PAR2-mediated epigenetic upregulation of α-synuclein contributes to the pathogenesis of Parkinson׳s disease

Inhibition of Protease-Activated Receptor-2 Activation in Parkinson's Disease Using 1-Piperidin Propionic Acid

In Parkinson's disease, neuroinflammation is a double-edged sword; when inflammation occurs it can have harmful effects, despite its important role in battling infections and healing tissue. Once triggered by microglia, astrocytes acquire a reactive state and shift from supporting the survival of neurons to causing their destruction. Activated microglia and Proteinase-activated receptor-2 (PAR2) are key points in the regulation of neuroinflammation. 1-Piperidin Propionic Acid (1-PPA) has been recently described as a novel inhibitor of PAR2. The aim of our study was to evaluate the effect of 1-PPA in neuroinflammation and microglial activation in Parkinson's disease. Protein aggregates and PAR2 expression were analyzed using Thioflavin S assay and immunofluorescence in cultured human fibroblasts from Parkinson's patients, treated or untreated with 1-PPA. A significant decrease in amyloid aggregates was observed after 1-PPA treatment in all patients. A parallel decrease in PAR2 expression, which was higher in sporadic Parkinson's patients, was also observed both at the transcriptional and protein level. In addition, in mouse LPS-activated microglia, the inflammatory profile was significantly downregulated after 1-PPA treatment, with a remarkable decrease in IL-1β, IL-6, and TNF-α, together with a decreased expression of PAR2. In conclusion, 1-PPA determines the reduction in neuroglia inflammation and amyloid aggregates formation, suggesting that the pharmacological inhibition of PAR2 could be proposed as a novel strategy to control neuroinflammation.

Gut microbiota defined epigenomes of Alzheimer's and Parkinson's diseases reveal novel targets for therapy

The origins of Alzheimer's disease (AD) and Parkinson's disease (PD) involve genetic mutations, epigenetic changes, neurotoxin exposure and gut microbiota dysregulation. The gut microbiota's dynamic composition and its metabolites influence intestinal and blood-brain barrier integrity, contributing to AD and PD development. This review explores protein misfolding, aggregation and epigenetic links in AD and PD pathogenesis. It also highlights the role of a leaky gut and the microbiota-gut-brain axis in promoting these diseases through inflammation-induced epigenetic alterations. In addition, we investigate the potential of diet, probiotics and microbiota transplantation for preventing and treating AD and PD via epigenetic modifications, along with a discussion related to current challenges and future considerations. These approaches offer promise for translating research findings into practical clinical applications.

Synucleinopathies: Intrinsic and Extrinsic Factors

α-Synucleinopathies are a group of neurodegenerative disorders characterized by alterations in α-synuclein (α-syn), a protein associated with membrane phospholipids, whose precise function in normal cells is still unknown. These kinds of diseases are caused by multiple factors, but the regulation of the α-syn gene is believed to play a central role in the pathology of these disorders; therefore, the α-syn gene is one of the most studied genes. α-Synucleinopathies are complex disorders that derive from the interaction between genetic and environmental factors. Here, we offer an update on the landscape of the epigenetic regulation of α-syn gene expression that has been linked with α-synucleinopathies. We also delve into the reciprocal influence between epigenetic modifications and other factors related to these disorders, such as posttranslational modifications, microbiota participation, interactions with lipids, neuroinflammation and oxidative stress, to promote α-syn aggregation by acting on the transcription and/or translation of the α-syn gene.

PAR2: The Cornerstone of Pancreatic Diseases

It has been 30 years since the first member of the protease-activated receptor (PAR) family was discovered. This was followed by the discovery of three other receptors, including PAR2. PAR2 is a G protein-coupled receptor activated by trypsin site-specific proteolysis. The process starts with serine proteases acting between arginine and serine, creating an N-terminus that functions as a tethered ligand that binds, after a conformational change, to the second extracellular loop of the receptor, leading to activation of G-proteins. The physiological and pathological functions of this ubiquitous receptor are still elusive. This review focuses on PAR2 activation and its distribution under physiological and pathological conditions, with a particular focus on the pancreas, a significant producer of trypsin, which is the prototype activator of the receptor. The role in acute or chronic pancreatitis, pancreatic cancer, and diabetes mellitus will be highlighted.

