The efficacy and safety of a fixed-dose combination of apocynin and paeonol, APPA, in symptomatic knee OA: A double-blind, randomized, placebo-controlled, clinical trial.

OBJECTIVE: Apocynin (AP) and paeonol (PA) are low molecular weight phenolic compounds with a broad array of anti-inflammatory and immunoregulatory effects. This study assessed of a fixed-dose combination of APPA in people with symptomatic knee osteoarthritis (OA). METHODS: A multi-center, randomized, placebo-controlled, double-blind phase 2a trial enrolled participants with radiographic knee OA (Kellgren-Lawrence, KL, grades 2-3) and pain ≥40/100 on WOMAC pain subscale, and evaluated the efficacy and safety of oral APPA over a 28-day period. APPA 800 mg or matching placebo was administered twice daily in a 1:1 ratio. Post-hoc analyses explored the response to APPA in sub-groups with more severe pain and structural severity. RESULTS: The two groups were comparable at baseline; 152 subjects were enrolled and 148 completed the trial. There was no statistically significant difference between groups with respect to the primary outcome, WOMAC pain (mean difference between groups was -0.89, 95% CI: -5.62, 3.84, p = 0.71), nor WOMAC function or WOMAC total. However, predefined subgroup analyses of subjects with symptoms compatible with nociplastic/neuropathic pain features showed a statistically significant effect of APPA compared to placebo. Adverse events (mainly gastrointestinal) were mild to moderate. CONCLUSION: Treatment with APPA 800 mg twice daily for 28 days in subjects with symptomatic knee OA was not associated with significant symptom improvement compared to placebo. The treatment was well-tolerated and safe. While the study was not powered for such analysis, pre-planned subgroup analyses showed a significant effect of APPA in subjects with nociplastic pain/severe OA, indicating that further research in the effects of APPA in appropriate patients is warranted.

Application of a Carbon Fiber Microelectrode as a Sensor for Apocynin Electroanalysis.

In this study, a carbon fiber microelectrode (CF) was applied for the investigation of the electrochemical behavior of the natural antioxidant, apocynin (APO). Given the limited solubility of APO in water, a mixture of anhydrous acetic acid (AcH) with 20%, v/v acetonitrile (AN) and 0.1 mol L-1 sodium acetate (AcNa) was used. The electrochemical properties of APO were examined through linear sweep voltammetry (LSV), differential pulse voltammetry (DPV), and cyclic voltammetry (CV). The anodic oxidation of APO, which is the basis of the method used, proved to be diffusion-controlled and proceeded with a two-electron and one proton exchange. Both radicals and radical cations, arising from the first and second step of electrode reactions, respectively, underwent subsequent chemical transformations to yield more stable final products (EqCiEiCi mechanism). Using optimized DPV conditions, the anodic peak current of APO at a potential of 0.925 V vs. Ag/AgCl showed a good linear response within the concentration range of 2.7 × 10-6-2.6 × 10-4 mol L-1. The detection and quantification limits were determined as 8.9 × 10-7 and 2.7 × 10-6 mol L-1, respectively. The developed DPV method enabled the successful determination of APO in herbal extracts and in dietary supplements. It should be noted that this is the first method to be used for voltammetric determination of APO.

Apocynin exerts neuroprotective effects in fumonisin b1-induced neurotoxicity via attenuation of oxidative stress and apoptosis in an animal model.

