McKenna D J, Towers G H, Abbott F
J Ethnopharmacol. 1984 Apr;10(2):195-223. doi: 10.1016/0378-8741(84)90003-5.
Ayahuasca is a hallucinogenic beverage derived by boiling the bark of the Malpighiaceous liana Banisteriopsis caapi together with the leaves of various admixture plants, viz. Psychotria viridis, Psychotria carthagenensis , or Diplopterys cabrerana . B. caapi contains harmine, harmaline, and tetrahydroharmine while the admixtures contain N,N-dimethyltryptamine (DMT). DMT, a potent hallucinogen, is inactive orally due to degradation by visceral monoamine oxidase (MAO). The beta-carbolines, however, are highly active reversible inhibitors of MAO and may protect the DMT from deamination by MAO and render it orally active. This mechanism has been proposed to underlie the oral activity of ayahuasca but has not been experimentally confirmed. In the present study the constituents of the admixture plants and the alkaloids of eight ayahuasca samples from Peru were qualitatively and quantitatively analyzed using two-dimensional thin-layer chromatography (TLC), high pressure liquid chromatography (HPLC) and gas chromatography/mass spectrometry (GC/MS). Several B. caapi cultivars were quantitatively compared for variations in alkaloid content. Three admixture plants used rarely in the manufacture of ayahuasca were also screened for alkaloids. A selected sample of beta-carbolines were screened for activity as MAO inhibitors using an in vitro assay system, and structure/activity relationships were compared. Inhibition observed with single compounds was compared with the activity of selected samples of ayahuasca which were screened in the system and also with the activity of mixtures of beta-carbolines. The levels of DMT and beta-carbolines found in the ayahuasca samples examined in the present study were an order of magnitude greater than the levels reported in a previous study. Ayahuasca was found to be an extremely effective inhibitor of MAO in vitro and the degree of inhibition was directly correlated with the concentration of MAO-inhibiting beta-carbolines. Inhibition experiments using mixtures of beta-carbolines indicated that their effects in combination are additive, rather than synergistic or antagonistic. Implications of the results in understanding the pharmacology of ayahuasca are discussed.
阿亚瓦斯卡是一种致幻饮料，由马钱科藤本植物卡皮藤（Banisteriopsis caapi）的树皮与各种混合植物的叶子一起煮沸制成，这些混合植物包括绿心叶树（Psychotria viridis）、卡塔赫纳绿心叶树（Psychotria carthagenensis）或卡氏二翅萼（Diplopterys cabrerana）。卡皮藤含有哈尔明、哈尔马灵和四氢哈尔明，而混合植物含有N,N-二甲基色胺（DMT）。DMT是一种强效致幻剂，由于会被内脏单胺氧化酶（MAO）降解，口服时无活性。然而，β-咔啉是MAO的高效可逆抑制剂，可能会保护DMT不被MAO脱氨基并使其口服具有活性。有人提出这种机制是阿亚瓦斯卡口服活性的基础，但尚未得到实验证实。在本研究中，使用二维薄层色谱（TLC）、高压液相色谱（HPLC）和气相色谱/质谱联用（GC/MS）对混合植物的成分以及来自秘鲁的八个阿亚瓦斯卡样品中的生物碱进行了定性和定量分析。对几种卡皮藤品种的生物碱含量变化进行了定量比较。还对三种很少用于制造阿亚瓦斯卡的混合植物进行了生物碱筛选。使用体外检测系统对选定的β-咔啉样品进行了MAO抑制剂活性筛选，并比较了结构/活性关系。将单一化合物的抑制作用与在该系统中筛选的选定阿亚瓦斯卡样品的活性以及β-咔啉混合物的活性进行了比较。本研究中检测的阿亚瓦斯卡样品中发现的DMT和β-咔啉水平比先前研究报告的水平高一个数量级。发现阿亚瓦斯卡在体外是一种极其有效的MAO抑制剂，抑制程度与MAO抑制性β-咔啉的浓度直接相关。使用β-咔啉混合物的抑制实验表明，它们的联合作用是相加的，而不是协同或拮抗的。讨论了这些结果在理解阿亚瓦斯卡药理学方面的意义。
