Standardized Curcuma longa-Cannabis sativa extract derived from a traditional Thai formulation for psoriasis: anti-inflammatory activity, keratinocyte modulation, and skin-targeted delivery.

ETHNOPHARMACOLOGICAL RELEVANCE: Curcuma longa rhizomes and Cannabis sativa leaves are traditionally combined in Thai topical remedies using cottonseed oil. However, the pharmacological basis and dermal delivery of this combination remain unclear. AIM OF THE STUDY: This study evaluated a standardized Thai CL-CS combined extract (CLCS) by integrating phytochemical characterization, psoriasis-relevant biological activities, and ex vivo skin deposition and permeation, with comparison to the single extracts. MATERIALS AND METHODS: CLCS was standardized by validated HPLC using curcuminoids, ar-turmerone, and cannabidiol as markers. Anti-inflammatory activity was evaluated in RAW264.7 macrophages, while psoriasis-relevant activity was assessed in TNF-α/IL-17A-stimulated HaCaT keratinocytes. Skin deposition and permeation were evaluated using porcine ear skin and Franz diffusion cells. RESULTS: CLCS contained bisdemethoxycurcumin (18.79 ± 1.54 mg/g), demethoxycurcumin (12.89 ± 1.02 mg/g), curcumin (22.12 ± 1.62 mg/g), ar-turmerone (75.35 ± 3.94 mg/g), and cannabidiol (35.47 ± 2.39 mg/g). IC50 values were 41.22 ± 1.70 and 22.91 ± 0.51 μg/mL in HaCaT and RAW264.7 cells, respectively. At 12.5 μg/mL, CLCS inhibited NO and PGE2 production by 48.97 ± 0.88% and 91.15 ± 3.66%, respectively, and modulated psoriasis-associated genes. Cottonseed oil containing 20% DG achieved the highest skin deposition of BCM, DCM, and CM, with no detectable markers in the receptor compartment over 24 h. CONCLUSIONS: Standardized CLCS exhibited anti-inflammatory and psoriasis-relevant activities and preferential skin deposition, supporting its potential as a localized phytotherapeutic approach for psoriasis.