In this study, a new neurotensin (NT) analog was labeled with (99m) Tc via HYNIC chelator and tricine as coligand and investigated further. An NT (7-13) analog was prepared, and labeling with (99m) Tc was performed. The internalization rate and biodistribution of radiopeptide were studied in HT-29 cells and nude mice bearing tumor, respectively. Radiolabeling with (99m) Tc was performed at high specific activities (54 MBq/nmol) with an acceptable labeling yield (>95%). In vitro cell line studies showed a specific internalization uptake up to 13.23 ± 0.45% during 4 h which was blocked in the presence of excess cold peptide to 0.83 ± 0.15%. In biodistribution studies, uptake was observed in NT receptor-positive organs so that after 1 h the uptakes in mouse intestine and tumor were 1.23 ± 0.16% ID/g and 1.12 ± 0.11% ID/g, respectively. In animals co-injected with excess cold peptide, reduction uptake in tumor and intestines were 73% (1.10% vs. 0.29% ID/g at 4 h) and 61% (1.22% vs. 0.47% ID/g at 4 h) respectively. Predominant renal excretion pathway with a highest accumulation of activity in bladder was observed for this radiopeptide. This radiolabeled peptide could be a candidate for detection of NT positive tumors.

The need for new antibacterial drugs is justified because many pathogens are currently resistant to available antibacterial drugs, and this is an alarming threat to the health of future generations. 1, 3, 4-Oxadiazole has been shown to pose a wide range of antibacterial activity. Some of the marketed drugs also possess this heterocyclic moiety. Materials & Methods:The new derivatives of 1, 3, 4-oxadiazole were synthesized using a single-stage, high-yield method. Then, to measure the antibacterial activity of prepared derivatives agar well diffusion method was employed, and the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were determined at a concentration of 1mg/mL with three replications. Findings: Compounds 4a, 4d, and 4i exhibited a promising antibacterial activity against Acinetobacter baumannii PTCC1855. Among the three compounds mentioned, compound 4i showed the best performance with IZ=22±0.75 m.m , MIC=500µg/mL and MBC=125µg/mL at a concentration of 1mg/mL. Conclusion:The new 1, 3, 4-Oxadiazole derivative (4i) was shown to be a promising compound for pharmaceutical applications, by adding other functional groups to its structure, it is possible to increase the destructive power of the compound.

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Background: The enterococcal surface protein (Esp) is a high-molecular-weight surface protein of biofilm creating agent in Enterococcus faecalis. Oxadiazoles have a wide range of biological activities. Objective: This research aimed to examine the impact of new oxadiazole derivatives on the expression of Esp, playing an important role in promoting the biofilm formation ability of drug-resistant E. faecalis strains. Method: 1, 3, 4-oxadiazole derivatives were synthesized through a one-step synthesis. E. faecalis strains were collected and isolated from hospitals in Tehran. The antimicrobial properties of the synthesized materials against the isolated strains were investigated. RNA, DNA, and cDNA were extracted, and the relative expression of Esp in E. faecalis isolates was evaluated by real-time PCR. Docking study was performed by AutoDock vina software, and the resulting docking poses were analyzed using Discovery Studio 4.5 Client software. Results: The use of synthesized derivatives changed the Esp expression level in different isolates compared to the control sample. The two compounds containing naphthalene (4f) and methoxyphenyl (4g) caused respectively a 2-fold and a 3-fold decrease in Esp expression compared to the control sample. The compound 4f with the best binding energy among the compounds (-9.2) had the most hydrogen and hydrophobic bonds with the receptor-binding site. Conclusions: 1, 3, 4-oxadiazole derivatives, especially naphthalene and methoxyphenyl, act as inhibitors of bacterial biofilm formation and can be used in the pharmaceutical and biological industries.