Synthesis and biological evaluation of 125I-nebivolol as a potential cardioselective agent for imaging β1-adrenoceptors

Synthesis and biological evaluation of [131I]iodocarvedilol as a potential radiopharmaceutical for heart imaging

The optimization of the radiolabeling yield of carvedilol with iodine-131 was described. Dependence of the labeling yield of [¹³¹I]iodocarvedilol on the concentration of carvedilol, chloramine-T content, pH of the reaction mixture and reaction time was studied in details. Carvedilol was labeled with iodine-131 at pH 6 with a labeling yield of 92.6 ± 2.77% by using 100 µg carvedilol, 200 µg chloramin-T (CAT) and 30 min reaction time. The formed [¹³¹I]iodocarvedilol was nearly stable for a time up to one day. Biodistribution of [¹³¹I]iodocarvedilol was investigated in experimental animals. [^131/123I]iodocarvedilol was located in the heart with a concentration of 19.6 ± 0.41% of the injected dose at 60 min post injection. It has a high heart uptake and heart to liver ratio, both of which are beneficial for high-quality SPECT (single-photon emission computerized tomography) myocardial imaging. [^131/123I]iodocarvedilol solve most the drawbacks of the FDA (Food and Drug Administration) approved ^99mTc-sestamibi.

Development of Tamoxifen In Situ Gel Nanoemulsion for Ocular Delivery in Photoreceptor Degeneration Disorder: In Vitro Characterization, 131I-Radiolabeling, and In Vivo Biodistribution Studies

Purpose

The aim of our work is to develop an in situ ocular gellan gum–based nanoemulsion (NE) of tamoxifen TAM as an alternative drug delivery system to the oral route for the treatment of photoreceptor degeneration disorder.

Method

Six pseudoternary phase diagrams were developed using oil (oleic acid), surfactants (Tween 80 or Tween 20), a co-surfactant (polyethylene glycol 400), and water. The particle size, polydispersity index, and zeta potential of the developed systems were all measured. The safety of ocular application of the optimum system was established via in vivo histopathological investigation. To track the biodistribution of the optimum gel, iodine-131 (131I) was incorporated into the gel via coupling with TAM via direct electrophilic substitution reaction.

Results

Based on the obtained results, TAMNE-1 was chosen as the optimal system, with PS = 140.20 ± 1.50 nm, ZP =  − 27.86 ± 1.13 mV, and PDI = 0.20 ± 0.00%. In vitro release displayed a prolonged and sustained release of TAMNE-1 gel compared to TAM solution (plain eye drop). Transparent in situ TAMNE-1 gel was developed after the incorporation of the TAMNE-1 system into gellan gum aqueous solution (0.3% w/w). In this study, TAM was successfully radiolabeled with 131I for subsequent evaluation of the efficacy of the developed in situ gel system (TAMNE-1 gel) in vivo. The developed TAMNE-1 gel system was nonirritant and safe and the biodistribution studies showed better retention of TAMNE-1 gel than plain TAM eye drops.

Conclusion

The developed TAMNE-1 gel is able to enhance the ocular bioavailability of TAM and can go further with clinical evaluation.

Graphic Abstract

Evaluation of radioiodinated ethopabate as a potential tumor targeting agent

Overexpression of folate synthesis and folate receptor in a wide variety of tumors was reported. As a result, folate derivatives have emerged as a potential candidate for tumor imaging and therapy. Ethopabate is a structural analogue of para-aminobenzoic acid (PABA), a precursor of folic acid. Ethopabate was radiolabeled with radioiodine-131 (¹³¹I) via direct electrophilic substitution reaction. Several factors that might affect the radiolabeling yield were studied. Paper chromatography was utilized for testing and evaluation of [¹³¹I]iodoethopabate, and HPLC was used as a co-chromatographic tool to confirm the radiochemical yield. The biodistribution of [¹³¹I]iodoethopabate in normal and tumor-bearing mice was investigated. The radioiodination of ethopabate resulted in a radiochemical yield of 93.70 ± 0.19%. The biodistribution data revealed that [¹³¹I]iodoethopabate was taken up by tumors with promising target/non-target (T/NT) ratios. Where, the tumor to-blood ratios were 3.30 ± 0.40 and 4.06 ± 0.10 at 1 and 4 h post injection, respectively. As a result of these findings, [¹³¹I]iodoethopabate appears to have excellent tumor uptake and adequate stability to be used for diagnostic purpose in the future.

125I–Amoxicillin preparation as a guide tracer for inflammation detection

The objective of this study is to label Amoxicillin with radioactive iodine (125I-AC) via direct electrophilic substitution to act as a promising tracer for inflammation imaging. The highest labeling yield of 80% was achieved after studying all the parameters affecting the labeling reaction using Iodogen (IG) as an oxidizing agent. Molecular Modeling Structure was done using MOE program to predict the suitable 125I position. The product structure was established by a cold iodination reaction using Iodine-127. Biological evaluation of (125I-AC) was carried out using groups of inflamed mice with different exogenous agents such as E.Coli and Turpentine oil. The (125I-AC) shows an in vitro stability of about 97% after 24 h.While doing in vivo studies over 4 h, the tracer stability of 99% was observed.

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.

Radioiodination and biodistribution of newly synthesized 3-benzyl-2-([3-methoxybenzyl]thio)benzo[g]quinazolin-4-(3H)-one in tumor bearing mice

3-Benzyl-2-((3-methoxybenzyl)thio)benzo[g]quinazolin-4(3H)-one was previously synthesized and proved by physicochemical analyses (HRMS, 1H and 13C NMR). The target compound was examined for its radioactivity and the results showed that benzo[g]quinazoline was successfully labeled with radioactive iodine using NBS via an electrophilic substitution reaction. The reaction parameters that affected the labeling yield such as concentration, pH and time were studied to optimize the labeling conditions. The radiochemical yield was 91.2 ± 1.22% and the in vitro studies showed that the target compound was stable for up to 24 h. The thyroid was among the other organs in which the uptake of 125I-benzoquinazoline has increased significantly over the time up to 4.1%. The tumor uptake was 6.95%. Radiochemical and metabolic stability of the benzoquinazoline in vivo/in vitro and biodistribution studies provide some insights about the requirements for developing more potent radiopharmaceutical for targeting the tumor cells.