Peroxynitrite (ONOO[-]) is a reactive nitrogen species implicated in oxidative injury and impaired calcium handling. We examined whether ONOO[-] inactivates the cardiac sarco(endo)plasmic reticulum Ca[2+]-ATPase (SERCA2a) and whether heat shock protein 70 (Hsp70) preserves SERCA2a function during ONOO[-] exposure. Human embryonic kidney (HEK-293) cells were co-transfected with SERCA2a and either empty pMT2 vector (S2a-pMT2) or Hsp70 (S2a-Hsp70). Cells were untreated or exposed to ten nominal 250 μM additions of ONOO[-], delivered once per minute for 10 min. Hsp70 abundance was greater in S2a-Hsp70 cells, although the magnitude of this difference varied by treatment (interaction, p = 0.0015). SERCA2a abundance was unaffected by transfection condition or ONOO[-] exposure. Co-immunoprecipitation showed that Hsp70 and SERCA2a were present in the same protein complex under the conditions examined. ONOO[-] reduced maximal SERCA2a activity by approximately 20% in S2a-pMT2 cells (p = 0.03), whereas activity was preserved in S2a-Hsp70 cells. ONOO[-] also increased SERCA2a-associated reactive carbonyl content by approximately 80% in S2a-pMT2 cells (p = 0.01), with no increase in S2a-Hsp70 cells. SERCA2a 3-nitrotyrosine content and FITC-binding capacity did not differ among groups. These findings show that Hsp70 overexpression preserves SERCA2a activity during acute ONOO[-] exposure and that this protection is associated with reduced SERCA2a carbonyl accumulation.

This study utilizes a sensitive electrochemical method to investigate the polyphenolic content and antioxidant properties of three pharmaceutical products derived from Echinacea purpurea-Immunvita, Immulone, and C-Mune. An analytical evaluation was conducted with a glassy carbon electrode serving as the working electrode, a silver/silver chloride electrode as the reference, and a platinum wire as the counter electrode. Voltammetric analysis was employed to examine the characteristics of standard caffeic acid and the pharmaceutical samples within a citrate-phosphate electrolyte buffer. Results indicated a high antioxidant capacity and polyphenolic content within the products. Voltammetry proved to be an effective and sensitive approach for quantifying the total polyphenolic content and assessing the antioxidant activity of E. purpurea extracts. Furthermore, the hepatoprotective effects of these pharmaceuticals against lead acetate-induced liver injury were evaluated in Wistar rats. Fifty adult male rats were divided into five groups. Group I, the control; Group II was subjected to oral administration of 60 mg/kg body weight (B.W) of lead acetate for one week; Groups III, IV, and V received the same initial treatment as Group II, followed by a 10-day administration of 105 mg/kg BW Immunvita, 75 mg/kg BW Immulone, or 50 mg/kg BW C-Mune, respectively. Lead acetate ingestion elevated serum levels of alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), and gamma-glutamyl transferase (GGT). Co-administration of the examined pharmaceuticals significantly mitigated the elevation of liver enzymes, demonstrating their potential for hepatoprotective effects. Serum ALT levels remained above control values after treatment, likely due to persistent hepatocyte injury or the limited duration of supplementation.

Mitochondria are essential organelles responsible for cellular ATP production and contain their own mitochondrial DNA (mtDNA), which encodes key components of oxidative phosphorylation. Because mitochondria continuously generate reactive oxygen species (ROS), mtDNA is particularly susceptible to oxidative damage. Although DNA repair enzymes are present in mitochondria, the regulation of mtDNA repair and its impact on cellular responses to oxidative stress remain incompletely understood. Human 8-oxoguanine DNA glycosylase 1 (hOGG1) is a key enzyme in the base excision repair (BER) pathway, and the mitochondrial isoform hOGG1-2a contributes to the maintenance of mtDNA integrity. In this study, HeLaS3 cell lines stably overexpressing hOGG1-2a were established to examine responses to oxidative stress. hOGG1-2a overexpression was associated with reduced survival following H2O2 treatment, γ-ray exposure, heat shock, and ultraviolet C (UVC) irradiation. Apoptotic cell death increased after oxidative stress. Mitochondrial membrane potential assessed by JC-1 staining was significantly reduced in hOGG1-2a-overexpressing cells. Long-range PCR analysis revealed reduced mtDNA amplification efficiency, and oxidative stress was accompanied by a greater reduction of the mitochondrial enzyme Aconitase 2. These cells exhibited elevated basal ATP levels and altered ATP responses under oxidative stress conditions. In addition, mitochondrial superoxide-associated fluorescence detected by MitoSOX[™] was significantly increased. Combined long-range PCR and Sanger sequencing indicated reduced mtDNA amplification after H2O2 exposure without a marked increase in point mutations. Collectively, these findings suggest that hOGG1-2a overexpression sensitizes cells to oxidative stress and is associated with mitochondrial redox dysregulation, reduced mitochondrial membrane potential, altered ATP responses, and reduced mtDNA amplifiability during prolonged stress.

