Topical Trichosanthis Radix Water Extract Attenuates Atopic Dermatitis-Like Skin Inflammation: Marker Standardization, Network Pharmacology, and Preclinical Validation.

Trichosanthis Radix (TR) is a pharmacopeial crude drug traditionally used to clear heat, reduce swelling, expel pus, and generate fluids, suggesting potential relevance to inflammatory skin disorders such as atopic dermatitis (AD). In this study, we evaluated the AD-related activity of a TR water extract using an integrated workflow combining network-based target analysis, marker compound analysis, and experimental validation in vivo and in vitro. The overlap between predicted TR targets and AD-associated genes was analyzed using a protein-protein interaction network, and extract was analyzed by high performance liquid chromatography (HPLC)-evaporative light scattering detector (ELSD). Biological effects were examined in DNCB-induced murine dermatitis and TNF-α/IFN-γ-stimulated HaCaT keratinocytes. Twenty-five overlapping genes formed a compact interaction module enriched for immune signaling and lipid/nuclear receptor-related pathways, and HPLC-ELSD detected and quantified L-citrulline as a marker compound for TR extract standardization. Topical TR reduced dermatitis severity, attenuated epidermal hyperplasia, and decreased dermal mast cell accumulation, with more consistent effects at the higher dose. TR also lowered lesional chemokine transcripts, particularly CCL17/TARC and CCL5/RANTES, and was associated with reduced NLRP3 and IL-1β. In addition, TR suppressed DNCB-induced phosphorylation of MEK/ERK and JAK2-STAT1 and decreased p-STAT1 immunofluorescence. In HaCaT cells, TR attenuated cytokine-induced inflammatory effectors and phosphorylation of MEK/ERK and STAT1. These findings indicate that TR water extract mitigates AD-relevant inflammatory signaling while improving a barrier-associated outcome, supporting further constituent-resolved and mechanism-directed studies.