A new tyrosine kinase inhibitor from the marine brown alga Stypopodium zonale.

From the lipophilic extract of the marine brown alga Stypopodium zonale (Dictyotaceae) the new terpenoid compound stypoquinonic acid (1) together with the known compounds taondiol (2) and atomaric acid (3) were isolated. The structures of all isolates were determined from their spectroscopic data, including 1- and 2-dimensional NMR methods. The new compound, 1, and atomaric acid (3), showed inhibition of tyrosine kinase (p56lck).