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Measuring free ellagic acid: influence of extraction conditions on recovery by studying solubility and UV-Visible spectra

Williams, David J. and Edwards, David and Chaliha, Mridusmita and Sultanbawa, Yasmina (2016) Measuring free ellagic acid: influence of extraction conditions on recovery by studying solubility and UV-Visible spectra. Chemical Papers . ISSN 0366-6352

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Article Link(s): http://dx.doi.org/10.1515/chempap-2016-0038

Abstract

Recent investigations into plant tissues have indicated that the free form of the natural polyphenolic antioxidant, ellagic acid (EA), is much more plentiful than first envisaged; consequently a re-assessment of solvent systems for the extraction of this water-insoluble form is needed. As EA solubility and its UV-Vis spectrum, commonly used for detection and quantification, are both governed by pH, an understanding of this dependence is vital if accurate EA measurements are to be achieved. After evaluating the pH effects on the solubility and UV-Vis spectra of commercial EA, an extraction protocol was devised that promoted similar pH conditions for both standard solutions and plant tissue extracts. The extraction so devised followed by HPLC with photodiode-array detection (DAD) provided a simple, sensitive and validated methodology that determined free EA in a variety of plant extracts. The use of 100 % methanol or a triethanolamine-based mixture as the standard dissolving solvents were the best choices, while these higher pH-generating solvents were more efficient in extracting EA from the plants tested with the final choice allied to the plants’ natural acidity. Two of the native Australian plants anise myrtle (Syzygium anisatum) and Kakadu plum (Terminalia ferdinandiana) exhibited high concentrations of free EA. Furthermore, the dual approach to measuring EA UV-Vis spectra made possible an assessment of the effect of acidified eluent on EA spectra when the DAD was employed.

Item Type:Article
Business groups:Crop and Food Science
Keywords:ellagic acid; solubility; pH; UV-Vis spectra; Australian native plants
Subjects:Science > Biology > Biochemistry
Plant culture > Food crops
Deposited On:14 Apr 2016 02:23
Last Modified:14 Apr 2016 02:25

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