Improved Targeting and Tumor Retention of a Newly Synthesized Antineoplaston A10 Derivative by Intratumoral Administration: Molecular Docking, Technetium 99m Radiolabeling, andIn VivoBiodistribution Studies

Formulation of chitosan coated nanoliposomes for the oral delivery of colistin sulfate: in vitro characterization, 99mTc-radiolabeling and in vivo biodistribution studies

Colistin sulfate is a very important antibiotic for the treatment of multidrug-resistant Gram-negative infections. Unfortunately, it has low oral bioavailability and several side effects following parenteral administration. The present study aims to develop chitosan-coated colistin nanoliposomes to improve the stability in the gastrointestinal tract and to enhance the oral delivery of colistin. The chitosan-coated colistin nanoliposomes were obtained via thin-film evaporation and electrostatic deposition methods using either Span 60, Tween 65 or Tween 80 as surfactants with different cholesterol: surfactant: soya lecithin ratios. The influence of systems variables was further characterized by vesicle size analysis, zeta potential (ZP), poly dispersibility index (PDI), and also their entrapment efficiency percentage (EE %) was evaluated. Various systems were formed with vesicle sizes in the nano-range, 155.64 ± 12.53 nm to 315.64 ± 15.90 nm, and EE % of 45.2 ± 2.9% to 81.8 ± 2.9%. Moreover, the ZP value of the prepared nanoliposomes switched from a negative to a positive value after chitosan coating. To track the released colistin in vivo, technetium 99m (^99mTc) was incorporated into the optimum system (S-3) system via direct coupling with colistin. Chitosan-coated ^99mTc-colistin nanoliposome, ^99mTc-colistin suspension, and ^99mTc-chitosan-coated nanoliposomes (placebo) were administered orally into bacterial infection (Escherichia coli) bearing mice. The biodistribution results showed that chitosan-coated nanoliposome significantly enhanced the bioavailability of colistin compared to colistin suspension (the commercially available). Moreover, the system effectively improved the localization of colistin at the infected muscle. In conclusion, this approach offers a promising tool for enhanced oral delivery of colistin.

Miniaturized chromatographic systems for radiochemical purity evaluation of 131I-Ferulic acid as a new candidate in nuclear medicine applications

Recently, the anticancer activity of ferulic acid (FA) which is a caffeic acid derivative has been reported. Therefore, in this study FA was radiocaped with ¹³¹I^- to explore its potential as a tumor targeting agent. The radiolabeling process was carried out via electrophilic substitution reaction. The factors affecting labeling yield were optimized and the radiochemical purity (RCP) was assessed by various analytical techniques including paper chromatography (PC), thin layer chromatography (TLC), instant thin layer chromatography (ITLC), paper electrophoresis (PE) and high-performance liquid chromatography (HPLC). The RCP assay was extended to the utilization of miniaturized techniques including miniaturized PC (mini-PC), mini-TLC and mini-column chromatography (silica, sephadex-G25). Validation of mini-TLC, as one of ¹³¹I-FA RCP assay methods, was done according to ICH guidelines. Biodistribution studies of ¹³¹I-FA were performed on Ehrlich solid tumor bearing mice at various time points (5, 30, 60, 120 and 240 min), post injection. The radiolabeling yield of ¹³¹I-FA was 96.23 ± 0.45% and the miniaturized chromatographic systems showed high efficacy in RCP evaluation comparable to the conventional ones. Mini-TLC was proved to be specific, accurate, precise and linear. The tumor uptake of ¹³¹I-FA in solid tumor bearing mice was 4.35 ± 0.41 ID/g at 60 min with 2.79 as a tumor/muscle ratio. Consequently, ¹³¹I-FA could be used as a tumor targeting agent for nuclear medicine applications and the fast reaction monitoring could be achieved using miniaturized chromatographic techniques.

Radioiodination and in vivo assessment of the potential of newly synthesized pyrrolizine-5-carboxamides derivative in tumor model

Recently, pyrrolizine derivatives have been reported to possess numerous anticancer activities. In a previous study, (EZ)-6-((4-chlorobenzylidene)-amino)-7-cyano-N-(p-tolyl)-2,3-dihydro-1H-pyrrolizine carboxamide (EZPCA) compound was synthesized and the cytotoxic activity of EZPCA toward COX-2 enzyme (overexpressed in cancer cells) was reported. In order to assess the suitability of this compound as a promising pilot structure for in vivo applications, EZPCA was radiolabeled with radioiodine-131 (¹³¹I) and various factors affecting radiolabeling process were studied. Quality control studies of [¹³¹I]iodo-EZPCA were performed using paper chromatography and HPLC was used as a co-chromatographic technique for confirming the radiochemical yield. Biodistribution studies of [¹³¹I]iodo-EZPCA were undertaken in normal and tumor bearing mice. The radiochemical yield percentage of [¹³¹I]iodo-EZPCA was 94.20 ± 0.12%. The biodistribution results showed evident tumor uptake of [¹³¹I]iodo-EZPCA with promising target/non-target (T/NT) ratios. As a conclusion, these data suggest that [¹³¹I]iodo-EZPCA had high binding efficiency, high tumor uptake and sufficient stability to be used be used in diagnostic studies.