Celastrol, a potent antioxidant and anti-inflammatory drug, as a possible treatment for Alzheimer's disease

Characterization of global research trends and prospects on celastrol, a principal bioactive ingredient of Tripterygium wilfordii Hook F: bibliometric analysis

CONTEXT

Celastrol, acknowledged as a prominent exemplar of the potential for transforming traditional medicinal compounds into contemporary pharmaceuticals, has garnered considerable attention owing to its extensive pharmacological activities. The increasing volume of publications concerning celastrol highlights its importance in current scientific inquiry. Despite the growing interest in this compound, a bibliometric analysis focused on this subject remains to be undertaken.

OBJECTIVE

Our study explored a bibliometric approach to identify and characterize global research trends and frontiers related to celastrol, including mapping research outputs, influential contributors, and thematic areas, as well as highlighting gaps and opportunities for future investigations.

MATERIALS AND METHODS

In this study, we utilized the Web of Science Core Collection (WoSCC) to source and review articles related to celastrol published from 1997 to 2023. The bibliometric analysis was conducted using the R package 'Bibliometrix,' supplemented by visualization tools including CiteSpace, VOSviewer, and GraphPad Prism 10.

RESULTS

Celastrol related research papers have exhibited an upward trend annually and can be categorized into three distinct phases, each highlighting different areas of focus. China, the United States, and South Korea rank as the top three nations for publication volume, with varied research interests across these countries. Several prolific research teams have emerged, each with distinct areas of interest. Examining the primary research domains of celastrol (anti-inflammatory, anticancer, and toxicity) reveals a notable intersection between the first two domains.

DISCUSSION AND CONCLUSIONS

The scope and depth of celastrol research have been steadily expanding, with regional and team-specific variations. Key research areas include anti-inflammatory, anticancer, and toxicity studies. Future research is expected to focus on enhancing the effectiveness and reducing the toxicity of celastrol. Meanwhile, given the multi-target characteristics of celastrol's effects, integrating methods such as network biology and molecular simulation will provide a novel perspective for celastrol research.

Structural characterizations and bioactivities of fucoidans from Dyctyopteris membranaceae and Padina pavonica with in silico investigations

Fucoidans, a complex water-soluble sulfated polysaccharide is regarded as a valuable source of new drug development. The aim of this study was to characterize the chemical properties of fucoidans isolated from two brown algae Dyctyopteris membranaceae and Padina pavonica and to evaluate their anti-inflammatory, gastroprotective, antioxidant and immunomodulatory activities. The characterization of fucoidans was investigated with colorimetric techniques and Fourier transform infrared spectroscopy. The different macromolecular characteristics of fucoidans were determined by size exclusion chromatography. The immunomodulatory activity was evaluated using cytometric bead array technology to follow up the secretion of TNF-α in lipopolysaccharide activated THP-1 cells. The antioxidant effect was determined using the stable radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). The anti-inflammatory activity was evaluated using the carrageenan-induced rat paw edema model. The gastroprotective activity was determined using HCl/EtOH induced gastric ulcers in rats. Pharmacokinetic and molecular docking analysis was conducted. As a result, only fucoidan from D. membranaceae showed an effect on the synthesis of TNF-α in THP-1 cells induced by LPS with IC50 of 77 μg/mL. Fucoidans from both algae showed antioxidant properties with EC50 of 0.2 mg/mL for fucoidan from D. membranaceae, and 0.21 mg/mL for fucoidan from P. pavonica. Furthermore, isolated fucoidans from D. membranaceae and P. pavonica showed important anti-inflammatory activity with percentages of inhibition of oedema of 75 % and 57 %, respectively, at dose of 50 mg/kg, associated with significant gastroprotective activity with percentages of ulcer inhibition of 97 % and 88 %, respectively, at the same dose. Docking study showed the reactivity of this fucoidans. The study highlights the potential pharmacological importance of D. membranaceae and P. pavonica as sources of natural compounds with biological activities.

Ameliorating immune-dependent inflammation and apoptosis by targeting TLR4/MYD88/NF-κB pathway by celastrol mitigates the diabetic reproductive dysfunction

This study aimed to examine the protective effect of celastrol on testicular dysfunction in diabetic rats and the potential underlying mechanisms. All rats included in the study were divided into four groups: a control group treated with sodium citrate buffer and vehicle), a celastrol-treated control group, a streptozotocin (STZ)-induced diabetic group following insulin resistance, and a celastrol-treated diabetic group. Serum glucose, triglyceride, total cholesterol, high-density lipoprotein cholesterol, interleukin (IL)-1β, tumor necrosis factor-α, and testosterone levels were measured. In addition, the levels of testicular homogenate superoxide dismutase and malondialdehyde were assessed. Furthermore, testicular tissue relative toll-like receptor 4 (TLR4), nuclear factor kappa B (NF-κB), and myeloid differentiation factor 88 (MYD88) expressions were quantitatively measured using polymerase chain reaction. Histopathological and immunohistochemical studies were also conducted. The results revealed that treatment with celastrol significantly reduced TLR4, MyD88, and NF-κB expressions, and the levels of inflammatory mediators such as tumor necrosis factor-α and IL-1β in the testicular tissue of treated rats. These findings suggest that celastrol has the potential to be effective in the treatment of diabetes-induced testicular injury by inhibiting testicular inflammation, apoptosis, and oxidative stress.NEW & NOTEWORTHY Celastrol inhibits the production of proinflammatory cytokines in the testicular tissue by specifically targeting the TLR4/MyD88/NF-κB signaling cascade pathways. This indicates that celastrol may serve as a promising new therapeutic target for treating diabetic reproductive dysfunction.

Evaluation of Celastrol Antiviral Activity Against Equid Alphaherpesvirus Type 8 Infection

Equid alphaherpesvirus type 8 (EHV-8) is a contagious pathogen that causes reproductive disorders, respiratory diseases, and viral encephalitis in equids, resulting in significant economic losses for the global horse and donkey industries. Currently, there are no approved antiviral drugs or vaccines available for EHV-8 control. In this study, we investigated the antiviral efficacy of celastrol against EHV-8 both in vitro and in vivo. Our results demonstrated that celastrol significantly inhibited EHV-8 infection in Rabbit kidney (RK-13) and equine dermal cells (NBL-6) in a dose-dependent manner. Mechanistic studies revealed that celastrol interfered with viral replication at multiple stages of the infection cycle. Furthermore, we found that celastrol induced an antiviral interferon response through activation of the Nrf2/HO-1 signaling pathway. Importantly, celastrol treatment significantly reduced EHV-8 replication and ameliorated lung pathology in a mouse model. These findings suggest that celastrol may represent a promising therapeutic agent for the treatment of EHV-8 infections.

