Ultraviolet radiation screening compounds

Amongst the diversity of methods used by organisms to reduce damage caused by ultraviolet (UV) radiation, the synthesis of UV-screening compounds is a lmost ubiquitous. UV-screening compounds provide a passive method for the r eduction of UV-induced damage and they are widely distributed across the mi crobial, plant and animal kingdoms. They share some common chemical feature s. It is likely that on early earth strong selection pressures existed for the evolution of UV-screening compounds. Many of these compounds probably h ad other physiological roles, later being selected for the efficacy of UV s creening. The diversity in physiological functions is one of the complicati ons in studying UV-screening compounds and determining the true ecological importance of their UV-screening role. As well as providing protection agai nst ambient UV radiation, species with effective screening may also be at a n advantage during natural ozone depletion events. In this review the chara cteristics of a wide diversity of UV-screening compounds are discussed and evolutionary questions are explored. As research into the range of UV-scree ning compounds represented in the biosphere continues, so it is likely that the properties of many more compounds will be elucidated. These compounds, as well as providing us with insights into natural responses to UV radiati on, may also have implications for the development of artificial UV-screeni ng methods to reduce human exposure to UV radiation.