Catecholamine derivatives

Fig. 1 Fluorescence scan of the catecholamine derivatives (each ca. 10 ng) of noradrenaline (1), adrenaline (2), dopamine (3), dopa (4).

The distinction between a- and P-adrenergic receptors was first proposed by Ahlquist in 1948 based on experiments with various catecholamine derivatives to produce excitatory (a) or inhibitory (P) responses in isolated smooth muscle systems. Initially, a further subdivision into presynaptic a2- and postsynaptic oq-receptors was proposed. However, this anatomical classification of a-adrenergic recqrtor subtypes was later abandoned. 

Fig. 49. The dependence of the enhancement factor of catecholamine derivatives on the carbon number of n-alkyl sulfates as the hetaerons. The straight line obtained by least-squares analysis fits the expression, logi 0.22S ( 0.0317)Af where is the enhancement factor and N is the carbon number. The intercept is zero within experimental error. Reprinted with permission from HorvAth et al, (S4), Anal. Chem. Copyright 1977 by the American Chemical Society.

Norepinephrine is a catecholamine derived from dopamine that is a precursor to epinephrine. 

Dopamine is a catecholamine derived from tyrosine. Other catecholamines include epinephrine and norepinephrine. The biosynthetic pathway from tyrosine to dopamine, and the other catecholamines is shown in Figure 21.32. 

A Van t Hoff plot of In k vs. /T for a series of catecholamines derivatives is shown in Fig 7.3 and demonstrates a straight-line relationship. A general rule of thumb is that a 10°C increase in temperature will reduce the capacity factor of the column approximately two-fold (Schmitt et al., 1971). 

Spectrophotometric methods for the determination of catecholamine derivatives pyrocatechol, dopamine, levodopa, and methyldopa have been developed and applied to injections and tablets. One of the methods involves the oxidation of o-dihydroxy benzene derivatives by N-bromosuccinimide followed by oxidative coupling with isoniazide, leading to the formation of a red-colored product of maximum absorbance at 480-490 nm. 

Melmon, and M. Goodman, Conjugates of catecholamines. VI. Synthesis and 3-adrenergic activity of N-hydroxyalkyl catecholamine derivatives, J. Med. Chem. submitted. 

Catecholamine-derived tetrahydroisoquinolines can be stored within adrenergic neurons, " and when released can either activate or block a-adrenergic receptors. A number of 6,7-dihydroxytetrahydroisoquinolines related to dopamine were, therefore, studied for their inhibitory effects on the accumulation of dopamine by rat brain slices. 6,7-Dihydroxytetrahydroiso-quinoline and 5-( —)-salsolinol were found to be effective inhibitors of dopamine accumulation, while 7 -( + )-salsolinol was less potent. 6,7-Dihydroxytetra-hydroisoquinoline is both a directly and indirectly acting sympathomimetic agent. ... 

Szanto, D.A., Trinidad, P. and Walsh, F.C. (1998) Evaluation of carbon electrodes and electrosynthesis of coumestan and catecholamine derivatives in the FMOl-LC electrolyser. Journal... 

The dioximato-manganese(II) catalyst (3) increases the auto-oxidation rate of epinephrine (a catecholamine derivative) in Na2C03-NaHC03 buffer at room temperature. The proposed mechanism presumes the binding of O2 to the Mn complex, followed by the formation of a ternary intermediate active catalyst-02-substrate complex which disproportionates in the rate-determining step to the product adrenochrome. ... 

The reactions leading to the formation of highly fluorescent products following the oxidation of catecholamines and condensation with ethylenediamine are very complex, and only the product from NA is shown in Figure 1. This method is more sensitive than the trihydroxyindole method, and the fluorescent products are more stable, but it is a far less specific assay procedure. Ethylenediamine will condense with many catechol compounds to yield fluorescent derivatives. It is, therefore, essential to employ a very rigorous procedure for the isolation of the amines prior to assay. When such a procedure is used, involving, for example, the separation of acetylated catecholamine derivatives by paper chromatography, the ethylenediamine method provides one of the most sensitive assay procedures for DA. 

Fig. 13. The derived dose-response correlations of various catecholamine and oxedrine derivatives when influencing lipid mobilization in vitro. Material identical with that of Figs. 7 and 8. On left Lower halves of dose-response curves of oxedrine derivatives, and upper halves of those of catecholamine derivatives with H, Me, and iPr N-substitution. Steep slope of curves and compression of pDj values in the case of catecholamine derivatives are to be noted. On right Correlation between found relative pD values of the eight oxedrine derivatives given in Fig. 7 (abscissa) and relative pDj values of the correspondingly N-substituted catecholamines. Compare the experimentally obtained situation with the theoretical one in Fig. 12.

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