Multifaceted Applications of Luminescent Metalloporphyrin Derivatives: Fluorescence Turn-On Sensing of Nicotine and Antimicrobial Activity.

In this study, we designed and synthesized metalloporphyrin derivatives (with Ni and Zn) specifically intended for the fluorescence detection of nicotine in aqueous solutions. Our results showcased a notable selectivity for nicotine over other naturally occurring food toxins, exhibiting an exceptional sensitivity with a limit of detection as low as 7.2 nM. Through mechanistic investigations (1H NMR, FT-IR, etc.), we elucidated the binding mechanism, revealing the specific interaction between the pyridine ring of nicotine and the metal center, while the N atom pyrrolidine unit engaged in the hydrogen bonding with the side chain of the porphyrin ring. Notably, we observed that the nature of the metal center dictated the extent of interaction with nicotine; particularly, Zn-porphyrin demonstrated a superior response compared to Ni-porphyrin. Furthermore, we performed the quantitative estimation of nicotine in commercially available tobacco products. Additionally, we conducted the antibacterial (Staphylococcus aureus and Escherichia coli) and antifungal (Candida albicans) activities of the porphyrin derivatives.

Design and Synthesis of Metalloporphyrin Nanoconjugates for Dual Light-Responsive Antimicrobial Photodynamic Therapy.

Antimicrobial photodynamic therapy (APDT) utilizes photosensitizers (PSs) that eradicate a broad spectrum of bacteria in the presence of light and molecular oxygen. On the other hand, some light sources such as ultraviolet (UVB and UVC) have poor penetration and high cytotoxicity, leading to undesired PDT of the PSs. Herein, we have synthesized conjugatable mesosubstituted porphyrins and extensively characterized them. Time-dependent density functional theory (TD-DFT) calculations revealed that metalloporphyrin EP (5) is a suitable candidate for further applications. Subsequently, the metalloporphyrin was conjugated with lignin-based zinc oxide nanocomposites (ZnOAL and ZnOKL) to develop hydrophilic nanoconjugates (ZnOAL@EP and ZnOKL@EP). Upon dual light (UV + green light) exposure, nanoconjugates showed enhanced singlet oxygen generation ability and also demonstrated pH responsiveness. These nanoconjugates displayed significantly improved APDT efficiency (4-7 fold increase) to treat bacterial infection under dual light irradiation.

Novel Catalytic Antioxidant Formulation Decreases Oxidative Stress, Neuroinflammation and Cognitive Dysfunction in a Model of Nerve Agent Intoxication.

Reactive oxygen species have an emerging role in the pathologic consequences of status epilepticus. We have previously demonstrated the efficacy of a water-for-injection formulation of the meso-porphyrin catalytic antioxidant, manganese (III) meso-tetrakis (N-N-diethylimidazole) porphyrin (AEOL10150) against oxidative stress, neuroinflammation, and neuronal death initiated by kainic acid, pilocarpine, diisopropylflurophosphate (DFP), and soman. This previous dose and dosing strategy of AEOL10150 required smaller multiple daily injections, precluding our ability to test its efficacy against delayed consequences of nerve agent exposure such as neurodegeneration and cognitive dysfunction. Therefore, we developed formulations of AEOL10150 designed to deliver a larger dose once daily with improved brain pharmacodynamics. We examined four new formulations of AEOL10150 that resulted in 8 times higher subcutaneous dose with lower acute toxicity, slower absorption, longer half-life, and higher maximal plasma concentrations compared with our previous strategy. AEOL10150 brain levels exhibited improved pharmacodynamics over 24 hours with all four formulations. We tested a subcutaneous dose of 40 mg/kg AEOL10150 in two formulations (2% carboxymethyl cellulose and 4% polyethylene glycol-4000) in the DFP rat model, and both formulations exhibited significant protection against DFP-induced oxidative stress. Additionally, and in one formulation (4% polyethylene glycol-4000), AEOL10150 significantly protected against DFP-induced neuronal death, microglial activation, delayed memory impairment, and mortality. These results suggest that reformulation of AEOL10150 can attenuate acute and delayed outcomes of organophosphate neurotoxicity. SIGNIFICANCE STATEMENT: Reformulation of manganese (III) meso-tetrakis (N-N-diethylimidazole) porphyrin allowed higher tolerated doses of the compound with improved pharmacodynamics. Specifically, one new formulation allowed fewer daily doses and improvement in acute and delayed outcomes of organophosphate toxicity.