Anti-inflammatory effects of para-quinone methide derivatives on ulcerative colitis

A series of para-quinone methide derivatives were evaluated their anti-inflammatory activity. Through the screening of the lipopolysaccharide (LPS)-induced inflammatory cell model in Raw264.7 cells, it was found that the inhibitory activity of meta-substituted derivatives on NO production was superior to that of ortho- and para-substituted derivatives. Among them, in the inflammatory cell model, the meta-trifluoromethyl substituted para-quinone methide derivative 1i had the best activity in inhibiting LPS-induced excess generation of NO. And 1i could effectively inhibit the increase of ROS in inflammatory cells, the expression of iNOS related to the production of NO, and the expressions of inflammation related initiating protein TLR4, pro-inflammatory cytokines IL-6 and TNF-α, inflammasome NLRP3 and Caspase1. In the dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) mouse model, the active derivative 1i could inhibit DSS-induced colon shortening, and reverse DSS-induced pathological changes in colon tissue, such as inflammatory infiltration, structural destruction and crypt disappearance. 1i could effectively inhibit oxidative stress, inflammation and apoptosis in UC mice. Moreover, through the determination of serum biochemical indicators, tissue pathologies and tissue organ indexes, 1i could effectively reverse the damage to mouse liver and kidney caused by DSS, playing a protective role in liver and kidney of mice. In summary, 1i was an effective anti-inflammatory reagent and could be developed as a potential drug for anti-UC.

Celastrol attenuates the invasion and migration and augments the anticancer effects of olaparib in prostate cancer

BACKGROUND

Prostate cancer (PCa) is a leading malignancy among men globally, with rising incidence rates emphasizing the critical need for better detection and therapeutic approaches. The roles of HSP90AB1 and PARP1 in prostate cancer cells suggest potential targets for enhancing treatment efficacy.

METHODS

This study investigated the overexpression of HSP90AB1 and PARP1 in prostate cancer cells and the impact of HSP90AB1 knockdown on the sensitivity of these cells to the PARP inhibitor olaparib. We also explored the combined effect of olaparib and celastrol, an HSP90 inhibitor, on the clonogenic survival, migration, proliferation, and overall viability of prostate cancer cells, alongside the modulation of the PI3K/AKT pathway. An in vivo PC3 xenograft mouse model was used to assess the antitumor effects of the combined treatment.

RESULTS

Our findings revealed significant overexpression of HSP90AB1 and PARP1 in prostate cancer cells. Knockdown of HSP90AB1 increased cell sensitivity to olaparib. The combination of olaparib and celastrol significantly reduced prostate cancer cell survival, migration, proliferation, and enhanced cumulative DNA damage. Celastrol also downregulated the PI3K/AKT pathway, increasing cell susceptibility to olaparib. In vivo experiments demonstrated that celastrol and olaparib together exerted strong antitumor effects.

CONCLUSIONS

The study indicates that targeting both HSP90AB1 and PARP1 presents a promising therapeutic strategy for prostate cancer. The synergistic combination of celastrol and olaparib enhances the efficacy of treatment against prostate cancer, offering a potent approach to combat this disease.

Transcriptome and Metabolome Reveal Accumulation of Key Metabolites with Medicinal Properties of Phylloporia pulla

Phylloporia pulla, a macrofungal species in the Hymenochaetales, Basidiomycota, is known to enhance the nutritional and bioactive properties of rice through co-fermentation; however, its own secondary metabolites are not well understood. In this study, an integrative analysis of transcriptome and metabolome data revealed that the accumulation of steroids, steroid derivatives, and triterpenoids in P. pulla peaks during the mid-growth stage, while the genes associated with these metabolites show higher expression levels from the early to mid-growth stages. Weighted gene co-expression network analysis identified several modules containing candidate genes involved in the synthesis of steroids, steroid derivatives, and triterpenoids. Specifically, six key hub genes were identified, along with their connectivity to other related genes, as potential catalysts in converting the precursor lanosterol to celastrol. This study enhances our understanding of the secondary metabolites of P. pulla and is essential for the selective utilization of these bioactive compounds.

Celastrus orbiculatus Thunb. extracts and celastrol alleviate NAFLD by preserving mitochondrial function through activating the FGF21/AMPK/PGC-1α pathway

Objective

Non-alcoholic fatty liver disease (NAFLD) is a prevalent chronic liver disease globally, characterized by the accumulation of lipids, oxidative stress, and mitochondrial dysfunction in the liver. Celastrus orbiculatus Thunb. (COT) and its active compound celastrol (CEL) have demonstrated antioxidant and anti-inflammatory properties. Our prior research has shown the beneficial effects of COT in mitigating NAFLD induced by a high-fat diet (HFD) in guinea pigs by reducing hepatic lipid levels and inhibiting oxidative stress. This study further assessed the effects of COT on NAFLD and explored its underlying mitochondria-related mechanisms.

Methods

COT extract or CEL was administered as an intervention in C57BL/6J mice fed a HFD or in HepG2 cells treated with sodium oleate. Oral glucose tolerance test, biochemical parameters including liver enzymes, blood lipid, and pro-inflammatory factors, and steatosis were evaluated. Meanwhile, mitochondrial ultrastructure and indicators related to oxidative stress were tested. Furthermore, regulators of mitochondrial function were measured using RT-qPCR and Western blot.

Results

The findings demonstrated significant reductions in hepatic steatosis, oxidative stress, and inflammation associated with NAFLD in both experimental models following treatment with COT extract or CEL. Additionally, improvements were observed in mitochondrial structure, ATP content, and ATPase activity. This improvement can be attributed to the significant upregulation of mRNA and protein expression levels of key regulators including FGF21, AMPK, PGC-1α, PPARγ, and SIRT3.

Conclusion

These findings suggest that COT may enhance mitochondrial function by activating the FGF21/AMPK/PGC-1α signaling pathway to mitigate NAFLD, which indicated that COT has the potential to target mitochondria and serve as a novel therapeutic option for NAFLD.

Natural products with anti-tumorigenesis potential targeting macrophage

BACKGROUND

Inflammation is a risk factor for tumorigenesis. Macrophage, a subset of immune cells with high plasticity, plays a multifaceted role in this process. Natural products, which are bioactive compounds derived from traditional herbs or foods, have exhibited diverse effects on macrophages and tumorigenesis making them a valuable resource of drug discovery or optimization in tumor prevention.

PURPOSE

Provide a comprehensive overview of the various roles of macrophages in tumorigenesis, as well as the effects of natural products on tumorigenesis by modulating macrophage function.

METHODS

A thorough literature search spanning the past two decades was carried out using PubMed, Web of Science, Elsevier, and CNKI following the PRISMA guidelines. The search terms employed included "macrophage and tumorigenesis", "natural products, macrophages and tumorigenesis", "traditional Chinese medicine and tumorigenesis", "natural products and macrophage polarization", "macrophage and tumor related microenvironment", "macrophage and tumor signal pathway", "toxicity of natural products" and combinations thereof. Furthermore, certain articles are identified through the tracking of citations from other publications or by accessing the websites of relevant journals. Studies that meet the following criteria are excluded: (1) Articles not written in English or Chinese; (2) Full texts were not available; (3) Duplicate articles and irrelevant studies. The data collected was organized and summarized based on molecular mechanisms or compound structure.

