New bioactive adjacent bis-THF annonaceous acetogenins from Annona bullata.

Five new adjacent bis-THF annonaceous acetogenins, 32-hydroxybullatacin, 31-hydroxybullatacin, 30-hydroxybullatacin, and (2,4-cis and trans)-28-hydroxybullatacinones, were isolated from the ethanolic extract of the bark of Annona bullata Rich. (Annonaceae). The absolute configurations of the above five compounds, as well as those of (2,4-cis and trans)-32-, 31-, and 30-hydroxybullatacinones and (2,4-cis and trans)-bulladecinones, previously isolated from the same extract, were defined by the application of the advanced Mosher ester [methoxy(trifluoromethyl)phenyl acetate or MTPA] methodology. The determination of the absolute configuration of C-20 of (2,4-cis and trans)-bulladecinones to be S supports our hypothesis that the cyclization of the THF rings of (2,4-cis and trans)-bulladecinones starts from C-12 (the right side). The first five compounds listed above showed potent bioactivities in the brine shrimp lethality test (BST) and among six human solid tumour cell lines.