Effect of the nature of the chelated metal on the photodynamic activity of metalloporphyrins.

Coordination of metal ions by the tetrapyrrolic macrocyclic ring of porphyrin-based photosensitizers (PSs) affects their photophysical properties and consequently, their photodynamic activity. Diamagnetic metals increase the singlet oxygen quantum yield while paramagnetic metals have the opposite effect. Since singlet oxygen is considered the main cell-damaging species in photodynamic therapy (PDT), the nature of the chelated cation would directly affect PDT efficacy. This expectation, however, is not always supported by experimental results and numerous exceptions have been reported. Understanding the effect of the chelated metal is hindered because different chelators were used. The aim of this work was to investigate the effect of the nature of chelated cation on the photophysical and photodynamic properties of metalloporphyrins, using the same tetrapyrrole core as a chelator of Ag(II), Cu(II), Fe(III), In(III), Mn(III), or Zn(II). Results demonstrated that with the exception of Ag(II), all paramagnetic metalloporphyrins were inefficient as generators of singlet oxygen and did not act as PSs. In contrast, the coordination of diamagnetic ions produced highly efficient PSs. The unexpected photodynamic activity of the Ag(II)-containing porphyrin was attributed to reduction of the chelated Ag(II) to Ag(I) or to demetallation of the complex, caused by cellular reductants and/or by exposure to light. Our results indicate that in biological systems, where PSs localize to various organelles and are subjected to the action of enzymes, reactive metabolites, and reducing or oxidizing agents, their physicochemical and photosensitizing properties change. Consequently, the photophysical properties alone cannot predict the anticancer efficacy of a PS.

Metal Modulation: An Effortless Tactic for Refining Photoredox Catalysis in Living Cells.

The remarkable impact of photoredox catalytic chemistries has sparked a wave of innovation, opening doors to novel biotechnologies in the realm of catalytic antitumor therapy. Yet, the quest for novel photoredox catalysts (PCs) suitable for living systems, or the enhancement of catalytic efficacy in existing biocompatible PC systems, persists as a formidable challenge. Within this context, we introduce a readily applicable metal modulation strategy that significantly augments photoredox catalysis within living cells, exemplified by a set of metalloporphyrin complexes termed M-TCPPs (M = Zn, Mn, Ni, Co, Cu). Among these complexes, Zn-TCPP emerges as an exceptional catalyst, displaying remarkable photocatalytic activity in the oxidation of nicotinamide adenine dinucleotide (NADH), nicotinamide adenine dinucleotide phosphate (NADPH), and specific amino acids. Notably, comprehensive investigations reveal that Zn-TCPP's superior catalytic prowess primarily arises from the establishment of an efficient oxidative cycle for PC, in contrast to previously reported PCs engaged in reductive cycles. Moreover, theoretical calculations illuminate that amplified intersystem crossing rates and geometry alterations in Zn-TCPP contribute to its heightened photocatalytic performance. In vitro studies demonstrated that Zn-TCPP exhibits therapeutic potential and is found to be effective for photocatalytic antitumor therapy in both glioblastoma G98T cells and 3D multicellular spheroids. This study underscores the transformative role of "metal modulation" in advancing high-performance PCs for catalytic antitumor therapy, marking a significant stride toward the realization of this innovative therapeutic approach.

Metalloporphyrins Reduce Proteinuria in Podocyte Immune Injury: The Role of Metal and Porphyrin Moieties.

