Extracellular Heme Uptake and the Challenge of Bacterial Cell Membranes.

Iron is essential for the survival of most bacteria but presents a significant challenge given its limited bioavailability. Furthermore, the toxicity of iron combined with the need to maintain physiological iron levels within a narrow concentration range requires sophisticated systems to sense, regulate, and transport iron. Most bacteria have evolved mechanisms to chelate and transport ferric iron (Fe3+) via siderophore receptor systems, and pathogenic bacteria have further lowered this barrier by employing mechanisms to utilize the host's hemoproteins. Once internalized, heme is cleaved by both oxidative and nonoxidative mechanisms to release iron. Heme, itself a lipophilic and toxic molecule, presents a significant challenge for transport into the cell. As such, pathogenic bacteria have evolved sophisticated cell surface signaling and transport systems to obtain heme from the host. In this review, we summarize the structure and function of the heme-sensing and transport systems of pathogenic bacteria and the potential of these systems as antimicrobial targets.

Oxygen-Evolving Radiotherapy-Radiodynamic Therapy Synergized with NO Gas Therapy by Cerium-Based Rare-Earth Metal-Porphyrin Framework.

The efficacy of traditional radiotherapy (RT) has been severely limited by its significant side effects, as well as tumor hypoxia. Here, the nanoscale cerium (Ce)-based metaloxo clusters (Ce(IV)6)-porphyrin (meso-tetra (4-carboxyphenyl) porphyrin, TCPP) framework loaded with L-arginine (LA) (denoted as LA@Ce(IV)6-TCPP) is developed to serve as a multifarious radio enhancer to heighten X-ray absorption and energy transfer accompanied by O2/NO generation for hypoxia-improved RT-radiodynamic therapy (RDT) and gas therapy. Within tumor cells, LA@Ce(IV)6-TCPP will first react with endogenous H2O2 and inducible NO synthase (iNOS) to produce O2 and NO to respectively increase the oxygen supply and reduce oxygen consumption, thus alleviating tumor hypoxia. Then upon X-ray irradiation, LA@Ce(IV)6-TCPP can significantly enhance hydroxyl radical (•OH) generation from Ce(IV)6 metaloxo clusters for RT and synchronously facilitate singlet oxygen (1O2) generation from adjacently-coordinated TCPP for RDT. Moreover, both the •OH and 1O2 can further react with NO to generate more toxic peroxynitrite anions (ONOO-) to inhibit tumor growth for gas therapy. Benefitting from the alleviation of tumor hypoxia and intensified RT-RDT synergized with gas therapy, LA@Ce(IV)6-TCPP elicited superior anticancer outcomes. This work provides an effective RT strategy by using low doses of X-rays to intensify tumor suppression yet reduce systemic toxicity.

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.

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 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.

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.

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.

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.

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.

Peroxynitrite decomposition catalyst enhances respiratory function in isolated brain mitochondria.

Peroxynitrite (PN), generated from the reaction of nitric oxide (NO) and superoxide, is implicated in the pathogenesis of ischemic and neurodegenerative brain injuries. Mitochondria produce NO from mitochondrial NO synthases and superoxide by the electron transport chain. Our objective was to detect the generation of PN of mitochondrial origin and characterize its effects on mitochondrial respiratory function. Freshly isolated brain nonsynaptosomal mitochondria from C57Bl/6 (wild type, WT) and endothelial NO synthase knockout (eNOS-KO) mice were treated with exogenous PN (0.1, 1, 5 µmol/L) or a PN donor (SIN-1; 50 µmol/L) or a PN scavenger (FeTMPyP; 2.5 µmol/L). Oxygen consumption rate (OCR) was measured using Agilent Seahorse XFe24 analyzer and mitochondrial respiratory parameters were calculated. Mitochondrial membrane potential, superoxide, and PN were determined from rhodamine 123, dihydroethidium, and DAX-J2 PON green fluorescence measurements, respectively. Mitochondrial protein nitrotyrosination was determined by Western blots. Both exogenous PN and SIN-1 decreased respiratory function in WT isolated brain mitochondria. FeTMPyP enhanced state III and state IVo mitochondrial respiration in both WT and eNOS-KO mitochondria. FeTMPyP also elevated state IIIu respiration in eNOS-KO mitochondria. Unlike PN, neither SIN-1 nor FeTMPyP depolarized the mitochondria. Although mitochondrial protein nitrotyrosination was unaffected by SIN-1 or FeTMPyP, FeTMPyP reduced mitochondrial PN levels. Mitochondrial superoxide levels were increased by FeTMPyP but were unaffected by PN or SIN-1. Thus, we present the evidence of functionally significant PN generation in isolated brain mitochondria. Mitochondrial PN activity was physiologically relevant in WT mice and pathologically significant under conditions with eNOS deficiency.NEW & NOTEWORTHY Mitochondria generate superoxide and nitric oxide that could potentially react with each other to produce PN. We observed eNOS and nNOS immunoreactivity in isolated brain and heart mitochondria with pharmacological inhibition of nNOS found to modulate the mitochondrial respiratory function. This study provides evidence of generation of functionally significant PN in isolated brain mitochondria that affects respiratory function under physiological conditions. Importantly, the mitochondrial PN levels and activity were exaggerated in the eNOS-deficient mice, suggesting its pathological significance.

