Chemical composition, spectroscopic characterisation and thermal stability study of the essential oil of <i>Bursera morelensis</i> from Teotitlán de Flores Magón, Oaxaca, México

The essential oil of <i>B. morelensis</i> is an ingredient used in traditional medicine that possesses various biomedical properties, making it attractive for the development of pharmaceutical forms. For this reason, it is important to generate information about its spectral patterns to develop analytical methods that allow it to be identified and quantified. This study reports, for the first time, the characterisation by ¹H and ¹³C nuclear magnetic resonance (NMR), infra-red (IR), and ultraviolet-visible (UV-vis) spectroscopy. The essential oil was obtained from young stems (yield 0.14% v/w) and the major compound is the terpene α-phellandrene (56.13%). A stability study was carried out to evaluate the chemical and spectral changes of the oil exposed to high temperature. After 6 months at 40 °C, α-phellandrene remained as the major compound, but the abundance decreased (15.9%) producing other terpenes such as β-phellandrene, β-pinene, and 3-thujene, and oxidation products, including α-terpineol and caryophyllene oxide.