Secoiridoids from Gentiana siphonantha.

Repeated fractionations of the methanol extract of the subterranean parts (rhizomes and roots) of Gentiana siphonantha afforded two new and five known secoiridoids, in addition to the widespread plant constituents beta-sitiosterol, daucosterol and oleanolic acid. The structures of the new acyl secoiridoid glycosides were elucidated as 6'-gentisoyl 8-epikingiside and 2'-gentisoyl gelidoside mainly by a combination of high field NMR techniques. The known secoiridoids were identified as gentiolactone, gentiopicroside, sweroside, gelidoside and trifloroside. None of these constituents was active against human pathogenic fungi (Candida albican, Aspergillus flavus and Trichoderma viride). The chemotaxonomic significance of the isolates is discussed briefly.