Dolabrane-Type Diterpenoids with Immunosuppressive Activity from <i>Koilodepas hainanense</i>

Thirteen new dolabrane-type diterpenoids, koilodenoids A–M (1–13), including a chlorinated congener (2), along with six known analogues, were isolated from Koilodepas hainanense. The structures were determined by analysis of spectroscopic data, ECD spectra, and X-ray crystallographic studies. The absolute configuration of C-15 in the 15,16-diol unit of compounds 4 and 5 was established by using the dimolybdenum tetraacetate [Mo2(AcO)4]-induced ECD method. Compounds 4, 7, 16, 17, and 19 showed moderate to significant immunosuppressive activities against the proliferation of T and B lymphocytes in vitro, with compound 16 being the most potent (IC50 0.86 and 0.29 μM, respectively).从海南柯洛德木（Koilodepas hainanense）中分离得到13个新的半日花烷型二萜类（dolabrane-type diterpenoids）化合物柯洛德萜类A~M（1~13），其中包含1个含氯同系物（化合物2），另有6个已知类似物。所有化合物的结构均通过光谱数据分析、电子圆二色谱（ECD, Electronic Circular Dichroism）谱图以及X射线单晶衍射实验得以解析。化合物4和5的15,16-二醇结构单元中C-15位的绝对构型，通过四乙酸二钼[Mo₂(AcO)₄]诱导的电子圆二色谱法得以确定。体外实验表明，化合物4、7、16、17和19对T、B淋巴细胞的增殖具有中等至显著的免疫抑制活性，其中化合物16的活性最强，其针对T、B淋巴细胞增殖的半数抑制浓度（IC₅₀）分别为0.86 μM和0.29 μM。