Distribution of MAAs

Accumulation of mycosporine-like amino acids (MAAs) has been reported in a wide range of species in nature, including microalgae, macroalgae, cyanobacteria, phytoplankton, fungi, and some animals. This chapter describes the distribution of MAAs with a focus on macroalgae and cyanobacteria. MAAs biosynthesized by macroalgae have already been applied in cosmetic products, such as Helioguard 365 and Helinori. Macroalgae tend to accumulate multiple types of MAAs, and the types and accumulation levels are affected by changes in environmental factors. Regarding cyanobacteria, we focus on UV, salt, and osmotic stresses, temperature changes, and drought stress as environmental factors, and describe the species in which the accumulations of MAAs are induced by these stresses. UV-B irradiation is a common environmental factor that can induce the accumulation of MAAs in cyanobacteria, but induction by other abiotic stresses has been reported. These findings suggest that MAAs act as a multifunctional molecule that responds to a variety of environmental factors, not just as a UV absorber.