RESULTS

This review elucidates the multifaceted effect of macrophages on tumorigenesis, encompassing process such as inflammation, angiogenesis, and tumor cell invasion by regulating metabolism, non-coding RNA, signal transduction and intercellular crosstalk. Natural products, including vitexin, ovatodiolide, ligustilide, and emodin, as well as herbal remedies, have demonstrated efficacy in modulating macrophage function, thereby attenuating tumorigenesis. These interventions mainly focus on mitigating the initial inflammatory response or modifying the inflammatory environment within the precancerous niche.

CONCLUSIONS

These mechanistic insights of macrophages in tumorigenesis offer valuable ideas for researchers. The identified natural products facilitate the selection of promising candidates for future cancer drug development.

Celastrol alleviates diabetic vascular injury via Keap1/Nrf2-mediated anti-inflammation

Introduction: Celastrol (Cel) is a widely used main component of Chinese herbal medicine with strong anti-inflammatory, antiviral and antitumor activities. In the present study, we aimed to elucidate the cellular molecular protective mechanism of Cel against diabetes-induced inflammation and endothelial dysfunction. Methods: Type 2 diabetes (T2DM) was induced by db/db mice, and osmotic pumps containing Cel (100 μg/kg/day) were implanted intraperitoneally and were calibrated to release the drug for 28 days. In addition, human umbilical vein endothelial cells (HUVECs) were cultured in normal or high glucose and palmitic acid-containing (HG + PA) media in the presence or absence of Cel for 48 h. Results: Cel significantly ameliorated the hyperglycemia-induced abnormalities in nuclear factor (erythroid-derived 2)-like protein 2 (Nrf2) pathway activity and alleviated HG + PA-induced oxidative damage. However, the protective effect of Cel was almost completely abolished in HUVECs transfected with short hairpin (sh)RNA targeting Nrf2, but not by nonsense shRNA. Furthermore, HG + PA reduced the phosphorylation of AMP-activated protein kinase (AMPK), the autophagic degradation of p62/Kelch-like ECH-associated protein 1 (Keap1), and the nuclear localization of Nrf2. However, these catabolic pathways were inhibited by Cel treatment in HUVECs. In addition, compound C (AMPK inhibitors) and AAV9-sh-Nrf2 reduced Cel-induced Nrf2 activation and angiogenesis in db/db mice. Discussion: Taking these findings together, the endothelial protective effect of Cel in the presence of HG + PA may be at least in part attributed to its effects to reduce reactive oxygen species (ROS) and inflammation through p62/Keap1-mediated Nrf2 activation.

Furosemide Derails Human Lysozyme Fibrillation by Interacting with Aggregation Hot Spots: A Biophysical Comprehension

Kidney-associated human lysozyme amyloidosis leads to renal impairments;thus, patients are often prescribed furosemide. Based on this fact, the effect of furosemide on induced human lysozyme fibrillation, in vitro, is evaluated by spectroscopic, calorimetric, computational, and cellular-based assays/methods. Results show that furosemide increases the lag phase and decreases the apparent rate of aggregation of human lysozyme, thereby decelerating the nucleation phase and amyloid fibril formation, as confirmed by the decrease in the level of Thioflavin-T fluorescence. Fewer entities of hydrodynamic radii of ∼171 nm instead of amyloid fibrils (∼412 nm) are detected in human lysozyme in the presence of furosemide by dynamic light scattering. Moreover, furosemide decreases the extent of conversion of the α/β structure of human lysozyme into a predominant β-sheet. The isothermal titration calorimetry established that furosemide forms a complex with human lysozyme, which was also confirmed through fluorescence quenching and computational studies. Also, human lysozyme lytic activity is inhibited competitively by furosemide due to the involvement of amino acid residues of the active site in catalysis, as well as complex formation. Conclusively, furosemide interacts with Gln58, Ile59, Asn60, Ala108, and Trp109 of aggregation-prone regions 2 and 4 of human lysozyme, thereby masking its sites of aggregation and generating only lower-order entities that are less toxic to red blood cells than the fibrils. Thus, furosemide slows the progression of amyloid fibrillation in human lysozyme.

Comprehensive mass spectrometric metabolomic profiling of a chemically diverse collection of plants of the Celastraceae family

Natural products exhibit interesting structural features and significant biological activities. The discovery of new bioactive molecules is a complex process that requires high-quality metabolite profiling data to properly target the isolation of compounds of interest and enable their complete structural characterization. The same metabolite profiling data can also be used to better understand chemotaxonomic links between species. This Data Descriptor details a dataset resulting from the untargeted liquid chromatography-mass spectrometry metabolite profiling of 76 natural extracts of the Celastraceae family. The spectral annotation results and related chemical and taxonomic metadata are shared, along with proposed examples of data reuse. This data can be further studied by researchers exploring the chemical diversity of natural products. This can serve as a reference sample set for deep metabolome investigation of this chemically rich plant family.

SIRT3 Activation a Promise in Drug Development? New Insights into SIRT3 Biology and Its Implications on the Drug Discovery Process

Sirtuins catalyze deacetylation of lysine residues with a NAD+-dependent mechanism. In mammals, the sirtuin family is composed of seven members, divided into four subclasses that differ in substrate specificity, subcellular localization, regulation, as well as interactions with other proteins, both within and outside the epigenetic field. Recently, much interest has been growing in SIRT3, which is mainly involved in regulating mitochondrial metabolism. Moreover, SIRT3 seems to be protective in diseases such as age-related, neurodegenerative, liver, kidney, heart, and metabolic ones, as well as in cancer. In most cases, activating SIRT3 could be a promising strategy to tackle these health problems. Here, we summarize the main biological functions, substrates, and interactors of SIRT3, as well as several molecules reported in the literature that are able to modulate SIRT3 activity. Among the activators, some derive from natural products, others from library screening, and others from the classical medicinal chemistry approach.

Celastrol inhibits platelet function and thrombus formation

INTRODUCTION

Celastrol is an active pentacyclic triterpenoid extracted from Tripterygium wilfordii and has anti-inflammatory and anti-tumor properties. Whether Celastrol modulates platelet function remains unknown. Our study investigated its role in platelet function and thrombosis.

METHODS

Human platelets were isolated and incubated with Celastrol (0, 1, 3 and 5 μM) at 37 °C for 1 h to measure platelet aggregation, granules release, spreading, thrombin-induced clot retraction and intracellular calcium mobilization. Additionally, Celastrol (2 mg/kg) was intraperitoneally administrated into mice to evaluate hemostasis and thrombosis in vivo.

RESULTS

Celastrol treatment significantly decreased platelet aggregation and secretion of dense or alpha granules induced by collagen-related peptide (CRP) or thrombin in a dose-dependent manner. Additionally, Celastrol-treated platelets showed a dramatically reduced spreading activity and decreased clot retraction. Moreover, Celastrol administration prolonged tail bleeding time and inhibited formation of arterial/venous thrombosis. Furthermore, Celastrol significantly reduced calcium mobilization.

CONCLUSION

Celastrol inhibits platelet function and venous/arterial thrombosis, implying that it might be utilized for treating thrombotic diseases.

