IRIDOID MONO- AND DI-GLYCOSIDES IN MENTZELIA

Article abstract of DOI:10.1016/0031-9422(81)85221-1

Key Word Index - Mentzelia; Loasaceae; iridoid glycosides; allose; mentzelose; quinovose; deutzioside; epoxydecaloside; loganin; secoiridoids; scopolin; iridoid aglucone; mentzetriol; 13C NMR data; chemotaxonomy; biosynthetic considerations. Eight species of Mentzelia (Loasaceae) have been investigated for iridoid glycosides.In addition to the known glucosides deutzioside, decaloside, mongolioside, loganin and sweroside, several novel compounds have been isolated and characterized by chemical and spectroscopic means. 6'-O-Acetyl deutzioside was found in a single species, while the diglycosidic compounds glycosyl-decaloside and quinovosyl-decaloside were each isolated from one or more species.In addition, a novel compound, epoxydecaloside (=11-hydroxy-deutzioside), together with glycosyl-epoxydecaloside, allosyl-epoxydecaloside and mentzelosyl-epoxydecaloside are described.The last compound contains a 4-deoxy-α-L-erythro-pentapyranosyl moiety, whose parent sugar, named mentzelose, has not been encountered so far in nature.A non-glycosidic iridoid, mentzetriol, has been characterized solely by spectroscopic means and a structure is proposed.The secoiridoid secoxyloganin has been found for the first time in a plant source, and the coumarin glucoside scopolamin has been isolated from two species of Mentzelia. 13C and 1H NMR spectra of several iridoid compounds are presented.The biosynthesis of the compounds is considered and the systematic position of Loasaceae discussed concluding in a possible derivation from Cornalean ancestors.