Extraction, structural characterisation and evaluation of hydroxycinnamate esters of orchard grass ( Dactylis glomerata) as substrates for polyphenol oxidase

■■■ Polyphenol oxidase (PPO) activity has been reported in orchard grass ( Dactylis glomerata); however, to date, no endogenous substrates have been identified. In the present study, we report the isolation and structural elucidation of PPO substrates in this species. The free phenol fraction was ex...

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Bibliographic Details
Published in:Phytochemistry (Oxford) 2008-11, Vol.69 (16), p.2799-2806
Main Authors: Parveen, Ifat, Winters, Ana, Threadgill, Michael D., Hauck, Barbara, Morris, Phillip
Format: Article
Language:English
Subjects:
Biological and medical sciences
caffeoylquinic acid
catechol oxidase
Catechol Oxidase - chemistry
Catechol Oxidase - metabolism
Chemical constitution
chemical structure
Chromatography, High Pressure Liquid
coumaric acids
Coumaric Acids - chemistry
Coumaric Acids - isolation & purification
Coumaric Acids - metabolism
Dactylis - chemistry
Dactylis - enzymology
Dactylis glomerata
enzyme activity
enzyme substrates
Esters
Fundamental and applied biological sciences. Psychology
hydroxycinnamate ester
Hydroxycinnamate esters
Hydroxycitric acid
Isocitric acid
Orchard grass
Phenols - chemistry
Phenols - isolation & purification
plant biochemistry
Plant physiology and development
Polyphenol oxidase
spectral analysis
Spectrometry, Mass, Electrospray Ionization
Substrate Specificity
Threonic acid
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Summary:■■■ Polyphenol oxidase (PPO) activity has been reported in orchard grass ( Dactylis glomerata); however, to date, no endogenous substrates have been identified. In the present study, we report the isolation and structural elucidation of PPO substrates in this species. The free phenol fraction was extracted, separated by reverse-phase chromatography and six potential substrates, including two hydroxycinnamate esters, were identified by UV spectrometry, electrospray ionisation-tandem mass spectrometry (LC–ESI-MS n ) and 1D and 2D NMR analyses ( 1H NMR, 13C NMR, DEPT, COSY, HMQC and HMBC). Furthermore, three caffeoylquinic acids (3-CQA, 4-CQA and 5-CQA) were identified by comparison of their spectral data (ESI-MS) with those of known compounds and literature data. Five of these compounds were demonstrated to be substrates for orchard grass PPO.
ISSN:0031-9422
1873-3700
DOI:10.1016/j.phytochem.2008.08.019