The present study describes a novel non-radioactive methodology for in vivo non-invasive, real-time imaging of blood–brain barrier (BBB) permeability for conventional drugs, using nitroxyl radicals as spin-labels and magnetic resonance imaging (MRI).

Objectives: The present study describes a pharmacological strategy for the treatment of glioblastoma by redoxcycling 'mitocans' such as quinone/ascorbate combination drugs, based on their tumor-selective redox-modulating effects and tolerance to normal cells and tissues.Methods: Experiments were performed on glioblastoma mice (orthotopic model) treated with coenzyme Q0/ascorbate (Q0/A). The drug was injected intracranially in a single dose. The following parameters were analyzed in vivo using MRI orex vivo using conventional assays: tumor growth, survival, cerebral and tumor perfusion, tumor cell density, tissue redox-state, and expression of tumor-associated NADH oxidase (tNOX).Results: Q0/A markedly suppressed tumor growth and significantly increased survival of glioblastoma mice. This was accompanied by increased oxidative stress in the tumor but not in non-cancerous tissues, increased tumor blood flow, and downregulation of tNOX. The redox-modulating and anticancer effects of Q0/A were more pronounced than those of menadione/ascorbate (M/A) obtained in our previous study. No adverse drug-related side-effects were observed in glioblastoma mice treated with Q0/A.Discussion: Q0/A differentiated cancer cells and tissues, particularly glioblastoma, from normal ones by redox targeting, causing a severe oxidative stress in the tumor but not in non-cancerous tissues. Q0/A had a pronounced anticancer activity and could be considered safe for the organism within certain concentration limits. The results suggest that the rate of tumor resorption and metabolism of toxic residues must be controlled and maintained within tolerable limits to achieve longer survival, especially at intracranial drug administration.

Lecithinized superoxide dismutase (PC-SOD) was found to have a significantly improved half-life in the bloodstream and better pharmacological effects compared with unmodified SOD. However, there is no direct evidence that parenterally administered PC-SOD decreases superoxide levels in blood and tissues in vivo. In the present study, we investigated the ability of PC-SOD versus unmodified SOD as a superoxide scavenger in mice subjected to oxidative stress. Experiments were performed on a lipopolysaccharide (LPS) mouse model of acute inflammation known to be accompanied by the overproduction of superoxide in the blood. The mice were divided into four groups: untreated (healthy; n = 6), LPS-treated (n = 7), LPS/SOD-treated (n = 6), and LPS/PC-SOD-treated (n = 7) mice. SOD and PC-SOD were injected intravenously. Blood samples were collected at four time intervals and analyzed by electron paramagnetic resonance (EPR) spectroscopy using a nitroxide probe, 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (CMP). The following effects were observed: (i) In the blood of healthy mice, the EPR signal was significantly lower compared with the control (p < 0.001) and LPS-treated mice (p < 0.01); (ii) in the blood of LPS-treated mice, the EPR signal was identical to that of the control; and (iii) in the blood of LPS/SOD-treated mice collected immediately after enzyme injection, the EPR signal was significantly lower compared with the control (p < 0.01) and LPS-treated mice (p < 0.05). However, the effect disappeared in the samples collected 30 min and 1 h after enzyme injection. (iv) In LPS/PC-SOD-treated mice, the EPR signal was significantly lower compared with the control (p < 0.01) and LPS-treated mice (p < 0.05), even in the blood samples collected within 1 h after enzyme injection. The data indicate that the blood of healthy mice was characterized by a high reducing capacity, while the blood of LPS-treated mice was characterized by a high oxidative capacity. SOD decreased superoxide production immediately after enzyme injection. However, the effect was short-lived and disappeared within 30 min. PC-SOD effectively decreased superoxide production in the bloodstream of LPS-treated mice and restored the redox balance to the control level even two hours after enzyme injection. The effects of PC-SOD were more pronounced and long-lasting compared with those of SOD. The possible reason is the longer half-life of PC-SOD in the bloodstream, its better stability, and its slower clearance from the circulation due to the increased hydrophobicity of the enzyme and its interaction with plasma proteins. The data are discussed in the context of recent clinical trials showing that PC-SOD is a promising pharmaceutical product for adjuvant therapy of a variety of pathologies accompanied by inflammation, redox imbalance, and oxidative stress.

