Phenological Stage Dependent Variations in the Chemical Composition and Cyclooxygenase (COX) Inhibitory Activities of Origanum dubium Boiss. Essential Oils

This study investigated the essential oil yield, chemical composition, and COX-1/2 inhibitory activity of Origanum dubium during different developmental stages. Essential oil yield increased from 5.53% to 8.37%, peaking at the post-flowering stage. Chemical analysis revealed that oxygenated monoterpenes dominated the oil composition, with carvacrol as the principal component, increasing significantly from 64.4% to 86.9% across growth stages. The anti-inflammatory potential was evaluated by measuring COX-1/2 inhibitory activity, using ibuprofen as a positive control (73.53% inhibition). Essential oils exhibited moderate inhibition during vegetative (52.13%) and initial flowering (57.76%) stages, but inhibition notably improved at post-flowering (68.16%), approaching ibuprofen’s efficacy. These findings suggest that the rise in carvacrol concentration correlates with enhanced COX-1/2 inhibitory activity, highlighting the therapeutic potential of O. dubium essential oils as natural anti-inflammatory agents.