Effects of a standardized extract of asparagus officinalis stem on photoaging in the epidermal layer of the skin using cultured keratinocytes

Abstract

A standardized extract of Asparagus officinalis stem (EAS) is prepared from the lower residual parts of the plant. It is known to have antioxidative and neuroprotective activities. The purpose of the present study was to investigate the effects of EAS on photoaging in the epidermal layer of the skin using cultured keratinocytes. Normal human epidermal keratinocytes were irradiated or unirradiated with UV-B (10 mJ/cm2) and incubated with EAS (0.5 or 2 mg/mL) or vehicle. After 3 or 13 hours, molecular examinations were performed, and after 24 or 48 hours, cell viabilities were determined by a CCK-8 assay. EAS treatment upregulated the mRNA level of heparin-binding EGF-like growth factor in cultured keratinocytes 13 hours after UV-B irradiation. On the other hand, EAS downregulated caspase-9 and endothe-lin-1 mRNA levels in UV-treated keratinocytes. EAS also increased cell viability on keratinocytes 24 hours after UV-B irradiation. These results suggested that EAS might accelerate the migration of keratinocytes and protect the cells against damage induced by UV-B irradiation. Furthermore, EAS might inhibit melanocyte proliferation and UV-induced hyperpigmentation.