Depending on their central metal atom, metalloporphyrins (MPs) can attenuate or exacerbate the severity of immune-mediated kidney injury, and this has been attributed to the induction or inhibition of heme oxygenase (HO) activity, particularly the inducible isoform (HO-1) of this enzyme. The role of central metal or porphyrin moieties in determining the efficacy of MPs to attenuate injury, as well as mechanisms underlying this effect, have not been assessed. Using an antibody-mediated complement-dependent model of injury directed against rat visceral glomerular epithelial cells (podocytes) and two MPs (FePPIX, CoPPIX) that induce both HO-1 expression and HO enzymatic activity in vivo but differ in their chelated metal, we assessed their efficacy in reducing albuminuria. Podocyte injury was induced using rabbit immune serum raised against the rat podocyte antigen, Fx1A, and containing an anti-Fx1A antibody that activates complement at sites of binding. FePPIX or CoPPIX were injected intraperitoneally (5 mg/kg) 24 h before administration of the anti-Fx1A serum and on days 1, 3, 6, and 10 thereafter. Upon completion of urine collection on day 14, the kidney cortex was obtained for histopathology and isolation of glomeruli, from which total protein extracts were obtained. Target proteins were analyzed by capillary-based separation and immunodetection (Western blot analysis). Both MPs had comparable efficacy in reducing albuminuria in males, but the efficacy of CoPPIX was superior in female rats. The metal-free protoporphyrin, PPIX, had minimal or no effect on urine albumin excretion. CoPPIX was also the most potent MP in inducing glomerular HO-1, reducing complement deposition, and preserving the expression of the complement regulatory protein (CRP) CD55 but not that of CD59, the expression of which was reduced by both MPs. These observations demonstrate that the metal moiety of HO-1-inducing MPs plays an important role in reducing proteinuria via mechanisms involving reduced complement deposition and independently of an effect on CRPs.

Coaxial 3D printing of hierarchical structured hydrogel scaffolds for on-demand repair of spinal cord injury.

After spinal cord injury (SCI), endogenous neural stem cells (NSCs) near the damaged site are activated, but few NSCs migrate to the injury epicenter and differentiate into neurons because of the harsh microenvironment. It has demonstrated that implantation of hydrogel scaffold loaded with multiple cues can enhance the function of endogenous NSCs. However, programming different cues on request remains a great challenge. Herein, a time-programmed linear hierarchical structure scaffold is developed for spinal cord injury recovery. The scaffold is obtained through coaxial 3D printing by encapsulating a dual-network hydrogel (composed of hyaluronic acid derivatives and N-cadherin modified sodium alginate, inner layer) into a temperature responsive gelatin/cellulose nanofiber hydrogel (Gel/CNF, outer layer). The reactive species scavenger, metalloporphyrin, loaded in the outer layer is released rapidly by the degradation of Gel/CNF, inhibiting the initial oxidative stress at lesion site to protect endogenous NSCs; while the inner hydrogel with appropriate mechanical support, linear topology structure and bioactive cues facilitates the migration and neuronal differentiation of NSCs at the later stage of SCI treatment, thereby promoting motor functional restorations in SCI rats. This study offers an innovative strategy for fabrication of multifunctional nerve regeneration scaffold, which has potential for clinical treatment of SCI. STATEMENT OF SIGNIFICANCE: Two major challenges facing the recovery from spinal cord injury (SCI) are the low viability of endogenous neural stem cells (NSCs) within the damaged microenvironment, as well as the difficulty of neuronal regeneration at the injured site. To address these issues, a spinal cord-like coaxial scaffold was fabricated with free radical scavenging agent metalloporphyrin Mn (III) tetrakis (4-benzoic acid) porphyrin and chemokine N-cadherin. The scaffold was constructed by 3D bioprinting for time-programmed protection and modulation of NSCs to effectively repair SCI. This 3D coaxially bioprinted biomimetic construct enables multi-factor on-demand repair and may be a promising therapeutic strategy for SCI.

Mn(III) Porphyrin, MnTnBuOE-2-PyP5+, Commonly Known as a Mimic of Superoxide Dismutase Enzyme, Protects Cardiomyocytes from Hypoxia/Reoxygenation Induced Injury via Reducing Oxidative Stress.