Iron overload‑induced osteoporosis (IOO) is a growing concern, yet the underlying mechanisms remain obscure. Ferroptosis, an iron‑dependent lipid peroxidation‑driven cell death, and NADPH oxidase 4 (NOX4), a major source of reactive oxygen species (ROS), have been implicated separately, but their interplay in bone marrow stromal cells (BMSCs) under iron overload is unknown. Here we investigated whether melatonin, an endogenous indole with antioxidant properties, protects BMSCs from iron overload‑induced ferroptosis and osteogenic dysfunction by regulating NOX4 transcription. BMSCs were exposed to ferric ammonium citrate (FAC, 200 µM) with or without melatonin (100 µM) or the ferroptosis inhibitor ferrostatin‑1 (Fer‑1). FAC suppressed cell viability, elevated Fe[2+] and ROS, triggered classical ferroptotic mitochondrial damage (shrinkage, cristae loss), and impaired osteogenic differentiation (ALP activity, mineralization, Alp, Runx2, Col1a1, Osterix). Fer‑1 attenuated ROS and mitochondrial injury but did not reduce Fe[2+] accumulation, confirming ferroptosis downstream of iron loading. Melatonin did not lower Fe[2+] levels either; however, it effectively quenched ROS, restored mitochondrial ultrastructure, and rescued osteogenic function. Mechanistically, melatonin transcriptionally suppressed NOX4, as evidenced by reduced NOX4 mRNA and diminished NOX4 promoter activity in dual‑luciferase reporter assays, without affecting Fe[2+] levels. Collectively, melatonin alleviates ferroptosis and restores osteogenesis in iron‑overloaded BMSCs, an effect that is strongly associated with the transcriptional suppression of NOX4, independent of iron chelation. Our findings extend the established NOX4-ferroptosis mechanism to BMSCs and identify, for the first time, transcriptional suppression of NOX4 as a novel mechanism that is strongly indicated to contribute to melatonin's protective effects against iron overload-induced osteogenic dysfunction.

Antioxidant activity is commonly discussed in fields like chemistry, biology, nutrition, and medicine, but it is often viewed in functional terms rather than as a process controlled by basic radical kinetics. In many cases, antioxidant efficiency is described within a simple scavenging model, where antioxidants mainly intercept reactive radicals stoichiometrically and are then irreversibly consumed. While this model highlights an important aspect of antioxidant behavior, it does not fully capture the complexity of oxidative processes. In this review, antioxidant chemistry is examined as a competitive reaction network where chemical repair and regeneration pathways play a key mechanistic role. These pathways allow for the restoration of radical intermediates before damage terminates and enable the recycling of oxidized antioxidant species, thus extending antioxidant activity beyond just radical trapping. In this context, the identity of radicals, branching ratios, oxygen-dependent competition, and radical lifetimes are crucial factors that determine whether oxidative processes lead to propagation, termination, or repair. Special focus is given to phenolic antioxidants and to reaction networks involving the hydroperoxyl/superoxide couple (HO2•/O2•[-]). Although superoxide is often described as a weak oxidant or a precursor to more reactive species, its reactivity depends heavily on conditions. Under the right kinetic conditions, superoxide can participate in reductive pathways that contribute to antioxidant regeneration and radical repair. By combining insights from radiation chemistry, electrochemistry, and computational kinetics, this review highlights chemical repair as an important mechanistic component of antioxidant activity and offers a unified framework for understanding antioxidant function in various chemical and biological settings.

