0000000000352128
AUTHOR
Catherine Lavaud
30-Norfriedelane triterpenes from the stem bark ofCaloncoba glauca
Abstract The stem bark of Caloncoba glauca has yielded three friedelane triterpenes of which two are characterized by the loss of C-30 and the presence of a C-27, C-15 lactone. They were identified, with considerable use of long-range C H coupling studies, as the known compound trichadonic acid (3-oxofriedelan-27-oic acid) and two new 30-norfriedelane derivatives, 3,27-dioxo-30-norfriedelan-20(29)-en-27,15α-lactone (caloncobalactone) and 3,27-dioxo-21β-hydroxy-30-norfriedelan-20(29)-en-17,15α-lactone (21β-hydroxycaloncoba lactone).
New method for the determination of the absolute stereochemistry in antitumoral annonaceous acetogenins
Abstract The absolute configurations at the carbinol centers in several acetogenins were determined through p-bromophenylurethane derivatives and subsequent Mosher ester methodology. This method has been applied on α,α′-dihydroxylated adjacent bis-THF acetogenins with a threo/cis/threo/cis/erythro relative configuration membrarollin (1), a new acetogenin isolated from Rollinia membranacea seeds, rollimembrin (2), membranacin (3) and rolliniastatin-1 (4), and a threo/trans/threo/translerythro relative configuration motrilin (5), squamocin (6), and desacetyluvaricin (7). 1 was found to be the most potent inhibitor of the mammalian mitochondrial complex I.