Variations in Essential Oil Compositions and Cyclooxygenase (COX) Inhibiting Potential of Ruta chalepensis L. Essential Oils Obtained at Different Phenological Stages

This study examines the yield, composition, and COX inhibitory activity of essential oils from Ruta chalepensis L. obtained at various developmental stages. Essential oil yield decreased with plant maturity, reaching its lowest level during the post-flowering stage. Chemical analysis revealed the absence of terpenes, with notable shifts in aliphatic ketones. At the vegetative stage, 2-nonanone was dominant (58%), but declined to 26% in mature plants. In contrast, 2-undecanone increased from 34% to 63%, indicating a developmental shift in longer chain molecule biosynthesis. COX-1/2 inhibition assays showed that ibuprofen inhibited enzyme activity by 73.53%, whereas R. chalepensis essential oils exhibited significantly lower inhibition, suggesting weak anti-inflammatory activity. These results indicate that the essential oil does not account for the plant’s anti-inflammatory traditional medicinal use, and other constituents may be responsible for its therapeutic effects.