Antioxidant Detection in Berry Samples from Alaska

Berries and vegetables can be sources of beneficial phytochemicals that may have antioxidant activity in the human diet. Information on type and quantity of phytochemicals may open new crop opportunities for berries and vegetables harvested in Alaska. A method was developed for detecting ascorbic acid and eight phenolic acids on an HPLC instrument using a reverse phase Merck Chromolith C18 column. The method used UV absorbance detection at 280nm to separate a standard solution of the following nine phytochemicals: ascorbic acid, gallic acid, protocatechuic acid, p-hydroxybenzoic acid, p-hydroxyphenylacetic acid, caffeic acid, syringic acid, p-coumaric acid and ferulic acid. The mobile phase was a mixture (3.5% to 14% gradient) of organic solvent (5 parts acetonitrile: 2 parts methanol) and aqueous solvent (2 mmol aqueous trifluoroacetic acid - TFA) at a flow rate of 2 mL/min. In 2003, over 60 samples of berries and 60 samples of baby greens were extracted and analyzed. Plant samples were extracted by blending 10-20g of frozen plant tissue with 5 parts TFA. The extracts were centrifuged, diluted 4:1 and filtered (0.2 μm). Chromatograms from HPLC analysis for all samples were complex in peak size and number. Chromatograms for six extracts of high bush cranberries, Viburnum edule , exhibited intense peaks that indicate the presence of caffeic acid, based on retention times. Chromatograms for seven extracts of rose hips, Rosa acicularis , exhibited peaks that indicate the presence of ascorbic acid, based on retention times. Gallic acid and p-hydroxybenzoic acid are apparent minor components in the leaves of some baby greens. This research will continue in 2004 with more plant samples and further method development for detection of other phytochemicals.