Tryptophan and its metabolites are involved in different physiological and pathophysiological processes. Consequently, positron emission tomography (PET) tracers addressing tryptophan metabolic pathways should allow the detection of different pathologies like neurological disorders and cancer. Herein we report an efficient method for the preparation of fluorotryptophans labeled in different positions with ¹⁸F and their biological evaluation. 4–7-[¹⁸F]Fluorotryptophans ([¹⁸F]FTrps) were prepared according to a modified protocol of alcohol-enhanced Cu-mediated radiofluorination in 30–53% radiochemical yields. In vitro experiments demonstrated high cellular uptake of 4–7-[¹⁸F]FTrps in different tumor cell lines. 4, 5-, and 6-[¹⁸F]FTrps, although stable in vitro, suffered from rapid in vivo defluorination. In contrast, 7-[¹⁸F]FTrp demonstrated a high in vivo stability and enabled a clear delineation of serotonergic areas and melatonin-producing pineal gland in rat brains. Moreover 7-[¹⁸F]FTrp accumulated in different tumor xenografts in a chick embryo CAM model. Thus, 7-[¹⁸F]FTrp represents a highly promising PET probe for imaging of Trp metabolism.

中文翻译：

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7- [ ¹⁸ F]氟色氨酸作为一种新型正电子发射断层扫描（PET）探针的体内色氨酸代谢可视化的发现。

色氨酸及其代谢产物参与不同的生理和病理生理过程。因此，解决色氨酸代谢途径的正电子发射断层扫描（PET）示踪剂应允许检测不同的病理，例如神经系统疾病和癌症。在此，我们报告了一种制备¹⁸ F标记在不同位置的氟色氨酸的有效方法及其生物学评估。根据酒精增强的铜介导的放射性氟化的改良方案，以30-53％的放射化学收率制备4–7- [ ¹⁸ F]氟色氨酸（[ ¹⁸ F] FTrps）。体外实验表明，不同肿瘤细胞系中细胞对4-7- [ ¹⁸ F] FTrps的摄取很高。4、5和6- [¹⁸ F] FTrps虽然在体外稳定，但体内快速除氟。相反，7- [ ¹⁸ F] FTrp表现出较高的体内稳定性，并能够清楚地描绘出大鼠脑中的血清素能区域和产生褪黑激素的松果体。此外，在鸡胚CAM模型中，不同肿瘤异种移植物中积累了7- [ ¹⁸ F] FTrp。因此，7- [ ¹⁸ F] FTrp代表用于Trp代谢成像的高度有前途的PET探针。