Introduction To Alkaloids


Introduction to alkaloids (nicotine and cocaine)

Alkaloids, any of a class of naturally occurring organic nitrogen-containing bases. Alkaloids have diverse and important physiological effects on humans and other animals. Well-known alkaloids include morphine, strychnine, quinine, ephedrine, and nicotine.

Alkaloids are found primarily in plants and are especially common in certain families of flowering plants. More than 3,000 different types of alkaloids have been identified in a total of more than 4,000 plant species. In general, a given species contains only a few kinds of alkaloids, though both the opium poppy (Papaver somniferum) and the ergot fungus (Claviceps) each contain about 30 different types. Certain plant families are particularly rich in alkaloids; all plants of the poppy family (Papaveraceae) are thought to contain them, for example. The Ranunculaceae (buttercups), Solanaceae (nightshades), and Amaryllidaceae (amaryllis) are other prominent alkaloid-containing families. A few alkaloids have been found in animal species, such as the New World beaver (Castor canadensis) and poison-dart frogs (Phyllobates). Ergot and a few other fungi also produce them.  

The function of alkaloids in plants is not yet understood. It has been suggested that they are simply waste products of plants’ metabolic processes, but evidence suggests that they may serve specific biological functions. In some plants, the concentration of alkaloids increases just prior to seed formation and then drops off when the seed is ripe, suggesting that alkaloids may play a role in this process. Alkaloids may also protect some plants from destruction by certain insect species.

The chemical structures of alkaloids are extremely variable. Generally, an alkaloid contains at least one nitrogen atom in an amine-type structure—i.e., one derived from ammonia by replacing hydrogen atoms with hydrogen-carbon groups called hydrocarbons. This or another nitrogen atom can be active as a base in acid-base reactions. The name alkaloid (“alkali-like”) was originally applied to the substances because, like the inorganic alkalis, they react with acids to form salts. Most alkaloids have one or more of their nitrogen atoms as part of a ring of atoms, frequently called a cyclic system. Alkaloid names generally end in the suffix -ine, a reference to their chemical classification as amines. In their pure form most alkaloids are colourless, nonvolatile, crystalline solids. They also tend to have a bitter taste.

Alkaloid molecules are very sensitive to changes and fluctuations in the physical forces around them and physical life parameters. They circulate inside and outside the organism in physiological or ecological ways, and they have important impact on the basic life strategies, such as herbivory, carnivory, and omnivory. Alkaloids can be of endogenic or exogenic origin. Endogenic peptide alkaloids are proteins having alkaloids that mimic bioactivity. How their amino acid element changes to an alkaloid element in activities with receptors is not still known. Exogenic alkaloids probably add their own microscopic mark to the molecules. Novelization of the alkaloids occurs in nature but is also planned by chemists using a large list of possible reactions and inductions. Alkaloids can produce problems in nature and human behavior. Morphinism, narcosis, and addiction are diseases based on alkaloid bioactivity or the lack of activity by endo- and exoreceptors. Molecular additions can develop new medicines and functional food and feed, and their activity is based on a molecular or residue basis.


Nicotine, an organic compound that is the principal alkaloid of tobacco. (An alkaloid is one of a group of nitrogenous organic compounds that have marked physiological effects on humans.) Nicotine occurs throughout the tobacco plant and especially in the leaves. The compound constitutes about 5 percent of the plant by weight. Both the tobacco plant (Nicotiana tabacum) and the compound are named for Jean Nicot, a French ambassador to Portugal, who sent tobacco seeds to Paris in 1550.

Nicotine is the chief addictive ingredient in the tobacco used in cigarettes, cigars, and snuff. In its psychoactive effects, nicotine is a unique substance with a biphasic effect; when inhaled in short puffs it has a stimulant effect, but when smoked in deep drags it can have a tranquilizing effect. This is why smoking can feel invigorating at some times and can seem to block stressful stimuli at others. Nicotine is also an addictive drug, though, and smokers characteristically display a strong tendency to relapse after having successfully stopped smoking for a time. When ingested in larger doses, nicotine is a highly toxic poison that causes vomiting and nausea, headaches, stomach pains, and, in severe cases, convulsions, paralysis, and death.

Nicotine is commercially obtained from tobacco scraps and is used as an insecticide and as a veterinary vermifuge. Nitric acid or other oxidizing agents convert it to nicotinic acid, or niacin, which is used as a food supplement.


Cocaine hydrochloride, which is the powdered form of cocaine, is produced by converting coca paste obtained from the leaves, into the water-soluble salt form that is either snorted or injected into a vein. Cocaine base, or “crack” cocaine, is the base form of salt, which is usually made using sodium bicarbonate and can be smoked. Cocaine can also be taken orally, which is not common in developed countries, but remains widespread in the Andes. Injection, snorting, and the smoking of cocaine increase the rapidity with which cocaine enters the brain over the oral form, contributing to the euphoria and its reinforcing effects. Once ingested, cocaine is metabolized in two major inactive metabolites, benzoylecogonine (detected by most drug testing) and ecgonine methyl ester.

Cocaine use has become the most common cause of drug-related strokes. Cocaine use is rampant. In a 1990 study among 214 patients aged 15 to 44 years admitted to the San Francisco General Hospital during a 10-year period, 34% were drug users and cocaine was the predominant drug used. Cocaine is snorted or injected as cocaine hydrochloride or is smoked as the free-base alkaloidal form, usually called crack cocaine.

Crack cocaine is made by mixing aqueous cocaine hydrochloride with ammonia and sometimes baking soda. The free-base cocaine is usually smoked after the cocaine has become alkalinized and precipitated. Crack cocaine induces a more rapid increase in blood levels than cocaine hydrochloride and produces a more rapid high than does snorted or injected cocaine hydrochloride. Its use is associated with a higher frequency of brain infarcts.


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