Skin ageing is a complex process caused by both intrinsic and extrinsic factors and progressively losing the structure and function of the skin. Oxidative stress induced by reactive oxygen species (ROS) plays an important role in the process of human skin ageing, especially at the subcutaneous layer. Extrinsic skin ageing is driven mainly by environmental factors and external stresses such as ultraviolet radiation (UVR), pollution and lifestyle factors that also stimulate the production of ROS and generate oxidative stress.
Skin ageing is also a kind of inflammation process caused by a variety of intrinsic and extrinsic factors since various inflammatory cytokines are involved in the middle of the ageing mechanism.
Natural vs. synthetic peptides and polypeptides vs. tripeptides
Natural human peptides are known to be involved in immunity, stress, homeostasis and reproduction through cellular commu