Myocardial ischemia-reperfusion injury (I/R) causes damage to cardiomyocytes through oxidative stress and apoptosis. We investigated the cardioprotective effects of MnTnBuOE-2-PyP5+ (BMX-001), a superoxide dismutase mimic, in an in vitro model of I/R injury in H9c2 cardiomyocytes. We found that BMX-001 protected against hypoxia/reoxygenation (H/R)-induced oxidative stress, as evident by a significant reduction in intracellular and mitochondrial superoxide levels. BMX-001 pre-treatment also reduced H/R-induced cardiomyocyte apoptosis, as marked by a reduction in TUNEL-positive cells. We further demonstrated that BMX-001 pre-treatment significantly improved mitochondrial function, particularly O2 consumption, in mouse adult cardiomyocytes subjected to H/R. BMX-001 treatment also attenuated cardiolipin peroxidation, 4-hydroxynonenal (4-HNE) level, and 4-HNE adducted proteins following H/R injury. Finally, the pre-treatment with BMX-001 improved cell viability and lactate dehydrogenase (LDH) activity in H9c2 cells following H/R injury. Our findings suggest that BMX-001 has therapeutic potential as a cardioprotective agent against oxidative stress-induced H/R damage in H9c2 cardiomyocytes.

Metalloporphyrins as Tools for Deciphering the Role of Heme Oxygenase in Renal Immune Injury.

Renal immune injury is a frequent cause of end-stage renal disease, and, despite the progress made in understanding underlying pathogenetic mechanisms, current treatments to preserve renal function continue to be based mainly on systemic immunosuppression. Small molecules, naturally occurring biologic agents, show considerable promise in acting as disease modifiers and may provide novel therapeutic leads. Certain naturally occurring or synthetic Metalloporphyrins (Mps) can act as disease modifiers by increasing heme oxygenase (HO) enzymatic activity and/or synthesis of the inducible HO isoform (HO-1). Depending on the metal moiety of the Mp employed, these effects may occur in tandem or can be discordant (increased HO-1 synthesis but inhibition of enzyme activity). This review discusses effects of Mps, with varying redox-active transitional metals and cyclic porphyrin cores, on mechanisms underlying pathogenesis and outcomes of renal immune injury.

Molecular Dipole Modulation of Porphyrins to Enhance Photocatalytic Oxidation Activity for Inactivation of Intracellular Bacteria.

The regulation of molecular structures of porphyrin-based photosensitizers is crucial for yielding the effective singlet oxygen as one of the efficient photocatalytic reactive oxidation species. Here, we select methoxy substitution as an electron donor to decorate the porphyrin rings. Introducing a series of metal ions into porphyrin centers further prepares the methoxy-substituted metalloporphyrins (MPs, M = Co, Ni, Cu, Zn), with the hope of modulating their molecular dipole moments and photocatalytic activity. The theoretical calculation analyses show that the metal-free porphyrin center possesses a higher transition dipole and more delocalized orbitals, leading to efficient charge transfer and improved photocatalytic activity. The metalloporphyrin samples are then polymerized by poly(D, l-lactide-co-glycolide) to be applied to in vitro sterilization experiments. As expected, metal-free porphyrin has good antibacterial ability and good biocompatibility. Moreover, the highly effective bacteriostatic metal-free porphyrin achieves satisfactory photodynamic therapeutic outcomes against intracellular pathogens in cancer cells. This work demonstrates that the molecular dipole modulation of porphyrins is critical for their photocatalytic oxidation and antibacterial ability.

Scorpion-Shaped Zinc Porphyrins as Tetrafunctional TAR RNA Predators and HIV-1 Reverse Transcriptase Inhibitors.

HIV-1 reverse transcriptase (RT) inhibitors are fundamental to the discovery and development of anti-HIV drugs. Their main target is RT, and only a tiny number of them can bind to viral RNA. In this paper, five new Zn(II) porphyrin compounds were developed with different characters. ZnTPP4 has both the appearance and the functions of a scorpion with a rigid tail and stinger to selectively hunt HIV-1 TAR RNA based on the molecular recognition of hydrogen bonds, a fierce chelicera to bite RNA by metal coordination, mighty pedipalps to grasp the bound RNA by supramolecular inclusion, and a broad body maintaining the configuration of each functional area so that they can cooperate with each other and providing accommodation space for the bound RNA. This tetrafunctional Zn(II) porphyrin is relatively nontoxic to normal cells and can produce sensitive responses for RNA. Moreover, this work offers practical construction methodologies for medication of AIDS and other diseases closely related to RT like EBOV and SARS-CoV-2.

A water-soluble iron-porphyrin complex capable of rescuing CO-poisoned red blood cells.

