Apocynin prevents GM-CSF-induced-ERK1/2 activation and -neutrophil survival independently of its inhibitory effect on the phagocyte NADPH oxidase NOX2

Preventive Anti-inflammatory Effects of Apocynin on Acetic Acid-Induced Colitis in Rats

Ulcerative colitis is an inflammatory bowel disease with a complex aetiology characterised by abnormal immune responses and oxidative stress-induced tissue injury. Inflammatory cells play an important role in the progression of this pathology through the overproduction of reactive oxygen species (ROS) from various sources including the NADPH oxidases (NOXs). The aim of this study was to investigate the preventive effect of apocynin, a natural antioxidant molecule and a selective inhibitor of NOXs, on acetic acid (AA)-induced ulcerative colitis in rats. Our results first confirmed that apocynin has a high free radical scavenging capacity as well as a potent iron chelating ability. Oral pretreatment of rats with apocynin (200 mg/kg and 400 mg/kg) for 7 days prior to AA-induced colitis suppressed the increase in pro-oxidant markers in colonic homogenates and preserved colonic cytoarchitecture from acetic acid-induced damage. Oral administration of apocynin (200 mg/kg and 400 mg/kg) also reduced several systemic inflammatory markers such as alkaline phosphatase, iron, pro-inflammatory cytokines, C-reactive protein and myeloperoxidase. This study shows that apocynin protects rats from acetic acid-induced colonic inflammation and suggests that apocynin may have a promising beneficial effect in the prevention of ulcerative colitis.

NOX2 inhibition enables retention of the circadian clock in BV2 microglia and primary macrophages

Introduction

Sustained neuroinflammation is a major contributor to the progression of neurodegenerative diseases such as Alzheimer's (AD) and Parkinson's (PD) diseases. Neuroinflammation, like other cellular processes, is affected by the circadian clock. Microglia, the resident immune cells in the brain, act as major contributors to neuroinflammation and are under the influence of the circadian clock. Microglial responses such as activation, recruitment, and cytokine expression are rhythmic in their response to various stimuli. While the link between circadian rhythms and neuroinflammation is clear, significant gaps remain in our understanding of this complex relationship. To gain a greater understanding of this relationship, the interaction between the microglial circadian clock and the enzyme NADPH Oxidase Isoform 2 (NOX2) was studied; NOX2 is essential for the production of reactive oxygen species (ROS) in oxidative stress, an integral characteristic of neuroinflammation.

Methods

BV2 microglia were examined over circadian time, demonstrating oscillations of the clock genes Per2 and Bmal1 and the NOX2 subunits gp91phox and p47phox.

Results

The BV2 microglial clock exerted significant control over NOX2 expression and inhibition of NOX2 enabled the microglia to retain a functional circadian clock while reducing levels of ROS and inflammatory cytokines. These trends were mirrored in mouse bone marrow-derived primary macrophages.

Conclusions

NOX2 plays a crucial role in the interaction between the circadian clock and the activation of microglia/macrophages into their pro-inflammatory state, which has important implications in the control of neuroinflammation.

Recent Progress in Cyclic Aryliodonium Chemistry: Syntheses and Applications

Hypervalent aryliodoumiums are intensively investigated as arylating agents. They are excellent surrogates to aryl halides, and moreover they exhibit better reactivity, which allows the corresponding arylation reactions to be performed under mild conditions. In the past decades, acyclic aryliodoniums are widely explored as arylation agents. However, the unmet need for acyclic aryliodoniums is the improvement of their notoriously low reaction economy because the coproduced aryl iodides during the arylation are often wasted. Cyclic aryliodoniums have their intrinsic advantage in terms of reaction economy, and they have started to receive considerable attention due to their valuable synthetic applications to initiate cascade reactions, which can enable the construction of complex structures, including polycycles with potential pharmaceutical and functional properties. Here, we are summarizing the recent advances made in the research field of cyclic aryliodoniums, including the nascent design of aryliodonium species and their synthetic applications. First, the general preparation of typical diphenyl iodoniums is described, followed by the construction of heterocyclic iodoniums and monoaryl iodoniums. Then, the initiated arylations coupled with subsequent domino reactions are summarized to construct polycycles. Meanwhile, the advances in cyclic aryliodoniums for building biaryls including axial atropisomers are discussed in a systematic manner. Finally, a very recent advance of cyclic aryliodoniums employed as halogen-bonding organocatalysts is described.

Hepatoprotective effect of acetovanillone against methotrexate hepatotoxicity: Role of Keap-1/Nrf2/ARE, IL6/STAT-3, and NF-κB/AP-1 signaling pathways

This study targeted to examine the protective effects of acetovanillone (AV) against methotrexate (MTX)-induced hepatotoxicity. Thirty-two rats were allocated into four groups of eight animals; Group 1: Normal; Group 2: administered AV (100 ml/kg; P.O.) for 10 days; Group 3: challenged with MTX (20 mg/kg, i.p; single dose); Group 4: administered AV 5 days before and 5 days after MTX. For the first time, this study affords evidence for AV's hepatoprotective effects on MTX-induced hepatotoxicity. The underlined mechanisms behind its hepatic protection include counteracting MTX-induced oxidative injury via down-regulation of NADPH oxidase and up-regulation of Nrf2/ARE, SIRT1, PPARγ, and cytoglobin signals. Additionally, AV attenuated hepatic inflammation through down-regulation of IL-6/STAT-3 and NF-κB/AP-1 signaling. Network pharmacology analysis exhibited a high enrichment score between the interacting proteins and strongly suggested the intricate and essential role of the target proteins regulating MTX-induced oxidative damage and inflammatory perturbation. Besides, AV increased the in vitro cytotoxic activity of MTX toward PC-3, HeLa, and K562 cancer cell lines. On the whole, our investigation suggested that AV might be regarded as a promising adjuvant for the amelioration of MTX hepatotoxicity and/or increased its in vitro antitumor efficacy, and it could be used in patients receiving MTX.

Apocynin attenuates patulin-induced cytotoxicity through reduction of oxidation stress and apoptosis in HEK293cells

Patulin (PAT) is a natural mycotoxin that commonly contaminates fruits and their derivative products and has been proven to induce cytotoxicity and oxidative damage in renal cells. In the present study, we aimed to evaluate the effect of apocynin, a potent phenolic antioxidant isolated from plants, on PAT-induced cell injury in human embryonic kidney (HEK293) cells. Compared with 7.5 μM PAT treatment alone, 10 μM apocynin co-treatment elevated cell viability, alleviated lactate dehydrogenase release and reduced caspase activities. Furthermore, apocynin inhibited reactive oxygen species overproduction, re-established mitochondria membrane potential and elevated intracellular ATP content. In addition, the results showed that apocynin aggrandized reduced glutathione (GSH) content, reduced oxidized glutathione (GSSG) content, raised the GSH/GSSG ratio and elevated superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase activities. Collectively, results of the study clearly show that apocynin supplement may serve as an alternative intervention to protect HEK293 cells against cytotoxicity induced by PAT through reduction of oxidation stress and apoptosis.