Effects of zinc porphyrin and zinc phthalocyanine derivatives in photodynamic anticancer therapy under different partial pressures of oxygen in vitro.

Photodynamic therapy (PDT) is gradually becoming an alternative method in the treatment of several diseases. Here, we investigated the role of oxygen in photodynamically treated cervical cancer cells (HeLa). The effect of PDT on HeLa cells was assessed by exposing cultured cells to disulphonated zinc phthalocyanine (ZnPcS2) and tetrasulphonated zinc tetraphenylporphyrin (ZnTPPS4). Fluorescence microscopy revealed their different localizations within the cells. ZnTPPS4 seems to be mostly limited to the cytosol and lysosomes, whereas ZnPcS2 is most likely predominantly attached to membrane structures, including plasmalemma and the mitochondrial membrane. Phototoxicity assays of PDT-treated cells carried out under different partial pressures of oxygen showed dose-dependent responses. Interestingly, ZnPcS2 was also photodynamically effective at a minimal level of oxygen, under a nitrogen atmosphere. On the other hand, hyperbaric oxygenation did not lead to a higher PDT efficiency of either photosensitizer. Although both photosensitizers can induce a significant drop in mitochondrial membrane potential, ZnPcS2 has a markedly higher effect on mitochondrial respiration that was completely blocked after two short light cycles. In conclusion, our observations suggest that PDT can be effective even in hypoxic conditions if a suitable sensitizer is chosen, such as ZnPcS2, which can inhibit mitochondrial respiration.

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.

Oxidative Stress Underlies the Ischemia/Reperfusion-Induced Internalization and Degradation of AMPA Receptors.

Stroke is the fifth leading cause of death annually in the United States. Ischemic stroke occurs when a blood vessel supplying the brain is occluded. The hippocampus is particularly susceptible to AMPA receptor-mediated delayed neuronal death as a result of ischemic/reperfusion injury. AMPA receptors composed of a GluA2 subunit are impermeable to calcium due to a post-transcriptional modification in the channel pore of the GluA2 subunit. GluA2 undergoes internalization and is subsequently degraded following ischemia/reperfusion. The subsequent increase in the expression of GluA2-lacking, Ca2+-permeable AMPARs results in excitotoxicity and eventually delayed neuronal death. Following ischemia/reperfusion, there is increased production of superoxide radicals. This study describes how the internalization and degradation of GluA1 and GluA2 AMPAR subunits following ischemia/reperfusion is mediated through an oxidative stress signaling cascade. U251-MG cells were transiently transfected with fluorescently tagged GluA1 and GluA2, and different Rab proteins to observe AMPAR endocytic trafficking following oxygen glucose-deprivation/reperfusion (OGD/R), an in vitro model for ischemia/reperfusion. Pretreatment with Mn(III)tetrakis(1-methyl-4-pyridyl)porphyrin (MnTMPyP), a superoxide dismutase mimetic, ameliorated the OGD/R-induced, but not agonist-induced, internalization and degradation of GluA1 and GluA2 AMPAR subunits. Specifically, MnTMPyP prevented the increased colocalization of GluA1 and GluA2 with Rab5, an early endosomal marker, and with Rab7, a late endosomal marker, but did not affect the colocalization of GluA1 with Rab11, a marker for recycling endosomes. These data indicate that oxidative stress may play a vital role in AMPAR-mediated cell death following ischemic/reperfusion injury.

