Photoprotective Role of Mycosporine-like Aminoacids

Resumen

The threat from ultraviolet (UV) radiation has been present on Earth before the development of any kind of life. The ozone layer is responsible for filtering most of the UV radiation, but some still can enter the biosphere and affect life. Moreover, due to ozone reductions, the level of UV radiation has increased in many parts of the world and it is likely to increase even further in the near future. Several evolutionary adaptations have allowed living organisms to cope with UV radiation. Specifically, the damaging effects of UV radiation can be diminished by several photoprotective mechanisms, such as accumulation of UV absorbing substances which act as sunscreens. Mycosporine-like amino acids (MAAs) are a family of substances occurring in a wide variety of marine and terrestrial organisms known to have a photoprotective role, among other functions. All these compounds are low-molecular-weight water-soluble molecules capable of absorbing UV radiation with absorption maxima ranging between 310 and 360 nm. The UV screening function of MAAs and related compounds can be inferred from their photophysical features, such as strong UV absorption, lack of fluorescence and high photo-stability. In this contribution, we will summarize the biosynthesis and location of MAAs in different organisms, together with the isolation and structural characterization of MAAs. Also, we will describe the photophysical and photochemical properties of MAAs with an emphasis in the photoprotective role of these compounds