Endogenous Alkaloids in Man - Synthesis, Analytics, in vivo Identification, and Medicinal Importance*,1

Harman and norharman plasma levels in weaned alcoholics: correlations with depression and tobacco smoking

Based on the hypothesis that β-carbolines are involved in the pathogenesis of alcohol-related mood disturbance, harman and norharman levels were assayed in the blood plasma of alcoholics and correlated to the Hamilton Depression (HAM-D) scores after 3 and 5 weeks post-admission. Tobacco smoking was co-evaluated since it is known to influence β-carboline levels. After a 3-week period, plasma harman but not norharman was increased in depressed alcoholics and positively related to the HAM-D sum-score (r = 0.47; p < 0.04) and to tobacco smoking (r = 0.56; p < 0.02). Since no correlation between depression and smoking was found, these data could account for the higher incidence of depressive symptoms in withdrawn alcoholics with increased harman levels. The partial correlations support this hypothesis.

Endogenous alkaloids in man. XXVI. Determination of the dopaminergic neurotoxin 1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline (TaClo) in biological samples using gas chromatography with selected ion monitoring

Highly chlorinated beta-carbolines have a potential in vivo relevance to Parkinson's disease. In this paper, a gas chromatographic method for the determination of the neurotoxic 1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline (TaClo), the condensation product of tryptamine and chloral hydrate, is described. The specific and sensitive assay involves purification of the biological samples by solid-phase extraction with C18 cartridges, derivatization with heptafluorobutyric anhydride, and chromatography on a non-polar fused-silica capillary column. Detection of TaClo was achieved by the registration of characteristic mass fragments of the TaClo heptafluorobutyric amide derivative using selected ion monitoring. The method was utilized to detect and quantify TaClo in blood, urine, bile, faeces, and brain tissue of rats treated with this alkaloid-type heterocycle. Four-fold deuterium-labelled TaClo was used as an internal standard.

Determination of tetrahydro-beta-carbolines in urine by high-performance liquid chromatography with suppression of artefact formation

A high-performance liquid chromatographic method has been developed for the determination of urinary tetrahydro-beta-carbolines. When standing tryptamine with formaldehyde and acetaldehyde under extraction conditions, the significant amounts of artefact 1,2,3,4-tetrahydro-beta-carboline (TBC) and 1-methyl-1,2,3,4-tetrahydro-beta-carboline (MTBC) were formed in a short time. Urine samples added with 2-ethyl-1,2,3,4-tetrahydro-beta-carboline (an internal standard) were treated with fluorescamine, and then with glycine, followed by serial solvent extractions. Such a pretreatment using two-step reactions removed a precursor (trypamine) by extracting its fluorescamine derivative, and enhanced the detection response by consuming excess fluorescamine. It solved the analytical problem that artefact TBC and MTBC are formed during analysis. Reversed-phase ion-pair chromatography using a C8-column and trifluoroacetic acid as a counter ion completed a base-line separation of three analytes within 10 min. The calibration graphs showed a good linearity in the range 0.1-50.0 ng ml-1 of urine samples spiked with standard TBC and MTBC. In the spike experiment, the recovery and relative standard deviation were almost 100% and less than 3.0%, respectively, for both TBC and MTBC. The proposed method enables the determination of the genuine urinary concentrations of TBC and MTBC without involving their artefacts.

Endogenous alkaloids in man. XI. Analysis of glyoxylate-derived 1,3-thiazolidines by ion-pair-assisted reversed-phase chromatography

Reversed-phase ion-pair chromatography, using cetyltrimethyl ammonium hydrogensulphate as detergent, has been applied to the analysis of the highly polar glyoxylate-derived 1,3-thiazolidines 1, 2 and 3. On the base of this high-performance liquid chromatographic separation of the diastereomeric compounds 1a/b and 3a/b was achieved. Removal of the hydrophobic couterion by precipitation as its insoluble iodide, followed by an extraction with chloroform, seems to be a promising first step to establish ion-pair-assisted chromatography as a preparative high-performance liquid chromatographic method for the isolation of polar compounds.

A "chemical" concept for the therapy of glyoxylate-induced oxalurias (1)

Glyoxylic acid is the toxic principle of acquired and inherited oxalurias. A "chemical", not enzyme-mediated detoxication concept for the trapping of this aldehyde is described, based on a spontaneous formation of alkaloid-type heterocycles by reaction with biogenic amines or amino acids. 5,5-Dimethylthiazolidine-2(R,S)-4(S)-dicarboxylic acid, prepared by the condensation of D(-)-penicillamine with glyoxylic acid, was found to be formed quickly in vitro, to be stable in vivo and of good physiological compatibility. Renal elimination of the unchanged thiazolidine occurs mainly within 24 h, after administration of its calcium salt to NMRI-mice. Recovery up to 85% of the applied dose was quantitatively monitored by HPLC after derivatization to the corresponding fluorescent dansyl compound, which was unequivocally identified by MS analysis after isolation from mice urine.