[Optimized extraction of active components of Paeonia lactiflora and their antioxidant, anti-inflammatory and pigmentation-reducing effects for skin whitening].

OBJECTIVES: To optimize the extraction process of the active components of Radix Paeoniae Alba and assess the antioxidant, anti-inflammatory and pigmentation-reducing effects of Radix Paeoniae Alba extract (BST). Methods Molecular docking identified gallic acid, liquiritin, and paeoniflorin as potential tyrosinase inhibitors, and their contents in BST were determined with high-performance liquid chromatography (HPLC). Based on the contents of the 3 inhibitors, their tyrosinase-inhibiting activity, and DPPH radical scavenging capacity calculated using entropy weight method, the extraction conditions were optimized for solvent ratio, liquid-to-solid ratio, extraction time, and particle size. The inhibitory effects of BST on tyrosinase activity and melanin were assessed in α‑MSH-treated B16F10 cells, and its effect on reactive oxygen species (ROS) production was evaluated in H₂O₂-treated HaCaT cells. In a mouse model of melanogenesis induced by UVB radiation, the effect of BST gavage (100, 150, and 200 mg/kg) were evaluated by assessing skin conditions of the mice, Fontana-Masson staining, and detecting serum levels of cytokines related to melanogenesis, melanosome transport, metabolism, and inflammation.

RESULTS: The optimized parameters for BST extraction included 50% ethanol, liquid-to-solid ratio of 15:1, extraction time of 1 h, and 20-mesh particle size. BST exhibited strong free radical-scavenging activity and significantly reduced melanogenesis and increased tyrosinase protein in B16 cells, and lowered ROS production in HaCaT cells. In the mouse models of melanogenesis, BST significantly suppressed the melanogenic enzymes and inflammatory responses by reducing the levels of tyrosinase and TNF-α, thereby effectively reversed UVB-induced photoaging and hyperpigmentation.

CONCLUSIONS: The optimized BST extraction process is stable and predictable. BST shows good skin-whitening effect, which is mediated possibly by inhibiting tyrosinase activity and modulating oxidative stress and inflammatory pathways.