Inhibition of PAR-2 Attenuates Neuroinflammation and Improves Short-Term Neurocognitive Functions Via ERK1/2 Signaling Following Asphyxia-Induced Cardiac Arrest in Rats

OBJECTIVE

Global cerebral ischemia-induced neuroinflammation causes neurofunctional impairment following cardiac arrest. Previous studies have demonstrated that the activation of protease-activated receptor-2 (PAR-2) contributes to neuroinflammation. In the present study, we aimed to determine the potential treatment effect of PAR-2 inhibition against neuroinflammation in the setting of asphyxial CA (ACA) in rats.

METHODS

A total of 116 adult, male Sprague-Dawley rats were randomly divided into Sham (n = 18) and ACA (n = 98) groups. Time course, short-term outcome, and mechanism studies were conducted. All drugs were delivered intranasally. The effect of PAR-2 inhibitor FSLLRY-NH2 on neurocognitive functions was assessed by neurologic deficit score, number of seizures, and T-maze test, while hippocampal neuronal degeneration was evaluated by Fluoro-Jade C staining after ACA. Western blotting was performed for the mechanism study at 24 h following ACA. Selective PAR-2 agonist (AC55541) and ERK1/2 inhibitor (PD98059) were used for intervention.

RESULTS

Inhibition of PAR-2 decreased neuroinflammation, reduced the number of degenerating hippocampal neurons and improved neurocognitive functions following ACA. PAR-2 activator alone exerted opposite effects to PAR-2 inhibitor. PAR-2 mediated the augmented brain levels of proinflammatory cytokines by promoting the phosphorylation of ERK1/2.

CONCLUSIONS

PAR-2 inhibition diminished neuroinflammation and thereby reduced hippocampal neuronal degeneration and neurocognitive impairment following ACA. This effect was at least partly mediated via the PAR-2/ERK1/2 signaling.

Nuclear factor-kappa B (NF-κB) in pathophysiology of Parkinson disease: Diverse patterns and mechanisms contributing to neurodegeneration

Parkinson's disease (PD), the most common movement disorder, comprises several pathophysiologic mechanisms including misfolded alpha-synuclein aggregation, inflammation, mitochondrial dysfunction, and synaptic loss. Nuclear Factor-Kappa B (NF-κB), as a key regulator of a myriad of cellular reactions, is shown to be involved in such mechanisms associated with PD, and the changes in NF-κB expression is implicated in PD. Alpha-synuclein accumulation, the characteristic feature of PD pathology, is known to trigger NF-κB activation in neurons, thereby propagating apoptosis through several mechanisms. Furthermore, misfolded alpha-synuclein released from degenerated neurons, activates several signaling pathways in glial cells which culminate in activation of NF-κB and production of pro-inflammatory cytokines, thereby aggravating neurodegenerative processes. On the other hand, NF-κB activation, acting as a double-edged sword, can be necessary for survival of neurons. For instance, NF-κB activation is necessary for competent mitochondrial function and deficiency in c-Rel, one of the NF-κB proteins, is known to propagate DA neuron loss via several mechanisms. Despite the dual role of NF-κB in PD, several agents by selectively modifying the mechanisms and pathways associated with NF-κB, can be effective in attenuating DA neuron loss and PD, as reviewed in this paper.

Immune Profiling of Parkinson's Disease Revealed Its Association With a Subset of Infiltrating Cells and Signature Genes

Parkinson’s disease (PD) is an age-related and second most common neurodegenerative disorder. In recent years, increasing evidence revealed that peripheral immune cells might be able to infiltrate into brain tissues, which could arouse neuroinflammation and aggravate neurodegeneration. This study aimed to illuminate the landscape of peripheral immune cells and signature genes associated with immune infiltration in PD. Several transcriptomic datasets of substantia nigra (SN) from the Gene Expression Omnibus (GEO) database were separately collected as training cohort, testing cohort, and external validation cohort. The immunoscore of each sample calculated by single-sample gene set enrichment analysis was used to reflect the peripheral immune cell infiltration and to identify the differential immune cell types between PD and healthy participants. According to receiver operating characteristic (ROC) curve analysis, the immunoscore achieved an overall accuracy of the area under the curve (AUC) = 0.883 in the testing cohort, respectively. The immunoscore displayed good performance in the external validation cohort with an AUC of 0.745. The correlation analysis and logistic regression analysis were used to analyze the correlation between immune cells and PD, and mast cell was identified most associated with the occurrence of PD. Additionally, increased mast cells were also observed in our in vivo PD model. Weighted gene co-expression network analysis (WGCNA) was used to selected module genes related to a mast cell. The least absolute shrinkage and selection operator (LASSO) analysis and random-forest analysis were used to analyze module genes, and two hub genes RBM3 and AGTR1 were identified as associated with mast cells in the training cohort. The expression levels of RBM3 and AGTR1 in these cohorts and PD models revealed that these hub genes were significantly downregulated in PD. Moreover, the expression trend of the aforementioned two genes differed in mast cells and dopaminergic (DA) neurons. In conclusion, this study not only exhibited a landscape of immune infiltrating patterns in PD but also identified mast cells and two hub genes associated with the occurrence of PD, which provided potential therapeutic targets for PD patients (PDs).

