{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,28]],"date-time":"2026-01-28T20:18:48Z","timestamp":1769631528410,"version":"3.49.0"},"reference-count":50,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2025,9,8]],"date-time":"2025-09-08T00:00:00Z","timestamp":1757289600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Foundation for Science and Technology (FCT, Portugal) for financial support","award":["UIDB\/05937\/2020"],"award-info":[{"award-number":["UIDB\/05937\/2020"]}]},{"name":"Foundation for Science and Technology (FCT, Portugal) for financial support","award":["UIDP\/05937\/2020"],"award-info":[{"award-number":["UIDP\/05937\/2020"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sustainable Chemistry"],"abstract":"<jats:p>This study investigates the potential of Pinus pinaster subsp. atlantica bark, a forestry by-product from northern Portugal, as a source of phenolic compounds with strong antioxidant properties. Microwave-assisted extraction (MAE) was used to optimize recovery, assessing the effects of solvent composition (water, ethanol, and 50:50 water\u2013ethanol), extraction time (15 or 30 min), and temperature (90, 110, or 130 \u00b0C) 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\u201450:50 water\u2013ethanol, 130 \u00b0C, 15 min\u2014yielded 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\u00ae. MAE proved effective, 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.<\/jats:p>","DOI":"10.3390\/suschem6030026","type":"journal-article","created":{"date-parts":[[2025,9,8]],"date-time":"2025-09-08T11:51:12Z","timestamp":1757332272000},"page":"26","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Microwave-Assisted Extraction for the Sustainable Recovery and Valorization of Phenolic Compounds from Maritime Pine Bark"],"prefix":"10.3390","volume":"6","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4557-9776","authenticated-orcid":false,"given":"Diana","family":"Barros","sequence":"first","affiliation":[{"name":"CISAS\u2014Center for Research and Development in Agrifood Systems and Sustainability, Instituto Polit\u00e9cnico de Viana do Castelo, Rua Escola Industrial e Comercial de Nun\u2019\u00c1lvares, 4900-347 Viana do Castelo, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8480-9525","authenticated-orcid":false,"given":"Ricardo","family":"Pereira-Pinto","sequence":"additional","affiliation":[{"name":"CISAS\u2014Center for Research and Development in Agrifood Systems and Sustainability, Instituto Polit\u00e9cnico de Viana do Castelo, Rua Escola Industrial e Comercial de Nun\u2019\u00c1lvares, 4900-347 Viana do Castelo, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0618-1469","authenticated-orcid":false,"given":"\u00c9lia","family":"Fernandes","sequence":"additional","affiliation":[{"name":"CISAS\u2014Center for Research and Development in Agrifood Systems and Sustainability, Instituto Polit\u00e9cnico de Viana do Castelo, Rua Escola Industrial e Comercial de Nun\u2019\u00c1lvares, 4900-347 Viana do Castelo, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2075-5913","authenticated-orcid":false,"given":"Preciosa","family":"Pires","sequence":"additional","affiliation":[{"name":"CISAS\u2014Center for Research and Development in Agrifood Systems and Sustainability, Instituto Polit\u00e9cnico de Viana do Castelo, Rua Escola Industrial e Comercial de Nun\u2019\u00c1lvares, 4900-347 Viana do Castelo, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4825-2058","authenticated-orcid":false,"given":"Manuela","family":"Vaz-Velho","sequence":"additional","affiliation":[{"name":"CISAS\u2014Center for Research and Development in Agrifood Systems and Sustainability, Instituto Polit\u00e9cnico de Viana do Castelo, Rua Escola Industrial e Comercial de Nun\u2019\u00c1lvares, 4900-347 Viana do Castelo, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2025,9,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"524","DOI":"10.1007\/s10086-007-0896-6","article-title":"Exploitation of polyphenol-rich pine barks for potent antioxidant activity","volume":"53","author":"Ku","year":"2007","journal-title":"J. Wood Sci."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"838","DOI":"10.1016\/j.indcrop.2011.02.002","article-title":"The effect of different extraction techniques on extraction yield, total phenolic, and anti-radical capacity of extracts from Pinus radiata Bark","volume":"34","year":"2011","journal-title":"Ind. Crops Prod."},{"key":"ref_3","first-page":"163","article-title":"Inhibitory Effects of Pinus pinaster Aiton Subsp. Atlantica Bark Extracts Against Known Food Pathogens","volume":"79","author":"Barros","year":"2020","journal-title":"Chem. Eng. Trans."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"142","DOI":"10.1016\/j.indcrop.2014.11.052","article-title":"Microwave assisted extraction of maritime pine (Pinus pinaster) bark: Impact of particle size and characterization","volume":"65","author":"Chupin","year":"2015","journal-title":"Ind. Crops Prod."