Novel Isoalantolactone-Based Derivatives as Potent NLRP3 Inflammasome Inhibitors: Design, Synthesis, and Biological Characterization.

The NLRP3 inflammasome has been recognized as a promising therapeutic target in drug discovery for inflammatory diseases. Our initial research identified a natural sesquiterpene isoalantolactone (IAL) as the active scaffold targeting NLRP3 inflammasome. To improve its activity and metabolic stability, a total of 64 IAL derivatives were designed and synthesized. Among them, compound 49 emerged as the optimal lead, displaying the most potent inhibitory efficacy on nigericin-induced IL-1ß release in THP-1 cells, with an IC50 value of 0.29 µM, approximately 27-fold more potent than that of IAL (IC50: 7.86 µM), and exhibiting higher metabolic stability. Importantly, 49 remarkably improved DSS-induced ulcerative colitis in vivo. Mechanistically, we demonstrated that 49 covalently bound to cysteine 279 in the NACHT domain of NLRP3, thereby inhibiting the assembly and activation of NLRP3 inflammasome. These results provided compelling evidence to further advance the development of more potent NLRP3 inhibitors based on this scaffold.

Exploring the Immunomodulatory Properties of Red Onion (Allium cepa L.) Skin: Isolation, Structural Elucidation, and Bioactivity Study of Novel Onion Chalcones Targeting the A2A Adenosine Receptor.

Onions are versatile and nutritious food widely used in various cuisines around the world. In our ongoing pursuit of bioactive substances with health benefits from red onion (Allium cepa L.) skin, a comprehensive chemical investigation was undertaken. Consequently, a total of 44 compounds, including three previously unidentified chalcones (1-3) were extracted from red onion skin. Of these isolates, chalcones 1-4 showed high affinity to A2A adenosine receptor (A2AAR), and chalcone 2 displayed the best binding affinity to A2AAR, with the IC50 value of 33.5 nM, good A2AAR selectivity against A1AR, A2BAR, and A3AR, and high potency in the cAMP functional assay (IC50 of 913.9 nM). Importantly, the IL-2 bioassay and the cell-mediated cytotoxicity assay demonstrated that chalcone 2 could boost T-cell activation. Furthermore, the binding mechanism of chalcone 2 with hA2AAR was elucidated by molecular docking. This work highlighted that the active chalcones in red onion might have the potential to be developed as A2AAR antagonists used in cancer immunotherapy.

An epigenetic modifier enhances the generation of anti-phytopathogenic compounds from the endophytic fungus Chaetomium globosporum of Euphorbia humifusa.

Endophytic fungi are striking resources rich in bioactive structures with agrochemical significance. In order to maximize the opportunity of search for bioactive compounds, chemical epigenetic manipulation was introduced to enhance the structural diversity of the fungal products, and an UPLC-ESIMS and bioassay-guided separation was used to detect novel bioactive metabolites. Consequently, four previously undescribed compounds including two cyclopentenones (globosporins A and B) and two monoterpenoid indole alkaloids (globosporines C and D), as well as three known compounds, were isolated from the endophytic fungus Chaetomium globosporum of Euphorbia humifusa by exposure to a DNA methyltransferase inhibitor 5-azacytidine. Their structures including the absolute configurations were elucidated by the analysis of NMR spectroscopic data, HRESIMS, and TD-DFT-ECD calculations. The indole alkaloids (globosporines C and D) showed antimicrobial activities against three phytopathogenic microbes (Xanthomonas oryzae pv. oryzae, X. oryzae pv. oryzicola, and Pseudomonas syringae pv. lachrymans) with MICs in the range of 14-72 µg/mL. Mostly, globosporine D was proved to be potently anti-phytopathogenic against X. oryzae pv. oryzae in vitro and in vivo, which suggested that it has the potential to be developed as a candidate for the prevention of rice bacterial leaf blight. This work provides an efficient and environmentally friendly approach for expanding fungal products with agricultural importance.

The ethanolic extract of Artemisia anomala exerts anti-inflammatory effects via inhibition of NLRP3 inflammasome.