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.

A peroxidase mimetic protects skeletal muscle cells from peroxide challenge and stimulates insulin signaling.

Reactive oxygen species such as hydrogen peroxide have been implicated in causing metabolic dysfunction such as insulin resistance. Heme groups, either by themselves or when incorporated into proteins, have been shown to scavenge peroxide and demonstrate protective effects in various cell types. Thus, we hypothesized that a metalloporphyrin similar in structure to heme, Fe(III)tetrakis(4-benzoic acid)porphyrin (FeTBAP), would be a peroxidase mimetic that could defend cells against oxidative stress. After demonstrating that FeTBAP has peroxidase activity with reduced nicotinamide adenine dinucleotide phosphate (NADPH) and NADH as reducing substrates, we determined that FeTBAP partially rescued C2C12 myotubes from peroxide-induced insulin resistance as measured by phosphorylation of AKT (S473) and insulin receptor substrate 1 (IRS-1, Y612). Furthermore, we found that FeTBAP stimulates insulin signaling in myotubes and mouse soleus skeletal muscle to about the same level as insulin for phosphorylation of AKT, IRS-1, and glycogen synthase kinase 3ß (S9). We found that FeTBAP lowers intracellular peroxide levels and protects against carbonyl formation in myotubes exposed to peroxide. Additionally, we found that FeTBAP stimulates glucose transport in myotubes and skeletal muscle to about the same level as insulin. We conclude that a peroxidase mimetic can blunt peroxide-induced insulin resistance and also stimulate insulin signaling and glucose transport, suggesting a possible role of peroxidase activity in regulation of insulin signaling.

π-Extended Donor-Acceptor Porphyrins and Metalloporphyrins for Antimicrobial Photodynamic Inactivation.

Free base, zinc and palladium π-extended porphyrins containing fused naphthalenediamide units were employed as photosensitizers in antimicrobial photodynamic therapy (aPDT). Their efficacy, assessed by photophysical and in vitro photobiological studies on Gram-positive bacteria, was found to depend on metal coordination, showing a dramatic enhancement of photosensitizing activity for the palladium complex.

Antioxidant modulation of sirtuin 3 during acute inflammatory pain: The ROS control.

Oxidative stress induced post-translational protein modifications are associated with the development of inflammatory hypersensitivities. At least 90% of cellular reactive oxygen species (ROS) are produced in the mitochondria, where the mitochondrial antioxidant, manganese superoxide dismutase (MnSOD), is located. MnSOD's ability to reduce ROS is enhanced by the mitochondrial NAD+-dependent deacetylase sirtuin (SIRT3). SIRT3 can reduce ROS levels by deacetylating MnSOD and enhancing its ability to neutralize ROS or by enhancing the transcription of MnSOD and other oxidative stress-responsive genes. SIRT3 can be post-translationally modified through carbonylation which results in loss of activity. The contribution of post-translational SIRT3 modifications in central sensitization is largely unexplored. Our results reveal that SIRT3 carbonylation contributes to spinal MnSOD inactivation during carrageenan-induced thermal hyperalgesia in rats. Moreover, inhibiting ROS with natural and synthetic antioxidants, prevented SIRT3 carbonylation, restored the enzymatic activity of MnSOD, and blocked the development of thermal hyperalgesia. These results suggest that therapeutic strategies aimed at inhibiting post-translational modifications of SIRT3 may provide beneficial outcomes in pain states where ROS have been documented to play an important role in the development of central sensitization.

Multifunctional Microparticles Incorporating Gold Compound Inhibit Human Lung Cancer Xenograft.

