Characterization of UV-absorbing Mycosporine-like Amino Acids in Freshwater Cyanobacterium Nostoc calcicola

Mycosporine-like amino acids (MAAs) are gaining attention for their UV photoprotective properties and potential applications in biomedical fields, cosmetics, and toiletries. In this study, Nostoc calcicola a genus of cyanobacteria distributed in freshwater were tested for MAA production. This organism was provided by the Freshwater Algae Culture Collection of the Institute of Hydrobiology, the Chinese Academy of Sciences. It was isolated and cultured in the laboratory, in 500 ml glass flasks containing 300 ml of liquid medium BG11 treated on UV-B light 0.1 Wm–2. At different time, cultures were exposed to UV-B light at intensity 0.1 W. m-1 to determine the Maximum PSII photochemical (Fv/Fm). MAAs were extracted using 100% HPLC grade methanol and separated through high-performance liquid chromatography and liquid chromatography/mass spectrometry. Based on liquid chromatography/mass spectrometry analysis, one MAA compound was identified as porphyra. Thus, UV-B treatment of Nostoc calcicola significantly enhanced the production of UV-absorbing mycosporine-like amino acids (MAAs). The content of porphyra could reach up to 8.5 mg/g dry weight in Nostoc calcicola under UV-B treatments for 2 days. The present cyanobacteria could be used for biotechnology research and the UV-absorbing compound porphyra may be of great value in the development of novel sunscreens.