Unknown

Streptococcus gordonii DL1 and Porphyromonas gingivalis ATCC 33277 were used for activity evaluation. According to Clinical and Laboratory Standards Institute (CLSI) [25], the compounds were 1:2 serially diluted in BHI in a sterile 96-well plate (untreated, flat bottom, with lid, Evergreen Scientific) starting from their initial concentrations. Each well was then inoculated with 3 × 10^7 CFU/mL of S. gordonii and incubated for 24 h or P. gingivalis and incubated for 48 h. The solvents used to prepare the compounds were also tested on the bacteria. After that, the minimal inhibitory concentration (MIC), defined as the minimal concentration able to inhibit the visible bacterial growth, was determined as the clear well having the smallest concentration. All the clear wells were then plated on blood Columbia agar and incubated for 24 h as needed by S. gordonii or for 5 days as required by P. gingivalis. Finally, the minimal bactericidal concentration (MBC), corresponding to the lowest compound concentration killing the bacteria in the well, is determined from the Petri-plate showing no colonies and inoculated from the well with the lowest compound concentration.