You may be thinking the ORAC value is high in antioxidants, but it is important to consider that chocolate syrup can vary great in its cocoa content and that is where the flavanoids called anthocyanidin are coming from. Obviously, the more sugar and filler in the syrup, the less antioxidants it will have.
ORAC Source
USDA Database for the Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods, Release 2 - Prepared by Nutrient Data Laboratory, Beltsville Human Nutrition Research Center (BHNRC), Agricultural Research Service (ARS), U.S. Department of Agriculture (USDA) - May 2010