The protective effect of sinapic acid in osteoarthritis: In vitro and in vivo studies

Sinapic acid-pullulan based inflammation responsive nanomicelles for the local treatment of experimental inflammatory arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disorder of joints. It is one of the major causes of disability and morbidity worldwide. Administration of conventional drugs through the systemic route restricts the bioavailability of drugs, systemic toxicity, and reduced efficacy. We have introduced Rebamipide (Reb)-loaded Sinapic acid (SA)-Pullulan (PL) nanomicelles (Reb@SA-PL NMs), a nanotechnology based drug delivery system for the treatment of inflammatory arthritis. PL is a polysaccharide obtained from the fungus Aureobasidium pullulans, and SA is a bioactive polyphenol found in various plants. Both are classified by US-FDA Generally Recognised as Safe (GRAS) materials. Reb@SA-PL NMs found to be cytocompatible. Subsequently, intra-articular administration of Reb@SA-PL NMs enhances the anti-arthritic potential compared to free Reb drug in collagen-induced experimental inflammatory arthritis rat model. Reb@SA-PL NMs reduced the expression of RANKL receptor and Nf-κB. Reb@SA-PL NMs reverses the breakdown of type II collagen, MMP-13, and inhibits the pro-inflammatory markers. Reb@SA-PL NMs prevented bone erosion, cartilage degradation, joint oedema, and synovial inflammation. The results of the study demonstrated that Reb@SA-PL NMs, an enzyme-responsive drug delivery system, has excellent potential for alleviating inflammatory arthritis by blocking MMP-13 and RANKL.

The Multifaceted Protective Role of Nuclear Factor Erythroid 2-Related Factor 2 in Osteoarthritis: Regulation of Oxidative Stress and Inflammation

Osteoarthritis (OA) is a chronic degenerative joint disease characterized by the degradation of joint cartilage, subchondral bone sclerosis, synovitis, and structural changes in the joint. Recent research has highlighted the role of various genes in the pathogenesis and progression of OA, with nuclear factor erythroid 2-related factor 2 (NRF2) emerging as a critical player. NRF2, a vital transcription factor, plays a key role in regulating the OA microenvironment and slowing the disease's progression. It modulates the expression of several antioxidant enzymes, such as Heme oxygenase-1 (HO-1) and NAD(P)H oxidoreductase 1 (NQO1), among others, which help reduce oxidative stress. Furthermore, NRF2 inhibits the nuclear factor kappa-B (NF-κB) signaling pathway, thereby decreasing inflammation, joint pain, and the breakdown of cartilage extracellular matrix, while also mitigating cell aging and death. This review discusses NRF2's impact on oxidative stress, inflammation, cell aging, and various cell death modes (such as apoptosis, necroptosis, and ferroptosis) in OA-affected chondrocytes. The role of NRF2 in OA macrophages, and synovial fibroblasts was also discussed. It also covers NRF2's role in preserving the cartilage extracellular matrix and alleviating joint pain. The purpose of this review is to provide a comprehensive understanding of NRF2's protective mechanisms in OA, highlighting its potential as a therapeutic target and underscoring its significance in the development of novel treatment strategies for OA.

Ameliorative impacts of sinapic acid against mercuric chloride-induced renal toxicity: role of antioxidants and inflammatory cytokines

Because of their beneficial properties, natural products, especially medicinal plants, are becoming increasingly popular worldwide and play a significant role in research. This study was aimed to evaluate the nephroprotective effect of sinapic acid against mercuric chloride-induced renal toxicity in mice. The mice were allocated to four groups named a normal group (G1), model group (G2; received HgCl2, 1 mg/kg bw), treatments groups (G3 and G4: received 50 and 100 mg/kg bw of sinapic acid together with HgCl2). Mice received HgCl2 remarkably showed alteration in all examined biochemical biomarkers (urea, creatinine, and bilirubin), and induced alteration in blood cell picture and anemia. HgCl2 intoxication decreased both systemic and renal antioxidant activity and induced over all oxidative stress as indicated by alteration in inflammation and oxidative stress associated markers. HgCl2 affected renal histology with leukocytic and inflammatory cell infiltration, fibrosis and tubular necrosis. Administration of sinapic acid (50 and 100 mg/kg bw) markedly restored the HgCl2-induced oxidative stress (serum and renal: MDA, GSH, CAT, SOD, and T-AOC), proinflammatory cytokines (serum and renal: TNF-α, IL-6, IL-1β, and PGE2) and restored the changes on biochemical markers, and hematological parameters (hemoglobin, erythrocytes, platelets, and leukocytes). Taken together, the results of the present study disclose that sinapic acid has the potential to attenuate HgCl2-induced renal toxicity and may be an ideal choice against mercury poisoning.

Syringic acid alleviates cisplatin-induced ovarian injury through modulating endoplasmic reticulum stress, inflammation and Nrf2 pathway

BACKGROUND

Reproductive toxicity is one of the most important side effects of cisplatin (CIS) and leading to discontinuation of treatment. Syringic acid (SA) is a phenolic acid whose industrial use has increased in recent years due to its antioxidant properties. Recent reports highlight the importance of the supressed Nrf2 pathway in the molecular pathogenesis of CIS toxicity. Therefore, this study aimed to evaluate the therapeutic effect of SA on CIS-induced ovotoxicity through the Nrf2 pathway for the first time.