Natural compounds against nonalcoholic fatty liver disease: A review on the involvement of the LKB1/AMPK signaling pathway

Although various therapeutic approaches are used to manage nonalcoholic fatty liver disease (NAFLD), the best approach to NAFLD management is unclear. NAFLD is a liver disorder associated with obesity, metabolic syndrome, and diabetes mellitus. NAFLD progression can lead to cirrhosis and end-stage liver disease. Hepatic kinase B1 (LKB1) is an upstream kinase of 5'-adenosine monophosphate-activated protein kinase (AMPK), a crucial regulator in hepatic lipid metabolism. Activation of LKB1/AMPK inhibits fatty acid synthesis, increases mitochondrial β-oxidation, decreases the expression of genes encoding lipogenic enzymes, improves nonalcoholic steatohepatitis, and suppresses NAFLD progression. One potential opening for new and safe chemicals that can tackle the NAFLD pathogenesis through the LKB1-AMPK pathway includes natural bioactive compounds. Accordingly, we summarized in vitro and in vivo studies regarding the effect of natural bioactive compounds such as a few members of the polyphenols, terpenoids, alkaloids, and some natural extracts on NAFLD through the LKB1/AMPK signaling pathway. This manuscript may shed light on the way to finding a new therapeutic agent for NAFLD management.

Biomimetic nanoplatform with anti-inflammation and neuroprotective effects for repairing spinal cord injury in mice

Regeneration in the therapeutics of spinal cord injury (SCI) remains a challenge caused by the hyperinflammation microenvironment. Nanomaterials-based treatment strategies for diseases with excellent therapeutic efficacy are actively pursued. Here, we develop biodegradable poly (lactic-co-glycolic acid) nanoparticles (PLGA) obtained by loading celastrol (pCel) for SCI thrapy. Cel, as an antioxidant drug, facilitated reactive oxygen species (ROS) scavenging, and decreased the generation of pro-inflammatory cytokines. To facilitate its administration, pCel is formulated into microspheres by oil-in-water (O/W) emulsion/solvent evaporation technique. The constructed pCel can induced polarization of macrophages and obviously improved lipopolysaccharide (LPS) and interferon-γ (IFN-γ)-induced mitochondrial dysfunction, and increased neurite length in PC12 cells and primary neurons. In vivo experiments revealed that pCel regulated the phenotypic polarization of macrophages, prevented the release of pro-inflammatory cytokines, promoted myelin regeneration and inhibited scar tissue formation, and further improve motor function. These findings indicated that the neuroprotective effect of this artificial biodegradable nanoplatform is benefit for the therapy of SCI. This research opens an exciting perspective for the application of SCI treatment and supports the clinical significance of pCel.

Celastrol functions as an emerging manager of lipid metabolism: Mechanism and therapeutic potential

Lipid metabolism disorders are pivotal in the development of various lipid-related diseases, such as obesity, atherosclerosis, non-alcoholic fatty liver disease, type 2 diabetes, and cancer. Celastrol, a bioactive compound extracted from the Chinese herb Tripterygium wilfordii Hook F, has recently demonstrated potent lipid-regulating abilities and promising therapeutic effects for lipid-related diseases. There is substantial evidence indicating that celastrol can ameliorate lipid metabolism disorders by regulating lipid profiles and related metabolic processes, including lipid synthesis, catabolism, absorption, transport, and peroxidation. Even wild-type mice show augmented lipid metabolism after treatment with celastrol. This review aims to provide an overview of recent advancements in the lipid-regulating properties of celastrol, as well as to elucidate its underlying molecular mechanisms. Besides, potential strategies for targeted drug delivery and combination therapy are proposed to enhance the lipid-regulating effects of celastrol and avoid the limitations of its clinical application.

Arylcyanomethylenequinone Oximes: An Overview of Synthesis, Chemical Transformations, and Biological Activity

Quinone methides are a class of biologically active compounds that can be used in medicine as antibacterial, antifungal, antiviral, antioxidant, and anti-inflammatory agents. In addition, quinone methides have the potential to be used as pesticides, dyes, and additives for rubber and plastics. In this paper, we discuss a subclass of quinone methides: methylenequinone oximes. Although the first representatives of the subgroup were synthesized in the distant past, they still need to be additionally studied, while their chemistry, biological properties, and perspective of practical applications require to be comprehensively summarised. Based on the analysis of the literature, it can be concluded that methylenequinone oximes exhibit a diversified profile of properties and outstanding potential as new drug candidates and reagents in organic synthesis, both of electrophilic and nucleophilic nature, worthy of wide-ranging further research.

Plant-Based Antioxidants for Prevention and Treatment of Neurodegenerative Diseases: Phytotherapeutic Potential of Laurus nobilis, Aronia melanocarpa, and Celastrol

With the progress of medicine, especially in the last century, life expectancy increased considerably. As a result, age-related diseases also increased, especially malignancies and degenerative diseases of the central nervous system. The incidence and prevalence of neurodegenerative diseases steadily increased over the years, but despite efforts to uncover the pathophysiological processes behind these conditions, they remain elusive. Among the many theories, oxidative stress was proposed to be involved in neurodegenerative processes and to play an important role in the morbidity and progression of various neurodegenerative disorders. Accordingly, a number of studies discovered the potential of natural plant constituents to have significant antioxidant activity. This review focused on several plant-based antioxidants that showed promising results in the prevention and treatment of neurodegenerative diseases. Laurus nobilis, Aronia melanocarpa, and celastrol, a chemical compound isolated from the root extracts of Tripterygium wilfordii and T. regelii, are all known to be rich in antioxidant polyphenols.

Surface-Modified Inhaled Microparticle-Encapsulated Celastrol for Enhanced Efficacy in Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a rare and aggressive cancer affecting the pleural lining of the lungs. Celastrol (Cela), a pentacyclic triterpenoid, has demonstrated promising therapeutic potential as an antioxidant, anti-inflammatory, neuroprotective agent, and anti-cancer agent. In this study, we developed inhaled surface-modified Cela-loaded poly(lactic-co-glycolic) acid (PLGA) microparticles (Cela MPs) for the treatment of MPM using a double emulsion solvent evaporation method. The optimized Cela MPs exhibited high entrapment efficiency (72.8 ± 6.1%) and possessed a wrinkled surface with a mean geometric diameter of ~2 µm and an aerodynamic diameter of 4.5 ± 0.1 µm, suggesting them to be suitable for pulmonary delivery. A subsequent release study showed an initial burst release up to 59.9 ± 2.9%, followed by sustained release. The therapeutic efficacy of Cela MPs was evaluated against four mesothelioma cell lines, where Cela MP exhibited significant reduction in IC50 values, and blank MPs produced no toxicity to normal cells. Additionally, a 3D-spheroid study was performed where a single dose of Cela MP at 1.0 µM significantly inhibited spheroid growth. Cela MP was also able to retain the antioxidant activity of Cela only while mechanistic studies revealed triggered autophagy and an induction of apoptosis. Therefore, these studies highlight the anti-mesothelioma activity of Cela and demonstrate that Cela MPs are a promising inhalable medicine for MPM treatment.

