Galiridosid,ein Iridoidglucosid aus Galeopsis tetrahit L. (Labiatae)

From fresh leaves of Galeopsis tetrahit L. (Labiatae) a compound observed earlier only by paper chromatography and known as ‘Tetrahit-Pseudoindican’ or ‘Gal. tetr. 47’ has been isolated, and its constitution (II) as a new iridoid glucoside has been established. The name of galiridoside is proposed for this compound. Acetylation of galiridoside gave the tetraacetyl-derivative III. Catalytic reduction of II by Pd/C gave dihydrogaliridoside (IV). Basic hydrolysis of II with Ba(OH)₂ gave desepoxydihydroxy-galiridoside (VI). Reduction of galiridoside by lithium and ammonia yielded among other compounds a small amount of dideoxy-aucubin (XI), isolated as its tetraacetate XII. The NMR. spectra of galiridoside and its derivatives support the proposed structure and configuration.