The Fusarium verticillioides produces a mycotoxin, that is, fumonisin b1 (Fb1), which commonly infects corn and agricultural commodities. The Fb1 showed hepatotoxicity, neurotoxicity, and carcinogenicity in animals. Hence, the present investigation aimed to evaluate the effect of apocynin (AP) on Fb1-induced neurotoxic effects and its mechanism in the mice model and cell line. The male Balb/c mice, with the 6.75 mg/kg bwt of Fb1 were injected subcutaneously for 5 days to induce neurotoxicity. A significant elevation of serotonin (5-HT) was observed in mice treated with Fb1 in the whole brain showing biogenic amines may reflect Fb1 neurotoxicity, but the negatively regulated mechanisms were attenuated by the pretreatment of AP. In addition, AP pretreatment normalized apoptotic changes in histology and immunohistochemistry studies. In Western blotting studies, apoptotic genes were upregulated and oxidative stress genes were downregulated due to Fb1 treatment; while treating with AP, these gene expressions were rectified. Further cell cytotoxicity was investigated by MTT and lactate dehydrogenase (LDH) assays in SH-SY5Y cell line. MTT and LDH assays indicated the IC50 value to be 150 µM of Fb1, which was protected by 100 µg of AP. The electron microscopy evaluated the Fb1-induced apoptotic conditions and its cell morphology recovery by AP. These results suggest that nicotinamide adenine dinucleotide phosphate hydrogen oxidase-mediated reactive oxygen species is the primary upstream signal leading to increased Fb1-mediated neurotoxicity in mice. The use of the antioxidant AP reversed the toxin-induced oxidative stress and apoptosis by its antioxidant potency.

Targeting benign prostate hyperplasia treatments: AR/TGF-ß/NOX4 inhibition by apocynin suppresses inflammation and proliferation.

INTRODUCTION: Apocynin (Apo), an NADPH oxidase (NOX) inhibitor, has been widely used to treat various inflammatory diseases. However, the therapeutic effects of Apo on benign prostatic hyperplasia (BPH), a multifactorial disease associated with chronic inflammation and hormone imbalance, remain unknown. OBJECTIVES: The link between androgen signaling, reactive oxygen species (ROS), and prostate cell proliferation may contribute to the pathogenesis of BPH; therefore, the aim of this study was to identify the specific signaling pathway involved and to demonstrate whether the anti-oxidant Apo plays a role in the prevention and treatment of BPH. METHODS: Ingenuity pathway analysis and si-RNA transfection were conducted to demonstrate the androgen receptor (AR) and NOX4 linkage in BPH. Pathological markers of BPH were measured by H&E staining, immunoblotting, ELISA, qRT-PCR, and immunofluorescence to examine the effect of Apo. Rats stimulated with testosterone and BPH-1 cells were used as BPH models. RESULTS: AR and NOX4 network-mediated oxidative stress was upregulated in the BPH model. Next, we examined the effects of Apo on oxidative stress and chronic prostatic inflammation in BPH mouse models. In a testosterone-induced BPH rat model, Apo alleviated pathological prostate enlargement and suppressed androgen/AR signaling. Apo suppressed the upregulation of proinflammatory markers and promoted the expression of anti-oxidant factors. Furthermore, Apo regulated the TGF-ß/Glut9/activin pathway and macrophage programming. In BPH-1 cells, Apo suppressed AR-mediated proliferation and upregulation of TGFB and NOX4 expression by alleviating oxidative stress. Apo activated anti-oxidant and anti-inflammatory systems and regulated macrophage polarization in BPH-1 cells. AR knockdown partially abolished the beneficial effects of Apo in prostate cells, indicating AR-dependent effects of Apo. CONCLUSION: In contrast with existing BPH therapies, Apo may provide a new application for prostatic disease treatment, especially for BPH, by targeting the AR/TGF-ß/NOX4 signaling pathway.

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.

Histone deacetylase 9 exacerbates podocyte injury in hyperhomocysteinemia through epigenetic repression of Klotho.

