S-(2-18F-氟代乙基)-L-蛋氨酸的合成及其放射药理活性

目的研制肿瘤氨基酸代谢显像剂S-(2-18F-氟代乙基)-L-蛋氨酸(18FEMET),评价其区分炎症和肿瘤的价值.方法采用亲核取代反应,由两步法合成18FEMET.测定正常小鼠、肿瘤及炎症小鼠体内FEMET生物分布,对模型小鼠进行18FEMET PET显像,并与2-18F-2-脱氧-D-葡萄糖(FDG)和O-(2-18F-氟代乙基)-L-酪氨酸(FET)比较.结果 18FEMET手工合成时间约为70 min,未校正总放化产率为15%～25%,放化纯度大于95%.正常小鼠中胰腺、肾脏、结肠、肝和心脏等脏器摄取18FEMET较高,且放射性滞留时间较长,血液和脑摄取18FEMET较低.肿瘤细胞可高度摄取18FEMET,FDG和FET,炎症组织也可高度摄取FDG,但几乎不摄取18FEMET和FET.结论 18FEMET制备简便,能够区分肿瘤和炎症,可望成为一种有前景的特异性肿瘤氨基酸代谢PET显像剂.     

拟人参皂苷F11在大鼠体内的药物代谢研究

目的探讨拟人参皂苷F11在大鼠体内的药物代谢产物及其过程.方法ip拟人参皂苷F₁₁后,应用TLC分析排泄物中的代谢产物,并利用制备薄层分离制备代谢产物,通过波谱解析(MS,¹HNMR,¹³CNMR,¹H-¹HCOSY)确定其结构.结果从粪便中分离鉴定了3种代谢产物,分别为拟人参皂苷R_T5,ocotillol和1个新的代谢产物F-3-1,并确定其结构为6-O-α-L-吡喃鼠李糖基(1-2)-β-D-吡喃葡糖基-(20S,23S,24R)-达玛-20(24)-环氧-3β,6α,12β,23,25-五醇(6-O-α-L-rhamnopyranosyl-(1-2)-β-D-glucopyranosyl-(20S,23S,24R)-dammar-20(24)-epoxy-3-β,6α,12β,23,25-pentanol).但在尿液和胆汁中并未发现任何代谢产物.结论拟人参皂苷F₁₁不被肝脏代谢,但胆汁排泄物可在肠道被代谢为水解和氧化产物.     

6-氟-L-多巴合成及其对映纯度测定的研究

目的　合成6-氟-L-多巴(6-FDOPA) ,并测定其对映纯度。方法　以硝基藜芦醛(2)为原料,经亲核取代、还原碘化、手性相转移催化烷基化等多步反应得新化合物2-(2-氟-4,5-二甲氧苄基)-N-(二苯基甲叉)甘氨酸叔丁酯(8) ,8经水解反应制备终产物6-FDOPA ,用手性流动相和反相C₁₈柱的HPLC法测定其对映纯度。结果　合成6-氟-L-多巴总反应时间少于90min ,总产率约为33% ,对映纯度大于95%。结论　可大量合成6-FDOPA ,使自动合成6-[¹⁸F]-L-多巴成为可能。为6-[¹⁸F]-L-多巴的放射化学合成及其对映纯度的测定提供了可靠的技术     

衍生化GC法测定生物转化产品L-山梨糖及其中残余D-山梨醇的含量

设计了生物转化产品L-山梨糖及其中残余D-山梨醇的衍生化GC测定方法。以乙酸酐—吡啶(1∶1)为衍生化试剂对样品中残余D-山梨醇进行乙酰化GC测定,再以四氢硼钠为还原剂、乙酸酐为乙酰化试剂对样品中L-山梨糖进行还原乙酰化GC测定。结果表明,D-山梨醇及L-山梨糖分别在0.01999～2.999μg及4.00～24.00μg范围内呈线性。本法精密度及回收率均较好,可用于监测L-山梨糖生物转化终点及其成品中L-山梨糖及残余D-山梨醇的含量。     