We describe herein a small-molecule platform that exhibits key properties needed by an antidote for CO poisoning. The design features an iron-porphyrin complex with bulky substituents above and below the macrocyclic plane to provide a hydrophobic pocket for CO binding and to prevent the formation of inactive oxo-bridged dimers. Peripheral charged groups impart water solubility. We demonstrate that the Fe(II) complex of a porphyrin with 2,6-diphenyl-4-sulfophenyl meso substituents can bind CO, stoichiometrically sequester CO from carboxyhemoglobin, and rescue CO-poisoned red blood cells.

Conjugates of Porphyrinoid-Based Photosensitizers with Cytotoxic Drugs: Current Progress and Future Directions toward Selective Photodynamic Therapy.

Photodynamic therapy (PDT) is a treatment modality where light-mediated activation of photosensitizers in a patient's body leads to the generation of cytotoxic reactive oxygen species (ROS), eliminating cancer cells. One direction that has been firmly established over past years is the conjugation of photosensitizers with various molecules that demonstrate their own cytotoxic activity. As a result, improved selectivity and treatment outcomes are observed compared to those of unconjugated drugs. The attractiveness of such an approach is due to the variability of cytotoxic warheads and specific linkers available for the construction of conjugates. In this review, we summarize and analyze data concerning these inventions with the ultimate goal to find a promising conjugation partner for a porphyrinoid-based photosensitizer. The current challenges toward successful conjugation are also outlined and discussed. We hope that this review will motivate researchers to pay closer attention to conjugates and possibilities hidden in these molecules for the PDT of cancer.

Photophysical characterization and in vitro anti-leishmanial effect of 5,10,15,20-tetrakis(4-fluorophenyl) porphyrin and the metal (Zn(II), Sn(IV), Mn(III) and V(IV)) derivatives.

In this report 5 compounds were synthesized and structural and their photophysical characterization was performed (ΦΔ and Φf). Furthermore, in this in vitro study, their biological activity against Leishmania panamensis was evaluated. The photophysical behavior of these compounds was measured and high ΦΔ and low Φf was observed. Besides, DFT quantum calculations on the electronic structures were performed. Finally, the biological activity was determined by means of the compounds capacity to inhibit the viability of parasites using the MTT assay. The inclusion of the metal ions substantially modified the photophysical and biological properties in comparison with the free metal porphyrin (1). In fact, Zn2+ porphyrin derivative (2) showed a marked decrease of Φf and increase of ΦΔ. In this sense, using TDDFT approaches, a luminescent process for Sn4+ derivative (3) was described, where emissive states involve the ML-LCT transition. So, this led to a decrease in the singlet oxygen production (0.82-0.67). Biological results showed that all compounds inhibit the viability of L. panamensis with high efficiency; the decrease in the viability was greater as the concentration of exposure increased. Finally, under light irradiation the IC50 of L. panamensis against the Zn(II)-porphyrin (2) and V(IV)-porphyrin (5) was lower than the IC50 of the Glucantime control (IC50 = 2.2 and 6.95 µM Vs IC50 = 12.7 µM, respectively). We showed that the use of porphyrin and metalloporphyrin-type photosensitizers with exceptional photophysical properties can be successful in photodynamic therapy (PDT) against L. panamensis, being the diamagnetic ion Zn2+ a candidate for the preparation of metalloporphyrins with high singlet oxygen production.

Optimization, Characterization and Pharmacokinetic Study of Meso-Tetraphenylporphyrin Metal Complex-Loaded PLGA Nanoparticles.

The selection of technological parameters for nanoparticle formulation represents a complicated development phase. Therefore, the statistical analysis based on Box-Behnken methodology is widely used to optimize technological processes, including poly(lactic-co-glycolic acid) nanoparticle formulation. In this study, we applied a two-level three-factor design to optimize the preparation of nanoparticles loaded with cobalt (CoTPP), manganese (MnClTPP), and nickel (NiTPP) metalloporphyrins (MeP). The resulting nanoparticles were examined by dynamic light scattering, X-ray diffraction, Fourier transform infrared spectroscopy, MTT test, and hemolytic activity assay. The optimized model of nanoparticle formulation was validated, and the obtained nanoparticles possessed a spherical shape and physicochemical characteristics enabling them to deliver MeP in cancer cells. In vitro hemolysis assay revealed high safety of the formulated MeP-loaded nanoparticles. The MeP release demonstrated a biphasic profile and release mechanism via Fick diffusion, according to release exponent values. Formulated MeP-loaded nanoparticles revealed significant antitumor activity and ability to generate reactive oxygen species. MnClTPP- and CoTPP-nanoparticles specifically accumulated in tissues, preventing wide tissue distribution caused by long-term circulation of the hydrophobic drug. Our results suggest that MnClTPP- and CoTPP-nanoparticles represent the greatest potential for utilization in in anticancer therapy due to their effectiveness and safety.

