GPx x TrxR x catalase

While iron is essential in trace amounts, elevated level represents a serious health problem. Elevated iron level arises as a secondary consequence to hemochromatosis and anemias that necessitate frequent blood transfusions, leading to organ toxicity, particularly liver toxicity.

The current study investigated the potential ameliorating impact of theaflavin against the iron-elicited liver toxicity. A model of iron intoxication was established in male Wistar rats, and theaflavin was given over a 10-day period. Blood and liver specimens were collected and subjected to histopathological, ELISA, biochemical, and Western blotting investigations.

Theaflavin suppressed the iron-evoked liver injury as indicated by a significant decrease in activity of the hepatocellular enzymes in sera and improved hepatic histopathological architecture. Theaflavin activated the antioxidant transcription factor FOXO3a with upregulation of its responsive antioxidant gene products including thioredoxin reductase, superoxide dismutase, and catalase, along with reduced DNA oxidative modification. Equally important, theaflavin suppressed TLR2 inflammatory cascade as evidenced by a significant downregulation in protein expression of TLR2 and its adaptor protein MyD88, and inhibition of phosphorylation and nuclear translocation of its downstream inflammatory transcription factor NF-κB. In the same context, theaflavin markedly reduced levels of NF-κB-responsive cytokines TNF-α and IL-6. Interestingly, theaflavin repressed the iron-elicited hepatocellular ferroptosis as indicated by modulation of its biomarkers GPx4 and COX-2 protein expression, and levels of lipid hydroperoxides and hepatocellular iron load.

These findings emphasize the ameliorating impact of theaflavin against the iron-elicited liver toxicity and shed light on FOXO3a, TLR2/MyD88/NF-κB cascade, and ferroptosis as possible molecular targets.

In the relentless pursuit of next-generation antioxidants, we have unveiled two unprecedented flavonoids-alsospinones A (1) and B (2) from the ancient fern Alsophila spinulosa, among which carbon skeleton of compound 2 was reported for the first time. Both compounds demonstrate potent, dose-dependent scavenging of DPPH• radicals (IC₅₀ = 38.13 ± 3.79 and 22.81 ± 1.54 μmol/L). Both new compounds have shown potent antioxidant activity in dose dependent manner against biomarkers including CAT, GSH and MDA. Furthermore, molecular docking and 100-ns dynamics simulations reveal that these scaffolds engage CAT, glutathione peroxidase (GPX), and thioredoxin reductase (TrxR) with exceptional affinities (-13.9 to -18.2 kcal/mol), stabilized by key hydrogen bonds and π-anion contacts to active-site residues (Asp202, Arg203, Asn92, Glu104, Cys-Sec). ADMET profiling confirms their drug-like properties-optimal permeability, minimal cytochrome P450 inhibition, and negligible toxicity risk-especially for 2, which combines high solubility with superior metabolic clearance. Furthermore, this is the first study to describe detailed mechanism and structural insights of both compounds simultaneously: (i) modulate three major antioxidant enzymes (CAT, GPX, TrxR); (ii) reveal a ligand-mediated allosteric relay stabilizing both Cys clusters in TrxR; and (iii) link specific methoxy vs. hydroxyl substitutions to divergent Nrf2 activation and radical-scavenging efficiencies, providing new structure-guided cues for antioxidant drug design.

Antimony (Sb) ore exploitation and the use of Sb-containing drugs pose known health risks. This study investigated the toxicity of environmentally relevant concentrations of Sb (0.12-12 mg L^-1) on human umbilical vein endothelial cells (HUVECs). The 50 % lethal concentration (LC₅₀) of Sb to HUVECs was 11.4 mg L^-1. Exposing to high level of Sb induced cell cycle arrest by altering the expression of cell cycle regulators, inhibiting the transitions of G₀/G₁ to S and S to G₂/M. At 1.2 mg L^-1 Sb, CKD6 and p21 expressions in HUVECs changed to 0.75 and 1.32 folds that of no-Sb control, respectively (p < 0.01). At 12 mg L^-1 Sb, CDK2, CKD6, and p27 expressions decreased by 1.54, 4.41, and 1.54 folds (p < 0.001), while p21 expression increased by 3.03 folds (p < 0.001) as compared to control. Sb also led to cell apoptosis, evidenced by Annexin V-FITC/PI staining and changes in the expressions of Bax (1.21-1.30 folds, p < 0.01) and Bcl-2 (0.65-0.83 folds). Oxidative damage was a pivotal factor driving cell apoptosis, probably through down-regulating antioxidant genes (CAT, GPX1, and GSTP1) and up-regulating stress response genes (HO-1, SOD1, and TrxR1). The elevated H₂O₂ generated in mitochondria likely contributed to cell apoptosis due to the imbalance in H₂O₂ metabolism. These findings suggest that environmentally relevant concentrations of Sb can exert cytotoxicity to HUVECs, which should be of potential concern for human cardiovascular disease.