N-acetylcysteine inhibits kinase phosphorylation during 3T3-L1 adipocyte differentiation

Anthocyanin-enriched extract from Ribes nigrum inhibits triglyceride and cholesterol accumulation in adipocytes

Aim: Obesity is a chronic pathology of epidemic proportions. Mature adipocytes from a 3T3-L1 cell line were used as in vitro obesity model to test different bioactive compounds. We aim to evaluate cassis (Ribes nigrum) extract antioxidant activity and its antiadipogenic effect on mature adipocytes. Results: We produced an extract by using enzyme that combines cellulase and pectinase; we obtained high yield of the bioactive compound anthocyanin. Extract showed high antioxidant capacity. We conducted in vitro assays by adding the extract to adipocytes culture medium. Extract reduced intracellular levels of triglyceride by 62% and cholesterol by 32%. Conclusion: Enzymatic extract's high antioxidant activity was likely attributable to its high concentration of anthocyanin. This extract inhibits lipid accumulation in adipocytes.

The Xanthine Oxidase Inhibitor Febuxostat Suppresses Adipogenesis and Activates Nrf2

Xanthine oxidoreductase (XOR) is a rate-limiting enzyme in purine catabolism that acts as a novel regulator of adipogenesis. In pathological states, xanthine oxidoreductase activity increases to produce excess reactive oxygen species (ROS). The nuclear factor erythroid 2-related factor 2 (Nrf2) is a critical inducer of antioxidants, which is bound and repressed by a kelch-like ECH-associated protein 1 (Keap1) in the cytoplasm. The Keap1-Nrf2 axis appears to be a major mechanism for robust inducible antioxidant defenses. Here, we demonstrate that febuxostat, a xanthine oxidase inhibitor, alleviates the increase in adipose tissue mass in obese mouse models with a high-fat diet or ovariectomy. Febuxostat disrupts in vitro adipocytic differentiation in adipogenic media. Adipocytes appeared at day 7 in absence or presence of febuxostat were 160.8 ± 21.2 vs. 52.5 ± 12.7 (p < 0.01) in 3T3−L1 cells, and 126.0 ± 18.7 vs. 55.3 ± 13.4 (p < 0.01) in 10T1/2 cells, respectively. Adipocyte differentiation was further enhanced by the addition of hydrogen peroxide, which was also suppressed by febuxostat. Interestingly, febuxostat, but not allopurinol (another xanthine oxidase inhibitor), rapidly induced the nuclear translocation of Nrf2 and facilitated the degradation of Keap1, similar to the electrophilic Nrf2 activator omaveloxolone. These results suggest that febuxostat alleviates adipogenesis under oxidative conditions, at least in part by suppressing ROS production and Nrf2 activation. Regulation of adipocytic differentiation by febuxostat is expected to inhibit obesity due to menopause or overeating.

Peroxiredoxin 1 alleviates oxygen-glucose deprivation/ reoxygenation injury in N2a cells via suppressing the JNK/caspase-3 pathway

Objectives

Cerebral ischemia/reperfusion (I/R) injury inevitably aggravates the initial cerebral tissue damage following a stroke. Peroxiredoxin 1 (Prdx1) is a representative protein of the endogenous antioxidant enzyme family that regulates several reactive oxygen species (ROS)-dependent signaling pathways, whereas the JNK/caspase-3 proapoptotic pathway has a prominent role during cerebral I/R injury. This study aimed to examine the potential mechanism of Prdx1 in Neuro 2A (N2a) cells following oxygen-glucose deprivation and reoxygenation (OGD/R) injury.

Materials and Methods

N2a cells were exposed to OGD/R to simulate cerebral I/R injury. Prdx1 siRNA transfection and the JNK inhibitor (SP600125) were used to interfere with their relative expressions. CCK-8 assay, flow cytometry, and lactate dehydrogenase (LDH) assay were employed to determine the viability and apoptosis of N2a cells. The intracellular ROS content was assessed using ROS Assay Kit. Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot analyses were conducted to detect the expression levels of Prdx1, JNK, phosphorylated JNK (p-JNK), and cleaved caspase-3.

Results

Firstly, Prdx1, p-JNK, and cleaved caspase-3 expression were significantly induced in OGD/R-exposed N2a cells. Secondly, the knockdown of Prdx1 inhibited cell viability and increased apoptosis rate, expression of p-JNK, and cleaved caspase-3 expression. Thirdly, SP600125 inhibited the JNK/caspase-3 signaling pathway and mitigated cell injury following OGD/R. Finally, SP600125 partially reversed Prdx1 down-regulation-mediated cleaved caspase-3 activation and OGD/R damage in N2a cells.

Conclusion

Prdx1 alleviates the injury to N2a cells induced by OGD/R via suppressing JNK/caspase-3 pathway, showing promise as a potential therapeutic for cerebral I/R injury.

Elecampane (Inula helenium) Root Extract and Its Major Sesquiterpene Lactone, Alantolactone, Inhibit Adipogenesis of 3T3-L1 Preadipocytes

Recent studies have shown that Nur77 and AMPKα play an important role in regulating adipogenesis and isoalantolactone (ISO) dual-targeting AMPKα and Nur77 inhibits adipogenesis. In this study, we hypothesized that Inula helenium (elecampane) root extract (IHE), which contains two sesquiterpene lactones, alantolactone (ALA) and ISO, as major compounds, might inhibit adipogenesis. Here, we found that ALA and IHE simultaneously target AMPKα and Nur77 and inhibited adipogenic differentiation of 3T3-L1 cells, accompanied by the decreased expression of adipocyte markers. Further mechanistic studies demonstrated that IHE shares similar mechanisms of action with ISO that reduce mitotic clonal expansion during the early phase of adipogenic differentiation and decrease expression of cell cycle regulators. These results suggest that IHE inhibits adipogenesis, in part, through co-regulation of AMPKα and Nur77, and has potential as a therapeutic option for obesity and related metabolic dysfunction.

N-acetylcysteine delivery with silica nanoparticles into 3T3-L1 adipocytes

Background: The addition of 5 mM N-acetylcysteine (NAC) to 3T3-L1 adipocytes culture inhibits the accumulation of triglycerides (Tg) by 50%, but after 48 h uptake was only 16% of total NAC available. Based on these results, the aim of this study is to increase the NAC cellular uptake by encapsulating it in silica nanoparticles (NPs). Materials & methods: Silica NPs, 20 ± 4.5 nm in size, were developed, with an inner cavity loaded with 5 mM NAC. At 48 h after treatment, there was a dose-dependent cytotoxic effect. We attempted to reduce the cytotoxicity of silica NPs by coating them with bovine serum albumin. Results: While we obtained nontoxic bovine serum albumin coated NPs, their effect on Tg cellular accumulation was also reduced.