Prevention of ferroptosis in acute scenarios: an in vitro study with classic and novel anti-ferroptotic compounds.

Ferroptosis, an iron-dependent form of cell death, has critical roles in diverse pathologies. Data on the temporal events mediating the prevention of ferroptosis are lacking. Focused on temporal aspects of cytotoxicity/protection, we investigated the effects of classic (Fer-1) and novel [2,6-di-tert-butyl-4-(2-thienylthio)phenol (C1) and 2,6-di-tert-butyl-4-(2-thienylselano)phenol (C2)] anti-ferroptotic agents against RSL3-, BSO- or glutamate-induced ferroptosis in cultured HT22 neuronal cell line, comparing their effects with those of the antioxidants trolox, ebselen and probucol. Glutamate (5 mM), BSO (25 µM) and RSL3 (50 nM) decreased approximately 40% of cell viability at 24 h. At these concentrations, none of these agents changed cell viability at 6 h after treatments; RSL3 increased lipoperoxidation from 6 h, although BSO and glutamate only did so at 12 h after treatments. At similar conditions, BSO and glutamate (but not RSL3) decreased GSH levels at 6 h after treatments. Fer-1, C1 and C2 exhibited similar protective effects against glutamate-, BSO- and RSL3-cytotoxicity, but this protection was limited when the protective agents were delivered to cells at time-points characterized by increased lipoperoxidation (but not glutathione depletion). Compared to Fer-1, C1 and C2, the anti-ferroptotic effects of trolox, ebselen and probucol were minor. Cytoprotective effects were not associated with direct antioxidant efficacies. These results indicate that the temporal window is central in affecting the efficacies of anti-ferroptotic drugs in acute scenarios; ferroptosis prevention is improbable when significant rates of lipoperoxidation were already achieved. C1 and C2 displayed remarkable cytoprotective effects, representing a promising new class of compounds to treat ferroptosis-related pathologies.

Chagas Disease and Coumarins: A Review of Natural and Synthetic Coumarins As Anti-Trypanosoma Cruzi Agents.

The complexity of Chagas disease is still a challenge in endemic regions and an emergent public health problem in non-endemic countries. The causative agent of this neglected tropical disease, Trypanosoma cruzi, is mainly transmitted by triatomine vectors and possesses multiple epidemiologically important strains. Current chemotherapeutics are outdated and their limited efficacy is one of the major reasons for treatment discontinuation. In this context, the development of novel, safe and economically accessible antichagasic drugs is required. Various classes of heterocycles and natural compounds have been described as potential antichagasic scaffolds, and coumarins are no exception. These versatile compounds have a wide spectrum of biological activities, and numerous natural and synthetic coumarins have been reported with antichagasic potential. This review aims to discuss the available literature between 2001 and 2020 regarding natural and synthetic coumarins with anti- Trypanosoma cruzi activity. Moreover, some of the studies herein comprised are dedicated to the potential of coumarins to inhibit promising targets in Trypanosoma cruzi.

Natural and synthetic coumarins as antileishmanial agents: A review.

The neglected tropical disease leishmaniasis is still a major public health problem that affects millions of people worldwide. Related to poor-living conditions, this vector-borne disease presents multiple clinical manifestations - from asymptomatic to systemic conditions. The protozoans of the genus Leishmania are the etiologic agents transmitted through the bite of sandflies, the main vectors. Current pharmacological interventions are outdated and present several drawbacks, thus the search for new antileishmanial compounds is imperative. Medicinal chemists have been continuously investigating for new alternatives to combat leishmaniasis, and coumarins play a pivotal role in this search. Various biological properties have been described owing to coumarin's structural versatility combined with its unique features, including antileishmanial activity. The aim of this review is to highlight the most relevant studies between 1997 and 2020 and provide a guide for the development of new antileishmanial coumarins. Naturally occurring and synthetically designed coumarins are comprised in this review, along with a structure-activity relationship to provide an insight for further development of coumarins with antileishmanial activity.

New Probucol Analogues Inhibit Ferroptosis, Improve Mitochondrial Parameters, and Induce Glutathione Peroxidase in HT22 Cells.

Probucol, a hypocholesterolemic compound, is neuroprotective in several models of neurodegenerative diseases but has serious adverse effects in vivo. We now describe the design and synthesis of two new probucol analogues that protect against glutamate-induced oxidative cell death, also known as ferroptosis, in cultured mouse hippocampal (HT22) cells and in primary cortical neurons, while probucol did not show any protective effect. Treatment with both compounds did not affect glutathione depletion but still significantly decreased glutamate-induced production of oxidants, mitochondrial superoxide generation, and mitochondrial hyperpolarization in HT22 cells. Both compounds increase glutathione peroxidase (GPx) 1 levels and GPx activity, also exhibiting protection against RSL3, a GPx4 inactivator. These two compounds are therefore potent activators of GPx activity making further studies of their neuroprotective activity in vivo worthwhile.

Design, Synthesis, and In Vitro Evaluation of a Novel Probucol Derivative: Protective Activity in Neuronal Cells Through GPx Upregulation.

