Time-Dependent Modulation of Phenolics, Polysaccharides, and Bioactivities in Artemisia argyi Leaves During Solid-State Fermentation with Rhizopus oryzae

This study investigated the biotransformation of bioactive compounds in Artemisia argyi leaves, a traditional plant food, via solid-state fermentation (SSF) with Rhizopus oryzae. Over a 10-day period, total phenolic and flavonoid contents increased by 241.46% and 104.67%, respectively, while polysaccharides peaked on day 2. Antioxidant activity was significantly enhanced, with the values of half maximal inhibitory concentration (IC50) for DPPH, ABTS, hydroxyl, and superoxide anion radicals reduced by up to 59.26%. Chemical characterization via GC-MS revealed selective enrichment of oxygenated monoterpenes (e.g., eucalyptol, borneol), indicating fungal-mediated conversion of secondary metabolites. Fermented extracts exhibited potent xanthine oxidase inhibition (34.04% at 100 μg/mL), indicating potential anti-hyperuricemic activity, and tyrosinase inhibition (50.02%). Compared to liquid-state fermentation (LSF), previous studies have reported that SSF by R. oryzae provides a sustainable, low-moisture fermentation mode that can enhance metabolite stability and help preserve volatile components. These findings highlight an effective biotransformation strategy for valorizing herbal materials with enhanced antioxidant and enzyme inhibitory properties.