Anti-biofilm and kinetic studies of kaurane diterpenes that targets oral anaerobes

Abstract

In previous studies performed by our research group, it was evaluated the antibacterial activity of 12 ent-kaurane diterpenes against 14 bacteria isolated from endodontic infections. ent-Kaurenoic acid (1) and its sodium salt (2) displayed very promising MIC values (lower than 10 µg/mL) for Porphyromas gingivalis and Peptostreptococcus micros. Due to these results, antibiofilm and time-kill curves studies with 1 and 2 were performed against P. gingivalis and P. micros. Minimal Biofilm Inhibitory Concentrations (MBIC50) of 12.5 and 50 µg/mL were observed respectively for 1 and 2 against P. gingivalis. A 12.5 µg/mL MBIC50 value was achieved for both diterpenes when tested on P. micros. Kinetic studies (time-kill curve) allowed us to observe that 1 and 2 were able to completely kill P. gingivalis within 72 and 48 hours respectively at the same concentrations (3.12 µg/mL). P. micros showed to be more sensitive in the presence of both diterpenes, being eliminated within 12 hours (1; 3.12 µg/mL) and 18 hours (2; 6.25 µg/mL).