TETRACYCLIC AND PENTACYCLIC 6-C-MONOTERPENYL-5,7-DIOXYCOUMARINS FROM ERIOSTEMON-BRUCEI AND E-BRUCEI SUBSPECIES CINEREUS

An investigation of the aerial parts of Eriostemon brucei ssp. brucei and E. brucei ssp. cinereus revealed the presence, in one or both, of the coumarins eriobrucinol and 5'beta-hydroxyeriobrucinol and five further 6-C-monoterpenyl-5,7-dioxycoumarins which are reported as natural products for the first time. These were, from the type subspecies, trace amounts of the two eriobrucinol regioisomers, which had previously been synthesized, and from E. brucei ssp. cinereus 4'beta-hydroxyeriobrucinol and two tetracyclic coumarins which have been assigned the trivial names pseudobruceol-I and pseudobruceol-II. In addition the type subspecies yielded 5,7-dihydroxy-2-(n-nonaeicosanyl) chromone, which is also novel. All compounds were identified by means of comprehensive analysis of NMR spectra.