Recent studies have shown that probucol (PB), a hipocholesterolemic agent with antioxidant and anti-inflammatory properties, presents neuroprotective properties. On the other hand, adverse effects have limited PB's clinical application. Thus, the search for PB derivatives with no or less adverse effects has been a topic of research. In this study, we present a novel organoselenium PB derivative (RC513) and investigate its potential protective activity in an in vitro experimental model of oxidative toxicity induced by tert-butyl hydroperoxide (tBuOOH) in HT22 neuronal cells, as well as exploit potential protective mechanisms. tBuOOH exposure caused a significant decrease in the cell viability, which was preceded by (i) increased reactive species generation and (ii) decreased mitochondrial maximum oxygen consumption rate. RC513 pretreatment (48 h) significantly prevented the tBuOOH-induced decrease of cell viability, RS generation, and mitochondrial dysfunction. Of note, RC513 significantly increased glutathione peroxidase (GPx) activity and mRNA expression of GPx1, a key enzyme involved in peroxide detoxification. The use of mercaptosuccinic acid, an inhibitor of GPx, significantly decreased the protective activity of RC513 against tBuOOH-induced cytotoxicity in HT22 cells, highlighting the importance of GPx upregulation in the observed protection. In summary, the results showed a significant protective activity of a novel PB derivative against tBuOOH-induced oxidative stress and mitochondrial dysfunction, which was related to the upregulation of GPx. Our results point to RC513 as a promising neuroprotective molecule, even though studies concerning potential beneficial effects and safety aspects of RC513 under in vivo conditions are well warranted.

Synthesis and biological evaluation of 2-picolylamide-based diselenides with non-bonded interactions.

In this paper, we report the synthesis and biological evaluation of picolylamide-based diselenides with the aim of developing a new series of diselenides with O···Se non-bonded interactions. The synthesis of diselenides was performed by a simple and efficient synthetic route. All the products were obtained in good yields and their structures were determined by 1H-NMR, 13C-NMR and HRMS. All these new compounds showed promising activities when tested in different antioxidant assays. These amides exhibited strong thiol peroxidase-like (TPx) activity. In fact one of the compounds showed 4.66 times higher potential than the classical standard i.e., diphenyl diselenide. The same compound significantly inhibited iron (Fe)-induced thiobarbituric acid reactive species (TBARS) production in rat's brain homogenate. In addition, the X-ray structure of the most active compound showed non-bonded interaction between the selenium and the oxygen atom that are in close proximity and may be responsible for the increased antioxidant activity. The present study provides evidence about the possible biochemical influence of nonbonding interactions on organochalcogens potency.

Evaluation of the pharmacological properties of salicylic acid-derivative organoselenium: 2-hydroxy-5-selenocyanatobenzoic acid as an anti-inflammatory and antinociceptive compound.

The present study evaluated the antinociceptive and anti-inflammatory effects of per oral (p.o.) administration of salicylic acid-derivative organoselenium compounds in chemical models of nociception in mice. The compounds (50 mg/kg; p.o.) were administered 30 and 60 min before the nociceptive behavior and compared to the positive-control, acetylsalicylic acid (ASA; 200 mg/kg; p.o.). In addition, a dose-response curve (25-100 mg/kg) for compounds was carried out in the formalin test. When assessed in the chemical models, acetic acid-induced writhing behavior, formalin and glutamate tests, the compounds showed the following antinociceptive profile 1B>2B>1A>2A, suggesting a chemical structure-dependent relationship. Then, the anti-inflammatory properties and toxicological potential of compound 1B were investigated. Compound 1B, similar to the positive-control, ASA, diminished the edema formation and decreased the myeloperoxidase activity induced by croton oil (2.5%) in the ear tissue. The results also indicate that a single oral administration of 1B caused neither signs of acute toxicity nor those of gastrointestinal injury. The administration of 1B did not alter the water and food intakes, plasma alanine and aspartate aminotransferase activities or urea levels and cerebral or hepatic δ-aminolevulinate dehydratase activity. Salicylic acid-derivative organoseleniums, mainly compound 1B, have been found to be novel compounds with antinociceptive/anti-inflammatory properties; nevertheless, more studies are required to examine their therapeutic potential for pain treatment.

Activity of LaSOM 65, a monastrol-derived compound, against glioblastoma multiforme cell lines.

BACKGROUND/AIM: Despite recent progress in glioblastoma treatment, prognosis is still poor. Monastrol is a kinesin spindle protein (KSP) inhibitor and anticancer effects for this molecule have been reported. Here we describe the effect of LaSOM 65, a monastrol derivated compound, against glioma cell lines. MATERIALS AND METHODS: Cell counting, viability assay, lactate dehydrogenase (LDH) activity, cell-cycle analysis, immunofluorescence and organotypic hippocampal slice cultures were performed. RESULTS: LaSOM 65 reduced cell number and cell viability of gliomas cells, but did not cause arrest in the cell cycle at the G2/M phase. Measurement of LDH activity showed that LaSOM 65 induces necrosis after 48 h of treatment. CONCLUSION: LaSOM 65 appears to a be promising new molecule to treat glioblastoma since it promotes a decrease of cell growth and cell viability of glioma cells in vitro and does not induces the neurotoxic characteristics of the anti-mitotic drugs currently used.