海南含羞草中黄酮碳苷类化学成分的研究

目的研究海南含羞草(Mimosa pudica)的化学成分。方法利用Diaion HP-20，Toyopearl HW-40，MCI-Gel CHP-20，Sephadex LH-20，RP18及硅胶等柱色谱法对海南含羞草成分进行分离纯化，根据理化性质和光谱数据鉴定化合物的结构。结果分离鉴定了4个化合物：7,8,3′,4′-四羟基-6-C-［α-L-鼠李糖-(1→2)］-β-D-葡糖黄酮碳苷(I)，5,7,4′-三羟基-8-C-［α-L-鼠李糖(1→2)］-β-D-葡糖黄酮碳苷(II)，5,7,3′,4′-四羟基-6-C-［α-L-鼠李糖-(1→2)］-β-D-葡糖黄酮碳苷(III)，儿茶素(IV)。结论化合物I为新化合物，化合物II～IV为首次从该植物中分离得到。     

氟哌啶醇对大鼠离体海马脑片和原代神经元缺糖/缺氧和N-甲基-D-天冬氨酸损伤的保护作用

目的观察氟哌啶醇对大鼠离体海马脑片和原代神经元的缺糖/缺氧(OGD)和N-甲基-D-天冬氨酸(N-methyl-D-aspartate,NMDA)损伤的潜在保护作用及其机制。方法海马脑片OGD以无葡萄糖的人工脑脊液中通95% N₂+5% CO₂诱导。通过测定TTC染色后形成的红色产物来分析脑片活性。结果氟哌啶醇(1和10 μmol·L^-1)抑制OGD损伤,抑制率分别为17.7%和25%,而D₂多巴胺受体拮抗剂多潘立酮无此作用。NMDA也能显著降低海马脑片及原代神经元的活性,而氟哌啶醇可抑制这一损伤作用。结论氟哌啶醇对大鼠离体海马脑片OGD和原代神经元NMDA损伤有保护作用。     

HPLC测定安尔眠胶囊中2,3,5,4’-四羟基二苯乙烯-2-O-β-D-葡萄糖苷

目的 建立安尔眠胶囊中2,3,5,4’-四羟基二苯乙烯-2-O-β-D-葡萄糖苷（C₂₀H₂₂0₉）的含量测定方法。方法 采用高效液相色谱（HPLC）法,以Dionex Acclaim 120^® C₁₈色谱柱（150 mm×4.6 mm,5 μm）为分离柱,以乙腈-1%甲酸溶液（23：77）为流动相,体积流量1.0 mL/min,检测波长320 nm,柱温25 ℃。结果 2,3,5,4’-四羟基二苯乙烯-2-O-β-D-葡萄糖苷在0.010～0.200 μg呈现良好的线性关系（r=0.999 6）,平均回收率为97.35%,RSD为2.07%。结论 该方法<准确可靠,适用于安尔眠胶囊中2,3,5,4’-四羟基二苯乙烯-2-O-β-D-葡萄糖苷的含量测定。     

新型非环核苷膦酸L-氨基酸酯类化合物的设计、合成与抗乙型肝炎病毒活性

设计合成具有抗乙型肝炎病毒活性的非环核苷膦酸双L-氨基酸酯系列衍生物。以adefovir dipivoxil为先导化合物， 根据核苷L-氨基酸酯前药提高生物利用度及抗病毒活性的研究结果对先导化合物进行结构优化， 设计并合成一系列新型非环核苷膦酸双L-氨基酸类化合物， 确定其结构， 并通过测定其对HepG2 2.2.15细胞分泌的HBV-DNA的抑制作用评价其体外抗病毒活性。结果发现8个adefovir双L-氨基酸类化合物可显示不同程度活性， 其中化合物11的抗病毒活性最强、 选择性指数最高(EC₅₀ 0.095 2 μmol·L^-1, SI 69523)。以上研究提示L-氨基酸酯策略可适用于非环核苷膦酸的前药修饰， 以期发现有效抗HBV药物。     

L-和DL-正丁基东莨菪碱对大鼠子宫作用的比较

用放射配基结合法测定L-正丁基东莨菪碱，DL-正丁基东莨菪碱与阿托品对大鼠子宫M 胆碱受体的亲和力。结果表明，L-与DL-正丁基东莨菪碱对大鼠子宫M胆碱受体的亲和力十分相近，但都比阿托品弱。比较L-正丁基东莨菪碱、DL-正丁基东莨菪碱和阿托品对离体大鼠子宫的影响及对抗乙酰胆碱所致的子宫收缩作用，表明两种正丁基东莨菪碱对离体大鼠子宫无影响，而能对抗乙酰胆碱所致的子宫收缩，且作用相近，但都比阿托品弱。说明生物效应与其受体亲和力的大小相关。     

