| The primary objectives of this study were to devise a separation method capable of isolating oligomeric proanthocyanidins, test the proanthocyanidins in a number of in vitro biological assays including anticancer, antiadhesion, and antioxidant, and evaluate how bioactivity changes when blueberries are incorporated into processed food products. A novel separation method was successfully developed that isolated high molecular weight proanthocyanidin oligomers from other simpler polyphenols while eliminating sugars and other inactive compounds that interfere with in vitro biological assays. This study revealed that a wild blueberry (Vaccinium angustifolium Ait.) fraction rich in proanthocyanidins (fraction 5 from Toyopearl, extracted with 50% acetone) inhibited the growth of hepa-1c1c7 mouse liver cancer and LNCaP human prostate cancer cells without cytotoxicity, and inhibited adhesion of E. coli bacteria implicated in urinary tract infections. In an experiment comparing antiproliferation activity of wild and cultivated (Vaccinium corymbosum L.) blueberry fractions in LNCaP cells (androgen sensitive) to DU145 cells (androgen insensitive), LNCaP cell growth was dramatically reduced by three pro anthocyanidin-rich fractions (fraction 5 from wild blueberry; fractions 4 & 5 from cultivated blueberry) whereas DU145 cell growth was only slightly inhibited by one fraction (cultivated blueberry fraction 4). This data suggests proanthocyanidins may have an effect primarily on androgen dependent growth of prostate cancer cells. When wild and cultivated blueberries were heated in the course of food processing, antiproliferation activity in hepa-1c1c7 and LNCaP cells was compromised. Several blueberry food products were surveyed including fresh, individually quick frozen (IQF), freeze-dried, spray-dried, heat-dried, cooked, juice concentrate, pie filling, and jam. The products were fractionated and tested for total phenols, hepa-1c1c7 and LNCaP antiproliferation, FRAP antioxidant, and DPPH radical scavenging activity. In general, products that were heat processed retained a majority of the antioxidant activity and total phenolics found in unprocessed whole fruit (fresh and IQF). However, the heat treated products lacked or had diminished antiproliferation activity suggesting that although products may be high in phenolic compounds and antioxidant activity, other forms of bioactivity may be compromised by harsh processing methods. |
