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Investigation on biocatalytic properties of a peroxidase-active homogenate from onion solid wastes: An insight into quercetin oxidation mechanism

Paper ID Volume ID Publish Year Pages File Format Full-Text
35534 45094 2008 7 PDF Available
Title
Investigation on biocatalytic properties of a peroxidase-active homogenate from onion solid wastes: An insight into quercetin oxidation mechanism
Abstract

Enzyme-assisted bioremediation studies have been based to a large extent on the use of microbes (bacteria or fungi). On the other hand, plants and/or plant food wastes have been given much less attention or even disregarded. In some instances, however, oxidative enzymes from residual plant tissues have been shown to effectively degrade recalcitrant pollutants. In this regard, this study deals with the examination of some biocatalytic properties of a peroxidase-active homogenate, obtained from onion solid wastes. The examinations were carried out using the flavonol quercetin (3,3′,4′,5,7-pentahydroxyflavone), which is the physiological substrate of the enzyme. Quercetin oxidation by the homogenate/H2O2 system was shown to be optimum at pH values between 3 and 4 and temperature between 30 and 40 °C. Liquid chromatography–mass spectrometry analyses of a homogenate/H2O2-oxidised quercetin solution revealed the formation of four major products, including 3,4-dihydroxybenzoic acid (protocatechuic acid), 2,4,6-trihydroxybenzoic acid (phloroglucinol carboxylic acid), 2-(2-((3,4-dioxocyclohexa-1,5-dienyl)(hydroxyl)methoxy)-4,6-dihydroxyphenyl)-2-oxoacetic acid, and 2-(3,4-dihydroxybenzyloxy)-4,6-dihydroxybenzoic acid. Minor amounts of a quercetin heterodimer were also detected. The tentative identification of these substances permitted an approach to an unusual, putative oxidation pathway for quercetin, catalysed by onion peroxidase.

Keywords
AcOH, acetic acid; BGP, bitter gourd peroxidase; HRP, horseradish peroxidase; MeOH, methanol; OSWH, onion solid waste homogenate; PA, protocatechuic acid (3,4-dihydroxybenzoic acid); PCA, phloroglucinol carboxylic acid (2,4,6-trihydroxybenzoic acid); PGXA
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Investigation on biocatalytic properties of a peroxidase-active homogenate from onion solid wastes: An insight into quercetin oxidation mechanism
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Publisher
Database: Elsevier - ScienceDirect
Journal: Process Biochemistry - Volume 43, Issue 8, August 2008, Pages 861–867
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us