Saponins from maté (Ilex paraguariensis) amd other South American Ilex species: ten years research on Ilx saponins

RESUMO

Ilex paraguariensis is widely used in South Brazil, Argentinna, Paraguay and Uruguay as a beverage (maté) and also as a traditional medicinal plant. During the past ten years, we have systematically studied the saponins of the leaves of genuine maté (Ilex paraguariensis) and the other Ilex species reported as adulterants, searching for chemical differences. Here we give a brief account of the elucidated saponin structures. Ilex paraguariensis and Ilex dumosa can be considered as saponin rich species, containing between 5-10 per cent of crude saponins in the leaves, in opposition to other species that showed a lower saponin content. All the saponins from Ilex paraguariensis leaves identified up to now are glycosides of ursolic or oleanolic acid. From Ilex dumosa, the most frequently quoted maté adulterant, we have isolated and elucidated the structures of ten saponins, almost all of them being glycosides of oleanolic acid and one of 29-hydroxyoleanolic acid. In comparison, the saponin pattern for the other South American Ilex species investigated up to now is different. The saponins from I. pseudobuxus, I. argentina, I. taubertiana and I. theezans all have the aglycones derived from the 19alpha-hydroxyursolic acid. Saponins containing this type of aglycone were not found in the leaves of Ilex paraguariensis and Ilex dumosa. These are important features, that may have taxonomical significance. Furthermore, this knowledge is necessary to develop methodologies for quality control of maté products and to identify the compounds involved in the tast, flavor and pharmacological properties.