Derivatives of dopamine

It is a derivative of dopamine and has relatively P -selective action and it also activates receptors and do not have or receptor agonistic property. It increases the force of myocardial contraction and cardiac output without significant change in heart rate, blood pressure and peripheral resistance. It is used as inotropic agent and for short term management of CHF and also in patients who are unresponsive to digitalis. 

Method for catecholamines by HPLC. A few microlitres of a 10 3-Af solution of dopamine, norepinephrine or similar compounds are transferred to a small test-tube and diluted to 20 jul with 0.05 M sodium phosphate (pH 8) at 4 °C [ 102]. 10 jul of a 0.2% solution of fluorescamine in acetone are then added with vigorous shaking. An aliquot portion of this mixture is applied directly to the HPLC column. The derivatives are separated on Hitachi 3011 or 3010-OH gels (column, 50 cm X 3 mm) with methanol-0.05 M Tris-hydrochloric acid buffer of pH 8 (7 3) at room temperature at a flow-rate of 0.72 ml/min. The separation of fluorescamine derivatives of dopamine and norepinephrine with this system is shown in Fig.4.52. 

An active area of phenethylamine research continues to be the synthesis and pharmacological evaluation of analogues. The compounds studied include homologues of dopa, a-methyldopa, and dopamine, a-hydroxymethyl derivatives of dopa and tyrosine, halogenated derivatives of dopamine and phenylalanine, and analogues of dopamine " and tyramine as well as new catecholamines and amphetamines. ... 

Figure 12.2. Toxic derivatives of dopamine. These include hydrogen peroxide, the free hydroxy radical, and the quinone.

Yamanaka, Y. Walsh, M. J. and Davis, V. E. Salsolinol, an Alkaloid Derivative of Dopamine Formed in Vitro during Alcohol Metabolism. Nature 1970,227,1143. 

There are several biologically active lipid derivatives of dopamine, including the amide of dopamine and oleic acid, iV-oleayldopamine (OLDA), 98. One study attempted to correlate the presence of 98 in brain tissues. Figure 23.8 shows the U V/VIS absorption spectra in membrane fractions of brain homogenates after 1 min, 18 h, and 20 h of incubation with AT-oleoyl-dopamine (curve... 

The derivatives have an optimum fluorescence at an excitation wavelength of 340 nm and an emission wavelength of 455 nm. The adduct is relatively stable at a pH of 9-11 but it rapidly degrades to a non-fluorescent residue at low pH values. Consequently, when used as a pre-column derivatizing reagent the pH of the mobile phase should be kept fairly high, o-phthalaldehyde has been employed for derivatization in the analysis of dopamine (29), catecholamines (30) and histamines (31). 

Kobayashi, N. et al., Formation and occurrence of dopamine-derived betacyanins. Phytochemistry, 56, 429, 2001. 

Derivatives of (S) N-[(l-ethyl-2-pyrrohdinyl)methyl]-6-methoxy benzamide 3 are dopamine D2 receptor antagonists. Samanta et al. obtained the following MLR QSAR for 49 derivatives with the general structure 3 [30] ... 

Initial tests in the rat revealed a high degree of tissue compatibility of Dat-Tyr-Hex derived polymers. More detailed tests are now in progress. In addition, tyrosine derived polymers are currently being evaluated in the formulation of an intracranial controlled release device for the release of dopamine, in the design of an intraarterial stent (to prevent the restenosis of coronary arteries after balloon angioplasty), and in the development of orthopedic implants. The use of tyrosine derived polymers in these applications will provide additional data on the biocompatibility of these polymers. 

Welch MJ, Chi DY, Mathias CJ, Kilboum MR, Brodack JW, Katzenel-lenbogen JA. Biodistribution of A-alkyl and TV-fluoroalkyl derivatives of spiroperidol radiopharmaceuticals for PET studies of dopamine receptors. Appl Radiat Isot 1986 13 523-526. 

Hsin, L.-W., Dersch, C.M., Baumann, M.H. et al. (2002) Development of long-acting dopamine transporter ligands as potential cocaine-abuse therapeutic agents chiral hydroxyl-containing derivatives of l-[2-[bis (4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine and l-[2-(diphenylmethoxy)ethyl]-4-(3-phe-nylpropyl)piperazine. Journal of Medicinal Chemistry, 45 (6), 1321-1329. 

The pleasure derived from using tobacco is linked to the stimulation of dopamine-dependent neurotransmitter pathways in the brain, particularly in the meso-limbic system. The precise nature of this link remains controversial, but many of the neurophysiological processes underlying nicotine addiction are common to other addictive drugs with diverse pharmacological actions such as opiates, cannabis, alcohol and cocaine. 

The actions of dopamine are terminated through presynaptic reuptake. Some of the dopamine is then re-incorporated into vesicles, while the rest is metabolized (Fig. 46-3). Dopamine and its O-methyl derivative are both subject to the action of monoamine oxidase (MAO),... 

---