The high expression of the human epidermal growth factor receptor 2 (HER2) and the accessibility of its extracellular domain make it an ideal target for the targeted delivery of anti-tumor drugs as well as imaging agents. In this study, the heptapeptide leucine-threonine-valine-serine-proline-tryptophan-tyrosine (LTVSPWY) as a new small peptide for an anti-HER2 target was labeled by incorporating Tc to the cysteine-based ligands CGGG (Cys-Gly-Gly-Gly) and CSSS (Cys-Ser-Ser-Ser) linked to this peptide. BothTc-labeled peptides were evaluated for HER2 bindings as well as pharmacokinetics and tumor targeting. CGGG- and CSSS-LTVSPWY peptides were labeled with Tc using a gluconate ligand exchange. Cellular specific binding, affinities, and internalization of both peptides to the HER2 receptor were evaluated in the SKOV-3 cell line. Specific targeting of both peptides to the HER2 receptor was assessed in three cell lines with different levels of HER2 expression. Studies were performed in SKOV-3 tumor bearing mice for tumor targeting. Both peptides were labeled withTc with more than 99% efficiency and showed favorable stability in solution and serum. The HER2 binding affinities of both the radiolabeled peptides were inhibited up to 60% by the unlabeled peptide, as well as with trastuzumab antibody. We observed nanomolar binding affinities for both radiolabeled peptides. The tumor uptakes were 4.95 ± 4.84% and 3.84 ± 2.53% for the CSSS and CGGG chelators, respectively, at 1 h after injection. However, tumor uptakes were similar for both peptides at 4 h postinjection, although a higher tumor to background ratio and lower radioactivity retention in the kidney were observed for CSSS, leading to a clearer tumor image with injection of this peptide. These small new peptides were selectively targeted to the HER2 receptor, and introduction of a serine residue into the chelator improved the pharmacokinetics of Tc labeled LTVSPWY for clear tumor imaging in animals.

No abstract

Background: Gastrin-releasing peptide receptor (GRPR) is an important target for imaging of prostate cancer. The wide availability of single-photon emission computed tomography/computed tomography (SPECT/CT) and the generator-produced 99mTc can be utilized to facilitate the use of GRPR-targeting radiotracers for diagnostics of prostate cancers. Methods: Synthetically produced mercaptoacetyl-Ser-Ser-Ser (maSSS)-PEG2-RM26 and mercaptoacetyl-Ser-Glu-Ser (maSES)-PEG2-RM26 (RM26 = d-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2) were radiolabeled with 99mTc and characterized in vitro using PC-3 cells and in vivo, using NMRI or PC-3 tumor bearing mice. SPECT/CT imaging and dosimetry calculations were performed for [99mTc]Tc-maSSS-PEG2-RM26. Results: Peptides were radiolabeled with high yields (>98%), demonstrating GRPR specific binding and slow internalization in PC-3 cells. [99mTc]Tc-maSSS-PEG2-RM26 outperformed [99mTc]Tc-maSES-PEG2-RM26 in terms of GRPR affinity, with a lower dissociation constant (61 pM vs 849 pM) and demonstrating higher tumor uptake. [99mTc]Tc-maSSS-PEG2-RM26 had tumor-to-blood, tumor-to-muscle, and tumor-to-bone ratios of 97 ± 56, 188 ± 32, and 177 ± 79, respectively. SPECT/CT images of [99mTc]Tc-maSSS-PEG2-RM26 clearly visualized the GRPR-overexpressing tumors. The dosimetry estimated for [99mTc]Tc-maSSS-PEG2-RM26 showed the highest absorbed dose in the small intestine (1.65 × 10−3 mGy/MBq), and the effective dose is 3.49 × 10−3 mSv/MBq. Conclusion: The GRPR antagonist maSSS-PEG2-RM26 is a promising GRPR-targeting agent that can be radiolabeled through a single-step with the generator-produced 99mTc and used for imaging of GRPR-expressing prostate cancer.

An efficient, one-pot synthetic protocol toward a-alkylidene-g-butyrolacton-2-ones, a rather unexplored class of heterocyclic scaffolds starting from primary amines, methyl acetoacetate, and chloroacetyl chloride is described. The mixture of MeCNMeOH as a polar solvent triggers a new cycloaddition of the enaminone intermediate. The reaction is completed within 12 hours under reflux condition to produce the title compounds.

