Animal biodistribution, safety and validation study of dopamine transporter PET imaging agent ^18F-FECNT

This work was to investigate the pharmacologic characteristics of 18F-FECNT (2β-carbomethoxy-3β-(4-chlorophenyl)-8-(2-[18F]fluorcethyl)nortropane) as a dopamine transporter (DAT) PET imaging agent.Its partition coefficients were determined in n-octanol and phosphate buffer (PB) (pH 7.0 and pH 7.4).6-Hydroxydopamine (6-OHDA) left-sided lesioned Parkinsonian rats were established and validated by rotational behavior tests.Biodistribution in vivo in mice,autoradiography in normal and hemi-Parkinsonian rat brains,and toxicity test were performed.The results showed that partition coefficients were 34.14 (pH 7.0) and 56.41 (pH 7.4),respectively.Biodistribution exhibited rapid uptake and favorable retention in the mice brains.The major radioactivity was metabolized by the hepatic system.The autoradiography showed that 18F-FECNT was highly concentrated in striaturn,and that the left and the tight striatal uptake were symmetrical in normal SD rat brains.In left-sided lesioned PD rat brains,the striatal uptake of 18F-FECNT bilaterally decreased in comparison with normal rats.No significant uptake was visible in the 6-OHDA lesioned-sided striatal areas.The results demonstrated that 18F-FECNT binds to DAT was specific.Toxicity trial displayed that the acceptable dose per kilogram to mice was 625 times greater than that to human.These indicate that 18F-FECNT is a potentially safe and useful DAT PET imaging agent in the brain.     

Synthesis and biological evaluation of 18F-FB-NGA as a hepatic asialoglycoprotein receptor PET imaging agent

Abstract Asialoglycoprotein receptor （ASGP-R） is a hepatic membrane receptor that uniquely exists on the surface of mammalian hepatocytes, and has been used as target of liver functional imaging agents for many years. We labeled the Galactosyl-neoglycoalbumin （NGA） with 18F to get a PET molecular probe 18F-FB-NGA and evaluated its ability as a liver functional PET imaging agent. The 18F-FB-NGA was prepared with NGA by conjugation with N- succinimidyl-4-18F-fluorobenzoate （18F-SFB） and purified with PD-10 desalting column. The radiolabeling yield and radiochemical purity of 18F-FB-NGA were determined by radio-HPLC. Starting with 18F-F-, the total time for 18F-F/3 -NGA was about 120± 10 min. The decay-corrected radiochemical yield is about 25-30%. The radiochemical purity of purified 18F-FB-NGA was more than 98%. Labeled with 185-1850 MBq 18F-SFB, the specific activity of 18F -FB- NGA was estimated to be 7.8-78.3 TBq/mmol. Biodistribution of 18F-FB-NGA in normal mice was investigated after injection through the tail vein. The results showed that the liver accumulated 39.47±3.42 and 12.12±6.11%ID/g at 10 and 30 min after injection, respectively. Dynamic MicroPET images in mice were acquired with and without block after injection of the radiotracer, respectively. High liver activity accumulation was observed at 5 min after injection in normal group. On the contrary, the liver accumulation was significantly lower after block, indicating the specific binding to ASGP-R. J SF-FB-NGA is probably a potential PET liver imaging agent.     

肿瘤显像剂18F-氟代乙酸盐的自动化合成

为研究肿瘤显像剂18F-氟代乙酸盐(18F-FAC)的自动化合成工艺,采用"一锅法"和TRACERlab FXF-N自动化合成装置,以溴代乙酸苄酯为前体,在同一反应瓶中经亲核氟化、NaOH水解两步反应及HPLC系统分离纯化制备18F-FAC注射液.总合成时间约50 min,未校正放化产率和放化纯度分别大于45%和99%.采用"一锅法"自动化合成18F-FAC,操作简便,能满足科研和临床正电子发射断层显像的需要.     