PURPOSE: Gold porphyrin (AuP) is a complex that has been shown to be potent against various tumors. A biocompatible interpenetrating network (IPN) system comprised of polyethyleneglycol diacrylate (PEGdA) and chemically-modified gelatin has been shown to be an effective implantable drug depot to deliver AuP locally. Here we designed IPN microparticles complexed with AuP to facilitate intravenous administration and to diminish systemic toxicity. METHODS: We have synthesized and optimized an IPN microparticle formulation complexed with AuP. Tumor cell cytotoxicity, antitumor activity, and survival rate in lung cancer bearing nude mice were analyzed. RESULTS: IPN microparticles maintained AuP bioactivity against lung cancer cells (NCI-H460). In vivo study showed no observable systemic toxicity in nude mice bearing NCI-H460 xenografts after intravenous injection of 6 mg/kg AuP formulated with IPN microparticles. An anti-tumor activity level comparable to free AuP was maintained. Mice treated with 6 mg/kg AuP in IPN microparticles showed 100% survival rate while the survival rate of mice treated with free AuP was much less. Furthermore, microparticle-formulated AuP significantly reduced the intratumoral microvasculature when compared with the control. CONCLUSION: AuP in IPN microparticles can reduce the systemic toxicity of AuP without compromising its antitumor activity. This work highlighted the potential application of AuP in IPN microparticles for anticancer chemotherapy.

MnTBAP inhibits bone loss in ovariectomized rats by reducing mitochondrial oxidative stress in osteoblasts.

The development of postmenopausal osteoporosis is thought to be closely related to oxidative stress. Mn(III)tetrakis (4-benzoic acid) porphyrin (MnTBAP), a novel superoxide dismutase (SOD) mimetic, could protect osteoblasts from cytotoxicity and dysfunction caused by oxidative stress. However, it is still unclear whether MnTBAP has effect on the development of postmenopausal osteoporosis. Here, we demonstrated that MnTBAP can inhibit bone mass loss and bone microarchitecture alteration, and increase the number of osteoblasts while reducing osteoclasts number, as well as improve the BMP-2 expression level in ovariectomized rat model. Additionally, MnTBAP can also prevent oxidative stress status up-regulation induced by ovariotomy and hydrogen peroxide (H2O2). Furthermore, MnTBAP reduced the effect of oxidative stress on osteoblasts differentiation and increased BMP-2 expression levels with a dose-dependent manner, via reducing the levels of mitochondrial oxidative stress in osteoblasts. Taken together, our findings provide new insights that MnTBAP inhibits bone loss in ovariectomized rats by reducing mitochondrial oxidative stress in osteoblasts, and maybe a potential drug in postmenopausal osteoporosis therapy.

S-seco-porphyrazine as a new member of the seco-porphyrazine family - Synthesis, characterization and photocytotoxicity against cancer cells.

An important subgroup within the porphyrazine (Pz) family constitutes seco-porphyrazines, in the chemical structure of which one pyrrole unit is opened in the oxidative process. So far, there are only limited data on N-seco- and C-seco-Pzs. Here, the synthesis of a novel member of the Pzs seco-family, represented by an S-seco-tribenzoporphyrazine analogue, 22,23-bis(4-(3,5-dibutoxycarbonylphenoxy)butylsulfanyl)tribenzo[b,g,l]-22,23-dioxo-22,23-seco-porphyrazinato magnesium(II), is reported, with moderate 34% yield. The new derivative was characterized using NMR spectroscopy, UV-Vis spectroscopy, and mass spectrometry. In the photochemical study performed following the indirect chemical method with 1,3-diphenylisobenzofuran, S-seco-Pz revealed a high singlet oxygen quantum yield of 0.27 in DMF. Potential photocytotoxicity of S-seco-Pz was assessed in vitro on three cancer cell lines - two oral squamous cell carcinoma cell lines derived from the tongue (CAL 27, HSC-3) and human cervical epithelial adenocarcinoma cells (HeLa). In the biological study, the macrocycle was tested in its free form and after loading into liposomes. It is worth noting that S-seco-Pz was found to be non-toxic in the dark, with cell viability levels over 80%. The photocytotoxic IC50 values for free S-seco-Pz were 0.61, 0.18, and 4.1 µM for CAL 27, HSC-3 and HeLa cells, respectively. Four different liposomal compositions were analyzed, and the cationic liposomes revealed the highest photokilling efficacy, with the IC50 values for CAL 27, HSC-3, and HeLa cells at 0.24, 0.25, and 0.31 µM, respectively. The results of the photocytotoxicity study indicate that the new S-seco-tribenzoporphyrazine can be considered as a potential photosensitizer in photodynamic therapy of cancer, along with the developed cationic liposomal nanocarrier.