作者:Lauren C. Smith、Lucy Lin、Candy S. Hwang、Bin Zhou、Diane M. Kubitz、Huiying Wang、Kim D. Janda
DOI:10.1021/acs.chemrestox.8b00218
日期:2019.1.22
The leaves of the Mitragynine speciosia tree (also known as Kratom) have long been chewed, smoked, or brewed into a tea by people in Southeastern Asian countries, such as Malaysia and Thailand. Just this past year, the plant Kratom gained popularity in the United States as a “legal opioid” and scheduling it as a drug of abuse is currently pending. The primary alkaloid found in Kratom is a μ-opioid receptor agonist, mitragynine, whose structure contains a promising scaffold for immunopharmacological use. Although Kratom is regarded as a safe opioid alternative, here we report the LD50 values determined for its two main psychoactive alkaloids, mitragynine and 7-hydroxymitragynine, as comparable to heroin in mice when administered intravenously. Given Kratom’s recent emergence in the U.S., there is currently no diagnostic test available for law enforcement or health professionals, so we sought to design such an assay. Mitragynine was used as a starting point for hapten design, resulting in a hapten with an ether linker extending from the C9 position of the alkaloid. Bacterial flagellin (FliC) was chosen as a carrier protein for active immunization in mice, yielding 32 potential monoclonal antibodies (mAbs) for assay development. Antimitragynine mAbs in the range of micro- to nanomolar affinities were uncovered and their utility in producing a convenient lateral flow detection assay of human fluid samples was examined. Antibodies were screened for binding to mitragynine, 7-hydroxymitragynine, and performance in lateral flow assays. Two monoclonal antibodies were subcloned and further purified with 93 and 362 nM affinity to mitragynine. Test strip assays were optimized with a detection cut off of 0.5 μg/mL for mitragynine in buffer and urine (reflecting projected clinically relevant levels of drug in urine), which could be beneficial to law enforcement agencies and health professionals as the opioid epidemic in America continues to evolve.
长期以来,马来西亚和泰国等东南亚国家的人们一直咀嚼、吸食或将 Mitragynine speciosia 树(又称 Kratom)的叶子泡成茶。就在去年,Kratom 作为一种 "合法阿片类药物 "在美国大受欢迎,目前正等待将其列为滥用药物。在 Kratom 中发现的主要生物碱是一种 μ 阿片受体激动剂,即 mitragynine,其结构包含一个很有前景的免疫药理学用途支架。虽然 Kratom 被认为是一种安全的阿片类药物替代品,但我们在此报告了其两种主要精神活性生物碱(mitragynine 和 7-hydroxymitragynine)的半数致死剂量(LD50),其在小鼠体内静脉注射的半数致死剂量与海洛因相当。鉴于 Kratom 最近才在美国出现,目前还没有可供执法人员或卫生专业人员使用的诊断测试,因此我们试图设计这样一种检测方法。我们以桔梗碱为起点设计了一种单体,该单体带有一个从生物碱 C9 位置延伸出来的醚连接体。细菌鞭毛蛋白(FliC)被选为小鼠主动免疫的载体蛋白,从而产生了 32 种潜在的单克隆抗体(mAbs)用于检测开发。研究人员发现了亲和力在微摩尔至纳摩尔范围内的抗亚硝胺 mAbs,并考察了它们在对人体体液样本进行便捷的横向流动检测试验中的作用。对抗体与米曲宁、7-羟基米曲宁的结合以及在侧流检测中的性能进行了筛选。对两种单克隆抗体进行了亚克隆和进一步纯化,它们与米曲宁的亲和力分别为 93 和 362 nM。对试纸检测进行了优化,缓冲液和尿液中的米曲宁检测截止值为 0.5 μg/mL(反映了尿液中药物的预计临床相关水平),随着美国阿片类药物流行病的不断发展,这将有利于执法机构和医疗专业人员的工作。