a The MIC of Acetyl-11-keto-β-boswellic acid is 2 μg/ml.
MPC were performed on S. mutans ATCC 25175. The rate of mutation frequency was calculated by dividing total number of colonies appearing on the drug containing plate by total number of CFU plated. AKBA at 16 μg/ml (8 × MIC) completely suppressed the emergence of mutants. This concentration of AKBA at which no mutant was selected can be defined as the mutation prevention concentration (MPC).