Alkaloids of Eminium lehmannii

Abstract

Eminium lehmannii (Bunge) O. Kuntze is a rare relict species of the ancient family Araceae [1]. The genus Eminium includes eight species that are distributed primarily in the Mediterrean and Western Asian countries. Two species grow in Kazakhstan, E. lehmannii and E. alberty (Rgl.) Engl. [1]. Both are endemic and cited in the Red Book of Kazakhstan [2]. Tubers of this plant are used in folk medicine [1, 3]. According to the literature [3, 4], tubers contain alkaloids, saponins, and starch. The quantitative composition of leaf lipids and the composition of glycolipids and pigments from leaves and skin and core of tubers have been studied [5, 6]. Herein we communicate results from the first study of the alkaloid composition of E. lehmannii tubers. Alkaloids were isolated from the thick alcohol extract of the subterrean part of E. lehmannii (14% yield of extracted substances) by partitioning extraction using petroleum ether:water. This separated a fraction of nonpolar components (20% yield). The remaining aqueous alcohol solution was extracted with CHCl3. Column chromatography of the CHCl3 extract over silica gel isolated successively the alkaloids vomicine (4-hydroxy-19-methyl-16,19-seco-strychnidin-10,16-dione) (1) (0.015% yield of dry wt.) and strychnine (2) (0.025% yield). The molecular structures of these alkaloids were established by x-ray structure analyses (XSA). Figure 1 shows the molecular structure of 1 and intramolecular interactions from the XSA. Figure 2 shows the crystal packing of 1 with intermolecular interactions.