The acai berry is the fruit of the acai palm, native to tropical Central and South America. Freeze-dried acai powder was found to have antioxidant activity in vitro against superoxide and peroxyl radicals, and mild activity for peroxynitrite and hydroxyl radicals. The powder was reported to inhibit hydrogen peroxide-induced oxidation in neutrophils, and to have a slight stimulatory effect on the reactive radical, nitric oxide.
Extracts of acai seeds were reported to have antioxidant capacity in vitro against peroxyl radicals, similar to the antioxidant capacity of the pulp, with higher antioxidant capacity against peroxynitrite and hydroxyl radicals.
The anthocyanins of fruit likely have relevance to antioxidant capacity only in the plant's natural defensive mechanisms and in vitro.
The Linus Pauling Institute and European Food Safety Authority state that dietary anthocyanins and other flavonoids have little or no direct antioxidant food value following digestion. Unlike controlled test tube conditions, the fate of anthocyanins in vivo shows they are poorly conserved (less than 5%), with most of what is absorbed existing as chemically modified metabolites destined for rapid excretion. [Source: Wikipedia]
The ORAC value is expressed in micromoles of Trolox Equivalents per 100 grams of sample (this is the laboratory measure of ORAC).
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