Tin Mesoporphyrin Selectively Reduces Non-Small-Cell Lung Cancer Cell Line A549 Proliferation by Interfering with Heme Oxygenase and Glutathione Systems.

In order to maintain redox homeostasis, non-small-cell lung cancer (NSCLC) increases the activation of many antioxidant systems, including the heme-oxygenase (HO) system. The overexpression of HO-1 has been often associated with chemoresistance and tumor aggressiveness. Our results clearly showed an overexpression of the HO-1 protein in A549 NSCLC cell lines compared to that in non-cancerous cells. Thus, we hypothesized that "off-label" use of tin mesoporphyrin, a well-known HO activity inhibitor clinically used for neonatal hyperbilirubinemia, has potential use as an anti-cancer agent. The pharmacological inhibition of HO activity caused a reduction in cell proliferation and migration of A549. SnMP treatment caused an increase in oxidative stress, as demonstrated by the upregulation of reactive oxygen species (ROS) and the depletion of glutathione (GSH) content. To support these data, Western blot analysis was performed to analyze glucose-6-phosphate dehydrogenase (G6PD), TP53-induced glycolysis and the apoptosis regulator (TIGAR), and the glutamate cysteine ligase catalytic (GCLC) subunit, as they represent the main regulators of the pentose phosphate pathway (PPP) and glutathione synthesis, respectively. NCI-H292, a subtype of the NSCLC cell line, did not respond to SnMP treatment, possibly due to low basal levels of HO-1, suggesting a cellular-dependent antitumorigenic effect. Altogether, our results suggest HO activity inhibition may represent a potential target for selective chemotherapy in lung cancer subtypes.

Ascorbate-dependent and ascorbate-independent Mn porphyrin cytotoxicity: anticancer activity of Mn porphyrin-based SOD mimics through ascorbate-dependent and -independent routes.

OBJECTIVE: The aim of this study was to investigate how modifications at the periphery of the porphyrin ring affect the anticancer activity of Mn porphyrins (MnPs)-based SOD mimics. METHODS: Six compounds: MnTE-2-PyP with a short ethyl chain on the pyridyl ring; MnTnHexOE-2-PyP and MnTnOct-2-PyP with linear 8-atom alkyl chains, but the former with an oxygen atom within the alkyl chain; MnTE-2-PyPhP and MnTPhE-2-PyP with pyridyl and phenyl substituents, were investigated. Cytotoxicity was studied using pII and MDA-MB-231 cancer cell lines. Viability was assessed by the MTT (3-[4,5-dimethylthiazol-2-yl)]-2,5-diphenyltetrazolium bromide) assay and cell proliferation was determined by the sulforhodamine B assay. RESULTS: Cellular uptake was increased with the increase of the lipophilicity of the compounds, whereas reduction potential (E½) of the Mn(III)/Mn(II) redox couple shifted away from the optimal value for efficient redox cycling with ascorbate, necessary for ROS production. Amphiphilic MnPs, however, exerted anticancer activity by a mechanism not involving ROS. CONCLUSION: Two different processes account for MnPs cytotoxicity. MnPs with appropriate E½ act via a ROS-dependent mechanism. Amphiphilic MnPs with suitable structure damage sensitive cellular constituents, leading to the suppression of proliferation and loss of viability. Design of compounds interacting directly with sensitive cellular targets is highly promising in the development of anticancer drugs with high selectivity and specificity.

Efficient photodynamic inactivation of Leishmania parasites mediated by lipophilic water-soluble Zn(II) porphyrin ZnTnHex-2-PyP4.

