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

Chacón-Morales, Pablo A., Amaro-Luis, Juan M., Beltrán Rojas Fermín, Luis, Peixoto, Philippe A., Deffieux, Denis, Pouységu, Laurent, Quideau, Stéphane
Phytochemistry letters 2019 v.29 pp. 47-52
Austroeupatorium inulifolium, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, aerial parts, alcohols, antibacterial properties, labdane, oxidation, reaction mechanisms
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.