3-Monoterpenyl 2,4-Dioxygenated Quinoline Alkaloids From the Aerial Parts of Eriostemon australasius subsp. banksii (Rutaceae)

Abstract

An extract of the aerial parts of Eriostemon australasius Pers.subsp. banksii (A. Cunn. ex Endl .) P.G. Wilson ( Rutaceae ), collected from the Cape York Peninsula, has yielded four novel secondary metabolites. These were identified, by spectroscopic methods, as methyl (E)-4-(3′-methylbut-2′-enyloxy) cinnamate, cis-erioaustralasine [{rel}-1-acetoxymethyl-4,8′-epoxy-3-(1′β,2′β-epoxy-3′β,4′β-para-menth-3′-yl)quinolin-2-one], trans- erioaustralasine [{rel}-1-acetoxymethyl-4,8′-epoxy-3-(1′β,2′β-epoxy-3′β,4′α-para-menth-3′-yl)quinolin-2-one] and furoerioaustralasine [{rel}-2,2′β:4,8′-diepoxy-3-(1′β-hydroxy-3′α,4′α-para-menth-3′-yl) quinoline ]. The structure of cis-erioaustralasine was confirmed by X-ray crystallographic studies. The taxonomic significance of the occurrence of these alkaloids in E. australasius is discussed.