Five cucurbitacins, kuguacins A-E (1-5), together with three known analogues, 3beta,7beta,25-trihydroxycucurbita-5,(23E)-diene-19-al (6), 3beta,25-dihydroxy-5beta,19-epoxycucurbita-6,(23E)-diene (7), and momordicine I (8), were isolated from roots of Momordica charantia. Structures of 1-5 were elucidated by NMR and MS spectroscopic analysis. Among them, compounds 3-5 possess an unprecedented 25,26,27-trinorcucurbitane backbone. Compounds 3 and 5 showed moderate anti-HIV-1 activity with EC(50) values of 8.45 and 25.62 microg/ml, and exerted minimal cytotoxicity against C8166 cells (IC(50)>200 microg/ml), with a selectivity index more than 23.68 and 7.81, respectively.

中文翻译：

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苦瓜根中的三降葫芦烷和葫芦烷三萜类化合物

五种葫芦素，kuguacins AE (1-5)，连同三个已知的类似物，3beta,7beta,25-trihydroxycucurbita-5,(23E)-diene-19-al (6), 3beta,25-dihydroxy-5beta,19-从苦瓜的根中分离得到epoxycucurbita-6,(23E)-diene (7) 和momordicine I (8)。通过NMR和MS光谱分析阐明了1-5的结构。其中，化合物 3-5 具有前所未有的 25,26,27-trinorcucurbitane 主链。化合物 3 和 5 表现出中等的抗 HIV-1 活性，EC(50) 值为 8.45 和 25.62 microg/ml，对 C8166 细胞的细胞毒性最小（IC(50)>200 microg/ml），选择性指数更高分别低于 23.68 和 7.81。