Antioxidant nitroxides protect hepatic cells from oxidative stress-induced cell death

Resveratrol Upregulates Senescence Marker Protein 30 by Activating AMPK/Sirt1-Foxo1 Signals and Attenuating H2O2-Induced Damage in FAO Rat Liver Cells

Resveratrol (RSV) is a polyphenol with numerous biological functions, including anti-inflammatory, antioxidant, and anti-aging activities. The novel senescence marker protein-30 (SMP30) indicates aging, and it suppresses hepatic oxidative stress. However, the effects of RSV on SMP30 expression regulation remain unclear. We observed that RSV positively regulates SMP30 expression in rat hepatoma-derived FAO cells. However, this was abolished by Compound C and EX-527 that specifically inhibit AMP-activated protein kinase (AMPK) and Silent Information Regulator T1 (Sirt1), respectively. We predicted binding sites for AMPK, forkhead box protein O1 (Foxo1), and Sirt1 downstream molecules as possible SMP30 promoters using the JASPAR and UniProtKB databases. We identified a Foxo1 binding site in the promoter region of SMP30. Inhibiting Foxo1 with AS1842527 also decreased the RSV-induced upregulation of SMP30 expression. Moreover, RSV suppressed the substantial downregulation of SMP30 expression caused by oxidative stress and hydrogen peroxide (H2O2) and released accumulated lactate dehydrogenase. These results demonstrate that, as a novel food factor, RSV-induced upregulation of SMP30 by activating AMPK/Sirt1-Foxo1 signaling and may attenuates H2O2-induced oxidative damage. The findings of this study offer new perspectives of the anti-ageing properties of RSV.

Isothiazolone-Nitroxide Hybrids with Activity against Antibiotic-Resistant Staphylococcus aureus Biofilms

Isothiazolones are widely used as biocides in industrial processing systems and personal care products, but their use to treat infections in humans has been hampered by their inherent cytotoxicity. Herein, we report a strategy to alleviate isothiazolone toxicity and improve antibacterial and antibiofilm potency by functionalization with a nitroxide moiety. Isothiazolone-nitroxide hybrids 6 and 22 were prepared over three steps in moderate yields (58 and 36%, respectively) from (Z)-3-(benzylsulfanyl)-propenoic acid. Hybrid 22 displayed better activity (minimum inhibitory concentration (MIC) = 35 μM) than the widely used methylisothiazolinone (MIT 1, MIC = 280 μM) against methicillin-susceptible Staphylococcus aureus (MSSA). Hybrid 22 was even more active against drug-resistant strains, such as vancomycin-resistant Staphylococcus aureus (VRSA, MIC = 8.75 μM) over MIT 1 (MIC = 280 μM). The enhanced antibacterial activity of hybrid 22 over MIT 1 was retained against established MSSA and VRSA biofilms, with minimum biofilm eradication concentration (MBEC) values of 35 and 70 μM, respectively, for 22 (the MBEC value for MIT 1 against both strains was ≥280 μM). No toxicity was observed in human epithelial T24 cells treated with hybrid 22 in concentrations up to 560 μM using a lactate dehydrogenase assay.

Amphiphilic chitosan-polyaminoxyls loaded with daunorubicin: Synthesis, antioxidant activity, and drug delivery capacity

The binding of aminoxyls to polymers extends their potential use as antioxidants and EPR-reporting groups and opens up new horizons for tailoring new smart materials. In this work, we synthesized and characterized non-sulfated and N-sulfated water-soluble amphiphilic chitosans with a critical micelle concentration of 0.02-0.05 mg/mL that contain 13-18% of aminoglycosides bound with various aminoxyls. Chitosan-polyaminoxyls (CPAs) formed micelles with hydrodynamic radii R_h of ca. 100 nm. The EPR spectra of CPAs were found to depend on the rigidity of the aminoxyl-polymer bond and structural changes caused by sulfation. CPAs demonstrated antioxidant capacity/activity in three tests against reactive oxygen species (ROS) of various nature. The charge of micelles and structure of aminoxyls significantly affected their antioxidant properties. CPAs were low toxic against tumor (HepG2, HeLa, A-172) and non-cancerous (Vero) cells (IC₅₀ > 0.8 mM of aminoglycosides). Sulfated CPAs showed better water solubility and the ability of binding and retaining the anti-tumor antibiotic daunorubicin (DAU). DAU-loaded micelles of CPAs (CPAs-DAU) demonstrated a 1.5-4-fold potentiation of DAU cytotoxicity against several cell lines. CPAs-DAU micelles were found to affect the cell cycle in a manner markedly different from that of free DAU. Our results demonstrated the ability of CPAs to act as bioactive drug delivery vehicles.