MATERIAL AND METHODS

Thirty female rats were divided into 5 groups: control, CIS, CIS+SA (5 and 10 mg/kg) and only SA (per se, 10 mg/kg). CIS was administered intraperitoneally at a dose of 5 mg/kg on the 1st day, injections of SA followed by three consecutive days in the rats. Serum anti-mullerian hormone (AMH) levels and ovarian oxidative stress (OS), inflammation, endoplasmic reticulum stress (ERS), apoptosis and Nrf2 pathway markers were determined colorimetrically. Histopathological examinations of the ovaries with hematoxylin and eosin staining were also used to evaluate CIS-induced ovotoxicity.

RESULTS

The CIS treatment depleted serum AMH levels, caused histopathological findings and increased OS, inflammation, ERS and apoptosis levels in ovarian tissue. However, treatments with SA significantly ameliorated CIS-induced biochemical and histopathological changes by activating Nrf2 pathway.

CONCLUSION

The promising adjuvant potential of SA to alleviate CIS-related ovarian damage should be supported by more comprehensive studies.

Natural products in osteoarthritis treatment: bridging basic research to clinical applications

Osteoarthritis (OA) is the most prevalent degenerative musculoskeletal disease, severely impacting the function of patients and potentially leading to disability, especially among the elderly population. Natural products (NPs), obtained from components or metabolites of plants, animals, microorganisms etc., have gained significant attention as important conservative treatments for various diseases. Recently, NPs have been well studied in preclinical and clinical researches, showing promising potential in the treatment of OA. In this review, we summed up the main signaling pathways affected by NPs in OA treatment, including NF-κB, MAPKs, PI3K/AKT, SIRT1, and other pathways, which are related to inflammation, anabolism and catabolism, and cell death. In addition, we described the therapeutic effects of NPs in different OA animal models and the current clinical studies in OA patients. At last, we discussed the potential research directions including in-depth analysis of the mechanisms and new application strategies of NPs for the OA treatment, so as to promote the basic research and clinical transformation in the future. We hope that this review may allow us to get a better understanding about the potential bioeffects and mechanisms of NPs in OA therapy, and ultimately improve the effectiveness of NPs-based clinical conservative treatment for OA patients.

Grafting of sinapic acid onto glucosamine nanoparticle as a potential therapeutic drug with enhanced anti-inflammatory activities in osteoarthritis treatment

Glucosamine (Glu) is a cartilage and joint fluid matrix precursor that modulates osteoarthritic joint changes. To improve the enzymatic stability, glucosamine was developed into nanoglucosamine by the ionic gelation method through sodium tripolyphosphate (TPP) as cross-linking agent. The optimized mass ratio of Glu:TPP was (3:1) with the particle size 163 ± 25 nm and surface charge -5 mV. Then Sinapic acid (SA) as a natural phenolic acid with strong antioxidant and antimicrobial activities has been grafted onto glucosamine nanoparticles (GluNPs) with grafting efficiency (73 ± 6 %). The covalent insertion of SA was confirmed by UV-Vis, FTIR, 1HNMR, XRD, and FESEM analyses and the other physicochemical properties were also characterized. SA-g-GluNPs showed spherical shape with a mean diameter of 255 ± 20 nm and zeta potential +16 mV. The in vitro release profile of SA-g-GluNPs exhibited the sustained and pH-dependent drug release property. SA-g-GluNPs had a more pronounced effect on reducing the elevated levels of LPS-induced oxidative stress and pro-inflammatory cytokines than free SA in the human chondrocyte C28/I2 cell line. Furthermore, the antibacterial properties against E. coli and S. aureus were also improved by SA-g-GluNPs. This study demonstrated the potential of phenolic acid grafted GluNPs in therapeutic drug applications for chondroprotection and food industries.

The Protective Effect of Selenium Nanoparticles in Osteoarthritis: In vitro and in vivo Studies

Introduction

Osteoarthritis (OA) is a common chronic joint disease characterized by articular cartilage degeneration. OA usually manifests as joint pain, limited mobility, and joint effusion. Currently, the primary OA treatment is non-steroidal anti-inflammatory drugs (NSAIDs). Although they can alleviate the disease's clinical symptoms and signs, the drugs have some side effects. Selenium nanoparticles (SeNPs) may be an alternative to relieve OA symptoms.

Materials and Results

We confirmed the anti-inflammatory effect of selenium nanoparticles (SeNPs) in vitro and in vivo experiments for OA disease in this study. In vitro experiments, we found that SeNPs could significantly reduce the expression of nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), the major inflammatory factors, and had significant anti-inflammatory and anti-arthritic effects. SeNPs can inhibit reactive oxygen species (ROS) production and increased glutathione peroxidase (GPx) activity in interleukin-1beta (IL-1β)-stimulated cells. Additionally, SeNPs down-regulated matrix metalloproteinase-13 (MMP-13) and thrombospondin motifs 5 (ADAMTS-5) expressions, while up-regulated type II collagen (COL-2) and aggrecan (ACAN) expressions stimulated by IL-1β. The findings also indicated that SeNPs may exert their effects through suppressing the NF-κB p65 and p38/MAPK pathways. In vivo experiments, the prevention of OA development brought on by SeNPs was demonstrated using a DMM model.

