Essential oils have long been used to fight infections and treat various diseases. Peppermint (Mentha × piperita L.) is an herbal medicine that has been widely used in daily life since ancient times, and it has a wide range of applications in food, cosmetics, and medicine. Mint oil is refreshing because of its cool and comfortable smell; therefore, it is often used in ethnopharmacological studies. The present study investigated the effects of peppermint essential oil in electroencephalographic activity response to various visual stimuli. The electroencephalographic changes of participants during peppermint essential oil inhalation under white, red, and blue colour stimulations were recorded. A rapid Fourier transform analysis was used to examine the electroencephalograph power spectra of the various microstates induced by inhaling the oils. Peppermint essential oil had various effects on the brain when subjected to different visual stimuli. Alpha waves increased in the prefrontal area in the white-sniffing group, which facilitated learning and thinking. In the blue-sniffing group, the changes were less pronounced than those in the red group, and the increased alpha wave activity in the occipital area was more controlled, indicating that the participants’ visual function increased in this state. Based on EEG investigations, this is the first study to indicate that vision influences the effects of peppermint essential oils. Hence, the results of this study support the use of essential oils in a broader context to serve as a resource for future studies on the effects of different types of essential oils.

Candida albicans is a common opportunistic pathogen. Long-term use of azole antifungals faces challenges like resistance, necessitating novel agents. Tea tree oil (TTO), a natural broad-spectrum antimicrobial, shows promise, but its molecular mechanisms, particularly concerning novel cell death pathways, require clarification. This study comprehensively evaluated the antifungal mechanism of TTO against C. albicans using transcriptomics. Antifungal susceptibility assays were conducted to assess the effects of TTO and its components (4-terpineol, terpenes, and γ-pinene) on the growth of C. albicans hyphae and biofilms. Fluorescent labeling and biochemical analysis were employed to detect ferroptosis markers. Transcriptomic results indicate that TTO induces 423 differentially expressed genes and systematically inhibits the development of C. albicans hyphae through mechanisms such as oxidative stress, iron homeostasis disruption, disruption of cell wall integrity, and interference with ergosterol metabolism. Notably, the significant enrichment of redox enzyme activity and iron ion binding functions, along with changes in the glutathione metabolic pathway, suggest that ferroptosis may be involved in this process. Subsequent studies revealed that the compound 4-pinene most effectively inhibits the pathogenicity of C. albicans by suppressing its adhesion, hyphae formation, and biofilm formation, whereas terpinene induces the accumulation of reactive oxygen species (ROS) and increases lipid peroxidation in C. albicans; furthermore, following treatment with an iron-mediated apoptosis inhibitor, terpinene enhances the viability of the treated C. albicans cells.