3-0,4-0-dimethyl-dopamine

Zhou et al. [1025] described a simple drug-release system based on a P(Py)-poly(styrene sulfonate) (P(Py)/PSS) film electropolymerized on a Pt electrode. Upon reduction of this as-prepared film in an aqueous solution containing dopamine hydrobromide (Dopa-HBr) or dimethyl-dopamine-hydrobromide (MeDopa-HBr), the dopamine was incorporated into the CP as a cationic dopant (the amine group of Dopa forms a substituted alkyl ammonium ion in aqueous solution). Electrochemical re-oxidation of this CP-Dopa complex then caused release of the Dopa. Controlled release could be effected via controlled, coulometric application of charge and controlling the CP film thickness between 0.35 and 2.8 /tm. Release was however slow, of the order of minutes Fig. 24-3 shows a typical release pattern, monitored optically via solution Absorbance. These authors also showed that the anesthetic BNA could also be bound and released reversibly in the same manner as Dopa. 

Release of (protonated dimethyl dopamine) from IH -loaded PMP PSS (poly(N-MePy)/poly(styrene sulfonate)) films (1.3 im) upon application of potential step from open-circuit to (a) 0.4 V, (b) 0.5 V, and (c) 0.6 V. After Reference [1025], reproduced with permission. 

DMF, see Dimethylformamide DM SO, see Dimethyl sulfoxide DMT (dimethoxytrilyl ether), DNA synthesis and, 1114 DNA, see Deoxyribonucleic acid DNA fingerprinting, 1118-1119 reliability of, 1119 STR loci and, 1118 Dopamine, molecular model of. 930 Double bond, electronic structure of, 16... 

The enantiomers of the dopaminergic, and orally active 6,7,8,9-te-trahydro-jV,A-dimethyl-3 -benz[e]indol-8-amine (54) were studied for their actions on central dopamine and serotonin (5-HT) receptors [123]. The dopaminergic effects were shown to reside in the (- -)-(/ )-enantiomer. Very interestingly, it was shown that racemic (54) and its (- -)-(i )-enantiomer possess potent central 5-HT 1A receptor stimulating properties, which was not reported originally [124]. Still another indication of the trend in DA agonist SAR towards heterocyclic bioisosteres is given by compound (55) [125]. 

Dopamine-j3-oxidase contains copper and is inhibited [343] by copper-chelating agents such as 2,9-dimethyl-o-phenanthroline (XCV). The aminoguanidine... 

As a first step toward a dopamine-jS-hydroxylase mimic, basket-shaped receptor 17 was functionalized with two sets of bis-[2-(3,5-dimethyl-l-pyra-zolyl)ethyl]amine ligands to give compound 35 (see Scheme 5). Reaction of 35 with Cu(C104,)2-6H20 yielded complex 36 which was fully characterized [39], Ligand system 35 binds dopamine derivative 37 and phloroglucinol (1,3,5-trihydroxybenzene) with association constants of = 60 and 3500 respectively. The affinity of the Cu(I) analogon of 36 for 37 was very similar to that of 36 itself and amounted to Ka = 60 M L Resorcinol is bound in the cavity of the Cu(I) complex with a Xj-value of 2(XX) M". ... 

The oxidation of dopamine by ceruloplasmin yielded a free radical with a very short lifetime, characterized by an EPR signal at g = 2.006 Dimethyl-p-phenylenediamine was oxidized faster by the enzyme to the free radical Wurster s red, which was further oxidized by the enzyme in another one-electron step. The free radical seemed, moreover, to be stabilized by ceruloplasmin... 

Dihydroxyindole and 5,6-dihydroxyindole-2-carboxylic acid were shown to form after the red pigment stage that occurred during the conversion of DOPA into a melanin, by Raper, who isolated these compounds as their dimethyl ethers.72 The presence of 5,6-dihydroxyindoles in solutions of DOPA, dopamine, and noradrenaline which are undergoing oxidation has subsequently been confirmed by paper and thin-layer chromatography.118,120,222 5,6-Dihydroxyin-dole and 5,6-dihydroxyindole-2-carboxylic acid have recently been isolated from the alkali fusion products of sepiomelanin, indicating... 

