A new sesterterpene, sesteralterin (1), four new meroterpenes, tricycloalterfurenes A–D (2–5), and a known meroterpene, TCA-F (6), were obtained from the culture extract of an Alternaria alternata strain (k21-1) isolated from the surface of the marine red alga Lomentaria hakodatensis. The structures and relative/absolute configurations of these compounds were identified by spectroscopic analyses, mainly including 1D/2D NMR, ECD, and mass spectra and quantum chemical calculations. Compound 1 represents the first nitidasane sesterterpene naturally produced by fungi, and 2–5 feature a tetrahydrofuran unit rarely occurring in tricycloalternarenes. Compounds 1–6 were assayed for inhibition of the growth of four marine plankton and one marine alga-pathogenic bacterium.

中文翻译：

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Sesteralterin和Tricycloalterfurenes A–D：具有很少发生的海洋藻类表生真菌Alternaria alternata alternata k21-1的萜烯

一个新的sesterterpene，sesteralterin（1），四个新meroterpenes，tricycloalterfurenes A-d（2 - 5），和已知的meroterpene，TCA-F（6），从一个的培养提取物得到格孢菌株（k21-1 ）从海洋红藻Lomentaria hakodatensis的表面分离出来。通过光谱分析确定了这些化合物的结构和相对/绝对构型，主要包括1D / 2D NMR，ECD，质谱和量子化学计算。化合物1表示由真菌自然产生的第一nitidasane sesterterpene，和2 - 5其特征是四环呋喃单元很少出现在三环烷烃中。化合物1 - 6进行测定抑制四个海洋浮游生物和一个海藻致病细菌的生长。