N-乙酰基-L-谷氨酰基-泼尼松龙肾靶向前体药物研究

目的通过研究N-乙酰基-L-谷氨酰基-泼尼松龙的体内分布，考察该前体药物的肾靶向性。方法小鼠iv后，采用高效液相法，在规定时间段测定各组织脏器的泼尼松龙浓度, 并采用大鼠骨密度的测定仪确证前体药物的副作用。结果小鼠给药后15 min，前体药物组肾脏中泼尼松龙浓度为(86±8) μg·g^-1，泼尼松龙组为(57±4) μg·g^-1，60 min后前体药物组肾脏药物浓度为 (67±5) μg·g^-1；泼尼松龙组(42±4) μg·g^-1。大鼠给药30 d后，股骨的骨密度分别为(0.08±0.03) g·cm^-2 （泼尼松龙）和(0.14±0.06) g·cm^-2(前体药物组)。结论前体药物具有肾靶向性, 并能降低致骨质疏松的副作用。     

PET of insulinoma using ¹⁸F-FBEM-EM3106B, a new GLP-1 analogue

Derived from endocrine pancreatic beta cells, insulinomas express glucagon-like peptide-1 (GLP-1) receptor with high density and incidence. In this study, we labeled a novel GLP-1 analogue, EM3106B, with (18)F and performed PET imaging to visualize insulinoma tumors in an animal model. A GLP-1 analogue that contains multiple lactam bridges, EM3106B, was labeled with (18)F through a maleimide-based prosthetic group, N-2-(4-(18)F-fluorobenzamido)ethylmaleimide ((18)F-FBEM). The newly developed radiotracer was characterized by cell based receptor-binding assay, cell uptake and efflux assay. The stability in serum was evaluated by radio-HPLC analysis. In vivo PET imaging was performed in nude mice bearing subcutaneous INS-1 insulinoma tumors and MDA-MB-435 tumors of melanoma origin. Ex vivo biodistribution study was performed to confirm the PET imaging data. EM3106B showed high binding affinity (IC(50) = 1.38 nM) and high cell uptake (5.25 ± 0.61% after 120 min incubation). (18)F-FBEM conjugation of EM3106B resulted in high labeling yield (24.9 ± 2.4%) and high specific activity (>75 GBq/μmol at the end of bombardment). EM3106B specifically bound and was internalized by GLP-1R positive INS-1 cells. After intravenous injection of 3.7 MBq (100 μCi) of (18)F-FBEM-EM3106B, the INS-1 tumors were clearly visible with high contrast in relation to the contralateral background on PET images, and tumor uptake of (18)F-FBEM-EM3106B was determined to be 28.5 ± 4.7 and 25.4 ± 4.1% ID/g at 60 and 120 min, respectively. (18)F-FBEM-EM3106B showed low uptake in MB-MDA-435 tumors with low level of GLP-1R expression. Direct tissue sampling biodistribution experiment confirmed high tracer uptake in INS-1 tumors and receptor specificity in both INS-1 tumor and pancreas. In conclusion, (18)F-FBEM-EM3106B exhibited GLP-1R-receptor-specific targeting properties in insulinomas. The favorable characteristics of (18)F-FBEM-EM3106B, such as high specific activity and high tumor uptake, and high tumor to nontarget uptake, demonstrate that it is a promising tracer for clinical insulinoma imaging.     

Apoptosis imaging to monitor cancer therapy: the road to fast treatment evaluation?

