Antimicrobial activity of dehydroabietic acid derivatives (II)

The antimicrobial activity of several diterpene resin acid derivatives towards fungi and bacteria is well known. In this work fifteen dehydroabietic acid derivatives with different A/B junction at C-4 were tested against filamentous fungi, yeasts and bacteria. The results obtained showed that, except for the ester derivatives, which were inactive, all the tested compounds inhibited, with varying degrees of efficacy, the growth of the microorganisms. Gram-positive bacteria, Staphylococcus aureus was inhibited by the compounds containing alcohol and aldehyde functions, whereas no activity was observed towards Serratia marcescens and Pseudomonas aeruginosa. Penicillium expansum, an ubiquitous fungus, Botrytis cinerea, a phytopatogenic fungus and Trichophyton mentagrophytes, on human pathogenic fungus were also inhibited by several of the oxidized compounds. The aldehyde function seemed to be a requirement to the antifungal activity towards Candida species.