BACKGROUND: Artemisia anomala S. Moore (Compositae), known as "Nan-Liu-Ji-Nu" in traditional Chinese medicine (TCM), has been used to treat many inflammatory diseases, including enteritis, acute icteric hepatitis, rheumatism, toothache, tonsillitis, and chronic bronchitis, for centuries. Our preliminary studies have demonstrated that the ethanolic extract of A. anomala (EAA) might be with the potential of inhibiting the activation of the NLRP3 inflammasome. However, the anti-inflammatory activity of EAA based on NLRP3 inflammasome inhibition is still unclear. PURPOSE: This work aimed to elucidate the anti-inflammatory mechanism of EAA by inhibiting NLRP3 inflammasome activation. METHODS: Lipopolysaccharide (LPS)-primed bone marrow-derived macrophages (BMDMs) were used to evaluate the inhibitory effects on NLRP3 inflammasome activation. The level of IL-1ß was determined by ELISA. The expression levels of IL-1ß, caspase-1, NLRP3, and ASC were assayed using western blot analysis. ASC oligomerization and speck formation were detected by immunofluorescence microscopy. The measurements of intracellular chloride and potassium were conducted using N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide (MQAE) probe assay and inductively coupled plasma-optical emission spectrometry (ICP-OES), respectively. Mitochondrial reactive oxygen species (mtROS) were examined using the MitoSOX method. Acridine orange (AO) staining was used to detect the permeability of the lysosomal membrane. A DSS-induced ulcerative colitis model was established to evaluate the anti-inflammatory effects of EAA in vivo. Finally, high-performance liquid chromatography (HPLC) was employed to identify and quantify the major constituents of EAA. RESULTS: In BMDMs, EAA significantly inhibited the release of IL-1ß induced by LPS. The mechanistic study revealed that EAA inhibited NLRP3 inflammasome activation by blocking the oligomerization of ASC and suppressed the LPS-induced priming step. Furthermore, EAA protected lysosomes by inhibiting the TAK1-JNK pathway, thereby inhibiting the assembly of downstream NLRP3 inflammasome and the production of IL-1ß. In addition, EAA exerted potent protective effects in an ulcerative colitis model by decreasing the content of colonic IL-1ß and alleviating the process of ulcerative colitis. HPLC analysis identified eight main components of EAA, including isofraxidin (1), quercetin-7-O-ß-D-glucopyranoside (2), apigenin-7-O-ß-D-glucopyranoside (3), 7-methoxycoumarin (4), quercetin (5), luteolin (6), kaempferol (7), and eupatorin (8), Of these compounds, quercetin and kaempferol were found to be the most potent ingredients. CONCLUSION: These findings collectively reveal that EAA exerts anti-inflammatory effects by both suppressing the NLRP3 priming step and protecting lysosomes to inhibit NLRP3 inflammasome activation, suggesting that this traditional herbal medicine might be used to treat NLRP3-driven inflammatory diseases.

Modulation of LPS-induced inflammation in RAW264.7 murine cells by novel isoflavonoids from Millettia pulchra.

Millettia pulchra is a renowned anti-inflammatory herbal medicine in southeast provinces of China. However, the underlying anti-inflammation mechanism remained incompletely understood. Herein, four new isoflavones, pulvones A-D and eleven reported constituents were isolated from the stems of Millettia pulchra with their structures being elucidated by HRMS and NMR analysis. The anti-inflammatory activities of pulvones A and C were further evaluated due to the better inhibitory activity on nitric oxide production in LPS-stimulated RAW264.7 cells and no obvious cytotoxicity to RAW264.7 cells. Western blot showed that pulvones A significantly decreased the levels of iNOS and COX-2 proteins and pulvones C only decreased the level of iNOS protein. ELISA analysis demonstrated that pulvones A inhibited the production of both interleukin-6 (IL-6) and IL-1ß while pulvones C showed better suppression effect on IL-1ß production in LPS-stimulated RAW264.7 cells. Then, their potential inhibitory effects on NF-κB pathway were tested in LPS-stimulated RAW264.7 cells. Immunofluorescence and western blot assay showed that pulvones A and C reduced the nuclear translocation of NF-κB(p65) and interrupted IκB phosphorylation. The ADP-Glo™ kinase assay showed pulvones A and C could directedly inhibit the IKKß kinase activity with the inhibitory rate of 40%, which were also verified by docking study. Collectively, these results suggested that pulvones A and C's anti-inflammatory effects were relevant to the interruption of NF-κB activation by inhibiting IKKß kinase.

