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Efforts are underway to improve the diagnosis and treatment for neurological disorders like depression, anxiety, epilepsy, and schizophrenia. The G‐protein‐coupled receptors (GPCRs) 5‐HT7 receptor, the most recently identified member of 5‐HT receptor family dysregulation has an association with various central nervous system (CNS) disorders and its ligands have an edge as potential therapeutics. Here, we report the synthesis, characterization, and biological evaluation of diversely substituted methoxy derivatives of 2‐benzoxazolone arylpiperazine for targeting 5‐HT7 receptors. Out of all derivatives, only C‐2 substituted derivative, 3‐(4‐(4‐(2‐methoxyphenyl)piperazin‐1‐yl)butyl)benzoxazol‐2(3H)‐one/ABO demonstrate a high affinity for human 5‐HT7 receptors. [11C]ABO was obtained by O‐methylation of desmethyl‐precursor using [11C]CH3OTf in the presence of NaOH giving a high radiochemical yield of 25 ± 12% (decay‐corrected, n = 7) with stability up to 1.5 h postradiolabeling. In vitro autoradiography displays binding of [11C]ABO in accordance with 5‐HT7 distribution with a decrease of approximately 80% and 40% activity in the hippocampus and cerebellum brain region when administered with 10 µM cold ligand. Prefatory positron emission tomography scan results in Sprague‐Dawley (SD) rat brain revealed fast and high radioactivity build‐up in 5‐HT7 receptor‐rich regions, namely, the hippocampus (2.75 ± 0.16 SUV) and the cerebral cortex (2.27 ± 0.02 SUV) establishing selective targeting of [11C]ABO. In summary, these pieces of data designate [11C]ABO as a promising 5‐HT7 receptor ligand that can have possible roles in clinics after its further optimization on different animal models. [ABSTRACT FROM AUTHOR]

Vascular endothelial growth factor co‐receptor neuropilin‐1, NRP‐1, is one of the prime tumor targets owing to its overexpression in numerous carcinomas. A peptidic conjugate, DO3A−Et‐RPAR was synthesized in 97% purity. It was labeled with 99mTc in 98% efficiency and specific activity of 3.62 MBq/nmol. The agent displayed minimal toxicity of 15% in healthy HEK293 cells at 0.5 mM concentration post 72 h incubation. 99mTc‐DO3A−Et‐RPAR was 98.6% stable in human serum up to 24 h post labeling. Cellular uptake assays exhibited maximum NRP‐1‐specific uptake (20±0.26% activity at 2 h) with low nanomolar affinity (KD = 9.21±0.36 nM) in U‐87 MG cells. In vivo blood kinetics study of radioconjugate establishes stability and rapid clearance from the bloodstream with biological half‐life of t1/2 (fast), 52±0.2 min; and t1/2 (slow), 13 h 10±0.4 min. Biodistribution studies carried out in U‐87 MG xenograft mice showed tumor to muscle ratio of 8.3 at 2 h p.i. [ABSTRACT FROM AUTHOR]

An elevated translocator protein (18 kDa, TSPO) density is observed during inflammation in the brain and peripheral organs making it a viable target for imaging. Recently, our group has explored a pharmacophore skeleton acetamidobenzoxazolone for positron emission tomography (PET) and single photon emission computed tomography (SPECT) applications to target TSPO. 2-(2-(5-Bromo/chloro benzoxazolone)acetamide)-3-(1H-indol-3-yl)propionate (MBIP-Br/Cl) were synthesized by using tryptophan methyl ester and compared with 2-[5-(4-methoxyphenyl)-2-oxo-1,3-benzoxazol-3(2H)-yl]-N-methyl-N-phenyl acetamide (MBMP) through tracer techniques. Computational docking showed similar results for MBIP-Br/Cl in comparison to MBMP. Their ex vivo and in vivo biodistributions were assessed in TSPO-rich organs as well as their release kinetics 0–120 min post injection. The ex vivo biodistribution showed a 7 fold higher uptake (5.16%ID per g vs. 0.72%ID per g) in the heart and a 2.5 fold higher uptake (12.91%ID per g vs. 4.69%ID per g) in the lungs for 99mTc-MBIP-Cl compared to that of 99mTc-MBIP-Br at 15 min. These findings demonstrated that 99mTc-MBIP-Cl has improved pharmacokinetic properties compared to 99mTc-MBIP-Br for SPECT application and is comparable to [11C]MBMP. [ABSTRACT FROM AUTHOR]