Pyrrolizidine alkaloids of the endemic Mexican genus Pittocaulon and assignment of stereoisomeric 1,2-saturated necine bases
作者:Juan Camilo Marín Loaiza、Ludger Ernst、Till Beuerle、Claudine Theuring、Carlos L. Céspedes、Thomas Hartmann
DOI:10.1016/j.phytochem.2007.07.004
日期:2008.1
allows the separation and identification of the four stereoisomers as their diacetyl or trimethylsilyl derivatives. All otonecine esters that generally do not form N-oxides and the 1,2-saturated PAs were exclusively found as free bases, while the 1,2-unsaturated 7-angeloylheliotridine occurring in P. velatum was found only as its N-oxide. In a comparative study the 1H and 13C NMR spectra of the four stereoisomeric
墨西哥特有属 Pittacaulon(亚部落 Tussilagininae,部落 Senecioneae,菊科)属于分布在墨西哥和北美洲的单系属群。五种 Pittacaulon 物种代表具有扫帚状多汁枝条的灌木。所有物种都被发现含有吡咯里西啶生物碱 (PAs)。除了一个例外(即,Pittacaulon velatum 的茎不含 PA),在所有植物器官中都发现了 PA,在花头中含量最高(高达干重的 0.3%)。发现了三种结构类型的PA:(1)大环奥托辛酯,例如senkirkine和acetylpetasitenine;(2) 仅在根中发现的大环反花碱酯,例如千叶花碱,和 (3) 1,2-饱和花花碱与当归酸的单酯。对于不同立体异构体 1 的明确分配,2-饱和的necine 碱基建立了GC-MS 方法,该方法允许将四种立体异构体作为它们的二乙酰或三甲基甲硅烷基衍生物进行分离和鉴定。通常不形成 N-氧化物的所有