Celastrol targeting Nedd4 reduces Nrf2-mediated oxidative stress in astrocytes after ischemic stroke

Stroke is the second leading cause of death worldwide, and oxidative stress plays a crucial role. Celastrol exhibits strong antioxidant properties in several diseases; however, whether it can affect oxidation in cerebral ischemic-reperfusion injury (CIRI) remains unclear. This study aimed to determine whether celastrol could reduce oxidative damage during CIRI and to elucidate the underlying mechanisms. Here, we found that celastrol attenuated oxidative injury in CIRI by upregulating nuclear factor E2-related factor 2 (Nrf2). Using alkynyl-tagged celastrol and liquid chromatography-tandem mass spectrometry, we showed that celastrol directly bound to neuronally expressed developmentally downregulated 4 (Nedd4) and then released Nrf2 from Nedd4 in astrocytes. Nedd4 promoted the degradation of Nrf2 through K48-linked ubiquitination and thus contributed to astrocytic reactive oxygen species production in CIRI, which was significantly blocked by celastrol. Furthermore, by inhibiting oxidative stress and astrocyte activation, celastrol effectively rescued neurons from axon damage and apoptosis. Our study uncovered Nedd4 as a direct target of celastrol, and that celastrol exerts an antioxidative effect on astrocytes by inhibiting the interaction between Nedd4 and Nrf2 and reducing Nrf2 degradation in CIRI.

Natural Bioactive Compounds Targeting NADPH Oxidase Pathway in Cardiovascular Diseases

Cardiovascular disease (CVD) is the leading cause of death worldwide, in both developed and developing countries. According to the WHO report, the morbidity and mortality caused by CVD will continue to rise with the estimation of death going up to 22.2 million in 2030. NADPH oxidase (NOX)-derived reactive oxygen species (ROS) production induces endothelial nitric oxide synthase (eNOS) uncoupling and mitochondrial dysfunction, resulting in sustained oxidative stress and the development of cardiovascular diseases. Seven distinct members of the family have been identified of which four (namely, NOX1, 2, 4 and 5) may have cardiovascular functions. Currently, the treatment and management plan for patients with CVDs mainly depends on the drugs. However, prolonged use of prescribed drugs may cause adverse drug reactions. Therefore, it is crucial to find alternative treatment options with lesser adverse effects. Natural products have been gaining interest as complementary therapy for CVDs over the past decade due to their wide range of medicinal properties, including antioxidants. These might be due to their potent active ingredients, such as flavonoid and phenolic compounds. Numerous natural compounds have been demonstrated to have advantageous effects on cardiovascular disease via NADPH cascade. This review highlights the potential of natural products targeting NOX-derived ROS generation in treating CVDs. Emphasis is put on the activation of the oxidases, including upstream or downstream signalling events.

Anticancer Activity of the Bioactive Extract of the Morel Mushroom (Morchella elata, Ascomycetes) from Kashmir Himalaya (India) and Identification of Major Bioactive Compounds

Morel mushrooms, Morchella species are highly nutritional, excellently edible and medicinal. Anticancer activity of M. elata, growing in forests of Kashmir Himalaya was studied. Ethyl acetate extract of fruiting bodies of M. elata (MEAE) was evaluated for cytotoxicity by MTT assay using Daltons lymphoma ascites (DLA), human colon cancer (HCT-116) and normal cell lines. Anti-carcinogenic and antiangiogenic activities of MEAE were tested using mouse models. Proapoptotic activity was detected by double staining of acridine orange-ethidium bromide assay. MEAE was partially purified by column chromatography and the bioactive compounds were identified by LC-MS analysis. The bioactive extract of M. elata showed significant cytotoxicic activity against DLA (P < 0.05), HCT-116 cell lines (P < 0.05) and did not possess appreciable adverse effect on the viability of normal cells. At a concentration of 100 µg/mL, 60% cell death was observed in HCT-116 cell line while 80% cell death was found in DLA cell line. The extract also possessed profound anticarcinogenic, antiangiogenic and proapoptotic activities. LC-MS analysis showed celastrol (RT 9.504, C29H38O4, MW 450.27), convallatoxin (RT 9.60, C29H42O10, MW 550.27), cucurbitacin A (RT 11.97, C32H46O9, MW 574.71) and madecassic acid (RT 14.35, C30H48O6, MW 504.70) as the major bioactive components. Current experimental studies indicated that bioactive extract of M. elata possessed significant anticancer activity. Being an excellently edible mushroom, the potential therapeutic use of M. elata and its bioactive extract in complementary therapy of cancer is envisaged.

An intra-articular injectable phospholipids-based gel for the treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory and destructive arthropathy with a high deformity rate. Despite numerous studies and clinical trials, no curative treatment is available for large weight-bearing joints. Intra-articular (IA) injections could deliver high concentrations of drug to the afflicted joint and improve the drug efficacy while reducing systemic toxicity. However, free drugs are rapidly cleared from synovial fluid and do not significantly halt the progression of joint disease. Herein, a phospholipids-based controlled-release gel was prepared for sustained IA delivery of celastrol (CEL) and the therapeutic efficiency was evaluated in a rheumatoid arthritis rabbit model. The CEL-loaded gel (CEL-gel) contained up to 70% phospholipids yet was easy to inject. After injecting into the joint cavity, CEL-gel achieved sol to gel phase transition without special stimuli and gelling agent. In vitro release and in vivo pharmacokinetic studies evidenced the stable and sustained release action of CEL-gel. A single IA injection of CEL-gel could maintain therapeutic efficiency for about 25 d and showed much better anti-arthritic efficacy compared to repeated injections of free drug solution (CEL-sol). Furthermore, the IA injection of CEL-gel greatly reduced the systemic toxicity of CEL. With good biocompatibility and biodegradability, CEL-gel might be a promising IA drug delivery system.

The therapeutic potential of triptolide and celastrol in neurological diseases

Neurological diseases are complex diseases affecting the brain and spinal cord, with numerous etiologies and pathogenesis not yet fully elucidated. Tripterygium wilfordii Hook. F. (TWHF) is a traditional Chinese medicine with a long history of medicinal use in China and is widely used to treat autoimmune and inflammatory diseases such as systemic lupus erythematosus and rheumatoid arthritis. With the rapid development of modern technology, the two main bioactive components of TWHF, triptolide and celastrol, have been found to have anti-inflammatory, immunosuppressive and anti-tumor effects and can be used in the treatment of a variety of diseases, including neurological diseases. In this paper, we summarize the preclinical studies of triptolide and celastrol in neurological diseases such as neurodegenerative diseases, brain and spinal cord injury, and epilepsy. In addition, we review the mechanisms of action of triptolide and celastrol in neurological diseases, their toxicity, related derivatives, and nanotechnology-based carrier system.

