Plant inhibitors of metalloproteinases and the possibility of their aplication in the prevention of photoaging

Photoaging is a process of skin aging caused by long-term exposure to the ultraviolet radiations of the sun. Photoaging is characterized in part by wrinkles, altered pigmentation, loss of skin elasticity, increased roughness and dryness. The UV radiation releases enzymes called matrix metalloproteineases (MMPs) in human body. MMPs degrade the extracellular matrix (ECM). Skin ECM includes structural proteins such as: collagens, elastin, fibronectin, laminin, gelatin and agrecan. The destruction of ECM can lead to premature skin aging, angiogenesis, inflammation, apoptosis and tumor evolution. There are five types of MMPs: collagenases, gelatinases, stromelysins, matrylisins and membran-type MMPs. In photoaging a key role is played by MMP-1, MMP-2, MMP-3, MMP-9 and MMP-13. The activity of all MMPs is dependent on present inhibitors, both natural and synthetic. Known are four types of tissue inhibitors: TIMP-1, TIMP-2, TIMP-3 and TIMP-4. Besides, many researchers look for chemical substances as sources of new therapeutic agents. Their natural source are plants. Several plants, e.g., Macrocystis pyrifera (L.), Camellia sinensis (L.) and Eucommia ulmoides (Oliv.), are known to possess extracts able to inhibit MMPs.