Phlorotannins from the Brown Alga Analipus japonicus ¹

Abstract

New phloroglucinol derivatives were isolated from the ethanolic extract of Analipus japonicus (Harv.) Wynne, a north Pacific brown alga. Most of the compounds are fucols, i.e. phlorotannins in which the phloroglucinol units are connected by biaryl bonds. In addition to the four known oligomers difucol hexaacetate, trifucol nonaacetate, and tetrafucol-A and B dodecaacetates, two atropisomeric pentafucol pentadecaacetates, four atropisomeric hexafucol octadecaacetates, a heptafucol uneicosaacetate mixture, the following halogenated compounds could be isolated: bromo- and chlorotrifucol nonaacetate, 5′-bromo- and 5′-chlorotetrafucol-A dodecaacetate as well as 5′-bromo- and 5′-chloropentafucol-A pentadecaacetate. Three other phlorotannin derivatives belong to the phlorethol and fucophlorethol groups, respectively.