Fuhalols and deshydroxyfuhalols from the brown alga sargassum spinuligerum

Abstract Using a highly sophisticated HPLC method, 20 fuhalols and deshydroxyfuhalols were isolated from the ethanolic extract of the brown alga Sargassum spinuligerum . Because of their instability they were peracetylated before isolation. In addition to well known phlorotannins like deshydroxytetrafuhalol-A, tetrafuhalol-A, pentafuhalol-A, hexafuhalol-A, heptafuhalol-A, octafuhalol-A, nonafuhalol-A and undecafuhalol-A, the acetylated derivatives of deshydroxytetrafuhalol-C, deshydroxyhexafuhalol-A,-C and -D, deshydroxyoctafuhalol-C, octafuhalol-B, decafuhalol-A, dodecafuhalol-A, tetradecafuhalol-A, hexadecafuhalol-A, octadecafuhalol-A and eicosafuhalol-A are described for the first time. The last of them, containing twenty phloroglucinol units, is the largest phlorotannin isolated in purified form to date. The structural elucidation was carried out on the basis of 1 H, 13 C NMR and mass spectral data.