Molecular imaging of biological processes may allow detection of therapy effects before the tumor is reduced in size. The most frequently used PET tracer in oncology, 2-[18F]fluoro-2-deoxyglucose (FDG), suffers from low specificity due to uptake in inflammatory cells. The proliferation marker, 3'-[18F]fluoro-3'-deoxy-L-thymidine (FLT), is less influenced by the inflammatory response following therapy but here disease- and drug-specific effects need to be considered. Since cancer therapy mainly intends to eliminate cancer cells, imaging of cell death offers a direct way to image therapy response. This review gives an overview of the radiopharmaceutical development and in vivo evaluation of radioligands that have emerged so far for detection and assessment of apoptosis and necrosis. Two radiopharmaceuticals that can image cell death have made it to clinical trials for follow up of tumor treatment: i) 99mTc-and 123I-labelled AnxA5 for the response to treatment of for example lymphoma and lung cancer and ii) 18F-ML10 for the evaluation of brain tumors post-radiation. Other agents need further optimization.     

4-[18F]fluoroglutamic acid (BAY 85-8050), a new amino acid radiotracer for PET imaging of tumors: synthesis and in vitro characterization

There is a high demand for tumor specific PET tracers in oncology imaging. Besides glucose, certain amino acids also serve as energy sources and anabolic precursors for tumors. Therefore, (18)F-labeled amino acids are interesting probes for tumor specific PET imaging. As glutamine and glutamate play a key role in the adapted intermediary metabolism of tumors, the radiosynthesis of 4-[(18)F]fluoro l-glutamic acid (BAY 85-8050) as a new specific PET tracer was established. Cell-uptake studies revealed specific tumor cell accumulation.     

Automated commercial synthesis system for preparation of O‐(2‐[18F]fluoroethyl)‐L‐tyrosine by direct nucleophilic displacement on a resin column

A slightly modified automated commercial synthesis system for preparation of O‐(2‐[¹⁸F]fluoroethyl)‐l‐tyrosine (FET), an amino acid tracer for tumor imaging with positron emission tomography, is described. Direct nucleophilic fluorination of [¹⁸F]fluoride with 1,2‐di(4‐methylphenylsulfonyloxy)ethane on a quaternary 4‐(4‐methylpiperidinyl)‐pyridinium functionalized polystyrene anion exchange resin gave 1‐[¹⁸F]‐2‐(4‐methylphenylsulfonyloxy)ethane, then [¹⁸F]fluoroalkylation of l‐tyrosine yielded FET. The overall radiochemical yield with no decay correction was about 8–10%, the whole synthesis time was about 52 min, and the radiochemical purity was above 95%. Copyright © 2003 John Wiley & Sons, Ltd.     

Altered glucose homeostasis in alpha2A-adrenoceptor knockout mice

To elucidate the functions of alpha2-adrenoceptor subtypes in metabolic regulation, we determined plasma glucose and insulin levels and tissue uptake of the glucose analogue 2-[18F]fluoro-2-deoxy-d-glucose ([18F]FDG) in C57Bl/6J wild-type (WT) and alpha2A-adrenoceptor knockout (alpha2A-KO) mice at baseline and following alpha2-adrenoceptor agonist ((+)-4-(S)-[1-(2,3-dimethylphenyl)ethyl]-1H-imidazole (dexmedetomidine)) and antagonist (4-[2-ethyl-2,3-dihydro-1H-inden-2-yl]-1H-imidazole (atipamezole)) administration. Basal glucose levels were 30% lower in alpha2A-KO mice than in WT mice. In WT mice, dexmedetomidine lowered insulin and elevated glucose levels, and atipamezole reduced glucose levels. In alpha2A-KO mice, neither drug affected the glucose or insulin levels. [18F]FDG uptake was investigated in plasma, heart, liver, kidney, pancreas, lung, fat, and skeletal muscle. Cardiac [18F]FDG uptake was a sensitive indicator of sympathetic function. Liver [18F]FDG uptake conformed to the plasma glucose levels. In alpha2A-KO mice, drug effects on [18F]FDG tissue uptake were absent. Thus, the alpha2A-adrenoceptor is the alpha2-adrenoceptor subtype primarily involved in the regulation of blood glucose homeostasis in vivo.     