These reactions, which have provided a means of inhibiting the flavin-linked monoamine oxidases, enable us to end on a clinical note. The monoamine oxidases are responsible for the deamination of monoamines such as adrenaline, noradrenaline, dopamine, and serotonin, which act as neurotransmitters. Imbalances in the levels of monoamines cause various psychiatric and neurological disorders Parkinson s disease is associated with lowered levels of dopamine, and low levels of other monoamines are associated with depression. Inhibitors of monoamine oxidases may consequently be used to treat Parkinson s disease and depression. The flavin moiety is covalently bound to the enzyme by the thiol group of a cysteine residue (equation 9.17). The acetylenic suicide inhibitor N,N-dimethyl-propargylamine inactivates monoamine oxidases by alkylating the flavin on N-5.25 A likely mechanism for the reaction is the Michael addition of the N-5 of the reduced flavin to the acetylenic carbon 2... 

The n-arylpalladium bonds in these complexes are reactive and undergo insertion and substitution reactions. The reactions offer useful methods for regiospecific functionalization of aromatic rings, although the reactions are difficult to make catalytic in most cases. Insertion of styrene to AA-dimcthylbcnzylaminc complex (180) to form the stilbene derivative 185 occurs smoothly at room temperature in AcOH [5]. The reaction has been extended to the functionalization of the dopamine analogue (A,A-dimethyl-2-arylethylamine) 187 via the six-membered o/Y/zo-palladated complex 186 [118]. 

These effects are produced mostly by phenylpropanolamines present in the leaves. These include cathinone [4] (5 -a-aminopropiophenone), cathine [5] [(-)-IS, 2S-norpseudoephedrine] and (-) -IR, 2S-norephedrine (8). These substances have pharmacological properties similar to those of amphetamine [6] (81), as they induce the release and inhibit the uptake of dopamine and norepinephrine in CNS (82). In addition to the known phenylpropylamines, the presence of other amines such as meracathine, pseudomeracathine and meracathinone have been identified (83, 84). Cathinone, being a ketoamine base, is extremely unstable and, in particular, it can be transformed into (+)-norpseudoephedrine and (-)-norephedrine by an enzymatic reduction. It can also be oxidized to give 1-phenyl-l,2-propandione, while the cathinone dimers, such as 3,6-dimethyl-2,5-diphenylpyrazine are purely artifacts of the isolation (85). 

In the synthesis of 3-demethoxyerythratidinone, an erythrina alkaloid, the key step is the construction of a five-membered nitrogen heterocycle via stereoselective ns annulation The tributyltin hydride mediated radical cyclization of a dopamine dimethyl ether derivative 13 affords the diastereomer 14 with the required configuration in excellent yield. Through a three-step sequence the missing double bond is constructed to give the desired product. 

N-Methyl-3-hydroxy-4,5-dimethoxyphenylethylamine and iVN-dimethyl-3-hydroxy-4,5-dimethoxyphenylethylamine have been identified in L. williamsii. The former base was incorporated with high efficiency into pellotine (69), but not into (56) or (70). Results obtained previously, where pyruvate was shown to be a more specific precursor than acetate for anhalonidine (56), were confirmed. Alanine, and to a lesser extent glycine, could serve as C-2 units for (56). No significant results were obtained for (56) or (70) with formate or methionine. Although Ai-formyl- and A-acetyl-3-hydroxy-4,5-dimethoxyphenylethylamine are found in L. williamsii they were not incorporated intact into the isoquinoline alkaloids in the cactus, in accord with the discussion above. The mescaline precursors dopamine, 4-hydroxy-3-methoxyphenylethylamine, and 3,4-dihydroxy-5-methoxyphenylethylamine have been isolated from L. williamsii by radioisotope dilution. The presence of dopamine and 3,4,5-trihydroxyphenylethyl-amine was uncertain. 

The use of the mustard oil reaction prior to separation by TLC is mentioned in a few publications [54, 59]. One of these deals with the detection of 3,4-dimethoxy-phenylethylamine, the dimethyl ether of dopamine, in urine samples. The compound is converted to the isothiocyanate and separated on silica gel plates. These are then sprayed with a mixture of equal volumes of sulfuric acid and methanol and irradiated with UV light. An intense fluorescence develops and permits the detection of ng amounts of 3,4-dimethoxyphenylethylamine [54]. The derivative can be extracted with methanol for quantitative detetmination by spectrofluorimetry (excitation at 365 nm, fluorescence at 465 nm). The only other isothiocyanates which yielded a similar fluorescence were those of 3-methoxytyramine and 4-O-methyldopamine. Silica gel thin-layer plates have also been used to separate norephedrine from norpseudo-ephedrine as isothiocyanates [59]. 

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