Imbalance of Lysine Acetylation Contributes to the Pathogenesis of Parkinson's Disease

Parkinson’s disease (PD) is one of the most common neurodegenerative disorders. The neuropathological features of PD are selective and progressive loss of dopaminergic neurons in the substantia nigra pars compacta, deficiencies in striatal dopamine levels, and the presence of intracellular Lewy bodies. Interactions among aging and genetic and environmental factors are considered to underlie the common etiology of PD, which involves multiple changes in cellular processes. Recent studies suggest that changes in lysine acetylation and deacetylation of many proteins, including histones and nonhistone proteins, might be tightly associated with PD pathogenesis. Here, we summarize the changes in lysine acetylation of both histones and nonhistone proteins, as well as the related lysine acetyltransferases (KATs) and lysine deacetylases (KDACs), in PD patients and various PD models. We discuss the potential roles and underlying mechanisms of these changes in PD and highlight that restoring the balance of lysine acetylation/deacetylation of histones and nonhistone proteins is critical for PD treatment. Finally, we discuss the advantages and disadvantages of different KAT/KDAC inhibitors or activators in the treatment of PD models and emphasize that SIRT1 and SIRT3 activators and SIRT2 inhibitors are the most promising effective therapeutics for PD.

HSPA8 knock-down induces the accumulation of neurodegenerative disorder-associated proteins

Heat shock protein 70 family was demonstrated to play a critical role in protein homeostasis, a process profoundly impaired in neurodegenerative disorders. Neurodegenerative diseases are characterized by the accumulation of different kind of proteins and the formation of insoluble aggregates which are toxic for neurons. To explore the role of heat shock protein family 70 (in particular HSPA8 and HSPA1A) in the accumulation of proteins implied in neurodegeneration pathogenesis, in this study we verified in human SH-SY5Y neuroblastoma cells how HSPA8 or HSPA1A knock-down can affect protein levels of tau, superoxide dismutase 1 and α-synuclein. We found HSPA8 and HSPA1A reduction caused an increase of tau, superoxide dismutase 1 and α-synuclein protein levels. We also noticed HSPA8 knock-down increased α-synuclein oligomeric forms and mRNA expression. Our results suggest HSPA8 can play an important role in the homeostasis of tau, superoxide dismutase 1 and α-synuclein and in the balance between α-synuclein oligomeric and monomeric forms.

Mast Cell Activation, Neuroinflammation, and Tight Junction Protein Derangement in Acute Traumatic Brain Injury

Traumatic brain injury (TBI) is one of the major health problems worldwide that causes death or permanent disability through primary and secondary damages in the brain. TBI causes primary brain damage and activates glial cells and immune and inflammatory cells, including mast cells in the brain associated with neuroinflammatory responses that cause secondary brain damage. Though the survival rate and the neurological deficiencies have shown significant improvement in many TBI patients with newer therapeutic options, the underlying pathophysiology of TBI-mediated neuroinflammation, neurodegeneration, and cognitive dysfunctions is understudied. In this study, we analyzed mast cells and neuroinflammation in weight drop-induced TBI. We analyzed mast cell activation by toluidine blue staining, serum chemokine C-C motif ligand 2 (CCL2) level by enzyme-linked immunosorbent assay (ELISA), and proteinase-activated receptor-2 (PAR-2), a mast cell and inflammation-associated protein, vascular endothelial growth factor receptor 2 (VEGFR2), and blood-brain barrier tight junction-associated claudin 5 and Zonula occludens-1 (ZO-1) protein expression in the brains of TBI mice. Mast cell activation and its numbers increased in the brains of 24 h and 72 h TBI when compared with sham control brains without TBI. Mouse brains after TBI show increased CCL2, PAR-2, and VEGFR2 expression and derangement of claudin 5 and ZO-1 expression as compared with sham control brains. TBI can cause mast cell activation, neuroinflammation, and derangement of tight junction proteins associated with increased BBB permeability. We suggest that inhibition of mast cell activation can suppress neuroimmune responses and glial cell activation-associated neuroinflammation and neurodegeneration in TBI.

