Safety profiling and skin barrier characterization of a topical herbal cream containing <i>Ficus deltoidea</i> leaf extract

Ficus deltoidei, a medicinal plant traditionally used in Southeast Asia, is rich in bioactive flavonoids such as vitexin and isovitexin. Despite its long-standing use in traditional medicine, scientific validation of its dermatological benefits remains limited. This study aimed to evaluate the in vitro safety of F. deltoidea leaf extract and the efficacy of a topical herbal cream containing F. deltoidea leaf extract in promoting skin barrier recovery, including transepidermal water loss (TEWL), hydration, melanin, erythema and elasticity. The safety of F. deltoidea leaf extract was evaluated using three in vitro assays: a reconstructed human epidermis (RHE) model for irritation assessment, a direct peptide reactivity assay (DPRA) for skin sensitization potential and a direct cell contact cytotoxicity test on L-929 mouse fibroblast cells. The extract was categorized as a non-irritant in the RHE test, with tissue viability remaining above 50%. All acceptance criteria were met, showing an average peptide depletion of 10.21% in the DPRA, classifying it as low reactive, and it was found to be non-cytotoxic at a 0.1% concentration. An in vivo tape-stripping model was employed in 20 human volunteers to simulate superficial skin barrier disruption. The test sites were treated with F. deltoidea cream, placebo cream, or untreated skin (control). Treatment with F. deltoidea cream significantly accelerated skin barrier repair, as evidenced by a marked reduction in TEWL and improved hydration compared with the placebo and control groups. The formulation also reduced erythema and melanin levels, indicating anti-inflammatory and anti-melanogenic effects, and enhanced skin elasticity, suggesting anti-aging potential. Pearson's correlation analysis revealed strong interdependence among the parameters, with TEWL being negatively correlated with hydration (r = -0.96) and elasticity (r = -0.84), whereas hydration was positively correlated with elasticity (r = 0.95). The therapeutic effects of F. deltoidea cream are attributed to its flavonoid content and antioxidant properties. This study provides scientific support for the traditional use of F. deltoidea in skin-related treatments. Further investigations into the mechanism of ceramide synthesis in the stratum corneum are warranted.