Background/Aim: Leukemia therapy targets multiple molecular pathways, including non-oncogenic but clinically relevant factors such as Silent Information Regulator 1 (SIRT1), which acts either as a tumor suppressor or tumor promoter depending on its downstream targets, cancer type, and disease stage. Although small-molecule SIRT1 activators such as SRT-1720 have shown anticancer potential, their molecular mechanisms in leukemia remain insufficiently understood. This study aimed to elucidate the effects of SRT-1720 on the redox state and viability of leukemic lymphocytes and normal lymphocytes, as well as its ability to sensitize leukemic cells to anticancer drugs. Materials and Methods: The synergistic, additive or antagonistic antiproliferative effects of SRT-1720 and anticancer drugs were examined. The following parameters were analyzed: cell viability and proliferation – by trypan blue staining; apoptosis – by phosphatidylserine expression on the cell surface; and oxidative stress – by detecting intracellular levels of reactive oxygen species (ROS) and protein carbonyl products. Results: SRT-1720 potentiated the effects of most anticancer drugs in leukemic lymphocytes. Synergism was found in combination with: barasertib, bortezomib, cisplatin, MG-132, bleomycin, ABT-737, lonafarnib, everolimus, and palbociclib. SRT-1720 increased the tolerance of normal lymphocytes to anticancer drugs, as demonstrated for everolimus, barasertib, and doxorubicin. The synergistic cytotoxicity of SRT-1720 in combination with everolimus and barasertib was accompanied by overproduction of ROS and increased induction of apoptosis in leukemic lymphocytes, but not in normal lymphocytes. SRT-1720 favorably affected the viability of normal lymphocytes, reducing oxidative stress and cytotoxicity induced by doxorubicin at the concentrations used in our study. Conclusion: SRT-1720 induces oxidative stress and apoptosis in leukemic lymphocytes through SIRT1-independent pathway(s). In contrast, it enhances antioxidant defense in normal lymphocytes through a SIRT1-dependent pathway. These findings highlight the potential of SRT-1720 as an adjuvant to chemotherapy in T-ALL, particularly in drug combinations demonstrating strong synergism, which may allow dose reduction and decreased toxicity.

Background/Aim: Redox imaging is one of the fastest growing areas in diagnostics of pathologies accompanied by redox imbalance. We describe a multi-spin redox sensor (RS) and its application for redox imaging in mice using electron paramagnetic resonance (EPR) spectroscopy. Materials and Methods: The probe is composed of a quantum dot functionalized with a cyclodextrin shell, conjugated with nitroxide residues (TEMPO) and triphenylphosphonium to achieve intracellular delivery. The data were validated with a conventional spin probe, mito-TEMPO. Nitroxide probe (RS or mito-TEMPO) was injected intravenously in mice under anesthesia. Blood samples were collected from the tail vein at four time intervals within 2 hours and subjected immediately to analysis using EPR spectroscopy. Two hours after injection, mice were sacrificed, five organs were isolated, and tissue homogenates were prepared and subjected to EPR analysis. Results: RS had the same EPR contrast and significantly higher MRI contrast compared to mito-TEMPO. RS circulated longer in the bloodstream than mito-TEMPO, with both substances undergoing reduction in the blood. The distribution of RS and mito-TEMPO in different organs was equal, except for the brain. No adverse side effects were found in mice at the selected dose. Conclusion: Using a non-toxic nanoparticle in the chemical structure of RS as a carrier of nitroxide residues would enhance its translational relevance.