H2O2-Driven Anticancer Activity of Mn Porphyrins and the Underlying Molecular Pathways

Mn(III) ortho-N-alkyl- and N-alkoxyalkyl porphyrins (MnPs) were initially developed as superoxide dismutase (SOD) mimics. These compounds were later shown to react with numerous reactive species (such as ONOO-, H2O2, H2S, CO3•-, ascorbate, and GSH). Moreover, the ability of MnPs to oxidatively modify activities of numerous proteins has emerged as their major mechanism of action both in normal and in cancer cells. Among those proteins are transcription factors (NF-κB and Nrf2), mitogen-activated protein kinases, MAPKs, antiapoptotic bcl-2, and endogenous antioxidative defenses. The lead Mn porphyrins, namely, MnTE-2-PyP5+ (BMX-010, AEOL10113), MnTnBuOE-2-PyP5+ (BMX-001), and MnTnHex-2-PyP5+, were tested in numerous injuries of normal tissue and cellular and animal cancer models. The wealth of the data led to the progression of MnTnBuOE-2-PyP5+ into four Phase II clinical trials on glioma, head and neck cancer, anal cancer, and multiple brain metastases, while MnTE-2-PyP5+ is in Phase II clinical trial on atopic dermatitis and itch.

Mn porphyrins as a novel treatment targeting sickle cell NOXs to reverse and prevent acute vaso-occlusion in vivo

In sickle cell disease (SCD), adhesion of sickle red blood cells (SSRBCs) and activated leukocytes in inflamed venules affects blood rheology, causing vaso-occlusive manifestations and vital reduction in microvascular blood flow. Recently, we found that NADPH oxidases (NOXs) create a vicious feedback loop within SSRBCs. This positive feedback loop mediates SSRBC adhesion to the endothelium. We show for the first time the therapeutic effectiveness of the redox-active manganese (Mn) porphyrins MnTnBuOE-2-PyP5+ (MnBuOE; BMX-001) and MnTE-2-PyP5+ (MnE; BMX-010, AEOL10113) to treat established vaso-occlusion in a humanized sickle mouse model of an acute vaso-occlusive crisis using intravital microscopy. These Mn porphyrins can suppress SSRBC NOX activity. Subcutaneous administration of only 1 dose of MnBuOE or MnE at 0.1 to 2 mg/kg after the inflammatory trigger of vaso-occlusion, or simultaneously, reversed and reduced leukocyte and SSRBC adhesion, diminished leukocyte rolling, restored blood flow, and increased survival rate. Furthermore, MnBuOE and MnE administered to sickle mice subcutaneously at 0.1 to 1 mg/kg for 28 days (except on weekends) did not exacerbate anemia, which seemed to be due to downregulation of both SSRBC reactive oxygen species production and exposure of the eryptotic marker phosphatidylserine. In addition, Mn porphyrins ameliorated leukocytosis, venous blood gases, endothelial activation, and organ oxidative damage. Our data suggest that Mn porphyrins, likely by repressing NOX-mediated adhesive function of SSRBCs and activated leukocytes, could represent a novel, safe therapeutic intervention to treat or prevent the establishment of acute pain crises. These NOX-targeted antioxidants merit further assessment in SCD clinical trials.

Robust Mn(iii) N-pyridylporphyrin-based biomimetic catalysts for hydrocarbon oxidations: heterogenization on non-functionalized silica gel versus chloropropyl-functionalized silica gel

Simple neutral and cationic Mn porphyrins were immobilized on ordinary chromatographic silica or chloropropyl-functionalized silica supports to yield efficient and reusable biomimetic catalysts for C–H activation and oxyfunctionalization of alkanes.

