Microwave-assisted extraction for the sustainable recovery and valorization of phenolic compounds from maritime pine bark

Abstract

This study investigates the potential of Pinus pinaster subsp. atlantica bark, a forestry byproduct fromnorthernPortugal, as a source of phenolic compoundswithstrongantioxidant properties. Microwave-assisted extraction (MAE) was used to optimize recovery, assessing the effects of solvent composition (water, ethanol, and 50:50 water–ethanol), extraction time (15 or 30 min), and temperature (90, 110, or 130 ◦C) using a one-variable-at-a-time approach. High-Performance Liquid Chromatography (HPLC) profiling characterized the polyphenol composition. The results showed that solvent choice strongly influenced extract composition and bioactivity, with hydroethanolic and ethanolic extracts exhibiting the highest antioxidant activities in DPPH, ABTS, and ORAC assays. Optimal conditions—50:50 water–ethanol, 130 ◦C, 15 min—yielded 11.13% (w/w) extract, 3.10 mg GAE/mL total phenolics, and 2.01 mg CE/mL condensed tannins, comparable to commercial extracts such as Pycnogenol®. MAEprovedeffective, rapid, and solvent-efficient, enhancing phenolic recovery without degrading extract quality. These findings highlight the potential of P. pinaster bark extracts for biomedical, nutraceutical, and cosmetic applications, supporting the sustainable valorization of forestry residues and aligning with circular economy principles.