Discussion

Our results suggest that SeNPs may be a potential anti-inflammatory agent for treating OA.

Overview of Anti-Inflammatory and Anti-Nociceptive Effects of Polyphenols to Halt Osteoarthritis: From Preclinical Studies to New Clinical Insights

Knee osteoarthritis (OA) is one of the most multifactorial joint disorders in adults. It is characterized by degenerative and inflammatory processes that are responsible for joint destruction, pain and stiffness. Despite therapeutic advances, the search for alternative strategies to target inflammation and pain is still very challenging. In this regard, there is a growing body of evidence for the role of several bioactive dietary molecules (BDMs) in targeting inflammation and pain, with promising clinical results. BDMs may be valuable non-pharmaceutical solutions to treat and prevent the evolution of early OA to more severe phenotypes, overcoming the side effects of anti-inflammatory drugs. Among BDMs, polyphenols (PPs) are widely studied due to their abundance in several plants, together with their benefits in halting inflammation and pain. Despite their biological relevance, there are still many questionable aspects (biosafety, bioavailability, etc.) that hinder their clinical application. This review highlights the mechanisms of action and biological targets modulated by PPs, summarizes the data on their anti-inflammatory and anti-nociceptive effects in different preclinical in vitro and in vivo models of OA and underlines the gaps in the knowledge. Furthermore, this work reports the preliminary promising results of clinical studies on OA patients treated with PPs and discusses new perspectives to accelerate the translation of PPs treatment into the clinics.

The role of inflammation in cadmium nephrotoxicity: NF-κB comes into view

Kidney diseases are major health problem and understanding the underlined mechanisms that lead to kidney diseases are critical research points with a marked potential impact on health. Cadmium (Cd) is a heavy metal that occurs naturally and can be found in contaminated food. Kidneys are the most susceptible organ to heavy metal intoxication as it is the main route of waste excretion. The harmful effects of Cd were previously well proved. Cd induces inflammatory responses, oxidative injury, mitochondrial dysfunction and disturbs Ca²⁺ homeostasis. The nuclear factor-kappa B (NF-κB) is a cellular transcription factor that regulates inflammation and controls the expression of many inflammatory cytokines. Therefore, great therapeutic benefits can be attained from NF-κB inhibition. In this review we focused on certain compounds including cytochalasin D, mangiferin, N-acetylcysteine, pyrrolidine dithiocarbamate, roflumilast, rosmarinic acid, sildenafil, sinapic acid, telmisartan and wogonin and certain plants as Astragalus Polysaccharide, Ginkgo Biloba and Thymus serrulatus that potently inhibit NF-κB and effectively counteracted Cd-associated renal intoxication. In conclusion, the proposed NF-κB involvement in Cd-renal intoxication clarified the underlined inflammation associated with Cd-nephropathy and the beneficial effects of NF-κB inhibitors that make them the potential to substantially optimize treatment protocols for Cd-renal intoxication.

Sinapic Acid Ameliorates REV-ERB α Modulated Mitochondrial Fission against MPTP-Induced Parkinson's Disease Model

Parkinson’s disease (PD) is the second most common neurodegenerative disease worldwide, and accumulating evidence indicates that mitochondrial dysfunction is associated with progressive deterioration in PD patients. Previous studies have shown that sinapic acid has a neuroprotective effect, but its mechanisms of action remain unclear. The neuroprotective effect of sinapic acid was assayed in a PD mouse model generated by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) as well as in SH-SY5Y cells. Target protein expression was detected by western blotting. Sinapic acid treatment attenuated the behavioral defects and loss of dopaminergic neurons in the PD models. Sinapic acid also improved mitochondrial function in the PD models. MPTP treatment increased the abundance of mitochondrial fission proteins such as dynamin-related protein 1 (Drp1) and phospho-Drp1 Ser616. In addition, MPTP decreased the expression of the REV-ERB α protein. These changes were attenuated by sinapic acid treatment. We used the pharmacological REV-ERB α inhibitor SR8278 to confirmation of protective effect of sinapic acid. Treatment of SR8278 with sinapic acid reversed the protein expression of phospho-Drp1 Ser616 and REV-ERB α on MPTP-treated mice. Our findings demonstrated that sinapic acid protects against MPTP-induced PD and these effects might be related to the inhibiting abnormal mitochondrial fission through REV-ERB α.

Analysis of the anti-inflammatory potential of Brassica bioactive compounds in a human macrophage-like cell model derived from HL-60 cells

BACKGROUND

Chronic inflammatory diseases are major causes of global morbidity and mortality. Acute inflammation is meant to protect the body against foreign agents, but it also plays a major role in tissue repairment. Several mediators are involved in this process, including pro-inflammatory cytokines produced by macrophages. Occasionally, if the inflammatory response is not resolved, the acute inflammatory process can evolve into a chronic inflammation. Natural compounds from vegetables are considered as an important source of active agents with potential to treat or prevent inflammatory related pathologies and could be used as an alternative of the therapeutic agents currently in use, such as non-steroidal anti-inflammatory drugs (NSAIDs), which present several side effects.

