Valorisation of Whisky Distillery Waste as a Sustainable Source of Antioxidant and Antibacterial Properties with Neuroprotective Potential

Purpose Waste by-products such as pot ale are abundantly produced during the whisky distillation process and are conventionally used as livestock feed, however a significant proportion continues to require land and sea disposal. Here, the novel potential of whisky by-products as antioxidant and antibacterial agents was investigated. Methods The total phenolic content and antioxidant potential of waste by-products from whisky distillation were evaluated using FC and DPPH assays. Their DNA protective properties were assessed with gel electrophoresis. The cytotoxicity and cell protective effects of pot ale, in addition to its antibacterial activity, were also studied in this work. Results Pot ale demonstrated the strongest antioxidant activity of the by-products tested and could reduce DNA damage by 52% at 0.5 mg/mL. Furthermore, pot ale was non-toxic in a neuroblastoma cell line up to 5 mg/mL and protected against the toxic effects of two inducers of oxidative stress (rotenone and hydrogen peroxide) by up to 1.25-fold. Pot ale also showed potent antibacterial activity against Escherichia coli and Staphylococcus aureus with the minimum inhibitory concentration of 25 µg/mL and 1.56 µg/mL respectively. Conclusion This work provides the first evidence of the potential of whisky by-products as antioxidants and antimicrobials with no adverse effects in cells, thereby promoting a circular economy. Graphical Abstract