الفهرس 
Mechanism of Action :Only 14 pages are availabe for public view
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Abstract
The problems associated with skin aging range from minor cosmetic problems to major disfigurement with profound psychosocial consequences.
There are two clinically and biologically independent aging processes that occur simultaneously.
• The first is innate or intrinsic aging, which affects skin as it probably affects a variety of internal organs by slow, irreversible degeneration of tissue.
• The second process is extrinsic aging or photoaging, the result of exposure to the sunlight, primarily ultraviolet irradiation. Other factors which contribute in this process are air pollution, alcohol, tobacco, drugs and frequent weight gain and loss.
Histologic and ultrastructural studies have shown that alterations in photoaged skin are found in dermal connective tissue. The dermis lies below and provides mechanical support for the outer, protective layer of skin, the epidermis. The extracellular matrix in the dermis is composed primarily of type I collagen, with lesser amounts of type III collagen, elastin, proteoglycans, and fibronectin. Collagen fibrils are responsible for the strength and resiliency of skin.