Endometriosis and uterine leiomyomas are common chronic gynecologic diseases associated with immune dysregulation, inflammation, and aberrant cellular proliferation, processes that contribute to increased oxidative stress. Current management relies largely on surgical and hormonal interventions, highlighting the need for effective long-term nonhormonal therapeutic strategies. N-acetylcysteine (NAC), a glutathione precursor, exhibits antioxidant and anti-inflammatory properties that may target key mechanisms underlying both conditions. NAC functions as both a direct reactive oxygen species scavenger and regulator of intracellular redox homeostasis through replenishment of glutathione stores. These findings suggest that NAC may represent a potential adjunctive therapy warranting further investigation and may influence disease-associated biological pathways. Future clinical and translational studies are needed to define its efficacy, optimal dosing, and role in redox-based management of endometriosis and uterine leiomyomas.

Oxidative stress arising from excessive generation of free radical species in biological systems remains a major concern associated with several pathological conditions, thereby driving continuous interest in the development of effective antioxidants. Among various natural polyphenol-rich sources, Aloe vera is recognized as an important reservoir of bioactive antioxidant compounds. In the present study, five major polyphenols derived from Aloe vera were structurally modified through Sulfur and Selenium substitution at the hydroxyl and carbonyl functionalities to enhance their antioxidant potential. The changes in the thermodynamic parameters such as bond dissociation enthalpy, ionization potential, proton dissociation enthalpy, and electron transfer enthalpy were evaluated using density functional theory to elucidate the antioxidant mechanisms of the designed derivatives through the Hydrogen Atom Transfer, Single Electron Transfer followed by Proton Transfer, and Sequential Proton Loss followed by Electron Transfer pathways. Electronic properties and reactivity were further explored using frontier molecular orbital, molecular electrostatic potential, natural bond orbital, total density of states, transition state, and spin density distribution analyses. In addition, pharmacokinetic profiling was performed to evaluate the drug-likeness and biological suitability of the compounds. Molecular docking studies were conducted against the allosteric site of the antioxidant enzyme superoxide dismutase to investigate possible interactions that could enhance enzymatic activity through allosteric modulation. The computational results consistently demonstrated that Selenium-substituted derivatives exhibited the highest antioxidant activity, followed by Sulfur-substituted compounds, outperforming the parent molecules as well as standard antioxidant references including trans-Resveratrol, Gallic acid, and Fumaric acid. These findings reveal that chalcogen substitution can significantly improve the antioxidant efficiency of Aloe vera polyphenols and highlights the potential of Selenium-containing derivatives as promising candidates for the development of next generation antioxidants.

Lipid peroxidation (LPO) has long been implicated in the pathogenesis of various diseases and the role of antioxidants against LPO has been studied extensively. Recently, novel antioxidant functions of deuterated polyunsaturated fatty acids (D-PUFAs) in preventing LPO in the membranes and in humans have been reported by many research groups. The preventive and therapeutic potential of D-PUFAs against LPO and related diseases has received considerable attention, but the underlying molecular mechanisms and dynamics remain elusive. This hypothesis article summarizes state of the art preventive effects of D-PUFAs against LPO and cell damage reported in the literature and discusses the plausible mechanisms of action with an emphasis on the effects of membrane properties. Interestingly, it was found that cholesterol and oleic acid as well as D-PUFAs did not inhibit LPO in homogeneous solution, but they all suppressed LPO in the liposomal membranes, cell membranes, and partially in vivo. It is speculated that D-PUFAs suppress LPO in the membranes, at least in part, by physically obstructing the reaction between lipid peroxyl radicals and phospholipid substrates as well as by chemical and biochemical mechanisms. However, the proposed mechanism remains a hypothesis which should be validated directly in future experimental studies.

