Cytochemical assessment of brewers’ spent grain (BSG) extract bioactivities

Brewers’ spent grain (BSG) is a useful source of protein and phenolic compounds which can be obtained via different extraction methods. The aim of this thesis was to assess protein hydrolysates and phenolic extracts generated from BSG using various extraction procedures, for their potential as functional food ingredients with anti-inflammatory, antioxidant, anticancer and neuroprotective properties. Firstly, the anti-inflammatory effects of an alkaline-extracted BSG protein rich fraction and three ultrafiltration-generated fractions added to milk and subjected to simulated gastrointestinal digestion (SGID) was shown in Jurkat T cells. Enzyme extraction methods were then used to produce phenolic fractions with strong bioactivities. The cellular antioxidant potential of both black and pale BSG phenolic extracts isolated using carbohydrases was demonstrated in U937 cells and HepG2 cells. Following this, the ability of the most active phenolic extracts to enhance the antioxidant potential of flavoured water drinks before and after SGID was investigated. However, none of the phenolic extracts added to water drinks significantly increased antioxidant activity. In other studies the anti-cancer potential of a pale BSG phenolic extract was demonstrated, through the increase of apoptosis in U937 cells. Additionally, the neuroprotective potential of both black and pale BSG phenolic extracts was shown in SK-N-BE(2) neuronal cells, where extracts protected against hydrogen peroxide (H2O2)-induced cytotoxicity, H2O2-induced apoptosis and H2O2-induced lipid peroxidation. Finally, the cytotoxicity, anti-inflammatory activity and antioxidant potential of BSG protein hydrolysates generated using different extraction procedures was assessed and compared. Direct enzymatic hydrolysates demonstrated anti-inflammatory activity in Jurkat T cells and RAW 264.7 cells. Alkaline-extracted BSG protein hydrolysates, as well as a 10kDa permeate showed anti-inflammatory effects in RAW 264.7 cells. As well as this, unhydrolysed fractions, a direct enzymatic hydrolysate, alkaline-extracted BSG protein hydrolysates, as well as a 10kDa permeate also displayed cellular antioxidant effects in U937 cells and HepG2 cells