Pyrolysis-based valorization of Pinus sylvestris bark waste into bioactive fractions: LC–MS/MS analysis and antioxidant, anti-inflammatory, antidiabetic, and antibacterial activities

In this study, bark waste from the forest industry derived from Pinus sylvestris was processed by pyrolysis extraction, and the chemical compositions and biological activities of the resulting light (PLF) and heavy (PHF) fractions were comparatively investigated. When the extraction yields of the pyrolysis fractions were compared, PHF (20.80%) showed a significantly higher recovery than PLF (10.35%). Total phenolic content (TPC) was higher in the PHF (365.80 GAE/g), whereas total flavonoid content (TFC) was concentrated in the PLF (200.80 mg QE/g). LC–MS/MS analyses of the PHF fraction, which exhibited more pronounced biological activity, revealed caffeic acid (7190.65 µg/g) and protocatechuic acid (2694.30 µg/g) as the predominant phenolic compounds. Antioxidant capacity analyses indicated that the PLF exhibited stronger radical scavenging activity, lower IC50 values in DPPH and ABTS⁺• assays (50.01 and 101.60 µg/mL, respectively) and higher TAC values (901.00 mg TE/L). Fe3+ and Cu2+ reducing assays demonstrated strong redox activity in both fractions, with Cu2+ reducing capacity particularly higher in PLF. In enzyme inhibition studies, the PHF showed stronger inhibition against 5-lipoxygenase (IC50 = 29.28 µg/mL) and α-glucosidase (IC50 = 82.50 µg/mL) compared to PLF. The antibacterial potential of the fractions was assessed using Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, Staphylococcus aureus, Salmonella typhimurium, and Klebsiella pneumoniae. The PHF exhibited significant inhibition zones, particularly against P. aeruginosa (17.40 mm) and S. aureus (13.40 mm). Consequently, these findings suggest that pyrolysis-based fractionation may be an effective and sustainable method for converting P. sylvestris bark waste into functional fractions with high antioxidant, anti-inflammatory, antidiabetic, and antibacterial potential.