Radiosynthesis,in vitro and preliminary biological evaluation of [18F]2-amino-4-((2-((3-fluorobenzyl)oxy)benzyl)(2-((3-(fluoromethyl)benzyl)oxy)benzyl)amino)butanoic acid,a novel alanine serine cysteine transporter 2 inhibitor-based positron emission tomography tracer

The metabolic alterations in tumors make it possible to visualize the latter by means of positron emission tomography, enabling diagnosis and providing metabolic information. The alanine serine cysteine transporter-2 (ASCT-2) is the main transporter of glutamine and is upregulated in several tumors. Therefore, a good positron emission tracer targeting this transport protein would have substantial value. Hence, the aim of this study is to develop a fluorine-18-labeled version of a V-9302 analogue, one of the most potent inhibitors of ASCT-2. The precursor was labeled with fluorine-18 via a nucleophilic substitution of the corresponding benzylic bromide. The cold reference product was subjected to in vitro assays with [³H]glutamine in a PC-3 and F98 cell line to determine the affinity for both the human and rat ASCT-2. To evaluate the tracer potential dynamic μPET, images were acquired in a mouse xenograft model for prostate cancer. The tracer could be synthesized with an overall nondecay corrected yield of 3.66 ± 1.90%. in vitro experiments show inhibitor constants K_i of 90 and 125 μM for the PC-3 and F98 cells, respectively. The experiments in the PC-3 xenograft demonstrate a low uptake in the tumor tissue. We have successfully synthesized the radiotracer [¹⁸F]2-amino-4-((2-((3-fluorobenzyl)oxy)benzyl)(2-((3-(fluoromethyl)benzyl)oxy)benzyl)amino)butanoic acid. in vitro experiments show a good affinity for both the human and rat ASCT-2. However, the tracer suffers from poor in vivo tumor uptake in the PC-3 model. Briefly, we present the first fluorine-18-labeled derivative of compound V-9302, a promising novel ASCT-2 blocker used for inhibition of tumor growth.     

Selective synthesis of L-2-[18F]fluoro-alpha-methylphenylalanine via copper-mediated 18F-fluorination of (mesityl)(aryl)iodonium salt

L-2-[¹⁸F]fluoro-alpha-methylphenylalanine (2-[¹⁸F]FAMP) is a promising amino acid tracer for positron emission tomography (PET) imaging, yet the low production yield of direct electrophilic radiofluorination with [¹⁸F]F₂ necessitates further optimization of the radiolabeling process. This paper describes a two-step preparation method for L-2-[¹⁸F]fluoro-alpha-methylphenylalanine (2-[¹⁸F]FAMP) starting from [¹⁸F]fluoride. The (Mesityl)(L-alpha-methylphenylalanine)-2-iodonium tetrafluoroborate precursors with various protecting groups were prepared. The copper-mediated ¹⁸F-fluorination of the iodonium salt precursors successfully produced 2-[¹⁸F]FAMP. The highest radio chemical conversion of 57.6% was noted with N-Piv-protected (mesityl)(aryl)iodonium salt in the presence of 5 equivalent of Cu (OTf)₂. Subsequent deprotection with 57% hydrogen iodide produced 2-[¹⁸F]FAMP within 120 min in 21.4 ± 11.7% overall radiochemical yield with >95% radiochemical purity and an enantiomeric excess >99%. The obtained 2-[¹⁸F]FAMP showed comparable biodistribution profiles in normal mice with that of the carrier-added 2-[¹⁸F]FAMP. These results indicate that usefulness of copper mediated ¹⁸F-fluorination for the production of 2-[¹⁸F]FAMP, which would facilitate clinical translation of the promising tumor specific amino acid tracer. Individual facilities could adopt either production method based on radioactivity demand and equipment availability.     

Preclinical evaluation and pilot clinical study of [18F]AlF-labeled FAPI-tracer for PET imaging of cancer associated fibroblasts

In recent years, fibroblast activation protein (FAP) has emerged as an attractive target for the diagnosis and radiotherapy of cancers using FAP-specific radioligands. Herein, we aimed to design a novel ¹⁸F-labeled FAP tracer ([¹⁸F]AlF-P-FAPI) for FAP imaging and evaluated its potential for clinical application. The [¹⁸F]AlF-P-FAPI novel tracer was prepared in an automated manner within 42 min with a non-decay corrected radiochemical yield of 32 ± 6% (n = 8). Among A549-FAP cells, [¹⁸F]AlF-P-FAPI demonstrated specific uptake, rapid internalization, and low cellular efflux. Compared to the patent tracer [¹⁸F]FAPI-42, [¹⁸F]AlF-P-FAPI exhibited lower levels of cellular efflux in the A549-FAP cells and higher stability in vivo. Micro-PET imaging in the A549-FAP tumor model indicated higher specific tumor uptake of [¹⁸F]AlF-P-FAPI (7.0 ± 1.0% ID/g) compared to patent tracers [¹⁸F]FAPI-42 (3.2 ± 0.6% ID/g) and [⁶⁸Ga]Ga-FAPI-04 (2.7 ± 0.5% ID/g). Furthermore, in an initial diagnostic application in a patient with nasopharyngeal cancer, [¹⁸F]AlF-P-FAPI and [¹⁸F]FDG PET/CT showed comparable results for both primary tumors and lymph node metastases. These results suggest that [¹⁸F]AlF-P-FAPI can be conveniently prepared, with promising characteristics in the preclinical evaluation. The feasibility of FAP imaging was demonstrated using PET studies.     

