Silybin Derivative B1 Inhibits Myofibroblast Activation via Wnt/DAAM2 and Ameliorates Oral Submucous Fibrosis in Mice

INTRODUCTION AND AIMS: Oral submucous fibrosis (OSF) is a chronic, potentially malignant disorder (PMD) of the oral mucosa; however, current clinical therapies provide limited and often transient benefits. Silybin, a natural flavonolignan derived from milk thistle seeds, has demonstrated hepatoprotective and anti-fibrotic properties. However, the therapeutic efficacy and pharmacological mechanisms of silybin derivative B1 in OSF remain unclear. Therefore, this study evaluates the therapeutic potential of B1 in OSF and elucidates its underlying mechanisms. METHODS: Derivative B1 was synthesised through the structural modification of silybin. Its inhibitory effects on fibrosis-related proteins, including COL1A1, FN, and α-SMA, as well as on cell migration, were first evaluated in vitro. The in vivo therapeutic efficacy of B1 was investigated in an OSF mouse model. Transcriptomic analysis was further performed to investigate the pharmacological mechanisms underlying the anti-OSF activity of B1. RESULTS: In vitro experiments identified B1 as a potent anti-fibrotic candidate. B1 significantly reduced the protein expression of key fibrotic markers, including COL1A1, FN, and α-SMA. Wound-healing assays demonstrated that B1 significantly inhibited myofibroblast migration. B1 significantly ameliorated bleomycin-induced oral submucous fibrosis in mice in vivo. Transcriptome sequencing further revealed differential regulation of the Wnt pathway and identified DAAM2 as a predominantly downregulated gene. Functional experiments showed that B1 exerted its effects through the noncanonical Wnt pathway. CONCLUSION: B1 inhibits myofibroblast activation and migration through noncanonical Wnt/DAAM2 signalling pathway regulation, exerting anti-OSF effects. CLINICAL RELEVANCE: B1 may represent a promising adjunctive candidate for the early-stage management of OSF, and Wnt/DAAM2 signalling may serve as a potential therapeutic target in fibro-inflammatory oral disease.