Glia Maturation Factor and Mast Cell-Dependent Expression of Inflammatory Mediators and Proteinase Activated Receptor-2 in Neuroinflammation

Parkinson's disease (PD) is characterized by the presence of inflammation-mediated dopaminergic neurodegeneration in the substantia nigra. Inflammatory mediators from activated microglia, astrocytes, neurons, T-cells and mast cells mediate neuroinflammation and neurodegeneration. Administration of neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induces PD like motor deficits in rodents. 1-methyl-4-phenylpyridinium (MPP+), a toxic metabolite of MPTP activates glial cells, neurons and mast cells to release neuroinflammatory mediators. Glia maturation factor (GMF), mast cells and proteinase activated receptor-2 (PAR-2) are implicated in neuroinflammation. Alpha-synuclein which induces neurodegeneration increases PAR-2 expression in the brain. However, the exact mechanisms are not yet understood. In this study, we quantified inflammatory mediators in the brains of MPTP-administered wild type (Wt), GMF-knockout (GMF-KO), and mast cell knockout (MC-KO) mice. Additionally, we analyzed the effect of MPP+, GMF, and mast cell proteases on PAR-2 expression in astrocytes and neurons in vitro. Results show that the levels of interleukin-1beta (IL-1β), tumor necrosis factor-alpha (TNF-α), and the chemokine (C-C motif) ligand 2 (CCL2) were lesser in the brains of GMF-KO mice and MC-KO mice when compared to Wt mice brain after MPTP administration. Incubation of astrocytes and neurons with MPP+, GMF, and mouse mast cell protease-6 (MMCP-6) and MMCP-7 increased the expression of PAR-2. Our studies show that the absence of mast cells and GMF reduce the expression of neuroinflammatory mediators in the brain. We conclude that GMF along with mast cell interactions with glial cells and neurons during neuroinflammation can be explored as a new therapeutic target for PD and other neuroinflammatory disorders.

A role for DJ-1 against oxidative stress in the mammalian retina

We have previously reported the expression of Parkinson disease-associated genes encoding α-synuclein, parkin and UCH-L1 in the retina across mammals. DJ-1, or parkinsonism-associated deglycase, is a redox-sensitive protein with putative roles in cellular protection against oxidative stress, among a variety of functions, acting through distinct pathways and mechanisms in a wide variety of tissues. Its function in counteracting oxidative stress in the retina, as it occurs in Parkinson and other human neurodegenerative diseases, is, however, poorly understood. In the present study, we address the expression of DJ-1 in the mammalian retina and its putative neuroprotective role in this tissue in a well-known model of parkinsonism, the rotenone-treated rat. As a result, we demonstrate that the DJ1 gene is expressed at both mRNA and protein levels in the neural retina and retinal pigment epithelium (RPE) of all mammalian species studied. We also present evidence that DJ-1 functions in the retina as a sensor of cellular redox homeostasis, which reacts to oxidative stress by increasing its intracellular levels and additionally becoming oxidized. Levels of α-synuclein also became upregulated, although parkin and UCH-L1 expression remained unchanged. It is inferred that DJ-1 likely exerts in the retina a potential neuroprotective role against oxidative stress, including α-synuclein oxidation and aggregation, which should be operative under both physiological and pathological conditions.

Toll-like receptor 4 and protease-activated receptor 2 in physiology and pathophysiology of the nervous system: more than just receptor cooperation?

Toll-like receptor 4 (TLR4) and protease-activated receptor 2 (PAR2) play pivotal roles in the mammalian innate immune response. Notably, in addition to their involvement in detection of invading pathogens, PAR2 and TLR4 modulate the levels of cell death-induced sterile inflammation by activating pro- or anti-inflammatory downstream signaling cascades. Within the central nervous system, there is emerging evidence that both receptors are involved in synaptic transmission and brain plasticity. Furthermore, due to their prominent role in mediating neuroinflammation, PAR2 and TLR4 are associated with development and progression of neurodegenerative disorders including but not limited to Alzheimer’s disease, Parkinson’s disease and multiple sclerosis. In this article, we summarise the current knowledge on the cooperation between PAR2 and TLR4, discuss the potential cross-talk levels and highlight the impact of the cross-coupling on neuroinflammation.

