{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,24]],"date-time":"2026-03-24T15:16:48Z","timestamp":1774365408998,"version":"3.50.1"},"reference-count":38,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2010,12,16]],"date-time":"2010-12-16T00:00:00Z","timestamp":1292457600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>The antioxidant activity of the phenolic compounds present in industrial black liquors obtained from the two cooking processes (kraft and sulphite) used in Portugal to produce Eucalyptus globulus pulp was evaluated. The black liquors treated at several pH values were extracted with ethyl acetate. Phenolic fractions were further separated by liquid chromatography of the crude extracts of kraft liquor at pH = 6 and sulphite liquor at the original pH. Total phenolic content was determined in terms of gallic acid equivalents (Folin-Ciocalteu colorimetric method), and the antioxidant activity in the crude extracts at several pH values and in the separated fractions was measured using the DPPH test for radical scavenging capacity. The total phenolic content of crude extracts and separated fractions ranged from 92.7 to 181.6 and from 91.6 to 1,099.6 mg GAE\/g, respectively, while the antioxidant activity index (AAI) ranged from 2.20 to 3.41 and from 2.21 to 11.47 respectively, showing very strong antioxidant activity in all studied cases. The fractions separated by column chromatography were submitted to mass spectrometry analysis and the results were compared to others in the literature of natural products, mainly from Eucalyptus, and the characteristic bands of functional groups were identified by 1H-NMR and FTIR. These methods allowed the identification of 17 phenolic compounds.<\/jats:p>","DOI":"10.3390\/molecules15129308","type":"journal-article","created":{"date-parts":[[2010,12,17]],"date-time":"2010-12-17T11:57:53Z","timestamp":1292587073000},"page":"9308-9322","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":130,"title":["Antioxidant Activity of Lignin Phenolic Compounds Extracted from Kraft and Sulphite Black Liquors"],"prefix":"10.3390","volume":"15","author":[{"given":"H\u00e9lio","family":"Faustino","sequence":"first","affiliation":[{"name":"Textile & Paper Materials Research Unit, University of Beira Interior, 6201-001 Covilh\u00e3, Portugal"}]},{"given":"Nuno","family":"Gil","sequence":"additional","affiliation":[{"name":"Textile & Paper Materials Research Unit, University of Beira Interior, 6201-001 Covilh\u00e3, Portugal"}]},{"given":"Cec\u00edlia","family":"Baptista","sequence":"additional","affiliation":[{"name":"Textile & Paper Materials Research Unit, University of Beira Interior, 6201-001 Covilh\u00e3, Portugal"},{"name":"Department of Chemical and Environmental Engineering, ESTT, Polytechnic Institute of Tomar, 2300-313 Tomar, Portugal"}]},{"given":"Ana Paula","family":"Duarte","sequence":"additional","affiliation":[{"name":"Faculty of Health Sciences, University of Beira Interior, 6201-001 Covilh\u00e3, Portugal"},{"name":"Faculty of Health Sciences, Health Sciences Research Centre, 6201-001 Covilh\u00e3, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2010,12,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"39","DOI":"10.1023\/A:1021070006895","article-title":"Recent industrial applications of lignin: a sustainable alternative tononrenewable materials","volume":"10","author":"Lora","year":"2002","journal-title":"J. Polym. Environ."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"413","DOI":"10.1016\/j.desal.2006.03.094","article-title":"Extraction of lignin and hemicelluloses from kraft black liquor","volume":"199","author":"Wallberg","year":"2006","journal-title":"Desalination"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"2645","DOI":"10.1016\/j.bmc.2007.11.041","article-title":"Low molecular weight lignin suppresses activation of NF-[kappa]B and HIV-1 promoter","volume":"16","author":"Mitsuhashi","year":"2008","journal-title":"Bioorg. Med. Chem."},{"key":"ref_4","unstructured":"Chum, H.L.A., and Black, S.K.D. (1990). Process for Fractionating Fast-pyrolysis Oils, and Products Derived Therefrom, Midwest Research Institute."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1016\/S0961-9534(97)00021-4","article-title":"Separation of phenols from Eucalyptus wood tar","volume":"13","author":"Pakdel","year":"1997","journal-title":"Biomass Bioenerg."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"145","DOI":"10.1016\/S0308-8146(00)00223-5","article-title":"Natural antioxidants from residual sources","volume":"72","author":"Moure","year":"2001","journal-title":"Food Chem."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"3268","DOI":"10.1021\/jf010011r","article-title":"Phenols in citrus peel byproducts. Concentrations of hydroxycinnamates and polymethoxylated flavones in citrus peel molasses","volume":"49","author":"Manthey","year":"2001","journal-title":"J. Agr. Food Chem."