Analysis of the Molecular Structure of Hydroxychavicol, a Promising Oral Antibacterial

In order to better understand hydroxychavicol’s effectiveness as an oral antibacterial, its structural components were analyzed with respect to minimum inhibitory concentrations and minimum bactericidal concentrations against various oral bacteria. These structural components include the free hydroxy groups and allyl chain connected to hydroxychavicol’s benzene core. Six structural analogs of hydroxychavicol were tested against a range of oral bacteria using minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays. MIC results were obtained using serial microdilution techniques in 96-well plates with resazurin dye as a colorimetric indicator. Aliquots within each MIC concentration range were then placed on appropriate agar medium and the minimum bactericidal concentration was determined as the lowest concentration with no observed colony growth. A synergistic interaction was observed between the allyl chain and hydroxy groups on the benzene core of hydroxychavicol, which resulted in lower MICs against the tested oral bacteria. It was also found that a hydroxy group para to the allyl chain on the benzene ring resulted in more effective inhibition, with a MIC of <50 μg/mL against R. dentocariosa. Additionally, analytes possessing free hydroxy groups ortho to one another on the benzene ring resulted in MICs of 200-300 μg/mL or lower, whereas analytes with free hydroxy groups meta to one another on the benzene ring exhibited MICs of >1000 μg/mL. This study helps elucidate the structural components responsible for hydroxychavicol’s effectiveness as an oral antibacterial. The findings herein help to understand the mechanism of hydroxychavicol’s antibacterial properties and will be helpful in the design and synthesis of more effective oral antibacterial treatments.