Mesalamine was labelled with technetium-99m ( 99m Tc) in high radiolabelling yield (*98.4 %), in vitro stability (*4 h) and in serum persistence (*24 h). Optimum labelling conditions were investigated. The structure of the complex was confirmed using in silico analysis. Molecular docking was performed to evaluate the complex binding to its biochemical target, the PPARc receptor. Biodistribution and clearance studies were performed in normal and ulcerative colitis models in mice. The tracer's localization was highest (*65.2 %) in microbial model compared to chemical model (*42.4 %) and normal mice (*22.1 %) at 60 min post injection. All data supported the usefulness of 99m Tc-mesalamine as a radiotracer for ulcerative colitis.

Ulcerative colitis is a chronic disease having a regressive nature. Commonly used diagnostic methods have the disadvantage to be invasive, time-consuming, and expensive. Therefore, a new sensitive method for the detection and monitoring of disease activity is urgently needed in clinical practice. In the current investigation, radio complexation of olsalazine with technetium-99m, its characterization, and optimization of the labeling conditions were explored. Optimum radiochemical yield of (99m) Tc-olsalazine (97.6% ± 1.8%) was obtained via direct complexation with technetium-99m (~200 MBq) in the presence of stannous chloride dihydrate (100 µg) as reducing agent at pH 6. It was observed that the complex showed significant in vitro stability in serum at 37°C for more than 11 h. The computer-generated optimized geometries of the (99m) Tc-olsalazine were reported, and biodistribution studies were carried out using chemically and microbiologically mice-induced ulcerative colitis models. The tracer showed a good localization in both models and was excreted mainly via liver and to some extent via kidney. Imaging can be performed at 1-2 h post-injection; at that time, the background activity has cleared, and the activity is concentrated in the target site. All the gathered biological data supported the usefulness of (99m) Tc-olsalazine as a potential imaging agent for ulcerative colitis.

In this study, the labeling method of levofloxacin with technetium-99m and its biological evaluation were described.99m Tc-L-Flox was synthesized via direct complexation with technetium-99m in the presence of stannous chloride dihydrate as reducing agent. The optimum amounts of the reactants are: 1-2 mg levofloxacin, 150 mg stannous chloride dihydrate and 48-1490 MBq pertechnetate. The reaction mixture was bring to pH 6 and kept at room temperature for 30 min. The labeled levofloxacin was stable for more than 8 h. The in vivo evaluation of 99m Tc-L-Flox in man-induced inflammation models showed that this tracer was localized with different values. The live E. Coli model had the highest value which was 2.9%, the heat killed E. coli model had a value of 2.0%, and the turpentine oil model had a value of 1.2% at 24 post injection, while the non-inflamed muscle had activity of 0.5%. All the gathered biological data support the usefulness of 99m Tc-L-Flox as infection imaging agent. The freeze-dried form of Sn-L-Flox was prepared and found meet all the radiochemical and biological tests.

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