Skin Protective Effects of Acid-stress Sorghum Fermentation by Extremophile Monascus pilosus against UV-induced Inflammation and Photoaging

Ultraviolet (UV) radiation causes skin damage including oxidative stress, inflammation, and photoaging. Extremophile fermentation products have been found to effectively protect the skin from UV-induced damage. This study aimed to investigate the impact of acid-induced stress on the content of bioactive compounds, as well as the anti-inflammatory and anti-photoaging properties of sorghum fermentation by the extremophilic Monascus pilosus. The study compared acid-stress fermentation (ASF) of sorghum with conventional fermentation (CF) and examined differences in total phenolic content, antioxidant activity, and short-chain fatty acid levels. Using gas chromatography–mass spectrometry assay, the ASF sample had lower total phenolic content compared to CF, but significantly higher levels of short-chain fatty acids. Butyric acid was the predominant metabolite in the ASF sample, followed by propionic acid. The ASF sample exhibited superior protection for UV-irradiated human keratinocytes by inhibiting apoptosis, reducing ROS, and downregulating inflammatory mediators. It also decreased metalloproteinases expression levels, increased collagen and elastin production, and mitigated UV-induced photoaging. The effects of ASF samples were evaluated in volunteers, and the results confirmed the ASF sample's effectiveness in ameliorating UV-induced skin symptoms, including pigmentation, redness, and wrinkles. These findings conclude that acid-stress enhances the anti-inflammatory and anti-photoaging capabilities of Monascus pilosus fermented sorghum.