Interleukin-1β, interleukin-1 receptor antagonist, interleukin-6, interleukin-10, and tumor necrosis factor-α levels in CSF and serum in relation to the clinical diversity of Parkinson's disease

Several parameters representing the clinical diversity of Parkinson's disease (PD), including severity, phenotypes, cognitive decline, anxiety and depression were analyzed to examine the link with interleukin-1β (IL-1β), the interleukin-1 receptor antagonist (IL-1RA), IL-6, IL-10, and tumor necrosis factor-α (TNFα) and also to determine the relationship between levels of these factors in serum and cerebrospinal fluid (CSF). Significantly elevated serum IL-1β and IL-6 and reduced IL-1RA levels were found in the PD group. In CSF and serum, inflammatory factors behaved differently, with increased CSF TNFα indicating rapid PD progression, and increased IL-1β in serum. A low level of IL-6 was associated with a longer duration of PD. Anxiety, depression, non-tremor phenotype and late-onset PD correlated with a high serum level of IL-10. The serum TNFα level was lower in PD patients with mild cognitive impairment compared to controls. Serum IL-1β, IL-6 and IL-10 levels correlated with CSF markers.

Genetic risk factors in thrombotic primary antiphospholipid syndrome: A systematic review with bioinformatic analyses

BACKGROUND

Antiphospholipid Syndrome (APS) is an autoimmune multifactorial disorder. Genetics is believed to play a contributory role in the pathogenesis of APS, especially in thrombosis development and pregnancy morbidity. In the last 20 years, extensive research on genetic contribution on APS indicates that APS is a polygenic disorder, where a number of genes are involved in the development of its clinical manifestations.

AIMS

The aim of this systematic review is to evaluate the genetic risk factors in thrombotic primary APS. Additionally, to assess the common molecular functions, biological processes, pathways, interrelations with the gene encoded proteins and RNA-Seq-derived expression patterns over different organs of the associated genes via bioinformatic analyses.

METHODS

Without restricting the year, a systematic search of English articles was conducted (up to 4th September 2017) using Web of Science, PubMed, Scopus, ScienceDirect and Google Scholar databases. Eligible studies were selected based on the inclusion criteria. Two researchers independently extracted the data from the included studies. Quality assessment of the included studies was carried out using a modified New-Castle Ottawa scale (NOS).

RESULTS

From an initial search result of 2673 articles, 22 studies were included (1268 primary APS patients and 1649 healthy controls). Twenty-two genes were identified in which 16 were significantly associated with thrombosis in primary APS whereas six genes showed no significant association with thrombosis. Based on the NOS, 14 studies were of high quality while 6 were low quality studies. From the bioinformatic analyses, thrombin-activated receptor activity (q = 6.77 × 10^-7), blood coagulation (q = 2.63 × 10^-15), formation of fibrin clot (q = 9.76 × 10^-10) were the top hit for molecular function, biological process and pathway categories, respectively. With the highest confidence interaction score of 0.900, all of the thrombosis-associated gene encoded proteins of APS were found to be interconnected except for two. Based on the pathway analysis, cumulatively all the genes affect haemostasis [false discovery rate (FDR) = 1.01 × 10^-8] and the immune system [FDR = 9.93 × 10^-2]. Gene expression analysis from RNA-Seq data revealed that almost all the genes were expressed in 32 different tissues in the human body.

CONCLUSION

According to our systematic review, 16 genes contribute significantly in patients with thrombotic primary APS when compared with controls. Bioinformatic analyses of these genes revealed their molecular interconnectivity in protein levels largely by affecting blood coagulation and immune system. These genes are expressed in 32 different organs and may pose higher risk of developing thrombosis anywhere in the body of primary APS patients.

