Catecholamines naturally occurring

The phenylalkylamine hallucinogens show a close structural resemblance to the catecholamines, noradrenahne and dopamine. The prototype structure is found in mescaline, a naturally occurring substance. Modification of the mescaline molecule has led to synthetic amphetamine derivatives with hallucinogenic action. 

The adrenomimetic drugs can be divided into two major groups on the basis of their chemical structure the catecholamines and the noncatecholamines. The catecholamines include norepinephrine, epinephrine, and dopamine, all of which are naturally occurring, and several synthetic substances, the most important of which is isoproterenol (isopropyl norepinephrine). The skele-... 

The adrenomimetic drugs, including the naturally occurring catecholamines, initiate their responses by combining with a-, P-, or dopamine adrenoceptors. This interaction triggers a series of biochemical events starting within the effector cell membrane that eventually culminates in the production of a physiological response. 

Dopamine is a naturally occurring catecholamine it is the immediate biochemical precursor of the norepinephrine found in adrenergic neurons and the adrenal medulla. It is also a neurotransmitter in the CNS, where it is released from dopaminergic neurons to act on spe-cihc dopamine receptors (see Chapter 31). 

Another naturally occurring drug that is similar to amphetamine can be found in the cactus Lophophora williamsii. Extracts are used to prepare a drink called peyote that contains 3,4,5-trimethoxyphenyl-ethylamine(the meth and phenyl point to a molecule that is quite lipid soluble). Known as mescaline, this compound is structurally similar to the catecholamines dopamine and norepinephrine but seems to act more directly upon serotonin receptors because of the presence of the meth-oxy groups on the molecule. This feature of the compound s structure would make the compound more fat-soluble and therefore better able to enter the brain quickly and may explain... 

The most well known of the naturally occurring phenethylamine derivatives (Table I) are the transmitters of the sympathetic nervous system, epinephrine, norepinephrine, and dopamine. All these compounds are 3,4-dioxygenated in the aromatic nucleus and are collectively known as the catecholamines. Norepinephrine is the transmitter of most sympathetic postganglionic fibers, dopamine is the predominant transmitter of the mammalian extrapyramidal system and of several mesocortical and mesolimbic neuronal pathways, and epinephrine is the major hormone of the adrenal medulla (363). The literature that has accumulated on the action of these compounds in higher animals is enormous. Metanephrine and normetanephrine are known from animals as deactivated metabolites of epinephrine and norepinephrine that result from the action of the enzyme catechol O-methyltransferase (364). 

The biological function of amine oxidases involves the oxidation of biogenic amines formed during normal biological processes. In mammals, the monoamine oxidases are involved in the control of the serotonin catecholamine ratios in the brain, which in turn influence sleep and EEG patterns, body temperature, and mental depression. Two groups of amine oxidases are involved in the oxidative deamination of naturally occurring amines as well as foreign compounds. 

Disposition in the Body. Dopamine is a naturally occurring catecholamine and is considered to be the metabolic precursor of noradrenaline. It is inactivated after oral administration. It is excreted mainly as 3,4-dihydroxyphenylacetic acid (DOPAC) and 3-methoxy-4-hydroxyphenylacetic acid (homovanillic acid) noradrenaline and 3-methoxytyramine are also metabolites. Dopamine is a metabolite of levodopa. 

Dopamine is a naturally occurring catecholamine and central neurotransmitter capable of raising cardiac output, reducing peripheral resistance, and specifically increasing renal blood flow. Infusions (generally up to 10 micrograms/kg/hour) have proven valuable in shock and congestive heart failure. 

The three naturally occurring catecholamines dopamine, NE, and epinephrine are used as therapeutic agents. 

The naturally occurring catecholamines dopamine (1), norepinephrine (2), and epinephrine(3) (Figure 1) play key roles in neurotransmission, metabolism, and in the control of various physiological processes. For example, norepinephrine is the primary neurotransmitter in the sympathetic nervous system and also functions as a neurotransmitter in the central nervous system. Epinephrine, elaborated by the adrenal gland, has potent effects on the heart, vascular and other smooth muscles. Dopamine is an important neurotransmitter in the central nervous system, and has important peripheral effects in such organs as the kidney and heart. The importance of these effects has made the search for drugs that can mimic, inhibit, or otherwise modulate the effects of these catecholamines an important area of medicinal chemistry. 

Figure 1 Naturally occurring catecholamines Dopamine (1), norepinephrine (2), and epinephrine (3).

Some oxidations are mediated by hepatic enzymes localized outside the microsomal system. Alcohol dehydrogenase and aldehyde dehydrogenase, which catalyse a variety of alcohols and aldehydes such as ethanol and acetaldehyde, are found in the soluble fraction of the liver. Xanthine oxidase, a cytosolic enzyme mainly found in the liver and in small intestine, but also present in kidneys, spleen and heart, oxidizes mercaptopurine to 6-thiouric acid. Monoamine oxidase, a mitochondrial enzyme found in liver, kidney, intestine and nervous tissue, oxidatively deanoinates several naturally occurring amines (catecholamines, serotonin), as well as a number of drugs. 

Mimic naturally occurring catecholamines (epinephrine, norepinephrine and dopamine) or stimulate the release of norepinephrine Indications Alpha-adrenergic agonists used to treat hypotension Common drug examples ... 

Biogenic amines, biological amines biologically and pharmacologically important naturally occurring amines, occurring widely in plants and animals. They can be divided into 1. derivatives of ethanolamine, e.g. choline, acetylcholine, muscarine 2. polymethylene diamines, e.g. putrescine, cadaverine 3.polyamines, e.g. spermine 4. imidazolylalkylamines, e.g. histamine 5.phenylalkylamines, e.g. mescaline, tyra-mine, hordenine 6. catecholamines, e. g. adrenalin, nor-adrenalin and dopamine 7. indolylalkylamines, e.g. tryptamine, serotonin and 8. betaines, e.g. carnitine. 

Although the principal area of application of HPLC-ED has been in the analysis of naturally-occurring analytes, such as catecholamines, and pharmaceuticals in biological samples, HPLC-ED has also been applied to the analysis of pesticides and other analytes of interest to the toxicologist. This section details some of these additional applications,... 

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