Targeting HSP90 as a Novel Therapy for Cancer: Mechanistic Insights and Translational Relevance

Heat shock protein (HSP90), a highly conserved molecular chaperon, is indispensable for the maturation of newly synthesized poly-peptides and provides a shelter for the turnover of misfolded or denatured proteins. In cancers, the client proteins of HSP90 extend to the entire process of oncogenesis that are associated with all hallmarks of cancer. Accumulating evidence has demonstrated that the client proteins are guided for proteasomal degradation when their complexes with HSP90 are disrupted. Accordingly, HSP90 and its co-chaperones have emerged as viable targets for the development of cancer therapeutics. Consequently, a number of natural products and their analogs targeting HSP90 have been identified. They have shown a strong inhibitory effect on various cancer types through different mechanisms. The inhibitors act by directly binding to either HSP90 or its co-chaperones/client proteins. Several HSP90 inhibitors—such as geldanamycin and its derivatives, gamitrinib and shepherdin—are under clinical evaluation with promising results. Here, we review the subcellular localization of HSP90, its corresponding mechanism of action in the malignant phenotypes, and the recent progress on the development of HSP90 inhibitors. Hopefully, this comprehensive review will shed light on the translational potential of HSP90 inhibitors as novel cancer therapeutics.

Induction of the ER stress response in NRVMs is linked to cardiotoxicity caused by celastrol

Celastrol is a quinone methide triterpenoid extracted from the root bark of Tripterygium wilfordii Hook F, and it exhibits extensive biological activities such as anti-cancer effects. However, narrow therapeutic window together with undesired side effects limit its clinical application. In this study, we explore celastrol's cardiotoxicity using the methods of histology and cell biology. The results show that celastrol administration dose-dependently induces cardiac dysfunction in mice as manifested by left ventricular dilation, myocardial interstitial fibrosis, and cardiomyocyte hypertrophy. Exposure to celastrol greatly decreases neonatal rat ventricular myocyte (NRVM) viability and promotes its apoptosis. More importantly, we demonstrate that celastrol exerts its pro-apoptotic effects through endoplasmic reticulum (ER) stress and unfolded protein response. Furthermore, siRNA targeting C/EBP homologous protein, a pivotal component of ER stress-mediated apoptosis, effectively prevents the pro-apoptotic effect of celastrol. Taken together, our results demonstrate the potential cardiotoxicity of celastrol and a direct involvement of ER stress in the celastrol-induced apoptosis of NRVMs. Thus, we recommend careful evaluation of celastrol's cardiovascular effects when using it in the clinic.

Oxidative Stress in Calcific Aortic Valve Stenosis: Protective Role of Natural Antioxidants

Calcific aortic valve stenosis (CAVS) is the most prevalent heart valvular disease worldwide and a slowly progressive disorder characterized by thickening of the aortic valve, calcification, and subsequent heart failure. Valvular calcification is an active cell regulation process in which valvular interstitial cells involve phenotypic conversion into osteoblasts/chondrocytes-like cells. The underlying pathophysiology is complicated, and there have been no pharmacological treatments for CAVS to date. Recent studies have suggested that an increase in oxidative stress is the major trigger of CAVS, and natural antioxidants could ameliorate the detrimental effects of reactive oxygen species in the pathogenesis of CAVS. It is imperative to review the current findings regarding the role of natural antioxidants in CAVS, as they can be a promising therapeutic approach for managing CAVS, a disorder currently without effective treatment. This review summarizes the current findings on molecular mechanisms associated with oxidative stress in the development of valvular calcification and discusses the protective roles of natural antioxidants in the prevention and treatment of CAVS.

Drug Candidates for Autoimmune Diseases

Most of the immunosuppressive drugs used in the clinic to prevent organ rejection or to treat autoimmune disorders were originally isolated from fungi or bacteria. Therefore, in addition to plants, these are valuable sources for identification of new potent drugs. Many side effects of established drugs limit their usage and make the identification of new immunosuppressants necessary. In this review, we present a comprehensive overview of natural products with potent anti-inflammatory activities that have been tested successfully in different models of chronic inflammatory autoimmune diseases. Some of these candidates already have passed first clinical trials. The anti-inflammatory potency of these natural products was often comparable to those of established drugs, and they could be used at least in addition to standard therapy to reduce their dose to minimize unwanted side effects. A frequent mode of action is the inhibition of classical inflammatory signaling pathways, such as NF-κB, in combination with downregulation of oxidative stress. A drawback for the therapeutic use of those natural products is their moderate bioavailability, which can be optimized by chemical modifications and, in addition, further safety studies are necessary. Altogether, very interesting candidate compounds exist which have the potential to serve as starting points for the development of new immunosuppressive drugs.

Celastrol Downmodulates Alpha-Synuclein-Specific T Cell Responses by Mediating Antigen Trafficking in Dendritic Cells

Parkinson’s Disease (PD) is a neurodegenerative disease that affects the elderly. It is associated with motor dysfunction due to the accumulation of misfolded or aggregated fibrillar alpha-synuclein (α-syn) in the mid-brain. Current treatments are mainly focused on relieving the symptoms but are accompanied by side effects and are limited in halting disease progression. Increasing evidence points to peripheral immune cells underlying disease development, especially T cells contributing to α-syn-related neuroinflammation in PD. The onset of these cells is likely mediated by dendritic cells (DCs), whose role in α-syn-specific responses remain less studied. Moreover, Traditional Chinese medicine (TCM)-derived compounds that are candidates to treat PD may alleviate DC-T cell-mediated immune responses. Therefore, our study focused on the role of DC in response to fibrillar α-syn and subsequent induction of antigen-specific T cell responses, and the effect of TCM Curcumin-analog C1 and Tripterygium wilfordii Hook F-derived Celastrol. We found that although fibrillar α-syn did not induce significant inflammatory or T cell-mediating cytokines, robust pro-inflammatory T cell responses were found by co-culturing fibrillar α-syn-pulsed DCs with α-syn-specific CD4⁺ T cells. Celastrol, but not C1, reduced the onset of pro-inflammatory T cell differentiation, through promoting interaction of endosomal, amphisomal, and autophagic vesicles with fibrillar α-syn, which likely lead to its degradation and less antigen peptides available for presentation and T cell recognition. In conclusion, regulating the intracellular trafficking/processing of α-syn by DCs can be a potential approach to control the progression of PD, in which Celastrol is a potential candidate to accomplish this.

Mitochondria-targeted polymer-celastrol conjugate with enhanced anticancer efficacy

Celastrol, a natural triterpene extracted from traditional Chinese medicine, shows anticancer effects on various cancer cells. However, its poor water-solubility, short plasma half-life, and high systemic toxicity impede its applications in vivo, necessitating a stable drug delivery system to overcome these critical drawbacks. We present here a block copolymer, poly(2-(N-oxide-N,N-dimethylamino)ethyl methacrylate)-block-poly(2-hydroxyethyl methacrylate) (OPDMA-HEMA), as the carrier for celastrol delivery. The amphiphilic polymer-celastrol conjugate can self-assemble into nanoparticles in aqueous solutions. The OPDMA outer shell confers the nanoparticles with improved pharmacokinetics and efficient mitochondria targeting capacity, and profoundly potentiates celastrol's induction of immunogenic cell death, which collectively contribute to the enhanced therapeutic effects of celastrol in vivo. This mitochondria-targeted polymer-celastrol conjugate may promise the applications of celastrol in cancer treatment.

