Influence of drying process on chemical composition, antioxidant and enzyme-inhibitory activity of Helichrysum italicum essential oils

Introduction: Helichrysum italicum (Roth) G. Don, also known as immortelle, is a medicinal plant from the Mediterranean region. It is widely used in traditional medicine as an antiinflammatory and antimicrobial agent. Owing to the rich composition and beneficial effects of its essential oil, it is not only attractive for use in traditional medicine but also in pharmacy, medicine, and cosmetology. This study examines the chemical composition and biological activity of the essential oil obtained from fresh and dried immortelle, as well as the influence of the drying technique on the oil's quality. Methods: To isolate the essential oil from immortelle, fresh, naturally dried, and freeze-dried aerial parts of the plant were subjected to the hydrodistillation. The essential oils obtained were then characterized chemically and biologically. Results: GC-MS analysis showed that α-pinene (29.77%) was the dominant compound in the oil isolated from the fresh plant, while α-muurolene was the most abundant compound in samples obtained from dried plants (ranging from 30.03% to 20.15%). The essential oil isolated from the fresh plant exhibited the highest antioxidant activity, whereas the oil obtained from freeze-dried plants showed the lowest potential. In terms of amylase inhibition, similar activity was observed, while the situation was opposite for tyrosinase inhibition. Conclusion: This research provides a detailed insight into the influence of the drying technique on the chemical composition and biological activity of immortelle essential oil. The study demonstrates the potential of using immortelle essential oil as a natural agent for diabetes and hyperpigmentation control.