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Venkatesan, T., Choi, Y.-W., and Kim, Y.-K. (2019). Impact of Different Extraction Solvents on Phenolic Content and Antioxidant Potential of Pinus densiflora Bark Extract. Biomed. Res. Int., 2019.","DOI":"10.1155\/2019\/3520675"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"583","DOI":"10.1007\/s11157-022-09624-1","article-title":"Chemical composition and industrial applications of Maritime pine (Pinus pinaster Ait.) bark and other non-wood parts","volume":"21","author":"Carocho","year":"2022","journal-title":"Rev. Environ. Sci. Bio\/Technol."},{"key":"ref_7","unstructured":"San-Miguel-Ayanz, J., de Rigo, D., Caudullo, G., Houston Durrant, T., and Mauri, A. (2016). Pinus pinaster in Europe: Distribution, habitat, usage and threats. European Atlas of Forest Tree Species, Publications Office."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Conde, E., D\u00edaz-Reinoso, B., Moure, A., Hemming, J., Willf\u00f6r, S., Dom\u00ednguez, H., and Paraj\u00f3, J.C. (2013, January 1\u20135). Extraction of Phenolic and Lipophilic Compounds from Pinus pinaster Knots and Stemwood by Supercritical CO2. Proceedings of the IIIrd Iberoamerican Conference on Supercritical Fluids, Cartagena de Indias, Colombia. Available online: http:\/\/www.nupeg.ufrn.br\/prosciba\/prosciba2013\/Papers\/T2-19.pdf.","DOI":"10.1016\/j.supflu.2013.04.018"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Cuevas-Valenzuela, J., Vergara-Salinas, J.R., and P\u00e9rez-Correa, J.R. (2016). Solid\u2013Liquid Extraction of Polyphenols at Low Pressure. Advances in Technologies for Producing Food-Relevant Polyphenols, Taylor & Francis.","DOI":"10.1201\/9781315371245"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"8816","DOI":"10.1021\/acssuschemeng.9b00780","article-title":"Moderate Electric Fields as a Potential Tool for Sustainable Recovery of Phenolic Compounds from Pinus pinaster Bark","volume":"7","author":"Genisheva","year":"2019","journal-title":"ACS Sustain. Chem. Eng."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Plaza, M., Dom\u00ednguez-Rodr\u00edguez, G., Castro-Puyana, M., and Marina, M. (2018). Polyphenols analysis and related challenges. Polyphenols: Properties, Recovery, and Applications, Woodhead Publishing.","DOI":"10.1016\/B978-0-12-813572-3.00006-3"},{"key":"ref_12","unstructured":"Worsfold, P., Poole, C., Townshend, A., and Mir\u00f3, M. (2019). Extraction|Microwave-Assisted Extraction. Encyclopedia of Analytical Science, Academic Press. [3rd ed.]."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"248","DOI":"10.1016\/j.trac.2019.05.037","article-title":"Green extraction of natural products. Origins, current status, and future challenges","volume":"118","author":"Chemat","year":"2019","journal-title":"TrAC Trends Anal. Chem."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1417","DOI":"10.1016\/j.foodchem.2006.03.050","article-title":"Extraction of phenolics and essential oil from dried sage (Salvia officinalis) using ethanol\u2013water mixtures","volume":"101","author":"Durling","year":"2007","journal-title":"Food Chem."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1016\/S0308-8146(00)00288-0","article-title":"Phenolic content and antioxidant activity of olive extracts","volume":"73","author":"McDonald","year":"2001","journal-title":"Food Chem."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Chen, J., Thilakarathna, W., Astatkie, T., and Rupasinghe, H.P.V. (2020). Optimization of Catechin and Proanthocyanidin Recovery from Grape Seeds Using Microwave-Assisted Extraction. Biomolecules, 10.","DOI":"10.3390\/biom10020243"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Pals, M., Lauberte, L., Ponomarenko, J., Lauberts, M., and Arshanitsa, A. (2022). Microwave-Assisted Water Extraction of Aspen (Populus tremula) and Pine (Pinus sylvestris L.) Barks as a Tool for Their Valorization. Plants, 11.","DOI":"10.3390\/plants11121544"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"10","DOI":"10.1016\/j.foodres.2015.04.018","article-title":"Antioxidants: Characterization, natural sources, extraction and analysis","volume":"74","author":"Oroian","year":"2015","journal-title":"Food Res. Int."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"144","DOI":"10.5344\/ajev.1965.16.3.144","article-title":"Colorimetry of Total Phenolics with Phosphomolybdic-Phosphotungstic Acid Reagents","volume":"16","author":"Singleton","year":"1965","journal-title":"Am. J. Enol. Vitic."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"875","DOI":"10.1038\/nprot.2007.102","article-title":"Estimation of total phenolic content and other oxidation substrates in plant tissues using Folin-Ciocalteu reagent","volume":"2","author":"Ainsworth","year":"2007","journal-title":"Nat. Protoc."