New PET imaging agent for the serotonin transporter: [(18)F]ACF (2-[(2-amino-4-chloro-5-fluorophenyl)thio]-N,N-dimethyl-benzenmethanamine)

A new F-18-labeled phenylthiophenyl derivative specific for imaging of serotonin transporters (SERT) in the brain by positron emission tomography (PET) is described. Fluorinated phenylthiophenyl derivative, ACF, 2-[(2-amino-4-chloro-5-fluorophenyl)thio]-N,N-dimethyl-benzenmethanamine, was prepared by first coupling 2,5-dichloro-4-nitroaniline with 2-mercapto-N,N-dimethylbenzamide. The amino group of the coupled adduct was converted to a fluoro group through a Schiemann reaction. Subsequently, a one pot reduction of both nitro and amide groups by BH(3)-tetrahydrofuran yielded the nonradioactive ACF (yield 25%). In vitro binding assays using cell membrane homogenates of LLC cells expressing SERT, dopamine transporters (DAT), or norepinephrine transporters (NET) showed excellent binding affinity and selectivity for SERT (K(i) = 0.05, 3020, and 650 nM for SERT, DAT, and NET, respectively). For preparation of the [(18)F]ACF, the NH(2) group of the initially coupled adduct was converted to the trimethylammonium salt, which was replaced by [(18)F]fluoride in the presence of Kryptofix 222 and potassium carbonate. The final product, [(18)F]ACF, was obtained after a borane and stannous chloride reduction reaction. The combined two step reaction gave a radiochemical yield of 10-15% (EOB) and a radiochemical purity of >99%. Synthesis of the novel PET tracer, [(18)F]ACF, as a probe for binding to SERT in the brain was successfully achieved. The new tracer [(18)F]ACF showed excellent brain penetration and selective localization after an iv injection in rats (brain uptake at 2, 30, 60, 120, and 240 min was 3.27, 1.28, 0.69, 0.21, and 0.06% dose/organ, respectively). The hypothalamus/cerebellum ratio at 60 min post iv injection was 3.55. This specific localization in the hypothalamus was blocked by pretreatment of (+)McN5652. This novel ligand is a potential PET tracer for in vivo evaluation of SERT in the brain.     

Synthesis of [18F]Fluoroalanine and [18F]Fluorotamoxifen for Imaging Breast Tumors

Abstract

To develop ligands for imaging breast tumors, [¹⁸F]fluoro analogue of tamoxifen and [¹⁸F]fluoro-alanine were radiosynthesized. In vivo biodistribution studies were performed in mammary tumor-bearing rats. In studies on the biodistribution of an [¹⁸F]fluoro analogue of tamoxifen, tumor uptake decreased when rats were pretreated with diethylstilbestrol (DES), suggesting that tracer uptake in tumors was receptor-mediated. An estrogen receptor assay indicated that tumors have a receptor density of 7.5 fmol/mg protein. Studies of the distribution of [¹⁸F]fluoroalanine in tissue showed that the tumor-to-tissue ratio increases as a function of time. Positron emission tomography (PET) images of tumor-bearing rats demonstrated that tumors can be visualized 1 h after rats are injected with an [¹⁸F]fluoro analogue of tamoxifen. PET imaging of pigs after injection of 10 mCi of [¹⁸F]fluoro analogue of tamoxifen showed uterine uptake that could be blocked by DES (50 mg). The findings suggest that both radiotracers are useful for imaging breast tumors.