Cerebral ischemia-reperfusion injury (CIRI) involves complex pathological mechanisms, including ferroptosis. Curcumin exhibits neuroprotective properties, but its role in modulating ferroptosis during CIRI remains incompletely understood. This research explored how curcumin protects against ferroptosis in CIRI and the molecular mechanisms involved. In vivo, male MCAO rats were divided into Sham, MCAO, and curcumin low/medium/high-dose groups. Infarct volume, neurological deficit scores, and ferroptosis markers (MDA, Fe[2+], GSH, GPX4, FTH1, TfR1) were detected. In vitro, OGD/R-stimulated BV2 cells were administered with curcumin or Ferrostatin-1. GPX4 knockdown, KLF2, and KAT2A overexpression or knockdown were performed. ChIP, CCK-8, and western blotting were applied to identify H3K18ac modification, cell viability, and protein expression, respectively. In MCAO rats, curcumin administration led to a reduction in infarct size, better neurological outcomes, and a decrease in ferroptosis. In vitro, curcumin inhibited OGD/R-stimulated ferroptosis and enhanced H3K18 acetylation at the GPX4 promoter. Mechanistically, curcumin upregulated the transcription factor KLF2, which transcriptionally activated the histone acetyltransferase KAT2A. KAT2A mediated H3K18ac modification at the GPX4 promoter, leading to GPX4 upregulation and ferroptosis suppression. KLF2 knockdown abolished the protective effects of curcumin. In conclusion, Curcumin inhibited ferroptosis in CIRI by activating the KLF2/KAT2A/GPX4 signaling axis, highlighting a novel epigenetic mechanism and potential therapeutic strategy for ischemic stroke.

Antioxidants play a crucial role in the treatment of liver pathologies, given that oxidative stress is involved in the pathogenesis of many hepatic diseases. This study aimed to investigate the pharmacodynamic and pharmacokinetic properties of the antioxidant 2,6-diisobornyl-4-methylphenol (IBP) in a rat model of carbon tetrachloride (CCl4)-induced liver injury. The introduction of IBP resulted in a 1.4- to 2-fold decrease in serum hepatic enzyme levels, a 25% and 18% rise in glutathione peroxidase and superoxide dismutase concentrations, respectively, and a 14% reduction in hepatic catalase activity compared with the negative control. Treated animals exhibited a 45% reduction in malondialdehyde (a marker of oxidative stress) and an 18% decrease in interleukin-6 levels relative to controls. The compound mitigated CCl4-induced liver damage and promoted restoration of liver function. Liver pathology affected the plasma exposure of IBP after a single administration, but pharmacokinetics normalized following repeated dosing. Bioavailability was 60% after a single dose and increased to 119% after multiple administrations. IBP demonstrated significant hepatoprotective effects in CCl4-induced liver injury, mitigating lipid peroxidation, inflammation, and necrosis. The initial reduction in systemic exposure following a single dose in pathological conditions may be attributed to impaired absorption and elevated metabolic consumption due to oxidative stress.

Bicarbonate (HCO3[-]) is a key factor promoting the resveratrol (Res) degradation in culture media, yet the underlying mechanism remains unclear. This study investigated the role of carbonate radicals in the bicarbonate-promoted Res degradation in aqueous systems. The Res degradation and hypotaurine-taurine conversion, an indicator of carbonate radical formation, were analyzed by the high-performance liquid chromatography, while radical generation was monitored by the electron paramagnetic resonance (EPR) spectroscopy. Significant Res degradation occurred in the bicarbonate solutions even under the mildly acidic conditions, whereas the degradation in the NaOH was observed only at pH 8.7. The EPR analysis revealed the reactive radical formation, and the taurine production confirmed the presence of carbonate radicals. The addition of hypotaurine, superoxide dismutase, or dimethyl sulfoxide markedly suppressed the Res degradation, taurine formation, and the EPR signals. These results demonstrate that the carbonate radicals play a critical role in the Res oxidative degradation in the bicarbonate systems, and a mechanistic pathway is therefore proposed.

