Hemisynthesis and Bactericidal Activity of Several Substituted Benzoic Acid Esters of 13( S )-Labdan-8 α ,15-Diol, a Diterpene from Oxylobus glanduliferus

The diterpene 13( S )-labdan-8 α ,15-diol ( 1 ) was isolated in high yield from Oxylobus glanduliferus , a native species of Venezuelan Andean moorlands. Using this compound ( 1 ) as a starting material, it was possible to prepare 12 aromatic esters, which were structurally characterized by analysis of their spectroscopic data (IR, 1D and 2D NMR and MS). The bactericidal activity of these diterpene derivatives was evaluated against four bacterial strains [two Gram-positive and two Gram-negative]: Staphylococcus aureus , Enterococcus faecalis , Escherichia coli , and Pseudomonas aeruginosa .