New ninhydrin-reactive substance from red algae.

DURING an investigation on the free amino-acids in marine algae, I isolated a new ninhydrin-reactive substance from three species of red algae Chondrus ocellatus, Neodelsea yendoana and Iridaea cornucopiae by the use of anionic ion-exchange resin ‘Amberlite IR–45’ and ‘Dowex 2’. This substance gave an empirical formula C5H11O5NS and melted at 258° C. Optical rotation gave a value [α]13D = −1.15 (c = 5, M sodium hydroxide solution). It was not very sensitive to ninhydrin, but gave a bright brown colour with Plattner's reagent. Titration with 0.1 N sodium hydroxide, in alcoholic solution, gave a value 63.80 per cent (calculated as C4H7N—SO3H—COOH, 66.16 per cent). By the method of Kuhn and Roth, at least one radical, C—CH3, was estimated. The oxidation products obtained, after treatment with potassium permanganate solution, were taurine, alanine and propionic acid. From these results, the structure N-(l-carboxy-ethyl)-taurine, that is , was assumed. Crystals obtained from α-brompropionic acid and taurine by chemical synthesis corresponded well with the isolated substance not only in melting point but also in RF values on various paper chromatograms.