Preparation and biological evaluation of the new chlorin photosensitizer T3,4BCPC for detection and treatment of tumors

Emerging Applications of Porphyrins and Metalloporphyrins in Biomedicine and Diagnostic Magnetic Resonance Imaging

In recent years, scientific advancements have constantly increased at a significant rate in the field of biomedical science. Keeping this in view, the application of porphyrins and metalloporphyrins in the field of biomedical science is gaining substantial importance. Porphyrins are the most widely studied tetrapyrrole-based compounds because of their important roles in vital biological processes. The cavity of porphyrins containing four pyrrolic nitrogens is well suited for the binding majority of metal ions to form metalloporphyrins. Porphyrins and metalloporphyrins possess peculiar photochemical, photophysical, and photoredox properties which are tunable through structural modifications. Their beneficial photophysical properties, such as the long wavelength of emission and absorption, high singlet oxygen quantum yield, and low in vivo toxicity, have drawn scientists' interest to discover new dimensions in the biomedical field. Applications of porphyrins and metalloporphyrins have been pursued in the perspective of contrast agents for magnetic resonance imaging (MRI), photodynamic therapy (PDT) of cancer, bio-imaging, and other biomedical applications. This review discusses photophysics and the photochemistry of porphyrins and their metal complexes. Secondly, it explains the current developments and mode of action for contrast agents for MRI. Moreover, the application of porphyrin and metalloporphyrin-based molecules as a photosensitizer in PDT of cancer, the mechanism of the generation of reactive oxygen species (ROS), factors that determine the efficiency of PDT, and the developments to improve this technology are delineated. The last part explores the most recent research and developments on metalloporphyrin-based materials in bio-imaging, drug delivery, and the determination of ferrochelatase in bone marrow indicating their prospective clinical applications.

Nuclear medicine for photodynamic therapy in cancer: Planning, monitoring and nuclear PDT

Photodynamic therapy (PDT) is a modality with promising results for the treatment of various cancers. PDT is increasingly included in the standard of care for different pathologies. This therapy relies on the effects of light delivered to photosensitized cells. At different stages of delivery, PDT requires imaging to plan, evaluate and monitor treatment. The contribution of molecular imaging in this context is important and continues to increase. In this article, we review the contribution of nuclear medicine imaging in oncology to PDT for planning and therapeutic monitoring purposes. Several solutions have been proposed to plan PDT from nuclear medicine imaging. For instance, photosensitizer biodistribution has been evaluated with a radiolabeled photosensitizer or with conventional radiopharmaceuticals on positron emission tomography. The effects of PDT delivery have also been explored with specific SPECT or PET radiopharmaceuticals to evaluate the effects on cells (apoptosis, necrosis, proliferation, metabolism) or vascular damage. Finally, the synergy between photosensitizers and radiopharmaceuticals has been studied considering the Cerenkov effect to activate photosensitized cells.

Technetium-99m based small molecule radiopharmaceuticals and radiotracers targeting inflammation and infection

^99mTc-labeled antibiotics, antifungal drugs, antimicrobial peptides and COX-2 inhibitors are comprehensively reviewed.

Synthesis, Radiolabeling, and Bioevaluation of Bis(Trifluoromethanesulfonyl) Imide

Imidazolium salts have antitumor potential and toxicological effects on various microorganisms. The authors' aim is to synthesize a new imidazolium salt and to assess its pharmacokinetic and antitumor potentials by in vitro and in vivo studies. In this study, bis(trifluoromethanesulfonyl) imide (ITFSI) was synthesized and labeled with (131)I using the iodogen method. The efficiency of radiolabeling was determined with high yield (95.5% ± 3.7%). Pharmacokinetic properties of the compound were investigated in albino Wistar rats using radiolabeled compound. The radiolabeled compound ((131)I-ITFSI) has been stable during a period of 3 hours in human serum. The uptake of (131)I-ITFSI reached maximum in the spleen, liver, and blood at 60 minutes, large intestine and heart at 30 minutes, and ovary at 120 minutes. It is observed that intracellular uptake of the radiolabeled compound is higher in the CaCo-2 (colon adenocarcinoma tumor) cell line than HEK-293 (human epithelial kidney) cell line. In further study, antitumor potential of ITFSI on a colon adenocarcinoma tumor-bearing animal model may be investigated.

Rhenium-188 labelled meso-tetrakis[3,4-bis(carboxymethyleneoxy)phenyl] porphyrin for targeted radiotherapy: preliminary biological evaluation in mice

PURPOSE

This study focusses on a promising carrier system for therapeutic and imaging purposes using meso-tetrakis[3,4-bis(carboxymethyleneoxy)phenyl] porphyrin (T(3,4)CPP). To assess its potential for clinical use, we labelled T(3,4)CPP with (188)Re and analysed some kinetic biodistribution parameters after intravenous injection in mice.

