Antioxidant and Anti-Inflammatory Activities of Tannin Fraction of the Extract from Black Raspberry Seeds Compared to Grape Seeds

Abstract

Black raspberry seed extract and its tannin fraction were characterized and their antioxidant and anti-inflammatory activities were compared to grape seed extract and its tannin fraction. Tannin fraction of black raspberry seed extract was mostly composed of ellagitannins including pedunculagin, sanguiin H6 and H10 isomers and galloyl-bis-HHDP glucose isomer, while that of grape seed extract was composed of proanthocyanidins including proanthocyanidin dimers, trimers, tetramers, pentamers, their monogallates and hexamers. Antioxidant activities of the tannin fraction of black raspberry seed extract, measured by polyphenol content, FRAP, DPPH and ABTS assays, were significantly higher than those of grape seed extract. Anti-inflammatory activity of the tannin fraction of black raspberry seed extract, measured by NO assay, was also significantly higher than that of grape seed extract. The results indicate that black raspberry seeds have potential benefits as a source of natural antioxidant and anti-inflammatory agents comparable to grape seeds. Practical Applications Black raspberry and grape fruits are widely consumed in various ways including wine, juice or raw fruits. Many byproducts, including seeds and wine pomace, are an attractive source of functional compounds. Our results show that the tannins extracted from the seeds have potential antioxidant and anti-inflammatory activities. Thus, these results may help increase utilization of byproducts to make dietary supplements. This may also reduce the waste products generated by the industry and provide additional profit to farmers and manufacturers.