METHODS

In this research work we evaluated in vitro the anti-inflammatory activity of a series of ten phytochemicals present in Brassica, measured as the potential of those compounds to reduce the production of key pro-inflammatory cytokines (TNF-α, IL-6 and IL-1β) by a human macrophage-like cell model of HL-60 cells RESULTS: Most of the tested phytochemicals (including the most representative bioactive molecules of the major classes of compounds present in cruciferous foods such as glucosinolates, isothiocyanates, hydroxycinnamic acids, flavonols and anthocyanins) demonstrated significant anti-inflammatory activity at micromolar level in the absence of cytotoxic effects in this human macrophage-like cell model.

CONCLUSION

These data confirm that phytochemicals commonly obtained from Brassica may be potential therapeutic leads to treat or prevent human chronic inflammation and related diseases.

Sinapic acid inhibits pancreatic cancer proliferation, migration, and invasion via downregulation of the AKT/Gsk-3β signal pathway

Among digestive system cancers, the extremely poor prognosis of pancreatic cancer (PC) is a pressing concern. Nonoperative treatments such as targeted and immunotherapy, have improved the current situation, however, the accompanying side effects of these chemicals should not be ignored. Here, we discovered a novel hydroxycinnamic acid named sinapic acid (SA) derived from fruits, vegetables, cereals, and oil crops as an effective anti-PC molecule. Both the in vitro and in vivo models we designed showed that SA exhibited anticancer activities but not apoptosis induction. Research on the underlying mechanisms illustrated that AKT phosphorylation was blocked by SA, and the downstream Gsk-3β was downregulated subsequently. Our study revealed the inhibitory activity and underlying mechanisms of SA, providing evidence that SA is a potential strategy for cancer research and can be a promising option of PC chemotherapy.

Cynanchi atrati and Its Phenolic Constituent Sinapic Acid Target Regulator of Calcineurin 1 (RCAN1) to Control Skin Inflammation

Atopic dermatitis (AD) is a common inflammatory skin disorder, and numerous pharmacological approaches are employed to reduce symptoms. Natural products of plant-derived materials have been accepted as complementary therapy for the treatment of a wide range of inflammatory diseases. Cynanchi atrati (CA) is an oriental medicinal herb used in the treatment of acute urinary infection, febrile diseases, and laryngopharyngitis. However, the role of CA root extract in skin inflammation such as AD has not been explored yet. In this study, we examined the possible effect of CA root extract on skin inflammation and evaluated the underlying signaling mechanism using in vitro and in vivo modeling systems. Raw264.7 macrophages were used for in vitro experiments, and an oxazolone-induced AD mouse model was used to evaluate in vivo effects. CA extract significantly inhibited the expression levels of lipopolysaccharide (LPS)-induced pro-inflammatory cytokines such as interleukin-6 (IL-6) and interleukin-1β (IL-1β) in RAW264.7 macrophages. The CA root extract mediated suppression of pro-inflammatory cytokine expression and was associated with the decreased nuclear factor kappa B (NF-κB) gene transcriptional activation. Moreover, CA root extract attenuated the in vivo expression of IL-6 and tumor necrosis factor-α (TNF-α) and ear swelling in the AD mouse models. We also observed that the inhibitory effect of CA root extract on skin inflammation was accompanied by the upregulation of calcineurin 1 (RCAN1) expression, which functions in the inflammatory pathways by suppressing NF-κB signaling. We consistently observed that the immunosuppressive effect of CA root extract in AD was significantly perturbed in the RCAN1 knockout mice. In addition, we isolated a phenolic acid compound, sinapic acid (SA), from the CA root extract and found that SA consistently exerted an immunosuppressive effect in RAW264.7 macrophages by inducing RCAN1 expression. Our results provide the first evidence that CA root extract and its phenolic acid constituent, SA, modulate NF-κB signaling pathways by inducing RCAN1 expression in the skin inflammation process. Thus, we suggest that CA root extract has a therapeutic value for the treatment of AD by targeting endogenous immune regulators.

Sinapic Acid Alleviates Acute Pancreatitis in Association with Attenuation of Inflammation, Pyroptosis, and the AMPK/NF-κB Signaling Pathway

Among the diseases of the digestive system, the incidence of acute pancreatitis (AP) has increased. Although the AP is primarily self-limited, mortality remains high when it progressed to severe acute pancreatitis (SAP). Despite significant advances in new drug development, treatments for AP are not ideal. Here, we discovered a novel hydroxycinnamic acid, sinapic acid (SA), which is widely distributed in plants and is an effective treatment for AP. Using in vitro and in vivo models, we demonstrated that pretreatment with SA ameliorated cerulein-induced pancreatic damage and inflammation and inhibited the activation of Caspase-1 and Caspase-11, which mediate pyroptosis of pancreatic acinar cells during AP. These effects may occur through the inhibition of AMPK phosphorylation and downregulation of NF-[Formula: see text]B. Our findings demonstrate the therapeutic effects and reveal the underlying mechanisms of SA, which warrants its further study as an effective treatment for AP.

