Occurrence of UVA- and UVB-absorbing compounds in 152 species (206 strains) of marine microalgae

Abstract

Marine microalgae (152 species, 206 strains) from 12 classes were exam~ned for the presence of UVA-and UVB-absorbing compounds.Cultures were grown under white fluorescent light without supplementary UVA or UVB radiation and were extracted after harvest m tetrahydrofuran:methanol (20:80, v/v).Ratios of UV absorbance (280 to 390 nm) to chlorophyll a (chl a) (665 nm) obtained by spectrophotometry ranged from 0.18 to 6.75.Three groups of species were distinguished: those with low UV:chl a ratios (0.18 to 0.9, diatoms, green algae, cyanophytes, euglenophytes, eustlgmatophytes, rhodophytes, some dinoflagellates, some prymnesiophytes], those with intermed~ate ratlos (0.9 to 1.4, chrysophytes, some prasinophytes, some prymnesiophytes) and those with very high ratios (1.4 to 6.75, surface bloom-forming dinoflagellates, cryptoinonads, prymnesiophytes and raphidophytes).UV-absorbing pigments varied across species of the same algal class and strains of the same species.HPLC analysis of extracts of 5 species (1 diatom, 2 bloom-forming raphidophytes and 2 bloomforming dinoflagellates) showed suites of mycosporine-like amino acids in 4 of them, which included mycosporine-glycine, asterina-330, shinorme, porphyra-334 and palythine.The dinoflagellate Gymno-din~um catenatum also contained major quantities of unknown UV-absorbing compounds.