Improvement in antioxidant activities and cholesterol secretion inhibition abilities of black raspberry extracts upon maturation

This study was carried out to investigate the improvements in antioxidant activities and cholesterol secretion inhibiting abilities upon the maturation of black raspberry (Rubus occidentalis, collected from May to June) for determining the suitability of black raspberry extracts for use as functional food materials. During the maturation process, the black raspberry samples were extracted by water using the reflux extraction method. The antioxidant activities of the resulting water extracts were determined in terms of the reducing power and ferric reducing antioxidant power (FRAP) and it was found that these values were higher for the unripe black raspberry sample. The cholesterol secretion inhibition activities of the extracts were then examined in HepH2 cell, while the hydroxy-methylglutaryl-coenzyme A (HMG-CoA) reductase activity and cell viability were measured in HepG2 cell. In addition, cholesterol secretion was inhibited of unripe black raspberry in HepG2 cell. Furthermore, HMG-CoA reductase activity of the unripe black raspberry extract was found to be superior to those of the other extracts. These results, therefore, indicated that the antioxidant activity and cholesterol secretion inhibiting ability of black raspberry were reduced during maturation and thus the water extract of unripe black raspberry could be suitable for application in functional foods and medicial materials.