Mitochondrial Ferritin Is a Hypoxia-Inducible Factor 1α-Inducible Gene That Protects from Hypoxia-Induced Cell Death in Brain.

Aims: Mitochondrial ferritin (protein [FtMt]) is preferentially expressed in cell types of high metabolic activity and oxygen consumption, which is consistent with its role of sequestering iron and preventing oxygen-derived redox damage. As of yet, the mechanisms of FtMt regulation and the protection FtMt affords remain largely unknown. Results: Here, we report that hypoxia-inducible factor 1α (HIF-1α) can upregulate FtMt expression. We verify one functional hypoxia-response element (HRE) in the positive regulatory region and two HREs possessing HIF-1α binding activity in the minimal promoter region of the human FTMT gene. We also demonstrate that FtMt can alleviate hypoxia-induced brain cell death by sequestering uncommitted iron, whose levels increase with hypoxia in these cells. Innovation: In the absence of FtMt, this catalytic metal excess catalyzes the production of cytotoxic reactive oxygen species. Conclusion: Thus, the cell ability to increase expression of FtMt during hypoxia may be a skill to avoid tissue damage derived from oxygen limitation.

Carbon nanoparticles facilitate lymph nodes dissection and parathyroid glands identification in reoperation of papillary thyroid cancer.

The aim of the study was to investigate whether carbon nanoparticles (CNs) can improve the dissection of lymph nodes and protect parathyroid glands (PGs) during reoperation for patients with papillary thyroid carcinoma (PTC).PTC patients who previously underwent thyroidectomy and later received reoperation between January 2009 and January 2016 were retrospectively recruited. We compared the patients who had CN suspension injected into the residual thyroid gland with a control group of patients who did not have the injection. The primary endpoints were the number of lymph nodes dissected, the number of PGs identified and reimplanted, and the rate of postoperative hypoparathyroidism.CN suspension injection was conducted in 55 of 174 patients. The total number of lymph nodes and metastatic lymph nodes dissected between the 2 groups were not different (22.8 ±â€Š13.7 vs 21.0 ±â€Š13.3, P = .481 and 5.5 ±â€Š3.8 vs 4.8 ±â€Š4.0, P = .695). The number of central lymph nodes and metastatic central lymph nodes in the CN group was significantly higher than those dissected in the control group (8.7 ±â€Š6.9 vs 6.2 ±â€Š5.2, P = .037 and 2.7 ±â€Š1.9 vs 2.1 ±â€Š1.6, P = .012). More PGs were identified (2.42 ±â€Š1.15 vs 1.58 ±â€Š1.12, P = .001) and fewer were reimplanted (48 vs 90, P = .040) in the CN group. Patients who had CN suspension injection had a lower rate of transient hypoparathyroidism (14/55 vs 50/119, P = .043) but no significant difference in the rate of permanent hypoparathyroidism (1/55 vs 9/119, P = .173).CN suspension injection improves dissection of central lymph nodes and identification of PG in PTC patients undergoing reoperation and lowers the rate of postoperative transient hypoparathyroidism.

Mitochondrial Ferritin Protects Hydrogen Peroxide-Induced Neuronal Cell Damage.