MATERIALS AND METHODS

T(3,4)CPP was synthesized and labelled with (188)Re. Normal Kunming (KM) mice and melanoma- or hepatoma-bearing BALB/c nude mice were injected intravenously with 5.55 MBq (188)Re-labelled T(3,4)CPP and sacrificed at 0.5, 2, 4, and 24 h and 8, and 24 h, respectively.

RESULTS

The (188)Re-T(3,4)CPP yield was more than 95% with specific activity 16.9 GBq (mol)(-1), and Vitamin C (VC) could increase its stability in vitro. In normal KM mice, (188)Re-T(3,4)CPP had fast blood clearance (approximately 99%, 24 h postinjection), low retention in the vital organs and hepatotropic characteristics. In nude mice, more than 4.4 and 6.1% uptake per gram of tumour (%ID g(-1)) at 8 h postinjection was in melanoma and hepatoma, respectively; this remained as high levels after 24 h as 4.6 and 6.5%, respectively. At 8 h, the tumour/blood and tumour/muscle (T/M) ratios in melanomas and hepatoma bearing mice were 7.3, 13,and 7.0, 20, respectively. Twenty-four hours later, these high ratios still continued in existence which were 9.6, 19 and 10, 25, respectively.

CONCLUSION

The results obtained in this study indicate that (188)Re-T(3,4)CPP has better tumour affinity and retainable accumulation characteristics in carcinoma which can potentially be used for tumour-targeted radiotherapy.

Synthesis and preliminary biological studies of the novel conjugate 188Re-labeled meso-tetrakis(4-sulfophenyl)porphyrin in mice

OBJECTIVE

The objective of this study was to evaluate the biological behaviors of a novel (188)Re-labeled meso-tetrakis(4-sulfophenyl)porphyrin (TPPS(4)) in normal mice and tumor-bearing mice.

METHODS

TPPS(4) was synthesized and labeled by (188)ReO(4)(-). Normal KM mice and BALB/c nude mice bearing melanoma or hepatoma were prepared for distribution studies.

RESULTS

The [(188)Re]TPPS(4) yield was >98% with a specific activity of 11.2 GBq/mol, and vitamin C could increase its stability in vitro. In normal KM mice, [(188)Re]TPPS(4) had a fast blood clearance ( approximately 90%, 24 h postinjection), low retention in vital organs and hepatotropic characteristics. In nude mice, uptakes of >4.1% and 6.5% ID/g tumor at 8 h postinjection were observed in melanoma and hepatoma, respectively; this remained at high levels of 4.7% and 5.7%, respectively, after 24 h. At 8 h, the tumor/blood and tumor/muscle ratios in melanoma-bearing and hepatoma-bearing mice were 6.2-15.2 and 6.1-24.2, respectively. Twenty-four hours later, these high ratios still continued at 8.6-22.1 and 12-26.1, respectively.

CONCLUSION

The results obtained in this study indicate that [(188)Re]TPPS(4) has a high tumor affinity and retainable accumulation characteristics in carcinoma, which can potentially be used for tumor-targeted therapy.

Zinc octa-n-alkyl phthalocyanines in photodynamic therapy: photophysical properties, accumulation and apoptosis in cell cultures, studies in erythrocytes and topical application to Balb/c mice skin

Two octa-substituted phthalocyanines, namely 1,4,8,11,15,18,22,25-octakis(decyl)phthalocyaninato zinc(II) (ZnODPc) and 1,4,8,11,15,18,22,25-octakis(pentyl)phthalocyaninato zinc(II) (ZnOPPc), were investigated for their use in photodynamic therapy (PDT) after topical application. Both substances exhibited favourable properties as photosensitisers in vitro: absorption maxima around 700 nm with absorption coefficients of about 190000 (M(-1) cm(-1)), a singlet oxygen quantum yield of 0.47 +/- 0.02 (ZnODPc), and good accumulation in keratinocytes and fibroblasts. Cell death after phthalocyanine-photosensitisation appeared to occur mainly via apoptosis. The in vivo experiments demonstrated a good accumulation of the phthalocyanines after topical application in a tetrahydrofuran-azone formulation onto the dorsal skin of Balb/c mice: [(4.6-4.7) +/- 1.0]% of deposited dye could be recovered after 3 h from deposition. ZnODPc showed significantly better skin-photosensitising properties than ZnOPPc and is therefore a potential candidate for the treatment of psoriasis.