A Comparative Study on the Effects of Quinic Acid and Shikimic Acid on Cellular Functions of Staphylococcus aureus

Quinic acid (QA) and shikimic acid (SA), two kinds of natural organic acids, have been reported to exhibit potent antibacterial activity against Staphylococcus aureus. In this study, the effects of QA and SA on the cellular functions of S. aureus were investigated by measuring the intracellular pH, intracellular and extracellular ATP concentrations, succinate dehydrogenase activity, DNA content, and interactions between SA and QA with S. aureus DNA. Studies of the cellular functions demonstrated that QA could significantly decrease the intracellular pH, whereas SA had no effect on intracellular pH. QA and SA reduced succinate dehydrogenase activity and caused a significant decrease in intracellular ATP concentration but no proportional increase in extracellular ATP. Moreover, QA and SA both could remarkably reduce the DNA content of S. aureus and directly interact with genomic DNA. The results suggested that the effects of QA and SA on cellular functions were distinguishable, although the chemical structures of these two compounds were similar. In conclusion, the results of the present research suggested that SA and QA could be used as antibacterial agents in food preservation.