Sinapic Acid Attenuates Rheumatoid Arthritis Through Reducing Inflammation and Oxidative Stress by Downregulating IκB Kinase

Sinapic acid (SA) was reported to protect against inflammation in various types of diseases. However, the role of SA in rheumatoid arthritis remains unclear. This study was designed to investigate the role of SA on rheumatoid arthritis. Rheumatoid arthritis mouse model was established by collagen immunization [collagen-induced arthritis (CIA)]. Histological analysis of articular cartilage tissue was carried out by hematoxylin and eosin (H&E) staining. Serum concentrations of tumor necrosis factor alpha and interleukin 6 were determined through enzyme-linked immunosorbent assay (ELISA). Oxidative damage indexes such as superoxide dismutase activity, malondialdehyde detection, glutathione detection, and catalase were determined by biochemical analysis. The protein levels of related genes were determined using Western blot. In CIA model, SA treatment attenuated paw swelling and clinical score of arthritis, attenuated articular cartilage tissues edema and infiltration of inflammatory cells, suppressed inflammatory cytokines release, and attenuated oxidative damage indexes. Mechanically, SA suppressed immune responses through inhibiting the IκB kinase (IKKs). SA attenuates rheumatoid arthritis through reducing inflammation and oxidative stress by downregulating IKKs.

Sinapic Acid Reduces Oxidative Stress and Pyroptosis via Inhibition of BRD4 in Alcoholic Liver Disease

Alcoholic liver disease (ALD) is one of the main causes of death in chronic liver disease. Oxidative stress and pyroptosis are important factors leading to ALD. Bromodomain-containing protein 4 (BRD4) is a factor that we have confirmed to regulate ALD. As a phenolic acid compound, sinapic acid (SA) has significant effects in antioxidant, anti-inflammatory and liver protection. In this study, we explored whether SA regulates oxidative stress and pyroptosis through BRD4 to play a protective effect in ALD. Male C57BL/6 mice and AML-12 cells were used for experiments. We found that SA treatment largely abolished the up-regulation of BRD4 and key proteins of the canonical pyroptosis signalling in the liver of mice fed with alcohol, while conversely enhanced the antioxidant response. Consistantly, both SA pretreatment and BRD4 knockdown inhibited oxidative stress, pyroptosis, and liver cell damage in vitro. More importantly, the expression levels of BRD4 and pyroptosis indicators increased significantly in ALD patients. Molecule docking analysis revealed a potent binding of SA with BRD4. In conclusion, this study demonstrates that SA reduces ALD through BRD4, which is a valuable lead compound that prevents the ALD process.

Sinapic Acid Protects SH-SY5Y Human Neuroblastoma Cells against 6-Hydroxydopamine-Induced Neurotoxicity

Parkinson’s disease (PD) is characterized by progressive dopaminergic neuron loss or dysfunction and is the second most prevalent neurodegenerative disorder after Alzheimer’s disease. However, current therapeutic strategies for PD are limited to treating the outcomes of this disease rather than preventing it. Sinapic acid (SA) is a phenolic compound with potential antioxidant properties, which reportedly acts as a therapeutic agent against many diseases including cancer, as well as cardiac and liver diseases. However, little is known about the effects of SA against neurodegenerative disorders. Therefore, our study sought to evaluate the neuroprotective effects of non-cytotoxic concentrations of SA against 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in SH-SY5Y human neuroblastoma cells, which we used as an in vitro PD model. SA increased cell viability and rescued the cells from 6-OHDA-induced apoptotic cell death. Additionally, oxidative stress responses were significantly blocked by SA, including reactive oxygen species (ROS) overproduction and decreased expression levels of antioxidant proteins. Notably, SA also attenuated mitochondrial dysfunction and endoplasmic reticulum (ER) stress. Moreover, SA dramatically inhibited the activation of mitogen-activated protein kinase (MAPK) proteins. Taken together, our findings highlight the potential PD prevention effects of SA, as well as its underlying mechanisms, making this compound a promising prevention and treatment agent for PD.

Pharmacological Targeting of Heme Oxygenase-1 in Osteoarthritis

Osteoarthritis (OA) is a common aging-associated disease that clinically manifests as joint pain, mobility limitations, and compromised quality of life. Today, OA treatment is limited to pain management and joint arthroplasty at the later stages of disease progression. OA pathogenesis is predominantly mediated by oxidative damage to joint cartilage extracellular matrix and local cells such as chondrocytes, osteoclasts, osteoblasts, and synovial fibroblasts. Under normal conditions, cells prevent the accumulation of reactive oxygen species (ROS) under oxidatively stressful conditions through their adaptive cytoprotective mechanisms. Heme oxygenase-1 (HO-1) is an iron-dependent cytoprotective enzyme that functions as the inducible form of HO. HO-1 and its metabolites carbon monoxide and biliverdin contribute towards the maintenance of redox homeostasis. HO-1 expression is primarily regulated at the transcriptional level through transcriptional factor nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2), specificity protein 1 (Sp1), transcriptional repressor BTB-and-CNC homology 1 (Bach1), and epigenetic regulation. Several studies report that HO-1 expression can be regulated using various antioxidative factors and chemical compounds, suggesting therapeutic implications in OA pathogenesis as well as in the wider context of joint disease. Here, we review the protective role of HO-1 in OA with a focus on the regulatory mechanisms that mediate HO-1 activity.

