Antimicrobial diterpenes from Salvia reptans

The roots of Salvia reptans Jacq. (Labiatae) yielded 8 alpha 9 alpha-epoxy-7-ketoroyleanone I and horminone 2 as the major antimicrobial agents. These isolates were found to be active against Bacillus cereus, Micrococcus luteus, Staphylococcus aureus, Streptococcus faecalis and Escherichia coli (MIC 0.4-2.2 (mu g/ml). Some derivatives were prepared in an attempt to define some of the structural parameters needed for antimicrobial activity 12-Benzoylhorminone 5 was found to be more active against the tested organisms than I and 2. The identity of the compounds were confirmed by spectral analyses (UV, IR, NMR and EIMS).