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Naturally occurring phenols with antioxidant, antifungal and anti-browsing activity
Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Place, publisher, year, edition, pages
Sundsvall: Mid Sweden University , 2014. , 68 p.
Series
Mid Sweden University doctoral thesis, ISSN 1652-893X ; 198
National Category
Chemical Sciences
Identifiers
URN: urn:nbn:se:miun:diva-24028ISBN: 978-91-87557-77-4 (print)OAI: oai:DiVA.org:miun-24028DiVA: diva2:775414
Public defence
2014-09-26, 11:00
Supervisors
Available from: 2015-01-02 Created: 2015-01-02 Last updated: 2015-03-13Bibliographically approved
List of papers
1. Avenanthramides in Oats (Avena Sativa L.) and Structure-Activity Relationships
Open this publication in new window or tab >>Avenanthramides in Oats (Avena Sativa L.) and Structure-Activity Relationships
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2003 (English)In: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 51, no 3, 594-600 p.Article in journal (Refereed) Published
Abstract [en]

Eight avenanthramides, amides of anthranilic acid (1) and 5-hydroxyanthranilic acid (2), respectively, and the four cinnamic acids p-coumaric (p), caffeic (c), ferulic (f), and sinapic (s) acid, were synthesized for identification in oat extracts and for structure−antioxidant activity studies. Three compounds (2p, 2c, and 2f) were found in oat extracts. As assessed by the reactivity toward 1,1-diphenyl-2-picrylhydrazyl (DPPH), all avenanthramides except 1p showed activity. Initially, the antioxidant activity of the avenanthramides decreased in a similar order as for the corresponding cinnamic acids, that is: sinapic > caffeic > ferulic > p-coumaric acid. The avenanthramides derived from 2 were usually slightly more active than those derived from 1. All avenanthramides inhibited azo-initiated peroxidation of linoleic acid. 1c and 1s were initially the most effective compounds. The relative order of antioxidant activities was slightly different for the DPPH and the linoleic acid assays run in methanol and chlorobenzene, respectively.

Keyword
Avena sativa; avenanthramide; caffeic acid; cinnamic acid; p-coumaric acid; dehydrodicinnamic acid dilactone; DPPH; ferulic acid; radical scavengers; sinapic acid
National Category
Organic Chemistry
Identifiers
urn:nbn:se:miun:diva-12812 (URN)10.1021/jf020544f (DOI)
Available from: 2010-12-15 Created: 2010-12-15 Last updated: 2015-01-02Bibliographically approved
2. Extraction of Antioxidants from Spruce (Picea abies) Bark using Eco-friendly Solvents
Open this publication in new window or tab >>Extraction of Antioxidants from Spruce (Picea abies) Bark using Eco-friendly Solvents
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2012 (English)In: Phytochemical Analysis, ISSN 0958-0344, E-ISSN 1099-1565, Vol. 23, no 1, 1-11 p.Article in journal (Refereed) Published
Abstract [en]

Introduction - Antioxidants are known to avert oxidation processes and they are found in trees and other plant materials. Tree bark is a major waste product from paper pulp industries; hence it is worthwhile to develop an extraction technique to extract the antioxidants. Objective - To develop a fast and environmentally sustainable extraction technique for the extraction of antioxidants from bark of spruce (Picea abies) and also to identify the extracted antioxidants that are abundant in spruce bark. Methodology - A screening experiment that involved three different techniques was conducted to determine the best technique to extract antioxidants. The antioxidant capacity of the extracts was determined with DPPH (2,2-diphenyl-1-picrylhydrazyl) assay. Pressurised fluid extraction (PFE) turned out to be the best technique and a response surface design was therefore utilised to optimise PFE. Furthermore, NMR and HPLC-DAD-MS/MS were applied to identify the extracted antioxidants. Results - PFE using water and ethanol as solvent at 160 and 180°C, respectively, gave extracts of the highest antioxidant capacity. Stilbene glucosides such as isorhapontin, piceid and astringin were identified in the extracts. Conclusion - The study has shown that PFE is a fast and environmentally sustainable technique, using water and ethanol as solvent for the extraction of antioxidants from spruce bark. Copyright © 2011 John Wiley and Sons, Ltd. This paper includes four tables in which the extracted solid yield and the antioxidant capacity of spruce bark extracts were presented for the different extraction techniques, as well as the response surface coefficients for the optimised PFE were presented. © 2011 John Wiley and Sons, Ltd..

Keyword
Accelerated solvent extraction, Antioxidant, DPPH, Ethanol, Picea abies, Pressurised fluid extraction, Stilbene glucosides, Supercritical fluid extraction, Water
National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-14214 (URN)10.1002/pca.1316 (DOI)000298260100001 ()2-s2.0-82955198459 (Scopus ID)
Available from: 2011-07-19 Created: 2011-07-19 Last updated: 2015-01-02Bibliographically approved
3. Protective effects of synthetic and naturally occurring antioxidants in pulp products
Open this publication in new window or tab >>Protective effects of synthetic and naturally occurring antioxidants in pulp products
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2003 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, Vol. 18, 176-181 p.Article in journal (Refereed) Published
Abstract [en]

Various types of natural and synthetic antioxidants when added to handsheets of pulp in low concentrations (0.2% weight%) could significantly reduce the emission of hexanal. The most efficient compounds caused a 90% reduction after eight weeks. Their capacity to inhibit brightness reversion was limited.

National Category
Organic Chemistry
Identifiers
urn:nbn:se:miun:diva-12817 (URN)10.3183/NPPRJ-2003-18-02-p176-181 (DOI)
Available from: 2010-12-15 Created: 2010-12-15 Last updated: 2015-01-02Bibliographically approved
4. Radical-scavenging and antioxidant activity of avenanthramides
Open this publication in new window or tab >>Radical-scavenging and antioxidant activity of avenanthramides
2009 (English)In: Food Chemistry, ISSN 0308-8146, Vol. 113, no 2, 550-556 p.Article in journal (Refereed) Published
Abstract [en]

Avenanthramides are amides of cinnamoyl-anthranilic acids and, among cereals, are exclusively found in oats. This study investigated the structure-antioxidant activities of 15 avenanthramides with different substitution patterns in the two aromatic rings, seven of which were new avenanthramides synthesised and characterised in this study. Radical-scavenging activity was tested as reactivity towards 1,1-diphenyl-2-picrylhydrazyl (DPPH-). The activity increased with the number of radical-stabilising groups ortho to the phenolic hydroxy group. Both aromatic rings were independently important for activity, while conjugation across the amide bond was of minor importance. Antioxidant activity was determined as inhibition of linoleic acid oxidation. In contrast to the radical-scavenging activity, antioxidant activity was observed for most avenanthramides, and also for compounds with only one hydroxy group in either of the aromatic rings. Compared with alpha-tocopherol, the avenanthramides protected linoleic acid from oxidation to a smaller extent initially, but the effect lasted for a longer time.

Keyword
Antioxidants; Avenanthramides; 1, 1-Diphenyl-2-picrylhydrazyl; DPPH; Linoleic acid; Oats
National Category
Chemical Sciences
Identifiers
urn:nbn:se:miun:diva-8300 (URN)10.1016/j.foodchem.2008.07.101 (DOI)000261084600027 ()
Available from: 2009-01-18 Created: 2009-01-18 Last updated: 2015-01-02Bibliographically approved

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