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Tetrahydroisoquinohe alkaloids, which are known to be present not only in plants but also in animals, including mammals, can be considered as condensation products of 2-phenylethylamines (e.g., catecholamines) with aldehydes (e.g., acetaldehyde) or 2-0x0 acids (e.g., pyruvic acid). In this study the possibility of separating the optical isomers of several tetrahydroisoquinolines by high-performance liquid chromatography was investigated. For isosalsolme, tetrahydropapaveroline and laudanosoline a good enantiomeric separation could be achieved by applying P-cyclodextrin-bonded silica as stationary phase in connection with various mobile phases. With respect to laudanosoline, the addition of p-cyclodextrin as chiral selector to the mobile phase using a C,, reversed-phase column as stationary phase revealed an even higher resolution when compared with the chiral columns. All tested tetrahydroisoquinohes which could be well separated into enantiomers bear a hydroxyl group at carbon atom 7 as a common structural feature. Those alkaloids substituted with a methoxy group on position 7 instead of a hydroxyl group (e.g., salsolidine) failed to be resolved into their optical isomers. Therefore, the presence of a hydroxyl group on C7 of the aromatic ring seems to be conducive to steric discrimination. However, the separation results for 1-carboxysalsolinol were unsatisfactory although this molecule possesses a 7-hydroxyl group. In this case the existence of a carboxyl group on C1 reduced the chiral recognition and thus the enantiomeric resolution.

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