Although hyperhomocysteinemia (hHcys) has been recognized as an important independent risk factor in the progression of end-stage renal disease and the development of cardiovascular complications related to end-stage renal disease, the mechanisms triggering pathogenic actions of hHcys are not fully understood. The present study was mainly designed to investigate the role of HDACs in renal injury induced by hHcys. Firstly, we identified the expression patterns of HDACs and found that, among zinc-dependent HDACs, HDAC9 was preferentially upregulated in the kidney from mice with hHcys. Deficiency or pharmacological inhibition of HDAC9 ameliorated renal injury in mice with hHcys. Moreover, podocyte-specific deletion of HDAC9 significantly attenuated podocyte injury and proteinuria. In vitro, gene silencing of HDAC9 attenuated podocyte injury by inhibiting apoptosis, reducing oxidative stress and maintaining the expressions of podocyte slit diaphragm proteins. Mechanically, we proved for the first time that HDAC9 reduced the acetylation level of H3K9 in the promoter of Klotho, then inhibited gene transcription of Klotho, finally aggravating podocyte injury in hHcys. In conclusion, our results indicated that targeting of HDAC9 might be an attractive therapeutic strategy for the treatment of renal injury induced by hHcys.

[Intervention effect of apocynin on silicosis induced by silica in rats].

Objective: To investigate the intervention effect and its mechanism of apocynin, an inhibitor of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) on silicosis induced by silica (SiO(2)) in rats. Methods: In October 2021, 24 SPF SD male rats were divided into control group, silicosis model group and apocynin intervention group according to random number table method, with 8 rats in each group. SiO(2) was exposed by one-time intratracheal instillation. The rats in the apocynin intervention group were intraperitoneally injected with apocynin 50 mg/kg, 3 times a week, on the second day after treatment. The rats were sacrificed 28 days later, and lung coefficients were calculated after lung tissues were weighed. Hematoxylin-eosin staining and Masson staining were used to observe the lung histopathological changes in each group, respectively. The levels of NOX, reactive oxygen species (ROS), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) in lung tissue were detected. The expressions of interleukin-1 beta (IL-1ß), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) were determined by Enzyme-Linked Immunosorbent Assay (ELISA). The level of hydroxyproline (HYP) was detected by alkaline hydrolysate. The expressions of transforming growth factor beta 1 (TGF-ß1), E-cadherin (E-cad) and α-smooth muscle actin (α-SMA) in lung tissue were detected by Western blotting. Results: Compared with the control group, the body weight of silicosis model group was decreased, the lung tissue showed obvious inflammatory infiltration and fibrosis, and the levels of lung coefficient, IL-1ß, IL-6, TNF-α and TGF-ß1 were significantly increased (P<0.05). Compared with the silicosis model group, the lung tissue injury in the apocynin intervention group was significantly improved, the lung coefficient, NOX, ROS, MDA, IL-1ß, IL-6, TNF-α and TGF-ß1 levels were decreased, and the activity of GSH-Px was increased (P<0.05). Compared with the silicosis model group, the expressions of HYP and α-SMA were decreased and the level of E-cad was increased in the apocynin intervention group (P<0.05) . Conclusion: Apocynin may alleviate SiO(2)-induced fibrosis in silicosis rats by reducing oxidative stress, the release of inflammatory factors and inhibiting the process of epithelial-mesenchymal transition.

Apocynin exerts cytoprotective effects on dexamethasone-induced osteoblasts by inhibiting oxidative stress through the Nrf2 signalling pathway.

Steroid-induced femoral head necrosis (SIFHN) is a serious clinical complication that is caused by prolonged or excessive use of glucocorticoids (GCs). Osteoblast apoptosis and osteogenic differentiation dysfunction caused by GC-induced oxidative stress and mitochondrial impairment are strongly implicated in SIFHN. Apocynin (APO) is a kind of acetophenone extracted from an herb. In recent years, APO has received much attention for its antiapoptotic and antioxidant properties. This study aimed to investigate whether APO could protect against SIFHN and explore the mechanism. In our study, low-dose APO had no toxic effects on osteoblasts and restored dexamethasone (Dex)-treated osteoblasts by improving survival, inhibiting OS and restoring mitochondrial dysfunction. Mechanistically, APO alleviated Dex-induced osteoblast injury by activating the Nrf2 pathway, and the use of ML385 to block Nrf2 significantly eliminated the protective effect of APO. In addition, APO could reduce the formation of empty lacunae, restore bone mass and promote the expression of Nrf2 in SIFHN rats. In conclusion, APO protects osteoblasts from Dex-induced oxidative stress and mitochondrial dysfunction through activation of the Nrf2 pathway and may be a beneficial drug for the treatment of SIFHN.

