Chemical profile of craft brewer's spent yeast and its antioxidant and antiproliferative activities

Brewer's spent yeast (BSY) is a prevalent by-product of the brewing industry currently used in animal feed as a cheap source of protein. In this study, chemical composition of BSY from two different beer production (American IPA, BSY1, and Imperial Stout, BSY2) was characterized, aiming for potential use as nutraceutical sources. Cytotoxicity of BSY extracts was also tested in freshly isolated peripheral blood mononuclear cells (PBMCs) and in tumoral (pancreatic cancer tumor cells, PANC-1, and colorectal adenocarcinoma tumor cells, CACO-2) and non-tumoral (umbilical vein endothelial cells, HUVEC) cell lineages. BSY samples showed similar lipid and ash content, but slight differences in the content of reducing sugars, total proteins, moisture and total proteins. BSY2 sample presented higher glucans and phenolic compound concentrations than BSY1. Main phenolic compounds identified were xanthohumol, ferulic acid, p-coumaric acid (BSY1 and BSY2), and gallic acid (BSY2). BSY1 and BSY2 extracts showed similar antioxidant capacity. Neither BSY1 nor BSY2 were cytotoxic to PBMCs, HUVEC and CACO-2, but were cytotoxic to PANC-1 cells, in a concentration-dependent manner. Our findings revealed that the residue of brewery can be a value-added functional food product with an adjuvant role against PANC-1 cell lines.