Antibacterial activity of pimarane-type diterpenes against endodontic pathogens
In the present work, the in vitro antimicrobial activity of six natural pimarane-type diterpenes and two semi-synthetic derivatives were investigated against a panel of representative microorganisms responsible for dental root canal infections  (Porphyromonas gingivalis, Prevotella nigrescens, Prevotella intermedia, Prevotella buccae, Fusobacterium nucleatum, Bacteroides fragilis, Actinomyces naeslundii, Actinomyces viscosus, Peptostreptococcus micros, Enterococcus faecalis and Aggregatibacter actinomycetemcomitans). The broth microdilution method  was used for the determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values. The diterpenes ent-pimara-8(14),15-dien-19-oic acid (1), its sodium salt (2) and ent-8(14),15-pimaradien-3β-ol (3) (Figure 1) were the most active compounds, displaying MIC values very promising . Ours results also allow us to conclude that minor structural differences among these diterpenes significantly influence their antimicrobial activity, bringing new perspectives to the discovery of new chemicals for use as complement of the instrumental endodontic procedures.
Acknowledgements: FAPESP (Proc. 2009/18278–0) and CAPES
References: 1. Gomes et al. (1996) Endod J. 29: 235–241.
2. Porto et al (2009) Molecules 14: 191–199. Gibbons (2008) Planta Med. 74: 594–602.