Mycosporine-like amino acid (MAAs) production by Heterocapasa sp. (Dinophyceae) in indoor cultures

Abstract

The possibility of using mycosporine-like amino acids (MAAs), with an apparent sunscreen function in nature, as ultraviolet radiation (UVR) blockers to prevent skin injury has been raised by diverse authors. Production of MAAs by the dinoflagellate Heterocapsa sp. (Dinophyceae) is shown here. Three major peaks with absorption maxima at 330.8, 332.0 and 333.2 nm were detected by high performance liquid chromatography (HPLC) analysis of methanolic extracts in all tested conditions. Analysis of crude extract by mass spectroscopy with electrospray ionization (MS-EI) showed a set of molecular ions ([M+H] +) with main peaks being at m/ z 242.4, 288.4, 303.3 and 333.3 u.m.a. According to these data, along with retention times, the MAA profile of Heterocapsa sp. is assumed to be composed of shinorine ( λ max=334 nm), mycosporine–2-glycine ( λ max=331 nm) and palythinol ( λ max=332 nm). A constitutive MAA content of about 4 μg (10 6 cells) −1 was measured under exposure to PAR only. A maximal accumulation of MAA per culture volume of 1.1 mg l −1 was obtained after 72 h of exposure to PAR+UVA, while the highest production rate (0.025 mg l −1 h −1) was computed after 24 h of exposure to PAR+UVA+UVB.