南非菜刺绵羊藤亚种常称作腐蚀藤, 是一种无叶多肉植物，分布于澳大利亚北部干旱地区。据报道，此物种对牲畜有毒性，同时在传统医学中有所应用并具有潜在的抗癌活性。本文介绍了新颖的脂肪酸内酯类物质——半乳糖苷化物 cynaviminoside B (7) 和 cynavimigenin B (8)，以及新型脂肪酸内酯不含糖原的低聚物 cynavimigenin A (5) 和 cynaviminoside A (6)。Cynavimigenin B (8) 在脂肪酸内酯类物质中包含一个无前例的7-氧代二环[2.2.1]庚烷基团，很可能是由于一个其皮纳科尔式重排反应而产生的。有趣的是，这些分离产物只在癌症和正常人细胞系中表现出有限的细胞毒性，此外对乙酰胆碱酯酶和疥螨生物测定的活性也很低，这表明5-8不会引起此植物物种的有毒性。

Cynanchum viminale subsp. australe, more commonly known as caustic vine, is a leafless succulent that grows in the northern arid zone of Australia. Toxicity toward livestock has been reported for this species, along with use in traditional medicine and its potential anticancer activity. Disclosed herein are novel seco-pregnane aglycones cynavimigenin A (5) and cynaviminoside A (6), together with new pregnane glycosides cynaviminoside B (7) and cynavimigenin B (8). Cynavimigenin B (8) contains an unprecedented 7-oxobicyclo[2.2.1]heptane moiety in the seco-pregnane series, likely arising from a pinacol-type rearrangement. Interestingly, these isolates displayed only limited cytotoxicity in cancer and normal human cell lines, in addition to low activity against acetylcholinesterase and Sarcoptes scabiei bioassays, suggesting that 5-8 are not associated with the reported toxicity of this plant species.