Effect of Chimpi, dried citrus peel, on aquaporin-3 expression in HaCaT human epidermal keratinocytes

Background Chimpi, the dried peel of Citrus unshiu or Citrus reticulata, has various pharmacological effects. Chimpi extract was recently shown to affect the skin, including its inhibitory effect against atopic dermatitis. In this study, we analyzed the effects of Chimpi extract on the functional molecule aquaporin-3 (AQP3), which is involved in water transport and cell migration in the skin. Methods and Results Chimpi extract was added to HaCaT human skin keratinocytes, and the AQP3 expression level was analyzed. A wound healing assay was performed to evaluate the effect of Chimpi extract on cell migration. The components of Chimpi extract and fractions obtained by liquid-liquid distribution studies were added to HaCaT cells, and AQP3 expression was analyzed. Chimpi extract significantly increased AQP3 expression in HaCaT cells at both the mRNA and protein levels. Immunocytochemical staining revealed that Chimpi extract also promoted the transfer of AQP3 to the cell membrane. Furthermore, Chimpi extract enhanced cell migration. Hesperidin, narirutin, and nobiletin did not increase AQP3 levels. Although the components contained in the fractions obtained from the chloroform, butanol, and water layer increased AQP3, the active components could not be identified. Conclusions These results reveal that Chimpi extract may increase AQP3 levels in keratinocytes and increase the dermal water content. Therefore, Chimpi extract may be effective for the management of dry skin.