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 Mediterranean aromatic species owing to its essential oil, which is widely used in pharmaceutical, cosmetic, and nutraceutical applications. However, comparative phytochemical investigations simultaneously addressing essential oils and hydrosols from geographically isolated natural populations remain limited. In this study, we investigated essential oils and hydrosols 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 samples. Marked differences were observed among the hydrosol headspace profiles. Within the HS-SPME–GC–MS profiles, eucalyptol showed the highest relative peak-area contribution 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.