Ansede J H, Voyksner R D, Ismail M A, Boykin D W, Tidwell R R, Hall J E
Division of Drug Delivery and Disposition, School of Pharmacy, The University of North Carolina, Chapel Hill, NC 27599, USA.
Xenobiotica. 2005 Mar;35(3):211-26. doi: 10.1080/00498250500087671.
A new aza-analogue of furamidine, 6-[5-(4-amidinophenyl)-furan-2-yl]nicotinamidine (DB820), has potent in vitro antitrypanosomal activity; however, it suffers from poor oral activity because of its positively charged amidine groups. The dimethoxyamidine prodrug of DB820, N-methoxy-6-{5-[4-(N-methoxyamidino)phenyl]-furan-2-yl}-nicotinamidine (DB844), has potent oral activity in mouse models of both early-stage and CNS African trypanosomiasis. Metabolism of DB844 in human liver microsomes (HLM) was investigated using liquid chromatography-mass spectrometry (LC-MS/MS). The metabolism of DB844 in HLM was NADPH-dependent and resulted in the production of eight metabolites over a 90?min incubation. O-Demethylation and N-dehydroxylation reactions resulted in the metabolic conversion of DB844 to its active DB820 metabolite. Chromatographic conditions used for LC-MS analysis allowed for the separation and identification of all metabolites including positional isomers. Demethylation of either the phenyl or pyridine side of DB844 (DB844 m/z 366.2) resulted in the production of two metabolites (M1A, M1B), each with a molecular ion of m/z of 352.3 and MS(2) fragments of 288.1, 305.2, 321.2 and 335.2. However, the intensities of the MS(2) fragments were different among the two isomeric metabolites, and comparison to an authentic standard allowed for the structural determination of each metabolite. The isomeric metabolites M2A and M2B, resulting from amidoxime reductions of M1A and M1B, were also chromatographically separated and had distinguishable MS(2) profiles that allowed for their structural assignments when compared to an authentic standard. The di-amidoxime product resulting from O-demethylation of either side of DB844 was also identified as an abundant metabolite during microsomal incubations. The active antitrypanosomal metabolite, DB820, was the last metabolite to be formed and thus provides evidence that DB844 may effectively be metabolized to its active metabolite in vivo.
一种新的呋喃脒氮杂类似物，6-[5-(4-脒基苯基)-呋喃-2-基]烟脒(DB820)，具有强大的体外抗锥虫活性；然而，由于其带正电荷的脒基，口服活性较差。DB820的二甲氧基脒前药，N-甲氧基-6-{5-[4-(N-甲氧基脒基)phenyl]-呋喃-2-基}-烟脒(DB844)，在早期和中枢神经系统非洲锥虫病的小鼠模型中具有强大的口服活性。使用液相色谱-质谱联用(LC-MS/MS)研究了DB844在人肝微粒体(HLM)中的代谢。DB844在HLM中的代谢是NADPH依赖性的，在90分钟的孵育过程中产生了8种代谢产物。O-去甲基化和N-去羟基化反应导致DB844代谢转化为其活性代谢产物DB820。用于LC-MS分析的色谱条件允许分离和鉴定所有代谢产物，包括位置异构体。DB844(DB844 m/z 366.2)的苯基或吡啶侧去甲基化产生了两种代谢产物(M1A、M1B)，每种代谢产物的分子离子为m/z 352.3，MS(2)碎片为288.1、305.2、321.2和335.2。然而，两种异构体代谢产物中MS(2)碎片的强度不同，与真实标准品比较可确定每种代谢产物的结构。由M1A和M1B的偕胺肟还原产生的异构体代谢产物M2A和M2B也通过色谱分离，并且具有可区分的MS(2)谱，与真实标准品比较时可进行结构归属。在微粒体孵育过程中，DB844任一侧O-去甲基化产生的二偕胺肟产物也被鉴定为丰富的代谢产物。活性抗锥虫代谢产物DB820是最后形成的代谢产物，因此提供了证据表明DB844在体内可能有效地代谢为其活性代谢产物。
