasmic reticulum. This resulting increase in cytosolic calcium may provoke dysrhythmias. Fourth, caffeine blocks cardiac adenosine receptors, which have been shown to be antiarrhythmic.
The hypotension that has been noted with overdoses of caffeine is due primarily to two mechanisms. First, caffeineinduced tachydysrhythmias lead to inadequate filling of the heart and subsequent decrease in cardiac output. Second, caffeine augments β2-effects and causes subsequent vasodilation with resulting hypotension.

Методы очистки

Caffeine crystallises from water or absolute EtOH. [Beilstein 26 III/IV 2338.]