Pools of Free Amino Acids in Greek Marine Algae

Abstract

Isolation, identification and quantitative determination of 17 free amino acids was carried out in 39 marine plant organisms of the Greek coasts. Among them 10 were green algae ( Chlorophyceae ), 10 brown algae ( Phaeophyceae ), 17 red algae ( Rhodophyceae ) and 2 phanerogams. The distribution pattern in their free amino acid pools was the following. Glutamic acid was the main amino acid in all the algae examined with the exception of Halimeda tuna, Dictyopteris membranacea, Pterocladia capillacea, Corallina mediterranea, Antithamnion cruciatum f. fragilissima and the phanerogam Halophila stipulacea . Aspartic acid, alanine and threonine, serine, glutamine, asparagine followed in relative abundance. There was a trend for more alanine in the brown algae compared with the green and red algae. Glycine was a constant constituent of all the algae examined, but it was absent from Polysiphonia sp. This amino acid was present in a quantitatively lower degree than the foregoing amino acids. Leucine, isoleucine, valine, phenylalanine, lysine and arginine were less common than the eight above-mentioned constituents and were found occasionally in large amounts. Lastly, cysteine, tyrosine and histidine were rare and mostly detected in small quantities. Methionine was totally absent from all the algae and phanerogams examined. The comparison of the free amino acid patterns for each species does not provid'e sound evidence for its use in taxonomic studies of the natural occuring marine algae.