Apocynin, an NADPH Oxidase Enzyme Inhibitor, Prevents Amebic Liver Abscess in Hamster.

Amebiasis is an intestinal infection caused by Entamoeba histolytica. Amebic liver abscess (ALA) is the most common extraintestinal complication of amebiasis. In animal models of ALA, neutrophils have been shown to be the first cells to come into contact with Entamoeba histolytica during the initial phase of ALA. One of the multiple mechanisms by which neutrophils exhibit amebicidal activity is through reactive oxygen species (ROS) and the enzyme NADPH oxidase (NOX2), which generates and transports electrons to subsequently reduce molecular oxygen into superoxide anion. Previous reports have shown that ROS release in the susceptible animal species (hamster) is mainly stimulated by the pathogen, in turn provoking such an exacerbated inflammatory reaction that it is unable to be controlled and results in the death of the animal model. Apocynin is a natural inhibitor of NADPH oxidase. No information is available on the role of NOX in the evolution of ALA in the hamster, a susceptible model. Our study showed that administration of a selective NADPH oxidase 2 (NOX2) enzyme inhibitor significantly decreases the percentage of ALA, the size of inflammatory foci, the number of neutrophils, and NOX activity indicated by the reduction in superoxide anion (O2-) production. Moreover, in vitro, the apocynin damages amoebae. Our results showed that apocynin administration induces a decrease in the activity of NOX that could favor a decrease in ALA progression.

The Alzheimer's Disease Brain, Its Microvasculature, and NADPH Oxidase.

The deterioration of the brain's microvasculature, particularly in the hippocampus, appears to be a very early event in the development of Alzheimer's disease (AD), preceding even the deposition of amyloid-ß. A damaged microvasculature reduces the supply of oxygen and glucose to this region and limits the production of energy, ATP. The damage may be a function of the rise with age in the expression and activity of NADPH oxidase (NOX) in these microvessels. This rise renders these vessels vulnerable to the effects of oxidative stress and inflammation. The rise in NOX activity with age is even more marked in the AD brain where an inverse correlation has been demonstrated between NOX activity and cognitive ability. Apocynin, a putative NOX inhibitor, has been shown to block the damaging effects of NOX activation. Apocynin acts as a strong scavenger of H2O2, and as a weak scavenger of superoxide. Like apocynin, sodium oxybate (SO) has also been shown to block the toxic effects of NOX activation. The application of SO generates NADPH and ATP. SO inhibits oxidative stress and maintains normal cerebral ATP levels under hypoxic conditions. Moreover, it acts epigenetically to attenuate the expression of NOX. SO may delay the onset and slow the progress of AD by suppling energy and maintaining an antioxidative environment in the brain throughout the night. The slow wave activity produced by SO may also activate the glymphatic system and promote the clearance of amyloid-ß from the brain.

Does apocynin increase liver regeneration in the partial hepatectomy model?