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"243","DOI":"10.1016\/S0308-8146(03)00208-5","article-title":"Production of antioxidants from Eucalyptus globulus wood by solvent extraction of hemicellulose hydrolysates","volume":"84","author":"Cruz","year":"2004","journal-title":"Food Chem."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"2459","DOI":"10.1021\/jf001237h","article-title":"Antioxidant and antimicrobial effects of extracts from hydrolysates of lignocellulosic materials","volume":"49","author":"Cruz","year":"2001","journal-title":"J. Agr. Food Chem."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"163","DOI":"10.1016\/S0021-9673(03)01100-2","article-title":"Fast separation and determination of tyrosol, hydroxytyrosol and other phenolic compounds in extra-virgin olive oil by capillary zone electrophoresis with ultraviolet-diode array detection","volume":"1011","author":"Bonoli","year":"2003","journal-title":"J. Chromatogr. A"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"251","DOI":"10.1016\/S0021-9673(02)00111-5","article-title":"Capillary electrophoretic separation of phenolic diterpenes from rosemary","volume":"953","author":"Tena","year":"2002","journal-title":"J. Chromatogr. A"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"271","DOI":"10.1016\/j.aca.2004.02.053","article-title":"Development and validation of a high-performance liquid chromatographic method for the analysis of antioxidative phenolic compounds in fennel using a narrow bore reversed phase C18 column","volume":"512","author":"Parejo","year":"2004","journal-title":"Anal. Chim. Acta"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"263","DOI":"10.1016\/S0021-9673(01)88766-5","article-title":"Analysis of biomass pyrolysis liquids: separation and characterization of phenols","volume":"542","author":"Achladas","year":"1991","journal-title":"J. Chromatogr. A"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.chroma.2005.09.021","article-title":"Ultrasound-assisted extraction of phenolic compounds from strawberries prior to liquid chromatographic separation and photodiode array ultraviolet detection","volume":"1100","author":"Herrera","year":"2005","journal-title":"J. Chromatogr. A"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1016\/j.chroma.2007.01.119","article-title":"Comprehensive two-dimensional liquid chromatography with parallel gradients for separation of phenolic and flavone antioxidants","volume":"1149","author":"Cacciola","year":"2007","journal-title":"J. Chromatogr. A"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"179","DOI":"10.1016\/j.chroma.2006.02.009","article-title":"On-chip micellar electrokinetic chromatographic separation of phenolic chemicals in waters","volume":"1109","author":"Wakida","year":"2006","journal-title":"J. Chromatogr. A"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"387","DOI":"10.1016\/S0021-9673(00)01030-X","article-title":"Separation and determination of flavonoids and other phenolic compounds in cranberry juice by high-performance liquid chromatography","volume":"913","author":"Chen","year":"2001","journal-title":"J. Chromatogr. A"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"249","DOI":"10.1016\/S0021-9673(01)00598-2","article-title":"Separation of phenolic compounds by high-performance liquid chromatography with absorbance and fluorimetric detection","volume":"912","author":"Borges","year":"2001","journal-title":"J. Chromatogr. A"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"639","DOI":"10.1021\/ac00294a034","article-title":"Study of the steam distillation of phenolic compounds using ultraviolet spectrometry","volume":"58","author":"Norwitz","year":"1986","journal-title":"Anal. Chem."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"147","DOI":"10.1016\/S0308-8146(99)00106-5","article-title":"Solvent extraction of hemicellulosic wood hydrolysates: a procedure useful for obtaining both detoxified fermentation media and polyphenols with antioxidant activity","volume":"67","author":"Cruz","year":"1999","journal-title":"Food Chem."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"5195","DOI":"10.1021\/jf040075c","article-title":"Antioxidant phenols in barley (Hordeum vulgare L.) flour: comparative spectrophotometric study among extraction methods of free and bound phenolic compounds","volume":"52","author":"Bonoli","year":"2004","journal-title":"J. Agr. Food Chem."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"654","DOI":"10.1016\/j.foodchem.2008.06.026","article-title":"Antioxidant activity index (AAI) by the 2,2-diphenyl-1-picrylhydrazyl method","volume":"112","author":"Scherer","year":"2009","journal-title":"Food Chem."},{"key":"ref_23","first-page":"471","article-title":"The influence of total phenols content on antioxidant capacity in the whole grain extracts","volume":"28","author":"Hodzic","year":"2009","journal-title":"Eur. J. Sci. Res."