Heat Shock Factors in Protein Quality Control and Spermatogenesis

Proper regulation of cellular protein quality control is crucial for cellular health. It appears that the protein quality control machinery is subjected to distinct regulation in different cellular contexts such as in somatic cells and in germ cells. Heat shock factors (HSFs) play critical role in the control of quality of cellular proteins through controlling expression of many genes encoding different proteins including those for inducible protein chaperones. Mammalian cells exert distinct mechanism of cellular functions through maintenance of tissue-specific HSFs. Here, we have discussed different HSFs and their functions including those during spermatogenesis. We have also discussed the different heat shock proteins induced by the HSFs and their activities in those contexts. We have also identified several small molecule activators and inhibitors of HSFs from different sources reported so far.

Alzheimer's Disease and other Tauopathies: Exploring Efficacy of Medicinal Plant-derived Compounds in Alleviating Tau-mediated Neurodegeneration

Alzheimer's disease (AD), a major form of dementia, has been reported to affect more than 50 million people worldwide. It is characterized by the presence of amyloid-β (Aβ) plaques and hyperphosphorylated Tau-associated neurofibrillary tangles in the brain. Apart from AD, microtubule (MT)-associated protein Tau is also involved in other neurodegenerative diseases called tauopathies, including Pick's disease, frontotemporal lobar degeneration, progressive supranuclear palsy, and corticobasal degeneration. The recent unsuccessful phase III clinical trials related to Aβ- targeted therapeutic drugs have indicated that alternative targets, such as Tau, should be studied to discover more effective and safer drugs. Recent drug discovery approaches to reduce AD-related Tau pathologies are primarily based on blocking Tau aggregation, inhibiting Tau phosphorylation, compensating impaired Tau function with MT-stabilizing agents, and targeting the degradation pathways in neuronal cells to degrade Tau protein aggregates. Owing to several limitations of the currently available Tau-directed drugs, further studies are required to generate further effective and safer Tau-based disease-modifying drugs. Here, we review the studies focused on medicinal plant- derived compounds capable of modulating the Tau protein, which is significantly elevated and hyperphosphorylated in AD and other tauopathies. We have mainly considered the studies focused on Tau protein as a therapeutic target. We have reviewed several pertinent papers retrieved from PubMed and ScienceDirect using relevant keywords, with a primary focus on the Tau-targeting compounds from medicinal plants. These compounds include indolines, phenolics, flavonoids, coumarins, alkaloids, and iridoids, which have been scientifically proven to be Tau-targeting candidates for the treatment of AD.

Anti-Hyperalgesic Properties of Menthol and Pulegone

Context: Menthol, the main monoterpene found in Mentha piperita L. (M. piperita) is known to modulate nociceptive threshold and is present in different curative preparations that reduce sensory hypersensitivities in pain conditions. While for pulegone, a menthol-like monoterpene, only a limited number of studies focus on its putative analgesic effects, pulegone is the most abundant monoterpene present in Calamintha nepeta (L.) Savi (C. nepeta), a plant of the Lamiaceae family used in traditional medicine to alleviate rheumatic disorders, which counts amongst chronic inflammatory diseases.

Objectives: Here, we analyzed the monoterpenes composition of C. nepeta and M. piperita. We then compared the putative anti-hyperalgesic effects of the main monoterpenes found, menthol and pulegone, in acute inflammatory pain conditions.

Methods:C. nepeta and M. piperita extracts were obtained through pressurized liquid extraction and analyzed by gas chromatography-mass spectrometry. The in vitro anti-inflammatory activity of menthol or pulegone was evaluated by measuring the secretion of the tumour necrosis factor alpha (TNF α) from LPS-stimulated THP-1 cells. The in vivo anti-hyperalgesic effects of menthol and pulegone were tested on a rat inflammatory pain model.

Results: Pulegone and menthol are the most abundant monoterpene found in C. nepeta (49.41%) and M. piperita (42.85%) extracts, respectively. In vitro, both pulegone and menthol act as strong anti-inflammatory molecules, with EC50 values of 1.2 ± 0.2 and 1.5 ± 0.1 mM, respectively, and exert cytotoxicity with EC50 values of 6.6 ± 0.3 and 3.5 ± 0.2 mM, respectively. In vivo, 100 mg/kg pulegone exerts a transient anti-hyperalgesic effect on both mechanical (pulegone: 274.25 ± 68.89 g, n = 8; vehicle: 160.88 ± 35.17 g, n = 8, p < 0.0001), thermal heat (pulegone: 4.09 ± 0.62 s, n = 8; vehicle: 2.25 ± 0.34 s, n = 8, p < 0.0001), and cold (pulegone: 2.25 ± 1.28 score, n = 8; vehicle: 4.75 ± 1.04 score, n = 8, p = 0.0003). In a similar way, 100 mg/kg menthol exerts a transient anti-hyperalgesic effect on both mechanical (mechanical: menthol: 281.63 ± 45.52 g, n = 8; vehicle: 166.25 ± 35.4 g, n = 8, p < 0.0001) and thermal heat (menthol: 3.65 ± 0.88 s, n = 8; vehicle: 2.19 ± 0.26 s, n = 8, <0.0001).

Conclusion: Here, we show that both pulegone and menthol are anti-inflammatory and anti-hyperalgesic monoterpenes. These results might open the path towards new compound mixes to alleviate the pain sensation.

Celastrol and Melatonin Modify SIRT1, SIRT6 and SIRT7 Gene Expression and Improve the Response of Human Granulosa-Lutein Cells to Oxidative Stress

An excess of oxidative stress (OS) may affect several physiological processes fundamental to reproduction. SIRT1, SIRT6 and SIRT7 are involved in protection stress systems caused by OS, and they can be activated by antioxidants such as celastrol or melatonin. In this study, we evaluate SIRT1, SIRT6 and SIRT7 gene expression in cultured human granulosa-lutein (hGL) cells in response to OS inductors (glucose or peroxynitrite) and/or antioxidants. Our results show that celastrol and melatonin improve cell survival in the presence and absence of OS inductors. In addition, melatonin induced SIRT1, SIRT6 and SIRT7 gene expression while celastrol only induced SIRT7 gene expression. This response was not altered by the addition of OS inductors. Our previous data for cultured hGL cells showed a dual role of celastrol as a free radical scavenger and as a protective agent by regulating gene expression. This study shows a direct effect of celastrol on SIRT7 gene expression. Melatonin may protect from OS in a receptor-mediated manner rather than as a scavenger. In conclusion, our results show increased hGL cells survival with melatonin or celastrol treatment under OS conditions, probably through the regulation of nuclear sirtuins' gene expression.

