Chemical Composition and Antimicrobial Activity of Torreya nucifera Essential Oils against Oral Pathogens

Essential oils are natural substances extracted from various organs of multiple plant species, such as buds, flowers, leaves, stems, branches, roots, seeds, fruits, wood, and bark. The oils are used as a raw material for food flavoring, and as food additives and additives to cosmetics and perfumes. In this study, we investigated the composition of essential oils extracted from the branches and leaves of Torreya nucifera and their cytotoxicity and antibacterial activity against oral bacteria. Hydro-distilled T. nucifera essential oils (TNEs) were analyzed using gas chromatography-mass spectrometry (GC-MS). In total, 16 components were identified, with dl-limonene (43.95%), α-pinene (14.76%), δ-3 carene (8.94%), and δ-cadinene (5.42%) representing the main components. Antimicrobial activity tests were carried out using MIC, MBC and time kill assays against the oral bacteria, Streptococcus mutans (KCOM 1054) and Streptococcus sobrinus (KCOM 1157). TNEs showed bactericidal effect at 2X MIC against the oral bacteria. In vitro time kill assays were performed at 0.5, 1, and 2X MICs. Cytotoxicity was confirmed using MTT assay by analyzing the amount of formazan crystals via ELISA. Based on these results, we confirm the feasibility of TNEs as a natural antimicrobial agent for oral microorganisms.