Sinomenine from Sinomenium acutum Rhizome: A Promising Bioactive Ingredient Associated with Hair-Growth Promotion

Androgenetic alopecia (AGA) is characterized by disruption of the hair-growth cycle and alterations in growth-related and inflammatory signaling. Sinomenium acutum and its major compound, sinomenine (SIN), have been reported to possess antioxidant and anti-inflammatory activities; however, their effects on hair growth regulation remain unclear. Therefore, the aim of this study was to investigate the effects of S. acutum rhizome extract (SAE) and SIN on hair cycle transition and explore the associated molecular changes. In vivo and in vitro models were used to determine the effects of SAE and SIN and their correlation with hair-growth-promoting and inhibitory factors, as well as the associated Wnt/β-catenin signaling pathway and inflammatory responses. Sinomenine significantly upregulated the expression of vascular endothelial growth factor, basic fibroblast growth factor, and β-catenin but suppressed that of transforming growth factor-β1, dickkopf-1, and proinflammatory cytokines, which was associated with anagen phase induction. It also showed concentration-dependent effects in vitro at nanomolar concentrations, suggesting that it contributes to the activity of SAE. Histopathological analyses showed an increased number of anagen follicles and improved hair shaft elongation in the treated groups, consistent with enhanced anagen entry. In addition, sinomenine attenuated dihydrotestosterone (DHT)-induced changes in human dermal papilla cells (HDPCs), which were associated with growth factor and inflammatory markers. These findings suggest that SIN is a promising bioactive compound for hair care applications, although further validation is required.