Upregulation and stabilization of senescence marker protein-30 by epigallocatechin gallate against tert-butyl hydroperoxide-induced liver injury in vitro and in vivo

Senescence marker protein-30 (SMP30), a novel ageing marker, suppresses oxidative stress in the liver. However, studies on phytochemical-mediated regulation of SMP30 expression are lacking. Here, we showed that epigallocatechin gallate (EGCg), a polyphenol abundant in green tea, positively regulates SMP30 expression in the rat hepatoma-derived Fao cells. EGCg maintained SMP30 expression even in the presence of cycloheximide, a protein synthesis inhibitor. Furthermore, treatment of cells with tert-butyl hydroperoxide (tert-BHP), an oxidative promoter, decreased SMP30 expression and ERK1/2 phosphorylation, while EGCg treatment inhibited these effects. Male mice (7-week-old) were divided into 4 groups—Control (saline), tert-BHP (1.5 mmol/kg tert-BHP), EGCg + tert-BHP (30 mg/kg/day of EGCg and 1.5 mmol/kg tert-BHP), and EGCg (30 mg/kg/day). After oral EGCg administration for 6 consecutive days, EGCg + tert-BHP group mice were administered tert-BHP. The tert-BHP-administered mice showed decreased SMP30 expression in the liver and increased aspartate aminotransferase and alanine transaminase (hepatic injury marker enzymes) activities; however, EGCg treatment attenuated these changes. Thus, EGCg-induced SMP30 upregulation may alleviate tert-BHP-induced liver injury. The findings of this study offer new perspectives of the anti-ageing properties of EGCg.

Status of malondialdehyde, catalase and superoxide dismutase levels/activities in schoolchildren with iron deficiency and iron-deficiency anemia of Kashere and its environs in Gombe State, Nigeria

Background

Iron-deficiency anemia (IDA) or iron deficiency (ID) is by far the most common form of disorder affecting the cognitive development, physical growth and school performance of children in developing countries including Nigeria.

Objectives

In the present study, we aimed to examine whether IDA or ID, or both are associated with oxidative stress or otherwise by assessing the perturbations in oxidative stress markers including malondialdehyde (MDA), catalase (CAT) and superoxide dismutase (SOD).

Methods

Here, a total of eighty-one IDA, ID, and healthy control subjects of twenty-seven replicates each, were recruited and investigated. Human serum MDA, CAT and SOD levels were quantitatively analyzed using Enzyme-Linked Immunosorbant Assay.

Results

Mean serum MDA levels of IDA (5.10 ± 2.35 mmol/L) and ID (4.05 ± 1.35 mmol/L) groups were found to perturb significantly (p < 0.05), being higher than those of control (3.30 ± 0.95 mmol/L) subjects. Similarly, mean serum MDA levels of IDA (5.10 ± 2.35 mmol/L) group was found to be significantly (p < 0.05) higher when compared with ID (4.05 ± 1.35 mmol/L) subjects. Conversely, mean serum CAT and SOD activities of IDA (8.35 ± 2.21 ng/mL and 340.70 ± 153.65 ng/mL) group were found to differ significantly (p < 0.05), and those of ID (9.40 ± 1.47 ng/mL and 435.00 ± 144.75 ng/mL) subjects were found to perturb slightly (p > 0.05), being lower than those of control (10.40 ± 4.31 ng/mL and 482.12 ± 258.37 ng/mL) subjects.

Conclusions

Taken together, the results of the present study showed that lipid peroxidation was dramatically increased in both IDA and ID subjects in hydroperoxide-superoxide-dependent manner; in contrast, enzymatic antioxidant capacity was drastically decreased in both IDA and ID groups as evidenced by biochemical markers.