Sinapic acid ameliorates D-galactosamine/lipopolysaccharide-induced fulminant hepatitis in rats: Role of nuclear factor erythroid-related factor 2/heme oxygenase-1 pathways

BACKGROUND

Sinapic acid (SA) has been shown to have various pharmacological properties such as antioxidant, antifibrotic, anti-inflammatory, and anticancer activities. Its mechanism of action is dependent upon its ability to curb free radical production and protect against oxidative stress-induced tissue injuries.

AIM

To study the hepatoprotective effects of SA against lipopolysaccharide (LPS)/D-galactosamine (D-GalN)-induced acute liver failure (ALF) in rats.

METHODS

Experimental ALF was induced with an intraperitoneal (i.p.) administration of 8 μg LPS and 800 mg/kg D-GalN in normal saline. SA was administered orally once daily starting 7 d before LPS/D-GalN treatment.

RESULTS

Data showed that SA ameliorates acute liver dysfunction, decreases serum levels of alanine transaminase (ALT), and aspartate aminotransferase (AST), as well as malondialdehyde (MDA) and NO levels in ALF model rats. However, pretreatment with SA (20 mg/kg and 40 mg/kg) reduced nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation and levels of inflammatory cytokines (tumor necrosis factor-α and interleukin 6). Also, SA increased the activity of the nuclear factor erythroid-related factor 2/heme oxygenase-1 (Nrf2/HO-1) signaling pathway.

CONCLUSION

In conclusion, SA offers significant protection against LPS/D-GalN-induced ALF in rats by upregulating Nrf2/HO-1 and downregulating NF-κB.

Ergosterol limits osteoarthritis development and progression through activation of Nrf2 signaling

Osteoarthritis (OA) is a common joint disorder characterized by progressive articular cartilage degeneration and destruction and results in gradual disability among middle-aged and elderly patients. Our previous study demonstrated that depletion of nuclear factor erythroid 2-related factor 2 (Nrf2) exacerbated cartilage erosion in an OA model and that activation of the Nrf2 pathway could counter this process. As a downstream target of Nrf2, heme oxygenase (HO) degrades heme to free iron, biliverdin and carbon monoxide (CO), which protects against oxidative stress. Ergosterol (ER), which is extracted from fungi, is a newly discovered Nrf2 activator and displayed efficacy against myocardial injury. The present study aimed to investigate the potential protective effects of ER against cartilage damage during OA. Primary mouse chondrocytes were treated with ER for in vitro assays. Furthermore, mice that underwent destabilization of the medial meniscus surgery were orally administered with ER. Western blotting suggested that ER increased protein expression of Nrf2 and HO-1 in primary chondrocytes and articular cartilage from knee joints. Cartilage damage in knee joints was significantly reduced by ER treatment. Western blotting and PCR analysis confirmed that ER could also suppress the expression of MMP-9 and MMP-13 in vivo and in vitro. The present findings suggested that ER effectively alleviated cartilage degradation and that activation of the Nrf2-heme oxygenase 1 pathway may play a role in ER-mediated cartilage protection against OA.

Selective Extraction of Sinapic Acid Derivatives from Mustard Seed Meal by Acting on pH: Toward a High Antioxidant Activity Rich Extract

The aim of this paper is to study the effect of the pH on the extraction of sinapic acid and its derivatives from mustard seed meal. Solutions of acidic pH (pH 2), basic pH (pH 12) and distilled water (uncontrolled pH ~ 4.5) were tested at different percentages of ethanol. The maximum extraction yield for sinapic acid (13.22 µmol/g of dry matter (DM)) was obtained with a buffered aqueous solution at pH 12. For ethyl sinapate, the maximum extraction yield reached 9.81 µmol/g _DM with 70% ethanol/buffered aqueous solution at pH 12. The maximum extraction yield of sinapine (15.73 µmol/g _DM) was achieved with 70% ethanol/buffered aqueous solution at pH 2. The antioxidant activity of each extract was assessed by DPPH assay; the results indicated that the extracts obtained at pH 12 and at low ethanol percentages (<50%) exhibit a higher antioxidant activity than extracts obtained at acidic conditions. Maximum antioxidant activity was reached at pH 12 with buffer solution (11.37 mg of Trolox Equivalent/g _DM), which confirms that sinapic acid-rich fractions exhibit a higher antioxidant activity. Thus, to obtain rich antioxidant extracts, it is suggested to promote the presence of sinapic acid in the extracts.

Variability of sinapic acid derivatives during germination and their contribution to antioxidant and anti-inflammatory effects of broccoli sprouts on human plasma and human peripheral blood mononuclear cells