Improved preparation and chemical kinetics on fully automated synthesis of [18F]-THK523,a PET imaging probe for Tau pathologies

Extensive accumulation of neurofibrillary tangles(NFTs)consistently correlate with the degree of cognitive impairment and neuronal circuitry deterioration associated with Alzheimer's disease.However,no PET probe is currently available for selective detection of NFTs in the living human brain.[~(18)F]-THK523 was developed as a potential in vivo imaging probe for tau pathology.In this paper,we report a new protected precursor,2-((2-(4-((tert-butoxycarbonyl)amino)phenyl)quinolin-6-yl)oxy)ethyl 4-methylbenzenesulfonate(THK-7),instead of2-((2-(4-aminophenyl)quinolin-6-yl)oxy)ethyl 4-methylbenzenesulfonate(BF241),and an improved automated radiosynfhesis of[~(18)F]-THK523 and the study on chemical kinetics of the labeling reaction of[~(18)F]-THK523,with high-yield(70±5%,n=6,decay-corrected to end of bombardment),and high radiochemical purity(90%)and specific activity(2.5±0.5Ci/umol)from protected precursor on fully automated module at the end of radiosynthesis(45-55 min).The chemical kinetics for[~(18)F]-THK523 demonstrates that nucleophilic substitution can be carried out easily with protected precursor.     

简便、快速自动化合成肿瘤显像剂18F-氟代乙酸盐和1-H-1-(3-18F-2-羟基丙基)-2-18F-硝基咪唑

用"一锅法"和TRACERlab FXF-N自动化合成仪系统合成了18F-氟代乙酸盐(18F-FAC)和1-H-1-(3-18F-2-羟基丙基)-2-硝基咪唑(18F-FMISO).以溴代乙酸苄酯为前体,在同一反应瓶中经亲核氟化、NaOH水解两步反应及Sep Pak小柱分离纯化制备了18F-FAC注射液,总合成时间小于40 min,未经校正的放化产率和放化纯度分别大于45%和99%.以1-(2'-硝基-1'-咪唑基)-2-O-四氢吡喃基-3-O-甲苯磺酰基丙二醇为原料,用类似方法制备了18F-FMISO注射液,总合成时间小于40min,未经校正的放化产率和放化纯度分别大于40%和95%.采用"一锅法"自动化合成18F-FAC和18F-FMISO注射液,操作简便,该工艺可用制备2-18F-2-脱氧-D-葡萄糖(18F-FDG)的全自动化合成模块来制备18F-FAC和18F-FMISO注射液.     

Synthesis, radiolabeling and animal studies of [131I]MPPI: A 5-HT1A imaging agent

The synthesis and biological evaluation of serotonin (5-HT1A) imaging agent [131I]-4-iodo-N-{2-[4-(2-methoxyphenyl)-piperazin-1-yl]-ethyl}-N-pridin-2-yl-benzamide ([131I]MPPI) are reported. The chemical structure of aimed compound and intermediates were confirmed by IR, 1HNMR, and MS. Radiochemical purity was above 99% determined by TLC. Biodistribution of [131I]MPPI in rats displayed high uptake in hippocampus and low uptake in cerebellum. The ratio of the uptake of [131I]MPPI in hippocampus to that in cerebellum was 2.90 at 30 min post injection. The radioactivity in thyroid was 0.069 and 0.128% ID/g organ at 5 min and 120 min,respectively, and it was increased with time, which suggests that in vivo deiodination may be the major route of metabolism. Ex vivo autoradiography of brain section displayed significant decrease of radioactivity in hippocampus when pretreated with 8-OH-DPAT, a selective 5HT1A agonist, compared with control. These findings strongly suggested that 131I-MPPI could be used as an in vivo marker for studies of pharmacology of the 5-HT1A receptor system in animals.     

苯甲酰胺类多巴胺D2受体显像剂18F-FSABZM的合成和标记

将5-硝基取代苯甲酰胺类化合物经硝基还原、N-双羟乙基化、甲磺酰化等反应制备氟标记前体,用K222催化进行氟标记,合成了(S)-N-[(1-乙基-2-比咯烷基)甲基]-5-[N-(2-[18F]氟乙基)-N-甲基磺酰基]胺基-2-甲氧基苯甲酰胺(S)-N-[(1-ethyl-2-pyrrolidinyl)methyl]-5-[N-(2-[18F]fluoroethyl)-N-methylsulfonyl]amino-2-methoxy-benzamide,18F-FSABZM).标记前体、冷标记产物和各步合成中间体均经过核磁共振和质谱确证.结果显示,经HPLC检测,标记率为12%-15%,合成及纯化时间80-90 min,纯化后放化纯度大于97%,稳定性好.     

