Skin aging is attributed to intrinsic (chronological) aging and photoaging (extrinsic aging). Photoaging and intrinsic aging are induced by damage to human skin by repeated exposure to ultraviolet (UV) irradiation and the damage due to the passage of time, respectively. An alteration in collagen, which is the major structural component of skin, has been considered to be a cause of skin aging in naturally aged and photoaged skin. With increasing age, there is a sustained reduction of collagen and an elevated secretion of matrix-degrading enzymes called matrix metalloproteinases (MMP) in old skin as compared with young skin1. UV causes photoaging by generating reactive oxygen species, and this subsequently triggers a cascade of signaling mechanisms and this eventually causes a decrease of collagen, and an increase of MMP, inflammation, epidermal DNA damage and apoptosis. During this process, activator protein 1 (AP-1) is activated by UV irradiation and so AP-1-driven MMPs such as MMP-1 and MMP-9 are induced. The UV-induced MMPs can degrade collagen, which results in a collagen deficiency in photodamaged skin and eventually skin wrinkling2.