Effects of Vigna angularis extract and its active compound hemiphloin against atopic dermatitis-like skin inflammation

Vigna angularis is an edible crop and herbal medicine that is known to have antipyretic, anti-inflammatory, and anti-edema effects. Many studies have been conducted on the 95% ethanol extract of V. angularis, but there is little research on the 70% ethanol extract and hemiphloin, which is a new indicator component of the 70% ethanol extract of V. angularis. To investigate the in vitro anti-atopic effect and verify the mechanism action of 70% ethanol extract of V. angularis (VAE), TNF-α/IFN-γ-induced HaCaT keratinocytes were used. The VAE treatment alleviated TNF-α/IFN-γ-induced IL-1β, IL-6, IL-8, CCL17/TARC, and CCL22/MDC gene expressions and productions. VAE also inhibited the phosphorylation of MAPKs, including p38, ERK, JNK, STAT1, and NF-κB in TNF-α/IFN-γ-induced HaCaT cells. 2,4-dinitochlorobenzene (DNCB)-induced skin inflammation mice model, and HaCaT keratinocytes were used. In the DNCB-induced mouse model, VAE treatment alleviated ear thicknesses and IgE levels. Furthermore, VAE decreased IL-1β, IL-6, IL-8, CCL17/TARC, and CCL22/MDC gene expressions of DNCB-applied ear tissue. Additionally, we investigated the anti-atopic and anti-inflammatory effects of hemiphloin using TNF-α/IFN-γ-induced HaCaT keratinocytes and LPS-induced J774 macrophages. Treatment hemiphloin decreased gene expressions and productions of IL-1β, IL-6, IL-8, CCL17/TARC, and CCL22/MDC in TNF-α/IFN-γ-induced HaCaT cells. The phosphorylations of p38, ERK, STAT1, and NF-κB were inhibited by hemiphloin in TNF-α/IFN-γ-induced HaCaT cells. Finally, hemiphloin showed anti-inflammatory activities in LPS-induced J774 cells. It decreased LPS-induced NO productions and iNOS and COX-2 expressions. Treatment of hemiphloin also inhibited LPS-induced TNF-α, IL-1β, and IL-6 gene expressions. These results suggest that VAE is an anti-inflammatory agent for inflammatory skin diseases and that hemiphloin could be a therapeutic candidate for inflammatory skin diseases.