Two-dimensional TLC with adsorbent gradient for separation of quinolizidine alkaloids in the herb and in-vitro cultures of several<i>Genista</i>species

Abstract

Conditions have been established for TLC separation of a mixture of nine quinolizidine alkaloid standards (lupanine, methylcytisine, cytisine, hydroxylupanine, sophocarpine, lusitanine, retamine, sparteine, and l - α -isosparteine) and of alkaloid fractions from a variety of Genista species and from in-vitro cultures of members of this species. Optimization of the one-dimensional TLC separation of the nine alkaloid standards was performed on two types of layer, RP-18W and silica gel. The mixture of standards was also chromatographed by two-dimensional TLC on diol F 254S layers and by 2D TLC with an adsorbent gradient. In the last variant (so-called graft TLC) the first development was performed on a TLC diol plate and the second, in the perpendicular direction, on an RP-18W TLC plate. Only by 2D TLC with an adsorbent gradient was it possible to achieve full separation both of the standards and of alkaloid fractions from plant material. Under these conditions the presence of retamine, cytisine, sparteine, l - α -isosparteine, lupanine, and methylcytisine was discovered in all Genista species and in shoot cultures of G. tinctoria .