Volatile Profile and Antioxidant Activity of Three Helichrysum Species from the Eastern Mediterranean (Türkiye)

The aim of this study was to characterize the volatile constituents of three Helichrysum species (Asteraceae) of ecological and pharmacological relevance in Türkiye: Helichrysum arenarium subsp. Aucheri (Boiss.) P.H. Davis & Kupicha, H. plicatum subsp. plicatum DC., and H. stoechas subsp. barrelieri (Ten.) Nyman. Leaf and flower samples were collected during the vegetation period from the Anamur district (Mersin Province, Türkiye) and air-dried at room temperature. Volatile compounds were analyzed using headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME/GC–MS). A total of 84, 89 and 51 volatile compounds were identified in H. arenarium subsp. aucheri, H. plicatum subsp. plicatum, and H. stoechas subsp. barrelieri, respectively. The major constituents of H. arenarium subsp. aucheri were allyl bromide (10.62%), camphene (7.88%), and limonene (6.47%). In H. plicatum subsp. plicatum, α-pinene (35.86%), limonene (10.58%), p-cymene (6.02%), and trans-caryophyllene (5.49%) predominated, whereas H. stoechas subsp. barrelieri was characterized by α-copaene (13.92%), trans-caryophyllene (19.82%), and α-humulene (7.83%). In addition, the antioxidant potential of the studied species was assessed through total phenolic content determination, DPPH radical scavenging, and CUPRAC assays. Pronounced species-dependent differences were observed, with H. stoechas subsp. barrelieri exhibiting the highest phenolic content and CUPRAC reducing capacity, while H. plicatum subsp. plicatum showed the strongest DPPH radical scavenging activity. In contrast, H. arenarium subsp. aucheri consistently displayed lower antioxidant performance. The strong association between phenolic content and antioxidant activity underscores the role of phenolic compounds in the redox-related bioactivity of Helichrysum species and highlights their potential as valuable natural sources for pharmacological, aromatherapeutic applications.