Comparative chemical profiling of leaf essential oils from Cinnamomum kanehirae and related species using steam distillation and solvent extraction: Implications for plant-based classification

Abstract

Cinnamomum kanehirae Hayata, belonging to Lauraceae family, is an indigenous and endangered species of considerable economic importance in Taiwan. It plays a crucial role as the host for the economically valuable saprotrophic fungus, Taiwanofungus camphorates. However, accurate species identification poses a challenge due to the similarity in morphological features and frequent natural hybridization with closely related species. Acquiring high-quality and pure leaf oils becomes imperative for precise species identification and producing superior goods. In this study, our objective was to establish methodologies for analyzing the chemical composition of leaf essential oils and subsequently apply this knowledge to differentiate among three Cinnamomum species. Gas chromatography-mass spectrometry (GC/MS) was employed to scrutinize the chemical makeup of leaf essential oils from three closely related species: C. kanehirae, C. micranthum, and C. camphora. We utilized Steam Distillation (SD) and steam distillation-solvent extraction (SDSE) methods, with the SDSE-Hexane approach chosen for optimization, enhancing extraction efficiency and ensuring essential oil purity. Through the SDSE-Hexane method, we identified seventy-four compounds distributed across three major classes: monoterpenes hydrocarbons (0.0–7.0 %), oxygenated monoterpenes (3.8–90.9 %), sesquiterpenes hydrocarbons (0.0–28.3 %), and oxygenated sesquiterpenes (1.6–88.1 %). Our findings indicated the presence of more than one chemotype in both C. kanehirae and C. camphora, whereas no specific chemotype could be discerned in C. micranthum. Furthermore, clustering based on chemotypes allowed for the differentiation of samples from the three species. Notably, we demonstrated that the chemical compositions of grafted C. kanehirae remained largely unaffected by the rootstock. Conversely, natural hybrids between C. kanehirae and C. camphora exhibited profiles more closely aligned with C. kanehirae. The optimized extraction method and the chemotype-based classification system established in this study present valuable tools for essential oil preparation, species identification, and further exploration into the genetic variation of Cinnamomum.