Phenolic-enriched fractions from brewers' spent grain possess cellular antioxidant and immunomodulatory effects in cell culture model systems

Abstract

Large quantities of brewers' spent grain (BSG), a co-product of the brewing industry, are produced annually. BSG contains hydroxycinnamic acids, and phenolic-rich extracts from BSG have previously demonstrated the ability to protect against oxidant-induced DNA damage. The present study investigated the anti-inflammatory potential of eight phenolic extracts from BSG: four pale (P1-P4) and four black (B1-B4) extracts. BSG extracts were more cytotoxic in Jurkat T than U937 cells, with lower IC₅₀ values in Jurkat T cells, measured using the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Pale BSG extracts P2 and P3 showed the greatest anti-inflammatory potential, significantly (P < 0.05) reducing interleukin-2 (IL-2), interleukin-4 (IL-4, P2 only), interleukin-10 (IL-10) and interferon-γ (IFN-γ) production. In addition, extracts P1-P3 and B2-B4 showed significant (P < 0.05) antioxidant effects, determined by the cellular antioxidant activity assays superoxide dismutase, catalase and glutathione content (GSH). Phenolic extracts from BSG, particularly the pale BSG extracts, have the ability to reduce a stimulated cytokine production and may also protect against cellular oxidative stress. Results of the present study highlight the potential of BSG phenolic extracts to act as functional food ingredients, providing an alternative use and improving the value of this brewing industry co-product.