A standardized extract of Asparagus officinalis stem prevents reduction in heat shock protein 70 expression in ultraviolet-B-irradiated normal human dermal fibroblasts: an in vitro study

Background: Heat shock protein 70 (HSP70) exhibits protective effects against ultraviolet (UV)-induced premature skin aging. A standardized extract of Asparagus officinalis stem (EAS) is produced as a novel and unique functional food that induces HSP70 cellular expression. To elucidate the anti-photoaging potencies of EAS, we examined its effects on HSP70 expression levels in UV-B-irradiated normal human dermal fibroblasts (NHDFs). Methods: NHDFs were treated with 1 mg/mL of EAS or dextrin (vehicle control) prior to UV-B irradiation (20 mJ/cm(2)). After culturing NHDFs for different time periods, HSP70 mRNA and protein levels were analyzed using real-time polymerase chain reaction and western blotting, respectively. Results: UV-B-irradiated NHDFs showed reduced HSP70 mRNA levels after 1-6 h of culture, which were recovered after 24 h of culture. Treatment with EAS alone for 24 h increased HSP70 mRNA levels in the NHDFs, but the increase was not reflected in its protein levels. On the other hand, pretreatment with EAS abolished the UV-B irradiation-induced reduction in HSP70 expression at both mRNA and protein levels. These results suggest that EAS is capable to preserve HSP70 quantity in UV-B-irradiated NHDFs. Conclusions: EAS exhibits anti-photoaging potencies by preventing the reduction in HSP70 expression in UV-irradiated dermal fibroblasts.