Novel nortriterpenoids from Aphanamixis grandifolia.

Four novel nortriterpenoids, 24,25-epoxy-tirucall-7,20(E)-diene-3,23-dione (1), 24,25,26,27-tetranortirucall-1,7-diene-23(21)-lactone (2), 3α-hydroxy-tirucall-7-ene-20-one (3), and 3-oxo-tirucall-7-ene-3,20-dione (4), together with one known compound mombasol (5) were isolated from the stem barks of Aphanamixis grandifolia. Their structures were elucidated on the basis of various spectroscopic analysis including electrospray ionization (ESI)-MS, high resolution (HR)-ESI-MS, IR, 1D- and 2D-NMR techniques (heteronuclear single quantum coherence (HSQC), heteronuclear multiple bond connectivity (HMBC) and rotating frame Overhauser enhancement spectroscopy (ROESY)), and by comparison of their spectral data with those reported. The absolute configuration of compound 1 was determined by circular dichroism (CD) exciton chirality.