Broccoli sprouts represent a health-promoting food, rich in antioxidant and anti-inflammatory phytochemicals, among which sulfur compounds are most extensively investigated. In this study, the phenolics of broccoli sprouts (Brassica oleracea var. italica'Cezar') were examined for variability during germination and influence on the bioactivity of sprouts. In the sprouts germinated in darkness, 31 compounds were identified by UHPLC-PDA-ESI-MS³ (18 sinapic acid derivatives, 8 glucosinolates, and 5 flavonoids) with sinapoyl components (SADs) prevailing among polyphenols. The total SADs decreased during germination (down to 4.85 mg per g dw in 6-day-sprouts), but the concurrent changes in molecular structures of the leading compounds (sinapine was replaced by sinapate sugar esters and sinapic acid) increased the antioxidant capacity of the sprouts. The glucosinolate-depleted 6-day-sprout extract (34.2 mg SADs per g dw) effectively protected human plasma components against peroxynitrite-induced oxidative damage in vitro (reduced the levels of 3-nitrotyrosine, lipid hydroperoxides and thiobarbituric acid-reactive substances) and enhanced the non-enzymatic antioxidant status of plasma. It also downregulated the release of pro-inflammatory cytokines (TNF-α, IL-6) from LPS-stimulated human peripheral blood mononuclear cells and increased the production of IL-10, an anti-inflammatory mediator. The relevant activity parameters of sinapic acid indicated that SADs might be linked to the observed effects. The results support the application of broccoli sprouts in oxidative stress- and inflammation-related diseases and the role of SADs as their bioactive components next to glucosinolates.

Protective effects of Erdosteine on interleukin-1β-stimulated inflammation via inhibiting the activation of MAPK, NF-κB, and Wnt/β-catenin signaling pathways in rat osteoarthritis

Osteoarthritis (OA), a degenerative arthropathy, is featured with progressive degradation of cartilage and a chondrocyte inflammatory response. Erdosteine (ER) showed the anti-oxidant properties and various anti-inflammatory effects in various diseases. However, whether it protects against OA remains unknown. In this study, we explore the potential therapeutic properties of ER on IL-1β-stimulated rat chondrocytes and its underlying mechanism in vitro and vivo. Cell viability, pro-inflammatory cytokines and the degradation of ECM biomarkers were tested to determine the effects of ER at 10, 20, and 40 μM doses on IL-1β-induced rat chondrocytes for 24 h in virto. In vivo, intra-articular injections of 50 μl of 100 mg/ml ER twice a week for 8 weeks. The results showed ER significantly suppressed the expressions of IL-1β-induced the production of inflammatory factors in a dose-dependent pattern (4.30-fold decrease in COX-2, p < 0.05; 4.77-fold decrease in iNOS, p < 0.05 at 40 μM in protein levels). Moreover, ER could attenuate the degradation of ECM in IL-1β-induced rat chondrocytes by repressing the expression of OA-related factors (2.40-fold decrease in ADAMTS-5, p < 0.05; 3.12-fold decrease in MMP1, p < 0.05; 3.97-fold decrease in MMP3, p < 0.05; and 2.62-fold decrease in MMP-13, p < 0.05 at 40 μM in protein levels). Furthermore, our study revealed that ER could inhibit the activations of IL-1β-induced MAPK and Wnt/β-catenin. Besides, ER could suppress the process of IL-1β-induced P65 from the cytoplasm into the nucleus. In vivo, ER delaied the osteoarthritis progression in rat OA models. Collectively, ER might become a new therapeutic agent for OA.

Chondroprotective and anti-inflammatory effects of amurensin H by regulating TLR4/Syk/NF-κB signals

The low-grade, chronic inflammation initiated by TLR4-triggered innate immune responses has a central role on early osteoarthritis. Amurensin H is a resveratrol dimer with anti-inflammatory and anti-apoptotic effects, while its effects on TLR-4 signals to inhibit osteoarthritis are still unclear. In the present study, treatment with amurensin H for 2 weeks in monosodium iodoacetate-induced mice significantly slows down cartilage degeneration and inflammation using macroscopic evaluation, haematoxylin and eosin (HE) staining and micro-magnetic resonance imaging. In IL-1β-stimulated rat chondrocytes, amurensin H suppresses the production of inflammatory mediators including nitric oxide, IL-6, IL-17, PGE2 and TNF-α using Greiss and ELISA assay. Amurensin H inhibits matrix degradation via decreasing levels of MMP-9 and MMP-13 using Western blot assay, promotes synthesis of type II collagen and glycosaminoglycan using immunostaining and safranin O staining, respectively. Amurensin H inhibits intracellular and mitochondrial reactive oxygen species (ROS) generation, and mitochondrial membrane depolarization using DCFH-DA, MitoSOX Red and JC-1 assay as well. IL-1β stimulates TLR4 activation and Syk phosphorylation in chondrocytes, while amurensin H inhibits TLR4/Syk signals and downstream p65 phosphorylation and translocation in a time and dose-dependent manner. Together, these results suggest that amurensin H exerts chondroprotective effects by attenuating oxidative stress, inflammation and matrix degradation via the TLR4/Syk/NF-κB pathway.

Quercetin alleviates rat osteoarthritis by inhibiting inflammation and apoptosis of chondrocytes, modulating synovial macrophages polarization to M2 macrophages