25 years of development of Mn porphyrins — from mimics of superoxide dismutase enzymes to thiol signaling to clinical trials: The story of our life in the USA

We have developed Mn porphyrins (MnPs) initially as mimics of superoxide dismutase (SOD) enzymes based on structure–activity relationships. Several cationic Mn porphyrins, being substituted with cationic ortho [Formula: see text]-alkyl- or alkoxyalkylpyridyl groups in meso positions of the porphyrin ring, have been identified as potential therapeutics based on their high SOD-like activity and high bioavailability. Two of those [Mn(III) meso-tetrakis([Formula: see text]-ethylpyridinium-2-yl)porphyrin, MnTE-2-PyP[Formula: see text] (BMX-010, AEOL10113) and Mn(III) meso-tetrakis(Nn-butoxyethylpyridinium-2-yl)porphyrin, MnTnBuOE-2-PyP[Formula: see text] (BMX-001)] are now in five Phase II clinical trials. Studies of ours, and those of others, contributed to the understanding of the diverse activities of these compounds. With biologically compatible potentials and four biologically accessible oxidation states, Mn porphyrins interact with numerous reactive species, both as oxidants and reductants. Among those reactions, their abilities to (catalytically) oxidize [Formula: see text]-glutathionylate protein thiols may perhaps be their major in vivo mode of action. Via [Formula: see text]-glutathionylation, MnPs modulate actions of signaling proteins and, in turn, cellular apoptotic and proliferative pathways. During the major part of our stay in the USA, our lives have been dedicated to Mn porphyrins. Our families and especially our son and his three babies have been our inspiration not to give up on a life often burdened with hardship. It is thus our immense pleasure to see our compounds in clinical trials. Above all, we hope that our story will inspire future researchers to persevere — women in particular.

Mn Porphyrin-Based Redox Active Drugs Improve Anemia and Reduce Organ Damage in a Murine Model of Sickle Cell Disease

Sickle cell disease (SCD) is caused by a point mutation in the β-globin gene that leads to devastating downstream consequences including chronic hemolytic anemia, episodic vascular occlusion, and cumulative oxidative organ damage resulting in death. Targeting the mechanisms leading to organ injury could bring out therapeutic approaches. Sickle red blood cell (RBC) oxidative damage, which leads to hemolysis, could participate in endothelial activation and organ damage. Recently, we show that NADPH oxidases (NOXs) are a major player in generating reactive oxygen species (ROS) within sickle RBCs to mediate adhesion and vaso-occlusion. We have now evaluated the effects of reducing ROS in sickle RBCs on hemolysis, and its consequences on endothelial activation and organ damage in sickle mice in vivo. To inactive RBC NOXs, thus reduce ROS levels, we used the redox-active manganese (Mn) porphyrins, MnTnBuOE-2-PyP5+ (MnBuOE) and MnTE-2-PyP5+ (MnE), commonly known as superoxide dismutase (SOD) mimics. Treatments of sickle mice for 4 weeks with 0.1 mg/kg MnBuOE and 1 mg/kg MnE significantly reduced sickle RBC ROS production profile compared to sickle RBC ROS levels in the control vehicle group (p<0.05), suggesting that Mn porphyrins protects sickle RBCs especially against NOX activation. Mn porphyrins also significantly affected apoptosis-like RBC death called eryptosis characterized by accelerated membrane senescence and PS externalization. Sickle mice-treated with vehicle showed 4.98±0.6% annexin V-positive sickle RBCs. However, 0.1 mg/kg MnBuOE and 1 mg/kg MnE markedly decreased the percentage of annexin V-binding sickle RBCs by 54% (p=0.0009) and 56% (p=0.0007), respectively. As a result of improved eryptosis, RBC counts rose from 5.23 x 106/mL in vehicle-treated sickle mice to 5.99 x 106/mL in MnE-treated mice. Hemoglobin (Hb) levels also rose from 7 g/dL in the vehicle group to 8.55 g/dL in MnE-treated mice. Accordingly, hematocrits rose from 26.1% in vehicle-treated mice to 28.59% in MnE-treated mice. Yet, reticulocyte counts were not significantly different between vehicle and MnE-treated sickle mice, implying less hemolysis and not an increase in RBC production. The effect of reduced hemolysis by Mn porphyrins on oxidative stress in different organs was next assessed. MnBuOE and MnE decreased ROS levels in the kidneys (p<0.03 for MnBuOE and MnE), liver (p<0.05 for MnBuOE and MnE), and spleen (p<0.004 for MnBuOE and MnE) compared to the vehicle-treated group. Since organ ROS levels were lowered, this outcome may be accompanied by down-regulation of activation of endothelial adhesion molecules VCAM-1, ICAM-1, and P-selectin, markers of endothelial dysfunction and disease severity and/or RBC and leukocyte adhesion in SCD. Indeed, adhesion molecule expression assays by qRT-PCR showed that MnBuOE suppressed ICAM-1 and VCAM-1 expression in the lungs (p<0.0001 and p=0.0054, respectively) and kidneys (p=0.0072 and p=0.0004, respectively), and P-selectin expression (p=0.0058) in the kidneys. MnE also down-regulated the expression of ICAM-1 in the lungs (p<0.0001) and kidneys (p=0.0125), and VCAM-1 (p=0.0038) in the kidneys. These drugs had no effect on ICAM-1, VCAM-1, and P-selectin expression in the liver and spleen. Based on these data, we assumed that Mn porphyrins might rescue damage of organs typically affected and impaired in SCD. Apoptosis and necrosis of the kidneys, liver, and spleen were assessed using annexin V apoptosis detection kit and H&E staining. Sickle mice treated with vehicle showed marked apoptosis in the kidney, liver, and spleen (p=0.0314) tissues, and necrosis. However, 0.1 mg/kg MnBuOE and 1 mg/kg MnE significantly decreased apoptosis (p<0.0001) and necrosis in the kidneys, and liver (p=0.0355). MnBuOE also reduced apoptosis (p=0.0314) and necrosis in the spleen. These data suggest that Mn porphyrins can alleviate organ impairment and damage via at least RBC and endothelial oxidative stress reduction. As a result of these beneficial outcomes of reduced hemolysis, endothelial oxidative damage and dysfunction, Kaplan-Meier survival curves showed a dramatic prolonged survival of sickle mice challenged with TNFα (p = .0009, log-rank test). Our data suggest that Mn porphyrins, by repressing NOX-mediated hemolysis could represent a novel therapeutic intervention to especially alleviate hemolysis-mediated endothelial activation and organ damage in SCD. Disclosures No relevant conflicts of interest to declare.