BACKGROUND: Hepayocyte loss may develop secondary to liver surgery and at this point liver regeneration plays a significant act in terms of liver reserve. The purpose of this research was to investigate the efficacy of apocynin on liver regeneration and preservation after partial hepatectomy in rats. METHODS: A total of 32 rats, have been divided into 4 groups (n: 8) for hepatectomy model. Inflammatory and antiinflammatory parameters were measured from blood and liver tissue samples. In addition, the effects of apocynin were examined immunohistochemically and histopathologically from liver tissue. RESULTS: In liver tissue samples, a significant difference has been found in glutathione peroxidase, total nitrite, catalase, oxidative stress index, total antioxidant and total oxidant status between sham and hepatectomy groups. A significant difference has been achieved between hepatectomy and posthepatectomy-Apocynin in terms of glutathione peroxidase and oxidative stress index. Total antioxidant status, oxidative stress index, and total oxidant status were significantly different only between the sham and the hepatectomy groups. Statistical differences were found between sham and hepatectomy groups and between hepatectomy and pre+post-hepatectomy-Apocynin groups in terms of serum glutathione, malondialdehyde, total nitrite, and L-Arginine. There were significant differences between the sham and hepatectomy groups, between hepatectomy and posthepatectomy-apocynin groups, between posthepatctomy-apocynin and pre+posthepatectomy-apocynin groups in terms of sinusoidal dilatation, intracytoplasmic vacuolization and glycogen loss (p < 0.001), in all histopathologic parameters except sinusoidal dilatation (p < 0.05). However, significant Ki-67 increases have been elaborated in hepatectomy, posthepatectomy-apocynin, and pre+posthepatectomy-apocynin groups compared to sham group (p < 0.001), in pre+posthepatectomy apocynin group compared to hepatectomy and posthepatectomy-apocynin groups (p < 0.001). DISCUSSION: Histopathology, immunohistochemistry, and biochemistry results of this study revealed that apocynin has a protective effect on enhancing liver regeneration in partial hepatectomy cases in rats.

The Effects of Apocynin on Monosodium Glutamate Induced Liver Damage of Rats.

Monosodium glutamate (MSG) is found in refined foods. Apocynin (APO) is a selective NADPH oxidase (NOX) inhibitor. The aim of this experimental study was to investigate possible effects of MSG and the curative effects of APO in rats. Twenty-eight male Sprague-Dawley rats were randomly divided into four groups (Normal control, APO, MSG and MSG + APO, n:7 for each group). The MSG and MSG + APO groups received 120 mg/kg MSG solution orally for 28 consecutive days. The APO and MSG + APO groups received 25 mg/kg APO solution orally for 5 days until the end of the experiment. At the end of the experiment, all rats were sacrificed and liver tissue and blood samples were taken for histological, ultrastructural, and biochemical analyses. In the MSG group, vacuolization and loss in glycogen content in the hepatocytes, leukocyte infiltration and fibrosis in the liver parenchyme and portal triads, were observed. Terminal deoxynucleotidyl transferase dUTP (TUNEL)-positivity and NADPH oxidase (NOX)-2-positivity were higher in the MSG group compared with the other experimental groups. The concentrations of alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), total bilirubin, malondialdehyde (MDA), and myeloperoxidase (MPO) were higher, whereas albumin, glutathione (GSH), and superoxide (SOD) levels were lower in the MSG group. All these data has been reversed in MSG + APO group. The histological and biochemical criteria indicated the prominent ameliorating effect of APO on MSG -induced liver injury.

In vitro-in vivo assessments of apocynin-hybrid nanoparticle-based gel as an effective nanophytomedicine for treatment of rheumatoid arthritis.

Apocynin (APO), a well-known bioactive plant-based phenolic phytochemical with renowned anti-inflammatory and antioxidant pharmacological activities, has recently emerged as a specific nicotinamide adenine dinucleotide phosphate-oxidase (NADPH) oxidase inhibitor. As far as we know, no information has been issued yet regarding its topical application as a nanostructured-based delivery system. Herein, APO-loaded Compritol® 888 ATO (lipid)/chitosan (polymer) hybrid nanoparticles (APO-loaded CPT/CS hybrid NPs) were successfully developed, characterized, and optimized, adopting a fully randomized design (32) with two independent active parameters (IAPs), namely, CPT amount (XA) and Pluronic® F-68 (PF-68) concentration (XB), at three levels. Further in vitro-ex vivo investigation of the optimized formulation was performed before its incorporation into a gel base matrix to prolong its residence time with consequent therapeutic efficacy enhancement. Subsequently, scrupulous ex vivo-in vivo evaluations of APO-hybrid NPs-based gel (containing the optimized formulation) to scout out its momentous activity as a topical nanostructured system for beneficial remedy of rheumatoid arthritis (RA) were performed. Imperatively, the results support an anticipated effectual therapeutic activity of the APO-hybrid NPs-based gel formulation against Complete Freund's Adjuvant-induced rheumatoid arthritis (CFA-induced RA) in rats. In conclusion, APO-hybrid NPs-based gel could be considered a promising topical nanostructured system to break new ground for phytopharmaceutical medical involvement in inflammatory-dependent ailments.

