betadex and salsolinol

D- and L-dihydroxyphenylalanine (D- and L-DOPA) and enantiomers of the tetrahydroisoquinoline alkaloids salsolinol (SAL), 1-carboxysalsolinol (1-CSAL), and cis-3-carboxysalsolinol (3-CSAL) were chromatographed using sulfated beta-cyclodextrin (S-beta-CD) as a chiral selector in mobile phases with conventional reversed-phase ODS columns. S-beta-CD is a very effective chiral selector for SAL and 3-CSAL, less effective although still useful for resolving D- and L-DOPA, and gives only meager separation of the optical isomers of 1-CSAL. Stoichiometries of the complexes which form between S-beta-CD and SAL enantiomers are 1:1. Interactions between carboxylated substances and S-beta-CD appears to be more complex. Retention of the solutes studied is characterized by favorable negative enthalpy and unfavorable negative entropy changes. Enthalpy changes outweigh entropy values.

Topics: Antiparkinson Agents; beta-Cyclodextrins; Chromatography, High Pressure Liquid; Cyclodextrins; Dihydroxyphenylalanine; Isoquinolines; Stereoisomerism; Sulfuric Acids; Thermodynamics

Both electrophoretic and chromatographic transport mechanisms are combined in electrochromatographic separation. In this paper, we developed a model of enantioselectivity in capillary electrochromatography (CEC) which can be applied in the separation of both neutral and ionic compounds. The overall selectivity in enantioseparation is considered to be made up of two contributions: one is the intrinsic difference in formation constants of a pair of enantiomers, and the other is the conversion efficiency of the intrinsic difference into the apparent difference in the migration velocity. The model was illustrated through the chiral separation of (R)- and (S)-salsolinols. Under a positive electric field, enantioseparation of salsolinols was achieved on an ODS column with beta-cyclodextrin as a chiral mobile-phase additive. The experimental results are discussed in relation to the effect of separation parameters, such as the direction and size of electric field and properties of the stationary and mobile phases. It was demonstrated that if both electrophoretic and partitioning mechanisms produce positive effects, high overall selectivity in CEC can be obtained. For pressurized-driven electrochromatography, although the column efficiency is sacrificed due to the introduction of hydrodynamic flow, the increased selectivity significantly reduced the requirement of large column plate numbers for resolution.

Topics: beta-Cyclodextrins; Buffers; Chromatography, Micellar Electrokinetic Capillary; Cyclodextrins; Electromagnetic Fields; Isoquinolines; Models, Theoretical; Stereoisomerism

A chromatographic procedure was devised for the quantitative determination of the enantiomers of salsolinol and N-methylsalsolinol, which are biologically important alkaloids. The enantiomers of salsolinol and N-methylsalsolinol were completely separated using beta-cyclodextrin in a reversed-phase ion-pair system. The HPLC method was sensitive enough to detect the isoquinolines at a concentration less than 0.1 pmol per injection. The presence of (R)- and (S)-salsolinol was confirmed in fermented foods and beverages, while N-methylsalsolinol was not detected. On the other hand, the (R)-enantiomers of both salsolinol and N-methylsalsolinol were found to predominate in the human brain.

Topics: beta-Cyclodextrins; Beverages; Brain Chemistry; Chromatography, High Pressure Liquid; Cyclodextrins; Food Analysis; Fruit; Humans; Isoquinolines; Molecular Conformation; Reproducibility of Results; Salsoline Alkaloids; Tetrahydroisoquinolines; Wine

A novel method for direct separation of the enantiomers of salsolinol and N-methylsalsolinol was devised. The enantiomers were completely separated with ion-pair chromatography on a reversed-phase column with beta-cyclodextrin as a chiral mobile phase additive and sodium 1-heptanesulfonate as a counterion. The mechanism for enantioseparation with this ion-pair system containing beta-cyclodextrin was discussed. The effects of beta-cyclodextrin, counterions, pH, ionic strength, and organic solvent on retention were investigated, and a retention model was proposed and proved to be consistent with the experimental data. A preliminary study of the enantiomeric composition of salsolinol and N-methylsalsolinol in banana and in human brain was made as an example of the application of this assay.

Topics: beta-Cyclodextrins; Brain Chemistry; Chromatography, High Pressure Liquid; Chromatography, Ion Exchange; Cyclodextrins; Fruit; Humans; Isoquinolines; Stereoisomerism

A reliable and sensitive high-performance liquid chromatographic (HPLC) method is presented for the determination of total (free and conjugated) plasma dopamine and the enantiomers R- and S-salsolinol. Plasma is purified on two cartridges, containing primary and secondary amines and phenylboronic acid. Dopamine, R- and S-salsolinol are then separated by HPLC using a beta-cyclodextrin-OH phase column. The eluate is monitored electrochemically, without further purification nor derivatization. The method is suited for routine analysis. It allows the detection of total (free and conjugated) dopamine and R- and S-salsolinol in human plasma in concentrations as low as 0.02 ng/ml plasma. The sensitivity is sufficient to measure the naturally occurring levels of salsolinol.

Topics: beta-Cyclodextrins; Biogenic Amines; Chromatography, High Pressure Liquid; Cyclodextrins; Dopamine; Electrochemistry; Humans; Indicators and Reagents; Isoquinolines; Stereoisomerism