Increased systemic levels of norsalsolinol derivatives are induced by levodopa treatment and do not represent biological markers of Parkinson's disease.

Endogenously synthesised norsalsolinol derivatives are elevated in Parkinson's disease (PD) and have been considered potentially useful biological markers of the disease. However, little is known about the impact of dopaminergic drugs on the formation of these compounds. We prospectively examined the urine concentrations of norsalsolinol, N-methyl-norsalsolinol and salsolinol in 47 PD patients and 14 control subjects. Patients and control subjects were re-examined after approximately 1 year to assess long term changes. Norsalsolinol derivatives were low in controls and untreated patients with early PD. Increased urine concentrations of norsalsolinol derivatives were significantly associated with levodopa treatment. They were elevated more markedly in the urine of patients treated with high (>600 mg daily) doses of levodopa compared with patients receiving medium (300-600 mg) or low (<300 mg) doses of the drug. There was no correlation with disease parameters such as the severity of motor disability or deficits in the cognitive performance. In the patient group, the concentrations of all three norsalsolinol derivatives declined over the period of investigation, however, they still remained elevated compared with the control group. We conclude that systemic levels of norsalsolinol derivatives in treated patients with PD are likely to derive from the metabolism of levodopa and cannot be regarded as intrinsic markers of the disease. The limited ability of norsalsolinol derivatives to pass the blood-brain barrier prevents an intracerebral accumulation of these possibly harmful compounds, which are biochemically similar to the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine.

Fluorometric determination of 1,2,3,4-tetrahydro-6,7-dihydroxyisoquinoline in biological materials by HPLC.

In the belief that endogenous 1,2,3,4-tetrahydro-6,7-dihydroxyisoquinoline (DA-Fp) could be a potential marker involved in the etiology of various diseases such as Parkinsonism, we attempted to develop a fluorescence method for DA-Fp. It was synthesized by condensation of dopamine with formaldehyde according to an established method. Periodate was identified by screening from various oxidation reagents as a fluorescence reagent to DA-Fp. Optimal reaction conditions were obtained with 0.25 mM NaIO4 in 0.1 M phosphate buffer (pH 8.0) at 37 degrees C for 15 min. The fluorescence spectrum of the derivative showed that we had found a new reaction specific for DA-Fp. This reaction was coupled on-line to high performance liquid chromatography (HPLC), which enabled us to achieve a highly sensitive method for determining DA-Fp. A working curve was linear from 2 to 800 pmol of DA-Fp per injection. To determine DA-Fp in biological materials, the pretreatment before HPLC was optimized by hydrolysis of its conjugate and suppression of the artifact with l-phenylephrine. Urinary excretion of DA-Fp in men was measured by this new present method. The urinary excretion of endogenous DA-Fp increased in a rabbit given L-DOPA. The DA-Fp concentration was determined in rat brain. The significance of DA-Fp in these biological materials is discussed and evaluated. We conclude that the present method will be useful for studying tetrahydroisoquinolines involved in many diseases.

Salsolinol and norsalsolinol in human urine samples.

The tetrahydroisoquinoline alkaloids salsolinol and norsalsolinol were found in human urine samples in concentrations ranging from 0.1 to 29.5 ng/ml. Great interindividual variation was found in urine levels of these alkaloids in a collection of chronic alcoholics and in a group of nonalcoholics. Thus, levels of the individual alkaloids are insufficient markers for distinguishing between alcoholics and nonalcoholics. However, by using the concentration ratio of norsalsolinol and salsolinol, the so-called dopamine-aldehyde adduct ratio (DAAR), significant differences between alcoholics (median 1.3) and nonalcoholics (median 0.6) were detected. This concentration ratio could serve as a marker for the processor state of the dopaminergic system.

A new rapid method for the analysis of catecholic tetrahydroisoquinolines from biological samples by gas chromatography/mass spectrometry.

A new method for the analysis of tetrahydroisoquinolines (TIQ) from biological materials is described. The method combines extraction and acylation of the TIQs from urine in a one-step procedure followed by analysis by gas chromatography/mass spectrometry. By this extractive derivatization method, a decrease of the extraction time, to speed up sample preparation in order to minimize oxidative side reaction, has been achieved. The detection limits for the analysis of salsolinol and salsolin in urine were 10 fmol/ml sample volume. Tetrahydropapaveroline could only be detected in spiked urine samples with a detection limit of 1 pmol/ml urine. The method is not only restricted to urine samples, but can also be applied to a variety of tissue types, including blood components.

Dopamine-derived tetrahydroisoquinolines and Parkinson's disease.

