Sustainable recovery of bioactive compounds from forest residues using microwave-assisted extraction

• Bioactive compounds were extracted from pruning residues of the Atlantic mixed forest. • The solvent and raw materials were chosen based on the results of a screening. • The microwave assisted extraction with DES was optimized for two feedstock. • High extraction yields and antioxidant capacities of compounds were obtained. • Cytotoxicity assays indicated promising profiles, making them useful for cosmetics. This study investigates the potential of pruning residues from the Atlantic mixed forest, specifically bark and wood from black locust, oak, and birch, as sources of bioactive compounds. The raw materials were characterized, revealing a higher extractives content in bark (19–22 %) compared to wood, underscoring their distinct chemical profiles. A screening was carried out to narrow down the study and select the best solvent and the most promising raw materials for the extraction of bioactive compounds. Afterwards, two optimized models using microwave-assisted extraction and the selected solvent (choline chloride:1–4 butanediol (1:2) deep eutectic solvent) were developed, targeting birch bark and oak wood extractives. Both models demonstrated high predictive accuracy for extraction yield and antioxidant capacity, although the DPPH response showed slightly less robustness. Optimal extraction conditions converged on a treatment temperature of 53 °C, but differed in the liquid-to-solid ratio and the treatment time (18.6:1 and 8.5 min for birch bark and 15.7:1 and 20 min for oak wood). Extractives from birch bark exhibited superior antioxidant activity (41.4 mg TE/g RM) compared to oak wood (35 mg TE/g RM). Preliminary cytotoxicity and cell viability assays indicated promising safety profiles. These findings highlight the viability of forest pruning residues as sustainable sources of bioactive compounds with potential applications in cosmetics.