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"153","DOI":"10.1063\/1.4858646","article-title":"Condensed tannins from acacia mangium bark: Characterization by spot tests and FTIR","volume":"1571","author":"Bharudin","year":"2013","journal-title":"AIP Conf. Proc."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"897","DOI":"10.1016\/j.indcrop.2013.06.045","article-title":"Characterisation of maritime pine (Pinus pinaster) bark tannins extracted under different conditions by spectroscopic methods, FTIR and HPLC","volume":"49","author":"Chupin","year":"2013","journal-title":"Ind. Crops Prod."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"2712","DOI":"10.1016\/j.foodres.2011.05.026","article-title":"Chemical composition of dietary fiber and polyphenols of five different varieties of wine grape pomace skins","volume":"44","author":"Deng","year":"2011","journal-title":"Food Res. Int."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1016\/S0023-6438(95)80008-5","article-title":"Use of a free radical method to evaluate antioxidant activity","volume":"28","author":"Cuvelier","year":"1995","journal-title":"LWT Food Sci. Technol."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Coscueta, E.R., Reis, C.A., and Pintado, M. (2020). Phenylethyl Isothiocyanate Extracted from Watercress By-Products with Aqueous Micellar Systems: Development and Optimisation. Antioxidants, 9.","DOI":"10.3390\/antiox9080698"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"267","DOI":"10.1016\/j.foodchem.2003.06.020","article-title":"Extraction of antioxidant phenolics from almond hulls (Prunus amygdalus) and pine sawdust (Pinus pinaster)","volume":"85","author":"Pinelo","year":"2004","journal-title":"Food Chem."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1231","DOI":"10.1016\/S0891-5849(98)00315-3","article-title":"Antioxidant activity applying an improved ABTS radical cation decolorization assay","volume":"26","author":"Re","year":"1999","journal-title":"Free Radic. Biol. Med."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"23","DOI":"10.1016\/S0926-6690(02)00004-3","article-title":"Chemical characterisation of bark and of alkaline bark extracts from maritime pine grown in Portugal","volume":"16","author":"Fradinho","year":"2002","journal-title":"Ind. Crops Prod."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1016\/j.supflu.2011.10.016","article-title":"High pressure solvent extraction of maritime pine bark: Study of fractionation, solvent flow rate and solvent composition","volume":"62","author":"Seabra","year":"2012","journal-title":"J. Supercrit. Fluids"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"296","DOI":"10.1016\/j.jfda.2013.11.001","article-title":"Effect of extraction solvent on total phenol content, total flavonoid content, and antioxidant activity of Limnophila aromatica","volume":"22","author":"Do","year":"2014","journal-title":"J. Food Drug Anal."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"4561","DOI":"10.1007\/s11694-021-01028-z","article-title":"Comprehensive study on the antioxidant capacity and phenolic profiles of black seed and other spices and herbs: Effect of solvent and time of extraction","volume":"15","year":"2021","journal-title":"J. Food Meas. Charact."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Aryal, S., Baniya, M.K., Danekhu, K., Kunwar, P., Gurung, R., and Koirala, N. (2019). Total Phenolic Content, Flavonoid Content and Antioxidant Potential of Wild Vegetables from Western Nepal. Plants, 8.","DOI":"10.3390\/plants8040096"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"16","DOI":"10.1016\/j.foodchem.2019.03.025","article-title":"Effect of solvent and extraction technique on composition and biological activity of Lepidium sativum extracts","volume":"289","author":"Pomastowski","year":"2019","journal-title":"Food Chem."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"3751","DOI":"10.1002\/jssc.201000430","article-title":"Optimization of microwave-assisted extraction of polyphenols from apple pomace using response surface methodology and HPLC analysis","volume":"33","author":"Bai","year":"2010","journal-title":"J. Sep. Sci."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"307","DOI":"10.1016\/j.foodchem.2003.12.029","article-title":"Determination of rosmarinic acid and caffeic acid in aromatic herbs by HPLC","volume":"87","author":"Wang","year":"2004","journal-title":"Food Chem."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1016\/j.indcrop.2012.01.016","article-title":"Investigation on chemical composition, anticholinesterase and antioxidant activities of extracts and essential oils of Turkish Pinus species and pycnogenol","volume":"38","author":"Ustun","year":"2012","journal-title":"Ind. Crops Prod."