Osteoarthritis (OA) is a progressive joint disorder that is primarily characterized by the degeneration and destruction of the articular cartilage. Cartilage matrix degradation, production of proinflammatory mediators, chondrocyte apoptosis and activation of macrophages in the synovial are involved in OA pathogenesis. Current non-surgical therapies for OA mainly aim at relieving pain but can barely alleviate the progression of OA. Quercetin, a naturally occurring flavonoid has shown potent anti-inflammatory effects, however, its effects and underlying mechanisms on OA have seldom been systematically illuminated. In this study, we explored the protective effects of quercetin on repairing OA-induced cartilage injuries and its possible mechanisms. In vitro, quercetin remarkably suppressed the expression of matrix degrading proteases and inflammatory mediators, meantime promoted the production of cartilage anabolic factors in interleukin-1β-induced (IL-1β) rat chondrocytes. In addition, quercetin exhibited anti-apoptotic effects by decreasing intracellular reactive oxygen species (ROS), restoring mitochondrial membrane potential (MMP) and inhibiting the Caspase-3 pathway in apoptotic rat chondrocytes. Moreover, quercetin induced M2 polarization of macrophages and upregulated the expression of transforming growth factor β (TGF-β) and insulin-like growth factor (IGF), which in turn created a pro-chondrogenic microenvironment for chondrocytes and promoted the synthesis of glycosaminoglycan (GAG) in chondrocytes. In vivo, intra-articular injection of quercetin alleviated the degradation of the cartilage and the apoptosis of chondrocytes in a rat OA model. Moreover, the expression of TGF-β1 and TGF-β2 in the synovial fluid and the ratio of M2 macrophages in the synovial membrane were elevated. In summary, our study proves that quercetin exerts chondroprotective effects by inhibiting inflammation and apoptosis of chondrocytes, modulating synovial macrophages polarization to M2 macrophages and creating a pro-chondrogenic environment for chondrocytes to enhance cartilage repair under OA environment. It is suggested that quercetin may serve as a potential drug for OA treatment.

Astaxanthin protects against osteoarthritis via Nrf2: a guardian of cartilage homeostasis

Scope: Osteoarthritis (OA) is a progressive disease characterized by cartilage degradation. Astaxanthin (Ast), a natural compound with remarkable antioxidant activity and multiple medical applications due to its activation of Nrf2 signaling, has been studied for application to various degenerative diseases. Currently, however, little is known about its efficacy in treating OA. This study reports the effects of Ast on cartilage homeostasis in OA progression.

Methods: IL-1β, TNF-α, and tert-butyl hydroperoxide (TBHP) were used to impair cartilage homeostasis. Modulating effects of Ast on the Nrf2 signaling pathway, and damage-associated events including extracellular matrix (ECM) degradation, inflammation, oxidative stress, chondrocyte apoptosis, and in vivo cartilage degradation were examined.

Results: Ast attenuated ECM degradation of OA chondrocytes through the Nrf2 signaling, and ameliorated the IL-1β-induced inflammatory response and ECM degradation via blockade of MAPK signaling. Additionally, Ast alleviated TNF-α-induced ECM degradation and chondrocyte apoptosis by inhibiting the NF-κB signaling, suppressed TBHP-induced oxidative stress, and subsequently reduced chondrocyte apoptosis. In vitro results were finally corroborated in vivo by demonstrating that Ast attenuates the severity of cartilage destruction in a mouse model of OA.

Conclusions: Ast could protect against osteoarthritis via the Nrf2 signaling, suggesting Ast might be a potential therapeutic supplement for OA treatment.

Chondroprotective Effects of Genistein against Osteoarthritis Induced Joint Inflammation

Genistein is an isoflavone extracted from soybean (Glycine max). This compound has anti-inflammatory, anti-oxidative, and anti-cancer effects; however, the mechanism underlying the effects of genistein on IL-1β-stimulated human osteoarthritis (OA) chondrocytes remains unknown. Our objectives in this study were to explore the anti-inflammatory effects of genistein on IL-1β-stimulated human OA chondrocytes and to investigate the potential mechanisms which underlie them. Our results from an in-vitro model of osteoarthritis indicate that genistein inhibits the IL-1β-induced expression of the catabolic factors nitric oxide synthase 2 (NOS2), cyclooxygenase 2 (COX-2), and matrix metalloproteinases (MMPs). Genistein was shown to stimulate Ho-1 expression, which has been associated with Nrf-2 pathway activation in human chondrocytes. In a rat model, genistein was also shown to attenuate the progression of traumatic osteoarthritis. Taken together, these results demonstrate the effectiveness of genistein in mediating the inflammation associated with joint disorders. Our results also indicate that genistein could potentially serve as an alternative therapeutic treatment for OA.

The protective effect of sinapic acid in osteoarthritis: In vitro and in vivo studies

The anti-inflammatory effect of sinapic acid (SA) has been reported in several studies. However, whether SA has the same effect on osteoarthritis (OA) has yet to be clearly elucidated. We designed a series of in vitro and in vivo procedures to verify the above conjecture. Compared with controls, SA-pretreated human chondrocytes showed lower levels of interleukin (IL)-1β-induced IL-6, prostaglandin E2 (PGE2), nitric oxide (NO) and tumour necrosis factor-α (TNF-α) in vitro. Meanwhile, SA could also reverse the degradation of type II collage and aggrecan, as well as the overproduction of matrix metalloproteinase-9 (MMP-9) and matrix metalloproteinase-13 (MMP-13), inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2 and a disintegrin and metalloproteinase thrombospondin motifs (ADAMTS)-5. Furthermore, activation of nuclear factor κB (NF-κB), which was induced by IL-1β, was also inhibited by SA through the pathway of nuclear factor-erythroid 2-related factor-2 (Nrf2)/heme oxygenase 1. In vivo, SA could delay the progress of mice OA models. We propose that SA may be applied as a potential therapeutic drug in OA treatment.