| Abstract: | The tropical green seaweed Caulerpa taxifolia (VAHL ) C. AGARDH (Caulerpales) which is invading the Mediterranean is shown to contain trace amounts of two further novel terpenes, 7,7-C-didehydro-6-hydroxy-6,7-dihydrocaulerpenyne (= (4S, 6S,1E)-3-(Z)-acetoxymethylidene]-6-hydroxy-11-methyl-7-methylidenedodeca-1,10-dien-8-yne-1,4-diyl diacetate; 3a ) and taxifolione (= 6-methylhept-5-en-3-yn-2-one; 4 ). The former is the most active of the toxins so far isolated from this seaweed, both as an in vitro inhibitor of the growth of marine bacteria and as a cytotoxic agent toward marine ciliate protists. This suggests a central ecotoxicological role for triacetate 3a as an adjuvant factor in the invasion of the Mediterranean by this seaweed. Moreover, the almost equally toxic 10,11 -epoxycaulerpenyne ( 2 ) which is scarcely available from Nature for bioassays can now be obtained by peroxy-acid epoxidation of caulerpenyne ( 1 ), along with the 6,7-epoxycaulerpenynes 6b and 6a . The latter are very labile, 6a giving triacetate 3a , suggesting epoxides to be late biogenetic intermediates in C. taxifolia. |
