Multifunctional Cosmetic Applications of Houttuynia cordata Essential Oil: Enhancing Antioxidant, Antibacterial, and Wound Healing Activities in Topical Formulations

Houttuynia cordata essential oil (HCEO) shows significant potential as a multifunctional ingredient for acne-focused phytocosmetics. This study investigates its volatile compounds, antimicrobial, antioxidant, wound-healing, anti-melanogenic, and anti-inflammatory properties, along with the stability of topical formulations. GC-MS analysis identifies n -decanoic acid (46.3%), 2-undecanone (11.0%), and dodecanoic acid (7.2%) as the main components. HCEO exhibits strong antimicrobial activity, with an MBC of 3.125 µg/mL against Staphylococcus aureus , Cutibacterium acnes , and Candida albicans . It also shows antioxidant activity, with IC ₅₀ values of 13.25 mg/mL (DPPH) and 17.44 mg TEAC/g (FRAP). No cytotoxicity is observed in NIH/3T3 fibroblasts and RAW 264.7 macrophages at concentrations up to 500 µg/mL. HCEO enhances fibroblast migration by 26.94% at 400 µg/mL in wound scratch assays. It inhibits melanin synthesis in B16F10 and A375 cells, with IC ₅₀ values of 200.61 and 152.16 µg/mL, respectively, and tyrosinase activity, with an IC ₅₀ of 48.00 µg/mL. Additionally, HCEO reduces nitric oxide production in LPS-stimulated macrophages, with an IC ₅₀ of 176 µg/mL. An oil-in-water emulsion containing HCEO demonstrates better stability than a gel formulation. These findings suggest HCEO is a safe, stable, and effective natural ingredient for advanced skincare, particularly for acne and skin inflammation.