Enhancement of bioactive compounds, antioxidant capacity, and inhibitory effects on mushroom tyrosinase, α-glucosidase, and nitric oxide production in sorghum (Sorghum bicolor L.) via solid-state fermentation with Monascus purpureus

Abstract

Sorghum (Sorghum bicolor) is a gluten-free supercrop with a high content of phenolic compounds, along with anti-nutrient factors such as tannin that limit its use in food. In this study, we conducted solid-state fermentation for sorghum with Monascus purpureus to reduce the tannin content and value-added sorghum by enhancing biological properties. The results showed that fermented sorghum had 1.39- and 240 times higher total flavonoid and l-carnitine contents than non-fermented sorghum, while the tannin content was reduced by 2.26 times. Gallic acid and vanillic acid were newly detected, while catechin, caffeic acid, ferulic acid, vanillin, and protocatechuic acid contents of sorghum were enriched 2.73–14.42 times after fermentation. The antioxidant activities of sorghum increased by 1.45–1.98 times compared to non-fermented sorghum. The inhibition of α-glucosidase and mushroom tyrosinase of fermented sorghum was enhanced 2.0- and 1.42 times, while the inhibition of nitric oxide was maintained in LPS-stimulated RAW264.7 murine macrophage cells.