Determination of cinnamaldehyde, thymol and eugenol in essential oils by LC-MS/MS and antibacterial activity of them against bacteria

Abstract

Based on Liquid chromatography-tandem mass spectrometry (LC-MS/MS), A qualitative and quantitative method for simultaneous detection of 3 bioactive compounds, including cinnamaldehyde (CNM), thymol (THY) and eugenol (EUG) in plant essential oil was established in this study. We tested the antibacterial activity of 3 bioactive compounds. Several necessary tests for 12 steroids, such as LLOQ, recovery and precision, have verified the repeatability and practicability of the method. Then, the antibacterial activity of 3 bioactive compounds against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was evaluated by minimal inhibitory concentration and the synergistic antimicrobial effect. The results indicated that the MIC of CNM, THY and EUG against E. coli were 1.0, 1.0 mg/mL, and 0.5 µg/mL, respectively. And the MIC of CNM, THY and EUG against S. aureus were 0.5, 1.0 mg/mL, and 0.5 µg/mL, respectively. According to the results of fractional inhibitory concentration index (FICI), it is considered that CNM + THY and CNM + THY + EUG has obvious synergistic inhibitory effect on E. coli, and CNM + THY and CNM + EUG has obvious synergistic inhibitory effect on S. aureus. In addition, the trace metals in the treated bacteria were analyzed.