Synergistic activity of clove essential oil and thyme essential oil and their interaction against Malassezia furfur, Escherichia coli, Staphylococcus aureus
Dong He, Xi-qin Wu, Kegang Wu, Xianghua Chai, Ying-lin Liang, Xiangyu Zhang, Qin Cha, Wei Xie
Abstract
Plant essential oils have excellent antioxidant and antibacterial properties, which can greatly reduce microbial resistance. However, the odor and cost issues caused by their high concentration use remain the main bottlenecks in their application as antibacterial agents. The present study was conducted to evaluate inhibitory activity of essential oils (EOs) against Escherichia coli and Staphylococcus aureus, and focus on synergistic activity of EOs against Malassezia furfur. The minimum inhibitory concentrations and the active components of various EOs and their combination were determined using the agar dilution method and gas chromatography–mass spectrometry, respectively. The synergistic effect of EO combination on Malassezia furfur was evaluated by analyzing its growth, morphology, and cell membrane fluidity using growth curve analyses, scanning electron microscopy, and N-phenyl-1-naphthylamine method, respectively. Additionally, the antioxidant activity of the EOs combination was evaluated using the free radical scavenging method. The mixture of EOs exerted a synergistic effect on M. furfur, causing logarithmic growth phase lag, cell damage, decreased membrane fluidity, and the mixture of EOs also had synergistic effect on DPPH free radical scavenging. Conclusively, the combination of EOs investigated in this study exhibited good antibacterial ability against M. furfur, may have potential applications in seborrheic dermatitis.