Bioactive chemical constituents of Duboscia macrocarpa Bocq., and X-ray diffraction study of 11β, 12β-epoxyfriedours-14-en-3α-ol

Abstract A new γ-lactone triterpenoid, Evodoulolide ( 1 ) and a new triterpenoid Duboscic acid B ( 2 ), along with five known compounds, maslinic acid ( 3 ), arboreic acid ( 4 ), ( E )-3-(4-hydroxyphenyl)-N-[2-(4-hydroxyphenyl) ethyl] prop-2-enamide ( 5 ), ( E )-heptacos-19-enoic acid ( 6 ) and 11β,12β-epoxyfriedours-14-en-3α-ol ( 7 ) were isolated from the trunk wood of Duboscia macrocarpa . Their structures were elucidated from extensive 1 D- and 2 D-NMR and MS and by comparison of their spectra with published data. Compounds 1 , 3 , 5 and 6 exhibited significant α -glucosidase inhibitory activity. Compound 5 was found to be a potent inhibitor (IC 50  = 5.1 ± 0.1 μM) of α -glucosidase as compared to acarbose (IC 50  = 625.0 ± 1 μM) used as standard drug. These compounds did not show anti-glycation activity using the BSA-MG glycation model or inhibition against the α -chymotrypsin enzyme. The chemotaxonomic connotation of the isolated secondary metabolites is also herein described. The single-crystal X-ray and absolute configuration diffraction analysis of 11α, 12α-epoxyfriedours-14-en-3-ol ( 7 ) is also described here for the first time.