A novel cycloartane triterpenoid alkaloid, kleinhospitine E (1), six new cycloartane triterpenoids (2–7), three known cycloartane triterpenoids (8–10), and taraxerone (11) were isolated from a methanol extract of Kleinhovia hospita. Their structures were elucidated by 1D- and 2D-NMR spectroscopy as well as HRMS analysis. The absolute configurations of all isolated compounds were determined from their ECD spectra by comparison with theoretical values. Kleinhospitine E (1) is the first cycloartane alkaloid possessing an unusual γ-lactam with an oxopropylidene side chain. Compounds 2, 3, and 6 were assigned as cycloartane triterpenoids with a 9α,10α-cyclopropyl ring, which is found rarely among naturally occurring compounds, while 4 and 5 were established as isomers of compound 3 containing a 21,23-diacetal side chain. Biological evaluation revealed that compounds 4 and 9 exhibited more potent antiproliferative activities against a multidrug-resistant tumor cell line compared with its parent chemosensitive cell line. Furthermore, compound 6 exhibited submicromolar anti-HIV activity.

中文翻译：

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Kleinhovia hospita的Kleinhospitine E和Cycloartane Triterpenoids

一种新型的三萜类化合物环阿屯烷生物碱，kleinhospitine E（1），6个新的环阿屯烷三萜类化合物（2 - 7），三个已知的三萜类化合物环阿屯（8 - 10），和taraxerone（11）从的甲醇提取物中分离克兰树hospita。通过1D和2D-NMR光谱以及HRMS分析阐明了它们的结构。通过与理论值比较，从其ECD光谱中确定所有分离的化合物的绝对构型。Kleinhospitine E（1）是第一个具有不同寻常的带有氧亚丙基侧链的γ-内酰胺的环烷生物碱。化合物2，3，和6被指定为带有9α，10α-环丙基环的环戊烷三萜，这在天然存在的化合物中很少见，而4和5被确定为包含21,23-二缩醛侧链的化合物3的异构体。生物学评估表明，与其亲代化学敏感性细胞系相比，化合物4和9对多药耐药肿瘤细胞系表现出更强的抗增殖活性。此外，化合物6表现出亚微摩尔抗HIV活性。