Synthesis, radiolabeling and animal studies of [^131I]MPPI： A 5-HT1A imaging agent

The synthesis and biological evaluation of serotonin （5-HT1A） imaging agent [^131I]- 4-iodo-N-{2-[4-（2-methoxyphenyl）-piperazin-l-yl]-ethyl}-N-pridin-2-yl-benzamide （[^131I]MPPI） are reported. The chemical structure of aimed compound and intermediates were confirmed by IR, ^1HNMR, and MS. Radiochemical purity was above 99% determined by TLC. Biodistribution of [^131I]MPPI in rats displayed high uptake in hippocampus and low uptake in cerebellum. The ratio of the uptake of [^131I]MPPI in hippocampus to that in cerebellum was 2.90 at 30 rain post injection. The radioactivity in thyroid was 0.069 and 0.128% ID/g organ at 5 min and 120 rain, respectively, and it was increased with time, which suggests that in vivo deiodination may be the major route of metabolism. Ex vivo autoradiography of brain section displayed significant decrease of radioactivity in hippocampus when pretreated with 8-OH-DPAT, a selective 5HT1A agonist, compared with control. These findings strongly suggested that ^131I-MPPI could be used as an in vivo marker for studies of pharmacology of the 5-HT1A receptor system in animals.     

The preclinical pharmacological study of dopamine transporter imaging agent 18F-FP-β-CIT

The paper is to study pharmacologic characteristics of 18F-FP-β-CIT (18F-N-(3-fluoropropyl)-2β- carbomethoxy-3β- (4-iodophenyl)nortropane) as an imaging agent for dopamine transporter. The radiochemical purity of 18F-FP-β-CIT in aqueous solution was over 95% after standing at room temperature for 4h. Biodistribution displayed rapid uptake in rat brain (1.375 %ID/organ at 5min and 0.100 %ID/organ at 180 min) and the striatal uptake was 1.444,0.731, 0.397, 0.230 and 0.146 %ID/g at 5, 30, 60, 120 and 180 min, respectively. The values of striatum/cerebellum,striatum/frontal cortex and striatum / hippocampus in rat's brain at 30 min were 3.38, 2.17 and 2.40 respectively. The uptake in striatum can be blocked by β-CFT, suggesting that 18F-FP-β-CIT binds to DAT peculiarly. The compound was rapidly cleared from monkey's blood. The striatal uptake was bilaterally decreased in the left-sided lesioned PD rats, compared with normal control. Brain PET imaging studies in normal monkey showed that 18F-FP-β-CIT was concentrated in striatum. The test of undue toxicity showed that the dose received by mice was 1250 times as by human, which indicates that 18F-FP-β-CIT is very safe. So 18F-FP-β-CIT is a promising PET imaging agent for DAT with safety and validity.     

简便快速自动化合成报告基因表达PET显像剂18F-FHBG

用一锅法和TRACERlab FXF-N合成仪自动化合成9-(4-18F-3-羟甲基丁基)鸟嘌呤(188F-FHBG).以N2-(对甲氧苯基二苯基甲基)-9-[(4-甲苯磺酰基)-3-对甲氧苯基二苯基甲氧基-甲基丁基]鸟嘌呤为前体,在同一反应瓶中经亲核氟化、水解两步反应及SEP-PAK小柱分离纯化制备18 F-FHBG注射液,总合成时间<40 min,未校正放化产率为7%-12%(n>10),放化纯度>95%.用SEP-PAK分离纯化的一锅法,操作简便,很容易实现18F-FHBG的自动化合成.     