The phenolic phytocannabinoids frequently exhibit a prooxidant activity; however, its significance in their toxic/therapeutic action remains unclear. On the other hand, the predominant prooxidant character of mammalian cell cytotoxicity of hydroxybenzenes is demonstrated by a negative dependence of the cytotoxicity on the midpoint redox potential of phenoxyl radical/phenol couple (E(Ph-O•/Ph-OH) or E[2]7 at pH 7.0). However, the E[2]7 values of phytocannabinoids are unknown. Here using quantum mechanical calculations and cyclic voltammetry, the E[2]7 values of 10 phytocannabinoids containing resorcinol, 1-hydroxychromene, or 1-hydroxychromane moieties were estimated to be 0.72-0.82 V, i.e. close to or below that of resorcinol, 0.81 V. Using the above E[2]7 values, it was found that the cytotoxicity of phytocannabinoids in MH22a cells follows the same two-parameter regression as that of model hydroxybenzenes, i.e. it increased with decreasing E[2]7 and increasing octanol/water partition coefficient at pH 7.0 (log.D). The prooxidant nature of phytocannabinoid cytotoxicity was evidenced by the protective effects of antioxidants, and the potentiating effect of N,N[']-bis(2-chloroethyl)-N-nitrosourea (BCNU). On the other hand, the in vitro activity of phytocannabinoids against Plasmodium falciparum FcB1 strain was much greater than that of model hydroxybenzenes, and did not follow the same correlation. Unlike the lipophilicity-independent activity of hydroxybenzenes, the antiplasmodial activity of phytocannabinoids showed a trend to increase with their log D. These findings enabled to suggest that the mammalian cell cytotoxicity of phytocannabinoids may be largely determined by their induced oxidative stress, but their antiplasmodial activity may be determined by other, as yet poorly characterized, factors.

Caulerpa lentillifera is an edible green seaweed widely consumed in Southeast Asia and has been recognized for its nutritional and antioxidant properties. Previous studies demonstrated that its ethyl acetate extract (CLEA) exhibits strong free radical-scavenging and metabolic regulatory activities; however, its potential protective role against ultraviolet (UV)-induced oxidative stress has not yet been elucidated. Therefore, this study aimed to evaluate the photoprotective effects of CLEA on UV-induced cellular damage in keratinocytes (HaCaT) and fibroblasts (L929), and explore its underlying mechanisms. The results revealed that CLEA significantly improved cell viability following UV irradiation and attenuated intracellular reactive oxygen species (ROS) accumulation in both keratinocytes and fibroblasts. Mechanistically, CLEA enhanced nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and upregulated the mRNA expression of downstream antioxidant enzymes, particularly heme oxygenase-1 (HMOX1). In addition, CLEA suppressed UV-induced expression of matrix metalloproteinases, MMP1 and MMP3, while promoting procollagen synthesis, suggesting its role in preserving skin integrity. Collectively, these findings suggest that CLEA confers photoprotective effects against UV-induced oxidative stress and extracellular matrix degradation through activation of the Nrf2/HMOX1 pathway and inhibition of MMPs. This study highlights the potential of C. lentillifera extract as a natural photoprotective agent, warranting further in vivo and clinical investigations to validate its efficacy and safety.

Reactive oxygen species (ROS), produced by NADPH oxidase, promote contraction of the arteries. We hypothesized that (1) procontractile influence of NADPH oxidase derived ROS differs between α1- and thromboxane A2-receptor activation and (2) that such an influence is realized by the activation of different signaling pathways. Mesenteric arteries of rats were studied using wire-myography, Ca[2+]-fluorimetry and qPCR. Pan-NADPH oxidase inhibitor VAS2870 weakened contractile responses and [Ca[2+]]i rise to methoxamine (α1-adrenoceptor agonist) and U46619 (thromboxane A2 receptor agonist), this effect was more pronounced when U46619 was used. Suppression of Rho-kinase activity by Y27632 did not eliminate the effect of VAS2870 on both U46619- and methoxamine-induced contraction. The effect of VAS2870 persisted in the presence of LTCC (L-type voltage-gated Ca[2+] channels) blocker nimodipine during U46619-induced, but not methoxamine-induced contraction. In contrast, the effect of VAS2870 persisted in the presence of protein kinase C inhibitor GF109203X during methoxamine-induced, but not U46619-induced contraction. Among all NADPH oxidase isoforms mRNAs of Nox2 and Nox4 were the most abundant. NOX2 inhibitor GSK2795039, but not NOX1/4 inhibitor GKT137831, weakened significantly both methoxamine- and U46619-induced contraction. This effect was more pronounced in case of U46619-induced contraction. Thus, procontractile influence of ROS, produced by NADPH oxidase (mainly, by NOX2), is greater during contraction induced by thromboxane A2 than α1-adrenoceptor activation in rat mesenteric arteries. Such influence is realized by activation of LTCC when α1-adrenoceptors are stimulated and by activation of protein kinase C when thromboxane A2 receptors are stimulated.