Bacillus subtilis Fermentation Augments the Anti-Inflammatory and Skin Moisture Improvement Activities of Tetragonia tetragonoides through the Upregulation of Antioxidant Components

This study demonstrates that the fermentation of Tetragonia tetragonioides (T. tetragonioides) by Bacillus subtilis (B. subtilis) subsp. spizizenii enhances its antioxidant, anti-inflammatory, and skin-moisturizing activities. Fermented T. tetragonioides extracts (FTEs) showed a significant increase (p < 0.05) of approximately 1.3 to 3.07 times in their total polyphenol content (TPC), total flavonoid content (TFC), and vanillic acid content compared to pre-fermentation T. tetragonioides extracts (TEs). Additionally, the 2,2-diphenyl-1-picrylhydrazyl (DPPH)- and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical-scavenging activities were significantly higher (p < 0.05) in FTEs than in TEs, showing an increase of about 1.25 to 1.64 times. The anti-inflammatory effects, evaluated through the inhibition of nitric oxide (NO) in RAW 264.7 cells stimulated by lipopolysaccharide (LPS), revealed that FTEs exhibited significant (p < 0.05) NO inhibition activity at less than half the concentration of TEs. It is particularly noteworthy that the FTE at 200 μg/mL significantly suppressed the expression of the cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and tumor necrosis factor-alpha (TNF-α) proteins. In HaCaT cells, FTEs substantially (p < 0.001) increased the mRNA expression of filaggrin (FLG), hyaluronan synthase (HAS)-1, and HAS-3, indicating improved skin protection and moisturization. In conclusion, this study confirms that T. tetragonioides’ antioxidant, anti-inflammatory, and skin-moisturizing activities are enhanced by B. subtilis fermentation, suggesting the potential of FTEs as a cosmeceutical ingredient.