Changes Over the Fermentation Period in Phenolic Compounds and Antioxidant and Anticancer Activities of Blueberries Fermented by Lactobacillus plantarum

This study determined the effects of blueberry fermentation by Lactobacillus plantarum on antioxidant and anticancer activities. The fermented blueberries extracted with 80% ethanol (FBE) showed increased superoxide dismutase-like activity, increased scavenging of DPPH and alkyl radicals, and increased antiproliferative activity against human cervical carcinoma HeLa cells by inducing apoptosis. Seven representative phenolic compounds (malvidin 3-O-glucopyranoside, gallic acid, protocatechuic acid, catechol, chlorogenic acid, syringic acid, and epigallocatechin) in FBE were measured by high-performance liquid chromatography at different fermentation times. The content of each phenolic compound in the FBE was dependent on the fermentation period. Protocatechuic acid and catechol levels increased significantly with fermentation time. Of these three major compounds (protocatechuic acid, catechol, and chlorogenic acid), catechol showed the most significant anticancer activity when HeLa cells were treated with each of these three compounds alone or mixed in various ratios. Pearson's product-moment correlation analysis revealed that the increases in antioxidant and anticancer activities following blueberry fermentation were positively correlated with the phenolic acids present in FBE. PRACTICAL APPLICATION: Blueberries fermented with a tannase-producing lactic acid bacteria (LAB), Lactobacillus plantarum showed higher antioxidant activities and antiproliferative activities against human cervical carcinoma HeLa cells than did raw blueberries. L. plantarum fermentation biotransformed blueberry polyphenols into active phenol metabolites with strong antioxidant and antiproliferative activities. Our results suggest that fermented blueberries are rich in phenolic acids, which are a promising source of natural antioxidants and anticancer drugs and can be used as additives in food, pharmaceuticals, and cosmetic preparations.