Exploring techniques for extraction of silver fir (Abies alba)

Context: Silver fir (Abies alba) contains polyphenols and lignans with antioxidant and therapeutic properties. Efficient extraction methods are essential to preserve these compounds and maximize bioactivity. Objective: To compare extraction techniques and identify the optimal method for obtaining high-quality silver fir extracts with strong antioxidant activity and minimal cytotoxicity. Materials & methods: Extracts from bark and branches were prepared using subcritical water extraction (SWE, 70–200 °C), supercritical CO$_2$ extraction, and high-pressure ethanol extraction. Extracts were analyzed for total polyphenol content (TPC), lignan concentration (HPLC), antioxidant activity (DPPH and ABTS assays), and volatile profile (GC-MS). Cytotoxicity and cell migration were evaluated in HaCaT and Caco-2 cell lines via MTS and gap closure assays. Results: The SWE bark extract at 100 °C (SWE-BA-100) showed the highest TPC (73.8 mg GAE/g), lignan content (secoisolariciresinol 204.7 µg/mL), and antioxidant activity (DPPH: 24.2, ABTS: 32.0 mg GAE/g). Bark extracts had superior bioactive profiles compared to branches, though branch extractions gave higher yields. All extracts were non-cytotoxic. SWE-BA-100 inhibited cell migration, indicating a complex interaction between composition and cellular response. Discussion and Conclusion: SWE at 100 °C is a promising green method for producing potent antioxidant extracts from A. alba. Bark extracts offer strong antioxidant potential and safety for pharmaceutical, cosmetic, and nutritional uses. However, high lignan content may influence cellular behavior. Further studies should address the role of non-phenolic antioxidants and refine extraction strategies to balance efficacy and bioactivity.