Abstract

UV PROTECTING ABILITY OF SUNSCREEN LOTIONS PREPARED WITH EXTRACTS OF PISONIA GRANDIS R.BR

P. Lalitha*, Shubashini K Sripathi and P.Jayanthi

ABSTRACT

The skin, especially epidermis acts as a barrier and immunological organ in the human body and hence is particularly subjected to external harmful effects. Electromagnetic radiation is the chief environmental component to which skin is exposed daily and this comprises of UV radiation (UV-A (320-400 nm), UV-B (290-320 nm) and UV-C (200-290 nm), which have been reported to cause damaging effects to the skin.[1] UV-C radiation at short exposure time is extremely damaging to the skin [2] but is filtered by the atmosphere before reaching the earth. The ozone layer does not filter UV-B radiation completely and this is responsible for the damage due to sunburn (acute inflammation) [3] and intensification of photo-ageing.[4] UV-A radiation reaches the deeper layers of the epidermis and dermis resulting in damage to the elastic and collagen fibers of connective tissue of skin, and aggravates the premature aging of the skin. Ultraviolet radiations are considered a causative factor of skin cancer.[3] UV irradiation initiates and activates a complex cascade of biochemical reactions in human skin resulting in inflammation and free radical generation (both reactive oxygen and nitrogen species), which causes damage to the cellular proteins, lipids and carbohydrates accumulated in the dermal and epidermal compartments and thus contributing to the etiology of photoaging.[5] One of the strategies to prevent the damage caused by this cascade of reactions initiated by UV is prevention of its penetration into skin by the use of sunscreens containing antioxidants capable of quenching ROS.

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