ARS | Publication request: Stilbene, ellagic acid, flavonol, and phenolic content of muscadine grape (Vitis rotundifolia) cultivars

Submitted to: Pharmaceutical Crops
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 15, 2012
Publication Date: March 1, 2012
Citation: Marshall, D.A., Stringer, S.J., Spiers, J.D. 2012. Stilbene, ellagic acid, flavonol, and phenolic content of muscadine grape (Vitis rotundifolia) cultivars. Pharmaceutical Crops. 3:69-77.

Interpretive Summary: This study has found that a large range of levels of ellagic acid, phenolics, and stilbenes in muscadine grape skins. Many research articles have been published showing ellagic acid and resveratrol in muscadine juice or pulp. Most of these use only two or three of the most common varieties. Our findings show that these compounds are found in only a few varieties, and are not ubiquitous for muscadine juice or pulp. Ellagic acid was found in the skins of all varieties tested. This information can be used by muscadine geneticists to develop a healthier berry. Typically muscadine geneticists select for sweetness, firmness, skin thickness, disease resistance, and other attributes that are visual or palatable, but with an ever increasing drive for healthier foods, muscadines are a “hidden treasure”. Muscadine grapes are a unique member of the Vitis genus. The presence of ellagic acid and high phenolic content, and resveratrol make it undiscovered superfruit.

Technical Abstract: Antioxidant properties, ellagic acid, and polyphenolic were evaluated in 19 muscadine cultivars and 2 muscadine selections. Analysis was carried out on muscadine fruit skin, pulp and juice partitions. The major phenolics in muscadine juice, pulp and skins were identified by their retention times and characteristic spectra. Quantification was made by calibration curves of external standards for each of the analyzed compounds, trans and cis resveratrol, trans and cis piceid, ellagic acid, myricetin, quercetin and kaempferol. Free and total ellagic acid was found in muscadine juice of eight cultivars, in amounts up to 54.0 µg/g in Ison and 56.0 µg/g in Janet. In the pulp, free ellagic acid was only found in 3 cultivars, and total ellagic acid was found in 8 cultivars in amounts up to 57.0 µg/g for Janet and 77.0 µg/g for Southland. Trans resveratrol was found in two cultivars, Eudora and Janet in amounts of 0.9 µg/g and 4.3 µg/g respectively. In muscadine skin, free and total ellagic acid, myricetin, quercetin and kaempferol were found in all 21 cultivars analyzed and trans resveratrol was found in all cultivars except Alachua. Ellagic acid was the most abundant phenolic compound in muscadine grape skins. Total ellagic acid ranged from a low of 779.0 µg/g in Tara to 5554.0 µg/g in Southland. The presence of ellagic acid and other nutraceutical compounds in muscadine grape could add value and marketability to the crop due to the possible health benefits. This southern specialty could fast become the next “super fruit”.