The daily urinary excretion of salsolinol, 1,2-dehydrosalsolinol, and norsalsolinol, as free, glucuronide, and sulfate, has been measured in parkinsonian patients and age-matched controls in an attempt to examine whether the determination of dopamine-derived alkaloids in urine may be used as a marker of the decrease in brain dopamine levels associated with the disease. In contrast with a preliminary study where the daily urinary excretion of total salsolinol was significantly higher in young controls than in parkinsonians, in the present study no difference was found between parkinsonian patients and controls concerning salsolinol and norsalsolinol excretion. However, the urinary excretion of total 1,2-dehydrosalsolinol was significantly higher in the control group, owing to a statistically significant increase in its excretion as sulfate in this group. Further studies appear to be necessary to establish whether 1,2-dehydrosalsolinol, salsolinol, and/or any other dopamine-derived alkaloid may serve for the detection of subjects with dysfunctions of the dopaminergic system.

The influence of acute ethanol on the catecholamine system in man as reflected in cerebrospinal fluid and urine. A new condensation product, 1-carboxysalsolinol.

Urine and cerebrospinal fluid (CSF) were collected from 10 healthy male volunteers after ingestion of 120 g ethanol and under similar conditions without ethanol. Dopamine (DA), homovanillic acid (HVA), norepinephrine (NE), 4-hydroxy-3-methoxyphenylglycol (HMPG), 4-hydroxy-3-methoxymandelic acid (HMMA = VMA), 1-carboxysalsolinol (1-CSAL), salsolinol (SAL) and methylated salsolinol (M-SAL) were analyzed with gas chromatography-mass spectrometry. In CSF collected 6 h after ethanol intake the concentration of NE and its metabolite HMPG were significantly elevated (P less than 0.025 and P less than 0.005, respectively) compared to control conditions. The other compounds analyzed did not change significantly. In urine collected during 10 h after ethanol administration the excretion of HMMA was significantly reduced (P less than 0.01) and the HMPG/HMMA ratio was significantly elevated (P less than 0.005) reflecting a change in the peripheral red-ox state during ethanol oxidation. The excretion of DA and its major metabolite HVA did not change. However, the DA-derived condensation products 1-CSAL (from DA and pyruvate) increased (P less than 0.001), while SAL (from DA and acetaldehyde) decreased (P less than 0.005) after ethanol ingestion compared to the control situation. The increased excretion of 1-CSAL indicated that the ethanol metabolism interferes with the glucose metabolism, probably through an acetaldehyde-mediated inhibition of the pyruvate dehydrogenase complex.

Analysis of salsolinol and salsoline in biological samples using deuterium-labelled internal standards and gas chromatography--mass spectrometry.

Salsolinol and salsoline were labelled with deuterium using an acidic exchange reaction in 2HCl--2H2O. Two deuterium atoms were incorporated in both compounds. The deuterium-labelled salsolinol and salsoline were used as internal standards to determine picomol amounts of the corresponding unlabelled compound in the urine, cerebrospinal fluid, brain and liver. The salsolinol was purified on alumina and salsoline collected in the effluent. The compounds were analysed as their pentafluoropropionyl derivatives by gas chromatography on a 1% OV-17 column and were selectively detected with electron-impact mass spectrometry at the molecular ions M+ and M+--15. With human urine the precision of the methods were +/- 4.9% (coefficient of variation, n = 10) for salsolinol and +/- 2.2% for salsoline at a level of 0.100 nmol/ml. Administration of salsolinol to rats intraperitoneally (0.4 mmol/kg) resulted in levels of 1--2 nmol/g in striatum and limbic forebrain after 2 h, whereas the corresponding liver values were about 550 nmol/g. Control animals showed salsolinol values in liver of about 2 nmol/g and in striatum and limbic forebrain 1 nmol/g tissue.

Dopamine-related tetrahydroisoquinolines: significant urinary excretion by alcoholics after alcohol consumption.

Concentrations of dopamine-related tetrahydroisoquinolines (salsolinol and O-methylated salsolinol) were significantly higher in the daily urine samples of alcoholic subjects admitted for alcohol detoxification than in the daily urine samples of nonalcoholic control subjects. Salsolinol concentrations in alcoholic subjects appeared to drop to trace (control) values 2 to 3 days after admission, following the disappearance of ethanol and its reactive metabolite acetaldehyde from the blood. These results indicate that physiologically active tetrahydroisoquinolines increase in humans during long-term alcohol consumption, presumably because of acetaldehyde's direct condensation with catecholamines. The presence of these or similar condensation products in the urine could be useful as clinical indicators of prior blood acetaldehyde concentrations in chronic alcoholics.