BETAINES AND TERTIARY SULFONIUM COMPOUNDS FROM 62 SPECIES OF MARINE-ALGAE

From all 62 species of marine algae studied, either betaines or a tertiary sulphonium analogue or a mixture of the two types of compounds were extracted. Thus from this and earlier studies it would appear that either one or both of these classes of compounds are a constant feature of marine algae. Some compounds, in particular glycinebetaine, gamma-aminobutyric acid betaine, prolinebetaine and 3-dimethyl-sulphoniopropionate, have a common and widespread distribution, whereas other compounds, e.g. beta-prolinebetaine, trans-4-hydroxy-beta-prolinebetaine, N-acetyllaminine, delta-aminovaleric acid betaine and alpha-alaninebetaine, appear to have a very restricted occurrence. From Ptilota serrata, gamma-aminobutyric acid betaine, methyl ester, was isolated and characterized; this is the first record of this substance as a natural product. It was not detected in any of the other algae investigated. The yields of betaines and tertiary sulphonium compounds obtained by extraction of the algae were low, especially from the Phaeophyceae. Apart from Chaetomorpha capillaris, for which 2% (of dry weight) of glycinebetaine was recorded, the yield of the major betaine or tertiary sulphonium compound from the other species investigated was less than 1% (of dry weight) and frequently less than 0.1%. The similarity of the betaines and their tertiary sulphonium analogues found in different species of the same genus show that these compounds have taxonomic significance at the generic level.