Oxidative stress and iron accumulation are tightly associated with neurodegenerative diseases. Mitochondrial ferritin (FtMt) is identified as an iron-storage protein located in the mitochondria, and its role in regulation of iron hemeostasis in neurodegenerative diseases has been reported. However, the role of FtMt in hydrogen peroxide (H2O2)-induced oxidative stress and iron accumulation in neuronal cells has not been studied. Here, we overexpressed FtMt in neuroblastoma SH-SY5Y cells and induced oxidative stress by treating with extracellular H2O2. We found that overexpression of FtMt significantly prevented cell death induced by H2O2, particularly the apoptosis-dependent cell death. The protective effects involved inhibiting the generation of cellular reactive oxygen species, sustaining mitochondrial membrane potential, maintaining the level of anti-apoptotic protein Bcl-2, and inhibiting the activation of pro-apoptotic protein caspase 3. We further explored the mechanism of these protective effects and found that FtMt expression markedly altered iron homeostasis of the H2O2 treated cells as compared to that of controls. The FtMt overexpression significantly reduced cellular labile iron pool (LIP) and protected H2O2-induced elevation on LIP. While in H2O2 treated SH-SY5Y cells, the increased iron uptake and reduced iron release, in correlation with levels of DMT1(-IRE) and ferroportin 1, resulted in heavy iron accumulation, the FtMt overexpressing cells didn't show any significant changes in levels of iron transport proteins and in the level of LIP. These results implicate a neuroprotective role of FtMt on H2O2-induced oxidative stress, which may provide insights into the treatment of iron accumulation associated neurodegenerative diseases.

The Protective Role of Mitochondrial Ferritin on Erastin-Induced Ferroptosis.

Ferroptosis, a newly identified form of regulated cell death, is characterized by overwhelming iron-dependent accumulation of lethal lipid reactive oxygen species (ROS). Preventing cellular iron overload by reducing iron uptake and increasing iron storage may contribute to inhibit ferroptosis. Mitochondrial ferritin (FtMt) is an iron-storage protein that is located in the mitochondria, which has a significant role in modulating cellular iron metabolism. Recent studies showed that FtMt played inhibitory effects on oxidative stress-dependent neuronal cell damage. However, the potential role of FtMt in the progress of ferroptosis in neuronal cells has not been studied. To explore this, we established ferroptosis models of cell and drosophila by erastin treatment. We found that overexpression of FtMt in neuroblastoma SH-SY5Y cells significantly inhibited erastin-induced ferroptosis, which very likely was achieved by regulation of iron homeostasis. Upon erastin treatment, significant increases of cellular labile iron pool (LIP) and cytosolic ROS were observed in wild-type SH-SY5Y cells, but not in the FtMt-overexpressed cells. Consistent with that, the alterations of iron-related proteins in FtMt-overexpressed cells were different from that of the control cells. We further investigated the role of FtMt in erastin-induced ferroptosis in transgenic drosophila. We found that the wild-type drosophilas fed an erastin-containing diet didn't survive more than 3 weeks. In contrast, the FtMt overexpressing drosophilas fed the same diet were survival very well. These results indicated that FtMt played a protective role in erastin-induced ferroptosis.

Mitochondrial ferritin attenuates ß-amyloid-induced neurotoxicity: reduction in oxidative damage through the Erk/P38 mitogen-activated protein kinase pathways.

AIMS: Mitochondrial ferritin (MtFt), which was recently discovered, plays an important role in preventing neuronal damage in 6-hydroxydopamine-induced Parkinsonism by maintaining mitochondrial iron homeostasis. Disruption of iron regulation also plays a key role in the etiology of Alzheimer's disease (AD). To explore the potential neuroprotective roles of MtFt, rats and cells were treated with Aß(25-35) to establish an AD model. RESULTS: We report that knockdown of MtFt expression significantly enhanced Aß(25-35)-induced neurotoxicity as shown by dysregulation of iron homeostasis, enhanced oxidative stress, and increased cell apoptosis. Opposite results were obtained when MtFt was overexpressed in SH-SY5Y cells prior to treatment with Aß(25-35). Further, MtFt inhibited Aß(25-35)-induced P38 mitogen-activated protein kinase and activated extracellular signal-regulated kinase (Erk) signaling. INNOVATION: MtFt attenuated Aß(25-35)-induced neurotoxicity and reduced oxidative damage through Erk/P38 kinase signaling. CONCLUSION: Our results show a protective role of MtFt in AD and suggest that regulation of MtFt expression in neuronal cells may provide a new neuroprotective strategy for AD.