BACKGROUND: Photodynamic inactivation (PDI) is emerging as a promising alternative for cutaneous leishmaniasis (CL). The chemotherapy currently used presents adverse effects and cases of drug resistance have been reported. ZnTnHex-2-PyP4+ is a porphyrin with a high potential as a photosensitizer (PS) for PDI, due to its photophysical properties, structural stability, and cationic/amphiphilic character that can enhance interaction with cells. This study aimed to investigate the photodynamic effects mediated by ZnTnHex-2-PyP4+ on Leishmania parasites. METHODS: ZnTnHex-2-PyP4+ stability was evaluated using accelerated solvolysis conditions. The photodynamic action on promastigotes was assessed by (i) viability assays, (ii) mitochondrial membrane potential evaluation, and (iii) morphological analysis. The PS-promastigote interaction was studied. PDI on amastigotes and the cytotoxicity on macrophages were also analyzed. RESULTS: ZnTnHex-2-PyP4+, under submicromolar concentration, led to immediate inactivation of more than 95% of promastigotes. PDI promoted intense mitochondrial depolarization, loss of the fusiform shape, and plasma membrane wrinkling in promastigotes. Fluorescence microscopy revealed a punctate PS labeling in the parasite cytoplasm. PDI also led to reductions of ca. 64% in the number of amastigotes/macrophage and 70% in the infection index after a single treatment session. No noteworthy toxicity was observed on mammalian cells. CONCLUSIONS: ZnTnHex-2-PyP4+ is stable against demetallation and more efficient as PS than the ethyl analogue ZnTE-2-PyP4+, indicating readiness for evaluation in in vivo studies as an alternative approach to CL. GENERAL SIGNIFICANCE: This report highlighted promising photodynamic effects mediated by ZnTnHex-2-PyP4+ on Leishmania parasites, opening up perspectives for applications in CL pre-clinical assays and PDI of other microorganisms.

The antioxidant MnTBAP does not effectively downregulate CD4 expression in T cells in vivo.

The antioxidant MnTBAP was previously shown to down-regulate the surface expression of CD4 molecule in T cells. This observation obviously holds great potential impact in a number of pathological human conditions, including autoimmunity. Three different single doses of MnTBAP reduced the frequency of CD4high cells. However, the median florescent intensity (MFI) was not different. Initiation of in vivo pharmacotherapy or vehicle control was performed inC57BL/6 mice that were actively immunized for experimental autoimmune encephalomyelitis (EAE). In contrast to published reports, the mean frequency of CD4high cells, and the median fluorescent intensity (MFI) of CD4 was similar in both treatment groups. 25-day survival following active immunization among the MnTBAP treated animals compared to vehicle controls was16.6 ± 6.9 days vs 23.6 ± 2.7 days; (P value <0.05). We conclude that MnTBAP (Sack and Herzog, 2009 (Sack and Herzog, 2009)) does not effectively downregulate CD4 expression in T cells in vivo, probably due to extensive mechanism that distinguishes it from an in vitro model (Harding, 1993 (Harding, 1993)) possesses toxic properties that may limit its clinic use in possible doses that could deliver the immunomodulation through down regulation of CD4 expression, and (Saizawa et al., 1987 (Saizawa et al., 1987)) has limited availability in specific tissues, including the CNS.

Manganese(III) porphyrin oligomers as high-relaxivity MRI contrast agents.

Manganese(III) porphyrins (MnIIIPs) as MRI contrast agents (CAs) have drawn particular attention due to their high longitudinal relaxivity (r1) and unique biodistribution. In this work, two MnIIIP-based oligomers, MnPD and MnPT, were designed to further improve the relaxivity with ease of synthesis. The two compounds were fully characterized and their nuclear magnetic relaxation dispersion (NMRD) profiles were acquired with a fast field cycling NMR relaxometer. Both of the compounds exhibited extended high molar r1 at high fields, higher than that of Gd-DTPA, the first clinical gadolinium(III)-based MRI CA. The r1 value of per manganese atom increased with the increasing number of MnIIIP building blocks, suggesting rotational correlation time (τR) played dominant role in the r1 dispersion. The toxicity of the two MnIIIPs and the imaging effectiveness were estimated in vitro and in vivo. With good biocompatibility, significant contrast enhancement, and complete excretion in 24 h, MnPD and MnPT are both promising for high field clinical applications. The applied strategy also potentially provided a facile approach for creation of more MnIIIP oligomer as efficient T1 MRI CAs.