},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Feria-Reyes, R., Ram\u00edrez-Cruz, S.O., Ruiz-Aquino, F., Robledo-Taboada, L.H., S\u00e1nchez-Medina, M.A., Mijangos-Ric\u00e1rdez, O.F., Gabriel-Parra, R., Su\u00e1rez-Mota, M.E., Puc-Kauil, R., and Porcallo-Vargas, J. (2023). Pine Bark as a Potential Source of Condensed Tannin: Analysis through Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray (EDX). Forests, 14.","DOI":"10.3390\/f14071433"},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Jim\u00e9nez-Moreno, N., Volpe, F., Moler, J.A., Esparza, I., and Anc\u00edn-Azpilicueta, C. (2019). Impact of Extraction Conditions on the Phenolic Composition and Antioxidant Capacity of Grape Stem Extracts. Antioxidants, 8.","DOI":"10.3390\/antiox8120597"},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Tanase, C., Co\u0219arc\u0103, S., and Muntean, D.L. (2019). A Critical Review of Phenolic Compounds Extracted from the Bark of Woody Vascular Plants and Their Potential Biological Activity. Molecules, 24.","DOI":"10.3390\/molecules24061182"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"81112","DOI":"10.1007\/s11356-022-23337-6","article-title":"Extraction and characterization of phenolic compounds and their potential antioxidant activities","volume":"29","author":"Shi","year":"2022","journal-title":"Environ. Sci. Pollut. Res. Int."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"15","DOI":"10.1016\/j.fct.2012.09.021","article-title":"A review on antioxidants, prooxidants and related controversy: Natural and synthetic compounds, screening and analysis methodologies and future perspectives","volume":"51","author":"Carocho","year":"2013","journal-title":"Food Chem. Toxicol."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"669","DOI":"10.1016\/j.jfca.2006.01.003","article-title":"Comparison of ABTS, DPPH, FRAP, and ORAC assays for estimating antioxidant activity from guava fruit extracts","volume":"19","author":"Thaipong","year":"2006","journal-title":"J. Food Compos. Anal."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"3273","DOI":"10.1021\/jf0262256","article-title":"Assays for Hydrophilic and Lipophilic Antioxidant Capacity (oxygen radical absorbance capacity (ORACFL)) of Plasma and Other Biological and Food Samples","volume":"51","author":"Prior","year":"2003","journal-title":"J. Agric. Food Chem."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"204","DOI":"10.1016\/j.foodchem.2007.04.017","article-title":"Relationship between antioxidant capacity and total phenolic content of red, ros\u00e9 and white wines","volume":"105","author":"Perestrelo","year":"2007","journal-title":"Food Chem."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"37","DOI":"10.1016\/j.supflu.2008.05.005","article-title":"Fractioned SFE of antioxidants from maritime pine bark","volume":"47","author":"Braga","year":"2008","journal-title":"J. Supercrit. Fluids"},{"key":"ref_46","first-page":"1153","article-title":"Optimisation of Radio Frequency Assisted Extraction of Apple Peel Extract: Total Phenolic Contents and Antioxidant Activity","volume":"56","author":"Jusoh","year":"2017","journal-title":"Chem. Eng. Trans."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"704","DOI":"10.1016\/S0891-5849(99)00090-8","article-title":"Antioxidant activity and biologic properties of a procyanidin-rich extract from pine (pinus maritima) bark, pycnogenol","volume":"27","author":"Packer","year":"1999","journal-title":"Free Radic. Biol. Med."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"135202","DOI":"10.1016\/j.foodchem.2022.135202","article-title":"The mechanisms and applications of cryoprotectants in aquatic products: An overview","volume":"408","author":"Liu","year":"2023","journal-title":"Food Chem."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"671","DOI":"10.1007\/s00217-009-1101-5","article-title":"A comparative study of flavonoid contents and antioxidant activities of supercritical CO2 extracted pine barks grown in different regions of Turkey and Germany","volume":"229","author":"Otto","year":"2009","journal-title":"Eur. Food Res. Technol."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"14","DOI":"10.1039\/D0FO02324H","article-title":"Phenolic compounds: Current industrial applications, limitations and future challenges","volume":"12","author":"Albuquerque","year":"2021","journal-title":"Food Funct."}],"container-title":["Sustainable Chemistry"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2673-4079\/6\/3\/26\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T18:41:56Z","timestamp":1760035316000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2673-4079\/6\/3\/26"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,9,8]]},"references-count":50,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2025,9]]}},"alternative-id":["suschem6030026"],"URL":"https:\/\/doi.org\/10.3390\/suschem6030026","relation":{},"ISSN":["2673-4079"],"issn-type":[{"value":"2673-4079","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,9,8]]}}}