Apocynin alleviates weight gain and obesity-induced adipose tissue inflammation in high-fat diet-fed C57BL/6 mice.

Obesity involves chronic low-grade inflammation within adipose tissue. Apocynin (APO) is a therapeutic agent for the treatment of inflammatory diseases. Therefore, the present study aimed to investigate whether APO can reduce weight gain and obesity-induced adipose tissue inflammation. C57BL/6 mice were administered APO or orlistat (Orli) as a positive control with a high-fat diet (HFD) for 12 weeks. Lipopolysaccharide-stimulated 3T3-L1 adipocytes were used for the in vitro study. Our results showed a significantly lower white adipose tissue (WAT) mass index in 10 mg/kg APO-treated mice than in 20 mg/kg Orli-treated mice. Moreover, the protein expression of adipose triglyceride lipase, fatty acid synthase, sterol regulatory element-binding transcription factor 1, and peroxisome proliferator-activated receptor γ was reversed in the WAT of 10 mg/kg APO-treated mice. Furthermore, APO reduced the expression of the macrophage marker F4/80, decreased the mRNA levels of tumor necrosis factor-α and monocyte chemoattractant protein-1, and increased the mRNA levels of interleukin-10 in WAT. APO decreased the phosphorylation of c-Jun N-terminal kinase, extracellular signal-regulated kinase, and p65 in vivo and in vitro. Notably, APO had a stronger effect on the amelioration of adipose tissue inflammation than Orli did. Our findings lay the foundation for research on the use of APO as an agent to ameliorate weight gain and obesity-induced inflammatory diseases.

Elicitation of Inhibitory Effects for AGE-Induced Oxidative Stress in Rotator Cuff-Derived Cells by Apocynin.

Advanced glycation end-products (AGEs) play a critical supportive role during musculoskeletal disorders via glycosylation and oxidative stress. Though apocynin, identified as a potent and selective inhibitor of NADPH oxidase, has been reported to be involved in pathogen-induced reactive oxygen species (ROS), its role in age-related rotator cuff degeneration has not been well clarified. Therefore, this study aims to evaluate the in vitro effects of apocynin on human rotator cuff-derived cells. Twelve patients with rotator cuff tears (RCTs) participated in the study. Supraspinatus tendons from patients with RCTs were collected and cultured. After the preparation of RC-derived cells, they were divided into four groups (control group, control + apocynin group, AGEs group, AGEs + apocynin group), and gene marker expression, cell viability, and intracellular ROS production were evaluated. The gene expression of NOX, IL-6, and the receptor for AGEs (RAGE) was significantly decreased by apocynin. We also examined the effect of apocynin in vitro. The results showed that ROS induction and increasing apoptotic cells after treatment of AGEs were significantly decreased, and cell viability increased considerably. These results suggest that apocynin can effectively reduce AGE-induced oxidative stress by inhibiting NOX activation. Thus, apocynin is a potential prodrug in preventing degenerative changes of the rotor cuff.

Isolated Natural Antioxidants as a new Possible Therapeutic Alternative for the Treatment of Hypertension.

