Radiation Protection by Deferiprone in Animal Models

Deferiprone and Iron-Maltol: Forty Years since Their Discovery and Insights into Their Drug Design, Development, Clinical Use and Future Prospects

The historical insights and background of the discovery, development and clinical use of deferiprone (L1) and the maltol-iron complex, which were discovered over 40 years ago, highlight the difficulties, complexities and efforts in general orphan drug development programs originating from academic centers. Deferiprone is widely used for the removal of excess iron in the treatment of iron overload diseases, but also in many other diseases associated with iron toxicity, as well as the modulation of iron metabolism pathways. The maltol-iron complex is a recently approved drug used for increasing iron intake in the treatment of iron deficiency anemia, a condition affecting one-third to one-quarter of the world's population. Detailed insights into different aspects of drug development associated with L1 and the maltol-iron complex are revealed, including theoretical concepts of invention; drug discovery; new chemical synthesis; in vitro, in vivo and clinical screening; toxicology; pharmacology; and the optimization of dose protocols. The prospects of the application of these two drugs in many other diseases are discussed under the light of competing drugs from other academic and commercial centers and also different regulatory authorities. The underlying scientific and other strategies, as well as the many limitations in the present global scene of pharmaceuticals, are also highlighted, with an emphasis on the priorities for orphan drug and emergency medicine development, including the roles of the academic scientific community, pharmaceutical companies and patient organizations.

New Iron Metabolic Pathways and Chelation Targeting Strategies Affecting the Treatment of All Types and Stages of Cancer

There is new and increasing evidence from in vitro, in vivo and clinical studies implicating the pivotal role of iron and associated metabolic pathways in the initiation, progression and development of cancer and in cancer metastasis. New metabolic and toxicity mechanisms and pathways, as well as genomic, transcription and other factors, have been linked to cancer and many are related to iron. Accordingly, a number of new targets for iron chelators have been identified and characterized in new anticancer strategies, in addition to the classical restriction of/reduction in iron supply, the inhibition of transferrin iron delivery, the inhibition of ribonucleotide reductase in DNA synthesis and high antioxidant potential. The new targets include the removal of excess iron from iron-laden macrophages, which affects anticancer activity; the modulation of ferroptosis; ferritin iron removal and the control of hyperferritinemia; the inhibition of hypoxia related to the role of hypoxia-inducible factor (HIF); modulation of the function of new molecular species such as STEAP4 metalloreductase and the metastasis suppressor N-MYC downstream-regulated gene-1 (NDRG1); modulation of the metabolic pathways of oxidative stress damage affecting mitochondrial function, etc. Many of these new, but also previously known associated iron metabolic pathways appear to affect all stages of cancer, as well as metastasis and drug resistance. Iron-chelating drugs and especially deferiprone (L1), has been shown in many recent studies to fulfill the role of multi-target anticancer drug linked to the above and also other iron targets, and has been proposed for phase II trials in cancer patients. In contrast, lipophilic chelators and their iron complexes are proposed for the induction of ferroptosis in some refractory or recurring tumors in drug resistance and metastasis where effective treatments are absent. There is a need to readdress cancer therapy and include therapeutic strategies targeting multifactorial processes, including the application of multi-targeting drugs involving iron chelators and iron-chelator complexes. New therapeutic protocols including drug combinations with L1 and other chelating drugs could increase anticancer activity, decrease drug resistance and metastasis, improve treatments, reduce toxicity and increase overall survival in cancer patients.

Deferiprone: A Forty-Year-Old Multi-Targeting Drug with Possible Activity against COVID-19 and Diseases of Similar Symptomatology

The need for preparing new strategies for the design of emergency drug therapies against COVID-19 and similar diseases in the future is rather urgent, considering the high rate of morbidity and especially mortality associated with COVID-19, which so far has exceeded 18 million lives. Such strategies could be conceived by targeting the causes and also the serious toxic side effects of the diseases, as well as associated biochemical and physiological pathways. Deferiprone (L1) is an EMA- and FDA-approved drug used worldwide for the treatment of iron overload and also other conditions where there are no effective treatments. The multi-potent effects and high safety record of L1 in iron loaded and non-iron loaded categories of patients suggests that L1 could be developed as a “magic bullet” drug against COVID-19 and diseases of similar symptomatology. The mode of action of L1 includes antiviral, antimicrobial, antioxidant, anti-hypoxic and anti-ferroptotic effects, iron buffering interactions with transferrin, iron mobilizing effects from ferritin, macrophages and other cells involved in the immune response and hyperinflammation, as well as many other therapeutic interventions. Similarly, several pharmacological and other characteristics of L1, including extensive tissue distribution and low cost of production, increase the prospect of worldwide availability, as well as many other therapeutic approach strategies involving drug combinations, adjuvant therapies and disease prevention.

Structural and thermodynamic stability of uranyl-deferiprone complexes and the removal efficacy of U(vi) at the cellular level

Deferiprone (3-hydroxy-1,2-dimethyl-4(1H)-pyridone, DFP), which is a drug clinically used for removing heavy metals in vivo, was explored for its removal efficiency towards uranium. The reaction of uranyl nitrate hexahydrate with DFP at room temperature yielded the compound [(UO2)(H2O)(C7NO2H8)2]·4H2O (1), which crystallizes from a mixed solution of methanol and water (pH = 7.0). X-ray diffraction shows that the stable complexation of uranyl occurs from the coordination of two bidentate DFP ligands perpendicular to the O[double bond, length as m-dash]U[double bond, length as m-dash]O unit with a fifth coordinating oxygen atom coming from one water molecule, resulting in a pentagonal bipyramidal geometry. The formation constants of uranyl and DFP complexes were measured and the species distribution diagram illustrates that UO2L2 (94.6%) is the dominant uranyl-DFP complex in 0.1 M KCl solution at physiological pH = 7.4. The results from both crystallographic and potentiometric studies imply that the metal : ligand ratio is 1 : 2. The effectiveness of using DFP to remove uranium was examined at the cellular level, and the results suggest that it can significantly reduce the cellular uptake and increase the cellular release of U(vi) in renal proximal tubular epithelial cells (NRK-52E).