Abstract
Ultraviolet (UV) radiation is responsible for various damages to the skin, collectively referred to as photoaging. A key UV-induced effect on the skin is excessive degradation of collagen and related structural abnormalities. Camellia japonica is a flowering plant with cosmeceutical properties. In the present study, Camellioside A (CMDA), a triterpene saponin, was investigated for its effects against UVA-induced photoaging in HaCaT keratinocytes. CMDA was analyzed to determine its attenuating effects against UVA-induced overproduction of the collagen degradation enzyme, matrix metalloproteinase-1 (MMP-1), in UVA-irradiated immortalized human HaCaT keratinocytes. UVA irradiation significantly increased MMP-1 release from keratinocytes in addition to suppressing type Iα1 pro-collagen production. Treatment with CMDA reversed the effects of UVA irradiation on the production of MMP-1 and type Iα1 pro-collagen. UVA irradiation also stimulated the activation of p38, ERK and JNK mitogen-activated protein kinases (MAPKs) and their downstream transcription factor activator protein 1 (a heterodimer of c-Fos and c-Jun). MAPK activation and consequent phosphorylation of c-Fos and c-Jun were also inhibited by CMDA treatment. In conclusion, the present study indicated that CMDA may have potential antiphotoaging properties due to suppression of UVA-mediated MMP-1 production.