Oxidative stress is one of the main mechanisms involved in the pathophysiology of arterial hypertension, inducing direct effects on the vasculature, and contributing to endothelial dysfunction and consequent impairment of vascular relaxation. Despite a large number of pharmacological treatments available, intolerable side effects are reported, which makes the use of natural antioxidants a promising and complementary alternative for the prevention and treatment of hypertension. From this perspective, the current review aims to investigate and characterize the main antioxidants of natural origin for the treatment of hypertension. Antioxidants act in the inhibition or extinction of chemical reactions involving free radicals and consequently reduce the occurrence of damage caused by these cellular components. The main natural antioxidants for treating hypertension include caffeic acid, ferulic acid, curcumin, apocynin, quercetin, lipoic acid, and lycopene. The effects associated with these antioxidants, which make them therapeutic targets for decreasing high blood pressure, include increased activation of antioxidant enzymes, stimulation of nitric oxide bioavailability, and reduction in angiotensin-converting enzyme activity, arginase, and NADPH oxidase, whose effects contribute to reducing oxidative stress, improving endothelial function, and preventing cardiovascular dysfunctions. Thus, several products with antioxidant properties that are available in nature and their application in the treatment of hypertension are described in the literature. The therapeutic effects of these products seem to regulate several parameters related to arterial hypertension, in addition to combating and preventing the deleterious effects related to the disease.

Effects of Apocynin, a NADPH Oxidase Inhibitor, in the Protection of the Heart from Ischemia/Reperfusion Injury.

Ischemia and perfusion (I/R) induce inflammation and oxidative stress, which play a notable role in tissue damage. The aim of this study was to investigate the role of an NADPH oxidase inhibitor (apocynin) in the protection of the heart from I/R injury. Hearts isolated from Wistar rats (n = 8 per group) were perfused with a modified Langendorff preparation. Left ventricular (LV) contractility and cardiovascular hemodynamics were evaluated by a data acquisition program, and infarct size was evaluated by 2,3,5-Triphenyl-2H-tetrazolium chloride (TTC) staining. Furthermore, the effect of apocynin on the pro-inflammatory cytokines (IL-1ß, IL-6 and TNF-α) and anti-inflammatory cytokine (IL-10) was evaluated using an enzyme linked immunosorbent assay (ELISA). Hearts were subjected to 30 min of regional ischemia, produced by ligation of the left anterior descending (LAD) coronary artery, followed by 30 min of reperfusion. Hearts were infused with apocynin before ischemia, during ischemia or at reperfusion. To understand the potential pathways of apocynin protection of the heart, a nitric oxide donor (S-nitroso-N-acetylpenicillamine, SNAP), nitric oxide blocker (N (gamma)-nitro-L-arginine methyl ester, L-Name), nicotinic acid adenine dinucleotide phosphate (NAADP) inhibiter (Ned-K), cyclic adenosine diphosphate ribose (cADPR) agonist, or CD38 blocker (Thiazoloquin (az)olin (on)e compound, 78c) was infused with apocynin. Antioxidants were evaluated by measuring superoxide dismutase (SOD) and catalase (CAT) activity. Apocynin infusion before ischemia or at reperfusion protected the heart by normalizing cardiac hemodynamics and decreasing the infarct size. Apocynin treatment resulted in a significant (p < 0.05) decrease in pro-inflammatory cytokine levels and a significant increase (p < 0.05) in anti-inflammatory and antioxidant levels. Apocynin infusion protected the heart by improving LV hemodynamics and coronary vascular dynamics. This treatment decreased the infarct size and inflammatory cytokine levels and increased anti-inflammatory cytokine and antioxidant levels. This protection follows a pathway involving CD38, nitric oxide and acidic stores.

Identification of a Noxo1 inhibitor by addition of a polyethylene glycol chain.

