Skin‑Protective and Anti‑inflammatory Effects of Hibiscus syriacus L. (Mugunghwa): A Comparative Study of Five Parts of the Plant

Abstract

Aim: The skin barrier is vulnerable to internal and external elements. However, certain plant extracts have promise for protecting the skin. Hibiscus syriacus L. is a Korean national plant (mugunghwa) that has been traditionally used to treat some skin diseases; however, its pharmacological activities are poorly understood. The present study has evaluated the skin‑protective effect of mugunghwa flowers (MF), cortexes (MC), roots (MR), leaves (ML), and seeds (MS) in external factor‑stimulated human epidermal keratinocytes (HaCaTs), normal human dermal fibroblasts (NHDFs), and a widely used murine macrophage cell line (RAW 264.7 cells). Materials and Methods and Results: The active components were identified as palmitic acid and linoleic acid by high‑performance liquid chromatography analysis. The parts of mugunghwa had low 2,2‑diphenyl‑1‑picrylhydrazyl scavenging activities but moderate 2,2’‑azino‑bis (3‑ethylbenzothiazoline‑6‑sulfonic acid) diammonium salt scavenging capacity. All parts’ extracts at 100 µg/mL decreased nitric oxide production in inflammation‑induced RAW 264.7 cells and mRNA expression of the cytokines interleukin‑6/1β and the enzymes inducible nitric oxide synthase/ cyclooxygenase‑2. On HaCaTs, MF, MC, and MR (10–50 µg/mL) significantly increased hyaluronan production over that of controls. Moreover, MF activated NAD (P) H:quinone oxidoreductase 1 and heme oxygenase‑1 and inhibited intracellular reactive oxygen species production. Treatment with MF, MC, MR, ML, and MS (10 µg/mL) reduced the scratching wound site in NHDFs to be considered by vascular endothelial growth factor signaling activation.Conclusion: Taken together, among all the five parts of the mugunghwa plant, MF effectively inhibited lipopolysaccharide, ultraviolet B irradiation, and scratching wound‑induced inflammation in skin cells.

Keywords: Hibiscus syriacus L; hyaluronan; skin inflammation; ultraviolet B; wound