New β-dihydroagarofuran sesquiterpene polyesters isolated from the root bark of Celastrus angulatus

Abstract Three new β-dihydroagarofuran sesquiterpene polyesters, angulatin O (1β,2β-difuroyloxy-8α-isobutanoyloxy-9β-benzoyloxy-15-acetoxy-4α,6α-dihydroxy-β-dihydroagarofuran), angulatin Q (1β,6α,15-triacetoxy-2β,9α-difuroyloxy-4α-hydroxy-8β-isobutanoyloxy-β-dihydro-agarofuran), and angulatin R (1β,2β,6α,15-tetracetoxy-8β-isobutanoyloxy-9α-benzoyloxy-β-dihydroagarofuran), as well as six related and known compounds, β-dihydroagarofuran sesquiterpene polyesters, were isolated from the root bark of Celastrus angulatus. Extensive spectroscopic studies were conducted to elucidate the structures of the new compounds. The IR, HRESI-MS, 1D, and 2D NMR techniques were used to characterise the compounds.