Integrated Volatile Phytochemical Profiling of Wild Helichrysum italicum subsp. italicum Populations from the Tuscan Archipelago

Helichrysum italicum (Roth) G. Don subsp. italicum is one of the most valuable Mediter- ranean aromatic species owing to its essential oil, which is widely used in pharmaceutical, cosmetic, and nutraceutical applications. However, comparative phytochemical investiga- tions simultaneously addressing essential oils and hydrosols from geographically isolated natural populations remain limited. In this study, we investigated essential oils and hy- drosols from pooled plant material collected at six sites across the Tuscan Archipelago (Capraia, Elba, and Giglio Islands) by gas chromatography–mass spectrometry (GC–MS) and headspace solid-phase microextraction coupled with GC–MS (HS-SPME–GC–MS). The analyzed pooled site samples shared an essential-oil profile dominated by neryl acetate (24.90–34.01%), γ-curcumene (9.10–14.91%), α-pinene (5.05–14.17%), and neryl propionate (4.37–9.14%), while their relative abundances differed among the analyzed pooled site sam- ples. Marked differences were observed among the hydrosol headspace profiles. Within the HS-SPME–GC–MS profiles, eucalyptol showed the highest relative peak-area contri- bution in the four Capraia pooled samples (39.13–94.56%), whereas the Elba profile was dominated by neryl acetate (56.36%). The Giglio profile was mainly characterized by nerol (29.81%), fenchyl alcohol (21.72%), and 4-terpineol (16.56%). Overall, the results provide complementary descriptive information on the volatile composition of the analyzed pooled site samples and identify candidate compositional patterns requiring validation through independent biological sampling and replicated distillations.