},{"key":"ref_24","first-page":"569","article-title":"An analysis of water soluble components of Sappi Saiccor's effluent streams","volume":"31","author":"Ismail","year":"2005","journal-title":"Water SA"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1002\/jsfa.2740040304","article-title":"A chromatographic examination of the minor constituents of various tree zones","volume":"4","author":"Hillis","year":"1953","journal-title":"J. Sci. Food Agr."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"235","DOI":"10.1016\/j.ijfoodmicro.2006.10.031","article-title":"Antimicrobial and cytotoxic knotwood extracts and related pure compounds and their effects on food-associated microrganisms","volume":"115","author":"Pietarinen","year":"2007","journal-title":"Int. J. Food Microbiol."},{"key":"ref_27","unstructured":"Pettit, G.R., and Singh, S.B. (1996). Isolation, structural elucidation and synthesis of novel antineoplastic substances denominated \"combretastatins\". (5,569,786,29), US Patent."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"119","DOI":"10.1021\/np50049a016","article-title":"Isolation, structure, and synthesis of combretastatins A-1 and B-1, potent new inhibitors of microtubule assembly, derived from Combretum caffrum","volume":"50","author":"Pettit","year":"2004","journal-title":"J. Nat. Prod."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"841","DOI":"10.1016\/j.tet.2005.10.059","article-title":"A concise synthesis of polyhydroxydihydrochalcones and homoisoflavonoids","volume":"62","author":"Siddaiah","year":"2006","journal-title":"Tetrahedron"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"881","DOI":"10.1071\/CH99078","article-title":"Pigments of Fungi. LVII -Structure and X-ray crystallographic analysis of dermocanarin 10, a new naphthalene- dihydroanthracenone dimer from an australian Dermocybe toadstool","volume":"52","author":"Gill","year":"1999","journal-title":"Austr. J. Chem."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"625","DOI":"10.1248\/cpb.53.625","article-title":"Inhibitors of nitric oxide production from the rhizomes of Alpinia galanga: structures of new 8-9\u2019linked neolignans and sesquineolignan","volume":"53","author":"Morikawa","year":"2005","journal-title":"Chem. Pharm. Bull."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2275","DOI":"10.1023\/A:1005518625764","article-title":"Chemistry of Leichhardt's Grasshopper, Petasida ephippigera, and its host plants, Pityrodia jamesii, P. ternifolia, and P. pungens","volume":"26","author":"Fletcher","year":"2000","journal-title":"J. Chem. Ecol."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"2241","DOI":"10.1002\/rcm.4133","article-title":"Temperature-dependent release of volatile organic compounds of eucalypts by direct analysis in real time (DART) mass spectrometry","volume":"23","author":"Maleknia","year":"2009","journal-title":"Rapid Commun. Mass Spectrom."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"o4582","DOI":"10.1107\/S1600536807054384","article-title":"Methyl 3,4,5-trimethoxybenzoate","volume":"63","author":"Saeed","year":"2007","journal-title":"Acta Crystallogr. Section E"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"110","DOI":"10.1016\/j.jaap.2004.10.010","article-title":"Determining the influence of eucalypt lignin composition in paper pulp yield using Py-GC\/MS","volume":"74","author":"Hernando","year":"2005","journal-title":"J. Anal. Appl. Pyrol."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"129","DOI":"10.1016\/S0883-2927(01)00061-0","article-title":"Biomass burning - a review of organic tracers for smoke from incomplete combustion","volume":"17","author":"Simoneit","year":"2002","journal-title":"Appl. Geochem."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"4600","DOI":"10.1021\/jf052935a","article-title":"Chemical composition of abaca (Musa textilis) leaf fibers used for manufacturing of high quality paper pulps","volume":"54","author":"Gutierrez","year":"2006","journal-title":"J. Agr. Food Chem."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1151","DOI":"10.1016\/j.foodchem.2007.09.044","article-title":"Antioxidant activity of compounds isolated from the pyroligneous acid, Rhizophora apiculata","volume":"107","author":"Loo","year":"2008","journal-title":"Food Chem."}],"container-title":["Molecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1420-3049\/15\/12\/9308\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T22:04:07Z","timestamp":1760220247000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1420-3049\/15\/12\/9308"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2010,12,16]]},"references-count":38,"journal-issue":{"issue":"12","published-online":{"date-parts":[[2010,12]]}},"alternative-id":["molecules15129308"],"URL":"https:\/\/doi.org\/10.3390\/molecules15129308","relation":{},"ISSN":["1420-3049"],"issn-type":[{"value":"1420-3049","type":"electronic"}],"subject":[],"published":{"date-parts":[[2010,12,16]]}}}