Hepcidin is involved in iron regulation in the ischemic brain.

Oxidative stress plays an important role in neuronal injuries caused by cerebral ischemia. It is well established that free iron increases significantly during ischemia and is responsible for oxidative damage in the brain. However, the mechanism of this ischemia-induced increase in iron is not completely understood. In this report, the middle cerebral artery occlusion (MCAO) rat model was performed and the mechanism of iron accumulation in cerebral ischemia-reperfusion was studied. The expression of L-ferritin was significantly increased in the cerebral cortex, hippocampus, and striatum on the ischemic side, whereas H-ferritin was reduced in the striatum and increased in the cerebral cortex and hippocampus. The expression level of the iron-export protein ferroportin1 (FPN1) significantly decreased, while the expression of transferrin receptor 1 (TfR1) was increased. In order to elucidate the mechanisms of FPN1 regulation, we studied the expression of the key regulator of FPN1, hepcidin. We observed that the hepcidin level was significantly elevated in the ischemic side of the brain. Knockdown hepcidin repressed the increasing of L-ferritin and decreasing of FPN1 invoked by ischemia-reperfusion. The results indicate that hepcidin is an important contributor to iron overload in cerebral ischemia. Furthermore, our results demonstrated that the levels of hypoxia-inducible factor-1α (HIF-1α) were significantly higher in the cerebral cortex, hippocampus and striatum on the ischemic side; therefore, the HIF-1α-mediated TfR1 expression may be another contributor to the iron overload in the ischemia-reperfusion brain.

Neuroprotective mechanism of mitochondrial ferritin on 6-hydroxydopamine-induced dopaminergic cell damage: implication for neuroprotection in Parkinson's disease.

Neuronal iron homeostasis disruption and oxidative stress are closely related to the pathogenesis of Parkinson's disease (PD). Adult iron-regulatory protein 2 knockout (Ireb2(-/-)) mice develop iron accumulation in white matter tracts and nuclei in different brain area and display severe neurodegeneration in Purkinje cells of the cerebrum. Mitochondrial ferritin (MtFt), a newly discovered ferritin, specifically expresses in high energy-consuming cells, including neurons of brain and spinal cord. Interestingly, the decreased expression of MtFt in cerebrum, but not in striatum, matches the differential neurodegeneration pattern in these Ireb2(-/-) mice. To explore its effect on neurodegeneration, the effects of MtFt expression on 6-hydrodopamine (6-OHDA)-induced neuronal damage was examined. The overexpression of MtFt led to a cytosolic iron deficiency in the neuronal cells and significantly prevented the alteration of iron redistribution induced by 6-OHDA. Importantly, MtFt strongly inhibited mitochondrial damage, decreased production of the reactive oxygen species and lipid peroxidation, and dramatically rescued apoptosis by regulating Bcl-2, Bax and caspase-3 pathways. In conclusion, this study demonstrates that MtFt plays an important role in preventing neuronal damage in an 6-OHDA-induced parkinsonian phenotype by maintaining iron homeostasis. Regulation of MtFt expression in neuronal cells may provide a new neuroprotective strategy for PD.

Hepcidin, an antimicrobial peptide is downregulated in ceruloplasmin-deficient mice.

Hepcidin, a principle regulator of iron metabolism, is synthesized by the liver. Contradictory results have been reported on the regulation of hepcidin expression in response to serum transferrin saturation and liver iron content. In the present study, we explore the expression of murine hepcidin mRNA and further analyze the relationship between liver hepcidin mRNA expression, liver iron stores, and serum iron level utilizing ceruloplasmin gene knockout mice. We find that hepcidin expression correlates significantly with serum transferrin saturation, whereas there is a negative correlation of hepcidin expression with liver tissue iron level.