For the first time, a novel, simple, and highly efficient synthesis of N-aryl-N-[1,3]thiazino [3,4a] [1,3]benzimidazol-1-ylidenamines is presented. The one-pot reaction of o-phenylenediamine, aryl isothiocyanate, and methyl acetylenecarboxylate proceeds in toluene-dichloromethane without any catalyst under reflux conditions to produce the title compounds in 60-70% yield. From a mechanistic point of view, the reaction is proposed to occur via two cyclizations and four heteroatom-carbon bond formations.

This work tries to present theoretical studies and docking analysis on the small novel molecule irilone as a progesterone receptor (PR) effect supporter in endometrial and ovarian cancer cell lines. The quantum mechanical computations are done using B3LYP/6-31+G(d,p) level of theory on the molecule under study at room temperature. The theoretical calculations showed that irilone is a stable small molecule with high electrophilicity property. The density of states (DOS) graph indicated that the virtual orbitals of the said compound have more density than that of the occupied orbitals. The studies indicated that the title compound can make a complex with progesterone receptor (PR) using steric and hydrogen bond (HB) interactions. The docking analysis showed that the receptor (PR-B isoform) residues Pro-696, Gln-725, Met-759, Arg-766, Glu-695, Asp-697, Leu-758, Lys-822, Ile-699, Val-698 and Trp-755 play the main role in receptor-ligand complex formation.agents. On the other hand, the electronic properties study showed that the title molecule likes to make complex with progesterone receptor (PR) by steric and hydrogen bond interactions. The ligand-receptor docking analysis indicated that the receptor (PR-B isoform) residues Pro-696, Gln-725, Met-759, Arg-766, Glu-695, Asp-697, Leu-758, Lys-822, Ile-699, Val-698 and Trp-755 play the main role in irilone-PRB complex formation.

Radiolabelled peptides have attracted a great deal of attention due to their wide applicability in the development of target-specific radiopharmaceuticals. They can easily be used in diagnostic imaging as carriers for the delivery of radionuclides to tumors as well as for therapy. Previous investigations revealed that technetium(V) could form stable complexes with peptide-based ligands of N 3 S type such as Cys-Gly-Gly-Gly. Herein, a targeting HER-2 receptor peptide was labeled with technetium-99m ( 99m Tc) with two different types of tetrapeptide-based ligands, Cys-Gly-Gly-Gly and Cys-Ser-Ser-Ser. The effect of experimental parameters in the labeling procedure such as type of buffer solutions, pH of media, and type of exchange ligands were optimized toward obtaining maximum labeling yield. The optimum labeling conditions were different for two peptides. Shelf life of both labeled peptides was determined by analytical reversed-phase high-performance liquid chromatography (RP-HPLC) and thin layer chromatography (TLC) that showed radiochemical yield up to 95% even after 4 h.

The present research exploration will contain studying the molecular structure, bonds nature, stability, reactivity and electronic properties of the title molecule.The molecular optimization and all theoretical computations were carried out by density functional theory (DFT) method using the hybrid B3LYP (Becke, three-parameter, Lee-Yang-Parr) exchangecorrelation functional employing the 6-31G(d,p) basis set of theory. Quantum-mechanical (QM) computations of the molecular structure geometry of the molecule under study were calculated with scaled quantum mechanics. The global reactivity descriptors like energy gap (Eg), ionization potential (IP), electron affinity (EA), chemical hardness (η), chemical softness (S), electronegativity (χ), electronic chemical potential (µ) and electrophilicity index (ω) can be obtained from the energies of the frontier molecular orbitals (HOMO and LUMO). The calculated global reactivity indices indicated that metoclopramide which was a stable small molecule can bind with the residues of the dopamine D2 receptor (D2R). Molecular docking studies showed that the steric interactions of the ligand with the residues Phe 198, Phe 382, Ala 122, Thr 119, Ser 197, Trp 386, Phe 390, Val 115, Cys 118 and Asp 114 from the protein binding site are the main binding modes between the ligand and the receptor.