Terminalia chebula Retz. Fruit Extract Promotes Murine Hair Growth by Suppressing 5α-Reductase and Accelerating the Degradation of Dihydrotestosterone.

Background/Objectives: Androgenetic alopecia (AGA) is the most common hair loss disorder in dermatological practice. Its primary pathogenesis involves the conversion of testosterone to dihydrotestosterone (DHT) by type II 5α-reductase upon reaching dermal papilla cells (DPCs). DHT impairs DPCs' activity and inhibits hair growth. Although the FDA-approved drugs finasteride and minoxidil show certain efficacy, they are also associated with severe side effects. This study aims to explore the effects of Terminalia chebula fruit extract (TCFE) on hair growth and its underlying molecular mechanisms. Methods: We investigated the therapeutic potential of TCFE in hair follicle regeneration, employing a multi-level experimental approach combining in vitro analyses of DPCs, in vivo animal models of AGA, and ex vivo cultures of human hair follicles and scalp tissue. Results: First, RNA-seq analysis and RT-PCR validation revealed that TCFE treatment activated the Wnt and TGF-β3 signaling pathways in DPCs, particularly upregulating the AKR1C gene family, which is involved in DHT metabolism. TCFE also potently inhibited type II 5α-reductase activity and mitigated DHT-induced damage to DPCs. In an AGA mouse model, TCFE reversed the AGA phenotype with efficacy comparable to finasteride. However, unlike finasteride, TCFE specifically enhanced the expression of AKR1C1 and AKR1C3, indicating a distinct mechanism. Finally, in ex vivo organ cultures, TCFE suppressed hair follicle cell apoptosis, promoted proliferation, and thereby stimulated hair growth. Conclusions: These findings suggest that TCFE is a promising natural treatment for AGA, likely acting through multiple mechanisms, including Wnt pathway activation, 5α-reductase inhibition, and enhanced DHT degradation.