Reactive oxygen species (ROS) are a heterogeneous group of highly reactive ions and molecules derived from molecular oxygen (O2) which can cause DNA damage and lead to skin cancer. NADPH oxidase 1 (Nox1) is a major producer of ROS in the skin upon exposure to ultraviolet light. Functionally, Nox1 forms a holoenzyme complex that generates two superoxide molecules and reduces NADPH. The signaling activation occurs when the organizer subunit Noxo1 translocates to the plasma membrane bringing a cytochrome p450, through interaction with Cyba. We propose to design inhibitors that prevent Cyba-Noxo1 binding as a topical application to reduce UV-generated ROS in human skin cells. Design started from an apocynin backbone structure to generate a small molecule to serve as an anchor point. The initial compound was then modified by addition of a polyethylene glycol linked biotin. Both inhibitors were found to be non-toxic in human keratinocyte cells. Further in vitro experiments using isothermal calorimetric binding quantification showed the modified biotinylated compound bound Noxo1 peptide with a KD of 2 nM. Both using isothermal calorimetric binding and MALDI (TOF) MS showed that binding of a Cyba peptide to Noxo1 was blocked. In vivo experiments were performed using donated skin explants with topical application of the two inhibitors. Experiments show that ultraviolet light exposure of with the lead compound was able to reduce the amount of cyclobutene pyrimidine dimers in DNA, a molecule known to lead to carcinogenesis. Further synthesis showed that the polyethylene glycol but not the biotin was essential for inhibition.

Apocynin Ameliorates Monosodium Glutamate Induced Testis Damage by Impaired Blood-Testis Barrier and Oxidative Stress Parameters.

BACKGROUND: the aim of this study was to investigate the effects of apocynin (APO) on hormone levels, the blood-testis barrier, and oxidative biomarkers in monosodium glutamate (MSG) induced testicular degeneration. METHODS: Sprague Dawley male rats (150-200 g; n = 32) were randomly distributed into four groups: control, APO, MSG, and MSG + APO. MSG and MSG + APO groups were administered MSG (120 mg/kg) for 28 days. Moreover, the APO and MSG + APO groups received APO (25 mg/kg) during the last five days of the experiment. All administrations were via oral gavage. Finally, biochemical analyses were performed based on the determination of testosterone, follicle-stimulating hormone (FSH), luteinizing hormone (LH), malondialdehyde (MDA), glutathione (GSH), and superoxide dismutase (SOD), as well as light and transmission electron microscopic examinations, assessment of sperm parameters, ZO-1, occludin, NOX-2, and TUNEL immunohistochemistry were evaluated. RESULTS: MSG increased both the oxidative stress level and apoptosis, decreased cell proliferation, and caused degeneration in testis morphology including in the blood-testis barrier. Administration of apocynin reversed all the deteriorated morphological and biochemical parameters in the MSG + APO group. CONCLUSIONS: apocynin is considered to prevent testicular degeneration by maintaining the integrity of the blood-testis barrier with balanced hormone and oxidant/antioxidant levels.

The NADPH Oxidase Inhibitors Apocynin and Diphenyleneiodonium Protect Rats from LPS-Induced Pulmonary Inflammation.

Inflammation is the body's response to insults, for instance, lung inflammation is generally caused by pathogens or by exposure to pollutants, irritants and toxins. This process involves many inflammatory cells such as epithelial cells, monocytes, macrophages and neutrophils. These cells produce and release inflammatory mediators such as pro-inflammatory cytokines, lipids and reactive oxygen species (ROS). Lung epithelial cells and phagocytes (monocytes, macrophages and neutrophils) produce ROS mainly by the NADPH oxidase NOX1 and NOX2, respectively. The aim of this study was to investigate the effects of two NADPH oxidase inhibitors, apocynin and diphenyleneiodonium (DPI), on lipopolysaccharide (LPS)-induced lung inflammation in rats. Our results showed that apocynin and DPI attenuated the LPS-induced morphological and histological alterations of the lung, reduced edema and decreased lung permeability. The evaluation of oxidative stress markers in lung homogenates showed that apocynin and DPI inhibited LPS-induced NADPH oxidase activity, and restored superoxide dismutase (SOD) and catalase activity in the lung resulting in the reduction in LPS-induced protein and lipid oxidation. Additionally, apocynin and DPI decreased LPS-induced MPO activity in bronchoalveolar liquid and lung homogenates, TNF-α and IL-1ß in rat plasma. NADPH oxidase inhibition could be a new therapeutic strategy for the treatment of inflammatory lung diseases.