Deregulation of α-synuclein in Parkinson's disease: Insight from epigenetic structure and transcriptional regulation of SNCA

Understanding regulation of α-synuclein has long been a central focus for Parkinson's disease (PD) researchers. Accumulation of this protein in the Lewy body or neurites, mutations in the coding region of the gene and strong association of α-synuclein encoding gene multiplication (duplication/triplication) with familial form of PD have indicated the importance of this molecule in pathogenesis of the disease. Several years of research identified many potential faulty pathways associated with accumulation of α-synuclein inside dopaminergic neurons and its transmission to neighboring ones. Concurrently, an appreciable body of research is growing to understand the epigenetic and genetic deregulation of α-synuclein that might contribute to the disease pathology. Completion of the ENCODE (Encyclopedia of DNA Elements) project and recent advancement made in the epigenetic and trans factor mediated regulation of each gene, has tremendously accelerated the need to carefully understand the epigenetic structure of the gene (SNCA) encoding α-synuclein protein in order to decipher the regulation and contribution of α-synuclein to the pathogenesis of PD. We have also analyzed the detailed epigenetic structure of this gene with knowledge from ENCODE database, which may open new avenues in α-synuclein research. Interestingly, we have found that the gene contains several transcriptionally activate histone modifications and associated potential transcription factor binding sites in the non-coding areas that strongly suggest alternative regulatory pathways. Altogether this review will provide interesting insight of α-synuclein gene regulation from epigenetic, genetic and post-transcriptional perspectives and their potential implication in the PD pathogenesis.

Altered Expression of Brain Proteinase-Activated Receptor-2, Trypsin-2 and Serpin Proteinase Inhibitors in Parkinson's Disease

Neuroinflammation is thought to contribute to cell death in neurodegenerative disorders, but the factors involved in the inflammatory process are not completely understood. Proteinase-activated receptor-2 (PAR2) expression in brain is increased in Alzheimer's disease and multiple sclerosis, but the status of PAR2 in Parkinson's disease is unknown. This study examined expression of PAR2 and endogenous proteinase activators (trypsin-2, mast cell tryptase) and proteinase inhibitors (serpin-A5, serpin-A13) in areas vulnerable and resistant to neurodegeneration in Parkinson's disease at different Braak α-synuclein stages of the disease in post-mortem brain. In normal aged brain, expression of PAR-2, trypsin-2, and serpin-A5 and serpin-A13 was found in neurons and microglia, and alterations in the amount of immunoreactivity for these proteins were found in some brain regions. Namely, there was a decrease in neurons positive for serpin-A5 in the dorsal motor nucleus, and serpin-A13 expression was reduced in the locus coeruleus and primary motor cortex, while expression of PAR2, trypsin-2 and both serpins was reduced in neurons within the substantia nigra. There was an increased number of microglia that expressed serpin-A5 in the dorsal motor nucleus of vagus and elevated numbers of microglia that expressed serpin-A13 in the substantia nigra of late Parkinson's disease cases. The number of microglia that expressed trypsin-2 increased in primary motor cortex of incidental Lewy body disease cases. Analysis of Parkinson's disease cases alone indicated that serpin-A5 and serpin-A13, and trypsin-2 expression in midbrain and cerebral cortex was different in cases with a high incidence of L-DOPA-induced dyskinesia and psychosis compared to those with low levels of these treatment-induced side effects. This study showed that there was altered expression in brain of PAR2 and some proteins that can control its function in Parkinson's disease. Given the role of PAR2 in neuroinflammation, drugs that mitigate these changes may be neuroprotective when administered to patients with Parkinson's disease.

Biological evaluation of synthetic chalcone and flavone derivatives as anti-inflammatory agents

Flavonoids and chalcones are natural plant derived compounds with inherent therapeutic value for a range of human pathologies. In this study, a series of 24 substituted chalcones and flavones were synthesized and subsequently screened for anti-inflammatory effects on lipopolysaccharide (1 µg/ml)-activated BV-2 microglial cells by assessing initial production/release of nitric oxide (NO). The data obtained eliminate the majority of compounds as weak or non-effective, whereas 2'-hydroxy-3,4,5,3',4'-pentamethoxychalcone (1) and 2'-hydroxy-3,4,5-trimethoxychalcone (2) were potent, having an IC50 of 1.10 and 2.26 µM, respectively; with greater potency than L-N6-(1-iminoethyl)lysine selective iNOS inhibitor (IC50 = 3.1 µM) but less than steroidal dexamethasone (IC50 < 200 nM). The most potent compound (chalcone 1) attenuated NO parallel to reducing iNOS protein expression, events also corresponding to reduction of IL-1α, IL-10 and IL-6 pro-inflammatory cytokines. These findings suggest that the presence of electron donating groups OH and OCH3 on both A and B rings of synthetic compounds correlate to stronger anti-inflammatory potency.