Broom snakeweed (Gutierrezia sarothrae) and threadleaf snakeweed (G. microcephala) are suffrutescent plants found in many parts of western US rangelands and are possibly toxic to grazing livestock. The toxic components are not known, but it has been suggested that the diterpene acids may be both toxic and abortifacient. One hundred sixty-two samples of snakeweed were collected from 55 locations in Colorado, Oklahoma, New Mexico, Texas, Wyoming and Utah and were taxonomically classified. Samples were analyzed by GC-MS in a chemophenetic analysis and grouped into individual chemotypes based on diterpene acid content. The GC-MS profiles were found to be diverse showing at least eight different chemotypes. From each of the chemotypes the major diterpene acids were isolated and characterized by IR, MS and NMR spectroscopy. Twenty-one diterpenoids were identified and found to be a mix of furano, lactone, di-acid and esters of labdane, ent-labdane and chlerodane acids and alcohols. Only four of the 21 compounds isolated had been previously reported as occurring in G. sarathorea or G. microcephala, while another eight compounds were previously reported from other Gutierrezia or related species. Nine of the isolated diterpenoids have not been previously reported and their structure elucidation is reported.

中文翻译：

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来自 Gutierrezia sarothrae 和 G. microcephala 的二萜：化学多样性、化学表观学和对放牧牲畜毒性的影响

扫帚蛇草 (Gutierrezia sarothrae) 和线叶蛇草 (G. microcephala) 是在美国西部牧场的许多地方发现的黄化植物，可能对放牧的牲畜有毒。有毒成分尚不清楚，但有人认为二萜酸可能具有毒性和堕胎作用。从科罗拉多州、俄克拉荷马州、新墨西哥州、德克萨斯州、怀俄明州和犹他州的 55 个地点收集了 162 份蛇草样本，并进行了分类。样品在化学表型分析中通过 GC-MS 进行分析，并根据二萜酸含量分为不同的化学型。发现 GC-MS 谱是多种多样的，显示出至少八种不同的化学型。从每种化学型中分离出主要的二萜酸，并通过 IR、MS 和 NMR 光谱对其进行表征。确定了 21 种二萜类化合物，发现它们是呋喃诺、内酯、二酸和劳丹丹、恩劳丹和氯丹酸和醇的酯的混合物。之前已报告分离出的 21 种化合物中只有 4 种出现在 G. sarathorea 或 G. microcephala 中，而另外 8 种化合物之前曾报道来自其他 Gutierrezia 或相关物种。九种分离的二萜以前没有报道过，但已报道了它们的结构解析。