Preparation and bactericidal activity of oxidation derivatives of austroeupatol, an ent-nor-furano diterpenoid of the labdane series from Austroeupatorium inulifolium

Abstract From aerial parts of Austroeupatorium inulifolium was obtained austroeupatol ( 1 ). The treatment of 1 with IBX generated the ketone 2 and keto-aldehyde 3 . Due to the structural features of 1 , the hydroxy group corresponding to the primary alcohol (at C-19) is less reactive than the oxymethine hydroxy groups of the structure. The oxidative cleavage of 1 produced the hemiacetal 4 , since this reaction is quantitative and only this compound was detected, was proposed a reaction mechanism that involves the formation of a transition state that explain the generation of 4 . The bactericidal activity of these oxidation derivatives was evaluated against four (4) bacterial strains [two Gram-positive (+) and two Gram-negative (-)]: Staphylococcus aureus , Enterococcus faecalis , Escherichia coli and Pseudomonas aeruginosa.