Synthesis, radiolabeling and animal studies of [~(131)I]MPPI: A 5-HTB_(1A) imaging agent

1 Introduction In the last two decades, considerable progress has been made in the understanding of the central nervous system (CNS) serotonin system. It is an important neurotransmission network that regulates various physiological functions and behavior, including anxi-ety and affective states.P[1-3]P The family of receptors activated by the neurotransmitter serotonin has been divided into at least seven classes (5-HTB1-7B), some of them further subdivided into different subtypesP[4, 5]P…     

Radiosynthesis and biodistribution of [^18F]-tetracosactide using a semi-automated [^18F]SFB production module

In order to prepare a specific melanocortin type 2 receptor (MC2R) ligand, b1-24-corticotrophin was pre-pared in one-step reaction with [18F] SFB and b-1-24-corticotrophin pharmaceutical solution (1 mg/mL, pH=6.5). [18F]SFB was prepared in a semi-automated module in two steps with an overall radiochemical yield of 47% to EOB (not-decay corrected) in 90 min. The 18F-labeled intermediates and 18F-labeled peptide was checked by RTLC and HPLC. The results show that the radiochemical purity is >95% and the yield to EOB (not-decay corrected) is 29% for final 18F-labeled peptide at optimized conditions. Preliminary in vivo studies in normal mice were performed to deter-mine biodistribution of the 18F-labeled peptide for 150 min. The results show that the major tracer uptake is consistent with the natural distribution of MC2R receptors in mammals. Testes/blood and testes/muscle ratios for 18F-labeled peptide at 150 min were 184 and 1.56, respectively, and adipocyte/blood and adipocyte/muscle ratios at 120 min were 221 and 142, respectively. The data support the specific receptor binding of the radiolabeled peptide as reported for MC2R receptor accumulation in adipocytes and testes and demonstrates the retention of biological activity of the pep-tide. This tracer can be used in detection of MC2R distribution in malignancies and sex organ diseases.     

一锅法自动化合成3’-脱氧-3’-~(18)F-氟代胸苷和O-(2-~(18)F-氟代乙基)-L-酪氨酸

采用"一锅法"和TRACERlab FXF-N自动化合成装置,以3-N-t-叔丁氧羰基-1-[5'-O-(4,4'-二甲氧基三苯甲基)-2'-脱氧-3'-O-(4-硝基苯磺酰基)-β-D-苏型阿呋喃糖基]胸腺嘧啶为前体,在同一反应瓶中经亲核氟化、盐酸水解两步反应及HPLC分离纯化制备18F-FLT注射液.以乙二醇二对甲苯磺酸酯为起始原料,在同一反应瓶中经亲核氟化和烷基化两步反应及HPLC分离纯化得18F-FET注射液.18F-FLT和18F-FET总合成时间分别约为60 min和50 min,未校正的放化产率均大于20%,放化纯度均大于95%.18F-FLT和18F-FET注射液质量控制指标符合放射性药物质量要求.     

Radio-ligand receptor binding assay in vitro and animal biodistribution in vivo of 99Tcm-N-ethyl-N2S2-memantine as a potential NMDA receptor imaging agent

The pharmacologic characteristics of 99Tcm-N-ethyl-N2S2-memantine,an NMDA receptor imaging agent,was investigated.It was prepared by a one-step reaction from N-ethyl-N2S2-memantine.The affinity and specificity were determined by radio-ligand receptor binding assay(RRA).Biodistribution in vivo in mice was performed.The results showed that 99Tcm-N-ethyl-N2S2-memantine bound to a single site on NMDA receptor with a Kd of 584.32 nmol/L and a Bmax of 267.05 nmol/mg.A competitive analysis showed that such specific binding could be inhibited by specific inhibitors of NMDA receptor,such as ketamine and(+)-MK-801.The biodistribution exhibited rapid uptake and favorable retention in mice brains.The major radioactivity was metabolized by the hepatic system.A two-compartment model of C=4.49e-0.083t+1.42e-0.0016t was established,and the half life was 8.35 min in blood.In conclusion,the new radio-ligand 99Tcm-N-ethyl-N2S2-Memantine has a moderate affinity and specific binding to NMDA receptor,and can easily cross the blood-brain barrier(BBB).Therefore,it may be a potential NMDA receptor imaging agent.     

脑灌注显像剂IP的合成,碘标记和动物实验

实验表明，出现（ＩＰ）（对碘－γ，γ－二甲基－苯乙胺）分子结构上引入了甲基，提高了亲脂性，从而易于通过血脑屏障。该药物碘标记后有可能成为一种脑灌注显像剂。