Crystallographic identification of a series of manganese porphyrin complexes with nitrogenous bases

Studying the axial ligation behavior of metalloporphyrins with nitrogenous bases helps to better understand not only the biological function of heme-based protein systems, but also the catalytic properties of porphyrin-based reaction sites in other biomimetic synthetic support environments. Unlike iron porphyrin complexes, little is known about the axial ligation behavior of Mn porphyrins, particularly in the solid state with Mn in the +3 oxidation state. Here, we present the syntheses and crystal and molecular structures of three new high-spin manganese(III) porphyrin complexes with the different amine-based axial ligands imidazole (im), piperidine (pip), and 1,4-diazabicyclo[2.2.2]octane (DABCO), namely bis(imidazole)(5,10,15,20-tetraphenylporphyrinato)manganese(III) chloride chloroform disolvate, [Mn(C44H28N4)(C3H4N2)2]Cl·2CHCl3 or [Mn(TPP)(im)2]Cl·2CHCl3 (TPP = 5,10,15,20-tetraphenylporphyrin), (I), bis(piperidine)(5,10,15,20-tetraphenylporphyrinato)manganese(III) chloride, [Mn(C44H28N4)(C5H11N)2]Cl or [Mn(TPP)(pip)2]Cl, (II), and chlorido(1,4-diazabicyclo[2.2.2]octane)(5,10,15,20-tetraphenylporphyrin)manganese(III)–1,4-diazabicyclo[2.2.2]octane–toluene–water (4/4/4/1), [Mn(C44H28N4)Cl(C6H12N2)]·C6H12N2·C7H8·0.25H2O or [Mn(TPP)Cl(DABCO)]·(DABCO)·(toluene)·0.25H2O, (IV). A fourth complex, chlorido(pyridine)(5,10,15,20-tetraphenylporphryinato)manganese(III) pyridine disolvate, [Mn(C44H28N4)Cl(C5H5N)]·2C5H5N or [Mn(TPP)Cl(py)]·2(py), (III), acquired using different crystallization methods from published data, is also reported and compared to the previous structures.

Lactoferrin-modified nanoparticles loaded with potent antioxidant Mn-porphyrins exhibit enhanced antioxidative activity in vitro intranasal brain delivery model

In this study, for efficient intranasal brain delivery, we have prepared lactoferrin (Lf)-modified nanoparticles loaded with an amphiphilic Mn-porphyrin derivative, MndMImP3P (MnP) (Lf-NP-MnP).