Three New Butenolides from the Green Alga Caulerpa racemosa var. turbinata

Abstract Three new butenolides, caulerpalide A and a pair of enantiomers, (+)‐caulerpalide B and (−)‐caulerpalide B, together with seven known compounds, have been isolated from the green alga Caulerpa racemosa var. turbinata . All these structures were determined by spectroscopic techniques. The absolute configurations of caulerpalide A, (+)‐caulerpalide B and (−)‐caulerpalide B were elucidated by the method of ECD calculation. This is the first separation of butenolides from the algae of genus Caulerpa . Additionally, the antibacterial activities of the nine isolated compounds were also evaluated.