Leaves of Yellow Gentian (Gentiana lutea) as an Alternative Source of Bitter Secoiridoid Glycosides.

In a search for methods of manufacturing bitter principles from Gentiana lutea, mainly represented by gentiopicroside (1) and amarogentin (2), as an alternative to extraction from the roots of this plant, in this short communication it is shown that the leaves of this plant can be regarded as an additional source of such phytochemicals. Extraction of G. lutea leaves was coupled to solid-phase adsorption by differently structured solids as a separation technology step, providing a selective isolation of both these secondary metabolites in good to excellent yields. Thus, the extraction of bitter secoiridoids can be achieved in an equivalent or improved way rather than processing the roots of G. lutea while preserving the biodiversity of the species.

An improved method for the isolation of amarogentin, the bitter principle of yellow gentian roots.

Amarogentin is well known to be among the most bitter naturally occurring compound. Either as an individual one or extracts, amarogentin is used as a food additive and as a dietary supplement. The aim of the present investigation is to set-up a convenient process to selectively isolate amarogentin from the ethanolic roots extract of Gentiana lutea. The process consisted in the treatment of an aqueous suspension of such an extract with a panel of 21 solid inorganic / organic sorbents followed by filtration, desorption, and high performance liquid chromatography (HPLC) analyses. Among the solid materials tested, those containing Mg+2 in the frame of a lamellar structure provided very good adsorption yields in the range 86.4% - 99.9% (p < 0.05 at Student's t-test). The method we set up could be in principle useful to obtain a pure nature-derived food additive to provide bitter taste to foods and beverages.