Pfister J A, Gardner D R, Panter K E, Manners G D, Ralphs M H, Stegelmeier B L, Schoch T K
Poisonous Plant Research Laboratory, ARS, USDA, Logan, UT 84341, USA.
J Nat Toxins. 1999 Feb;8(1):81-94.
Larkspurs (Delphinium spp.) are toxic plants that contain numerous diterpenoid alkaloids which occur as one of two structural types: (1) lycotonine, and (2) 7,8-methylenedioxylycoctonine (MDL-type). Among the lycoctonine type alkaloids are three N-(methylsuccinimido) anthranoyllycoctonine (MSAL-type) alkaloids which appear to be most toxic: methyllycaconitine (MLA), 14-deacetylnudicauline (DAN), and nudicauline. An ester function at C-18 is an important structural requirement for toxicity. Intoxication results from neuromuscular paralysis, as nicotinic acetylcholine receptors in the muscle and brain are blocked by toxic alkaloids. Clinical signs include labored breathing, rapid and irregular heartbeat, muscular weakness, and collapse. Toxic alkaloid concentration generally declines in tall larkspurs with maturation, but alkaloid concentration varies over years and from plant to plant, and is of little use for predicting consumption by cattle. Knowledge of toxic alkaloid concentration is valuable for management purposes when cattle begin to eat larkspur. Cattle generally begin consuming tall larkspur after flowering racemes are elongated, and consumption increases as larkspur matures. Weather is also a major factor in cattle consumption, as cattle tend to eat more larkspur during or just after summer storms. Management options that may be useful for livestock producers include conditioning cattle to avoid larkspur (food aversion learning), grazing tall larkspur ranges before flowering (early grazing) and after seed shatter (late grazing), grazing sheep before cattle, herbicidal control of larkspur plants, and drug therapy for intoxicated animals. Some potentially fruitful research avenues include examining alkaloid chemistry in low and plains larkspurs, developing immunologic methods for analyzing larkspur alkaloids, developing drug therapy, and devising grazing regimes specifically for low and plains larkspur.
飞燕草（翠雀属植物）是有毒植物，含有多种二萜生物碱，这些生物碱有两种结构类型：（1）石蒜碱型，和（2）7,8-亚甲基二氧基石蒜碱型（MDL型）。在石蒜碱型生物碱中，有三种N-（甲基琥珀酰亚胺基）邻氨基苯甲酰石蒜碱（MSAL型）生物碱似乎毒性最强：甲基牛扁碱（MLA）、14-脱乙酰裸甲乌碱（DAN）和裸甲乌碱。C-18位的酯官能团是毒性的重要结构要求。中毒是由神经肌肉麻痹引起的，因为肌肉和大脑中的烟碱型乙酰胆碱受体被有毒生物碱阻断。临床症状包括呼吸费力、心跳快速且不规律、肌肉无力和虚脱。随着成熟，高飞燕草中的有毒生物碱浓度通常会下降，但生物碱浓度会因年份和植株而异，对预测牛的摄入量几乎没有用处。当牛开始食用飞燕草时，了解有毒生物碱浓度对于管理目的很有价值。牛通常在开花总状花序伸长后开始食用高飞燕草，并且随着飞燕草成熟，摄入量会增加。天气也是影响牛摄入量的一个主要因素，因为牛在夏季暴风雨期间或刚过后往往会食用更多的飞燕草。对畜牧生产者可能有用的管理选择包括训练牛避免食用飞燕草（食物厌恶学习）、在开花前（早期放牧）和种子散落之后（晚期放牧）放牧高飞燕草牧场、在牛之前放牧绵羊、对飞燕草植株进行化学除草以及对中毒动物进行药物治疗。一些可能有成效的研究途径包括研究矮飞燕草和平原飞燕草中的生物碱化学、开发分析飞燕草生物碱的免疫学方法、开发药物治疗方法以及专门为矮飞燕草和平原飞燕草设计放牧制度。