Topical application of celastrol alleviates atopic dermatitis symptoms mediated through the regulation of thymic stromal lymphopoietin and group 2 innate lymphoid cells

Atopic dermatitis is a chronic inflammatory skin disease, of which incidence is closely related to exposure to environmental pollutants and allergens. Thymic stromal lymphopoietin (TSLP) plays an important role in the early stages of atopic dermatitis development by inducing Th2 immune responses. In addition, TSLP regulates activation of group 2 innate lymphoid cells (ILC2), promoting the pathogenesis of atopic dermatitis. The aim of this study was to investigate whether celastrol alleviated atopic dermatitis symptoms by regulating TSLP expression and ILC2 stimulation. Celastrol suppressed TSLP production in mouse keratinocyte cells by inhibiting NF-ĸB activation. Topical application of celastrol significantly improved atopic dermatitis symptoms induced by house dust mite (HDM) in NC/Nga mice as determined by dermatitis score and histological assessment. Celastrol decreased the levels of TSLP in atopic dermatitis skin lesions of HDM-stimulated NC/Nga mice. Celastrol reduced levels of Th2 cytokines including IL-4, IL-5, and IL-13 in atopic dermatitis skin lesions of NC/Nga mice. Further, celastrol significantly reduced ILC2 population in atopic dermatitis skin lesions of NC/Nga mice. These results indicate that topical application of celastrol improved atopic dermatitis symptoms by lowering TSLP levels and concomitant immune responses. Data demonstrated that reduced TSLP levels and associated lower number of ILC2 cells alleviate atopic dermatitis symptoms induced by house dust mite.

GRAS-microparticle microarrays identify dendritic cell tolerogenic marker-inducing formulations

Microarrays, miniaturized platforms used for high-content studies, provide potential advantages over traditional in vitro investigation in terms of time, cost, and parallel analyses. Recently, microarrays have been leveraged to investigate immune cell biology by providing a platform with which to systematically investigate the effects of various agents on a wide variety of cellular processes, including those giving rise to immune regulation for application toward curtailing autoimmunity. A specific embodiment incorporates dendritic cells cultured on microarrays containing biodegradable microparticles. Such an approach allows immune cell and microparticle co-localization and release of compounds on small, isolated populations of cells, enabling a quick, convenient method to quantify a variety of cellular responses in parallel. In this study, the microparticle microarray platform was utilized to investigate a small library of sixteen generally regarded as safe (GRAS) compounds (ascorbic acid, aspirin, capsaicin, celastrol, curcumin, epigallocatechin-3-gallate, ergosterol, hemin, hydrocortisone, indomethacin, menadione, naproxen, resveratrol, retinoic acid, α-tocopherol, vitamin D3) for their ability to induce suppressive phenotypes in murine dendritic cells. Two complementary tolerogenic index ranking systems were proposed to summarize dendritic cell responses and suggested several lead compounds (celastrol, ergosterol, vitamin D3) and two secondary compounds (hemin, capsaicin), which warrant further investigation for applications toward suppression and tolerance.

The Therapeutic Potential of Celastrol in Central Nervous System Disorders: Highlights from In Vitro and In Vivo Approaches

Celastrol, the most abundant compound derived from the root of Tripterygium wilfordii, largely used in traditional Chinese medicine, has shown preclinical and clinical efficacy for a broad range of disorders, acting via numerous mechanisms, including the induction of the expression of several neuroprotective factors, the inhibition of cellular apoptosis, and the decrease of reactive oxygen species (ROS). Given the crucial implication of these pathways in the pathogenesis of Central Nervous System disorders, both in vitro and in vivo studies have focused their attention on the possible use of this compound in these diseases. However, although most of the available studies have reported significant neuroprotective effects of celastrol in cellular and animal models of these pathological conditions, some of these data could not be replicated. This review aims to discuss current in vitro and in vivo lines of evidence on the therapeutic potential of celastrol in neurodegenerative diseases, including Alzheimer’s and Parkinson’s diseases, amyotrophic lateral sclerosis, Huntington’s disease, multiple sclerosis, and cadmium-induced neurodegeneration, as well as in psychiatric disorders, such as psychosis and depression. In vitro and in vivo studies focused on celastrol effects in cerebral ischemia, ischemic stroke, traumatic brain injury, and epilepsy are also described.

Nuclear Receptor Nur77 Protects Against Abdominal Aortic Aneurysm by Ameliorating Inflammation Via Suppressing LOX-1

Background Abdominal aortic aneurysm (AAA) is a life-threatening vascular disorder characterized by chronic inflammation of the aortic wall, which lacks effective pharmacotherapeutic remedies and has an extremely high mortality. Nuclear receptor NR4A1 (Nur77) functions in various chronic inflammatory diseases. However, the influence of Nur77 on AAA has remained unclear. Herein, we sought to determine the effects of Nur77 on the development of AAA. Methods and Results We observed that Nur77 expression decreased significantly in human and mice AAA lesions. Deletion of Nur77 accelerated the development of AAA in mice, as evidenced by increased AAA incidence, abdominal aortic diameters, elastin fragmentation, and collagen content. Consistent with genetic manipulation, pharmacological activation of Nur77 by celastrol showed beneficial effects against AAA. Microscopic and molecular analyses indicated that the detrimental effects of Nur77 deficiency were associated with aggravated macrophage infiltration in AAA lesions and increased pro-inflammatory cytokines secretion and matrix metalloproteinase (MMP-9) expression. Bioinformatics analyses further revealed that LOX-1 was upregulated by Nur77 deficiency and consequently increased the expression of cytokines and MMP-9. Moreover, rescue experiments verified that LOX-1 notably aggravated inflammatory response, an effect that was blunted by Nur77. Conclusions This study firstly demonstrated a crucial role of Nur77 in the formation of AAA by targeting LOX-1, which implicated Nur77 might be a potential therapeutic target for AAA.

Natural Products with tandem Anti-inflammatory, Immunomodulatory and Anti-SARS-CoV/2 effects: A Drug Discovery Perspective against SARS-CoV-2

BACKGROUND

COVID-19 is still causing victims with long-term health consequences, mass deaths, and collapsing healthcare systems around the world. The disease has no efficient drugs. However, previous studies revealed that SARS-CoV-2 and SARS-CoV have 96% and 86.5% similarities in cysteine proteases (3CL^pro) and papain-like protease (PL^pro) sequences, respectively. This resemblance could be significant in the search for drug candidates with antiviral effects against SARS-CoV-2.

OBJECTIVE

This paper is a compilation of natural products that inhibit SARS-CoV 3CL^pro and PL^pro and, concomitantly, reduce inflammation and/or modulate the immune system as a perspective strategy for COVID-19 drug discovery. It also presents in silico studies performed on these selected natural products using SARS-CoV-2 3CL^pro and PL^pro as targets to propose a list of hit compounds.

METHOD

The plant metabolites were selected in the literature based on their biological activities on SARS-CoV proteins, inflammatory mediators, and immune response. The consensus docking analysis was performed using four different packages.

RESULTS

Seventy-nine compounds reported in the literature with inhibitory effects on SARS-CoV proteins were reported as anti-inflammatory agents. Fourteen of them showed in previous studies immunomodulatory effects. Five and six of these compounds showed significant in silico consensus as drug candidates that can inhibit PL^pro and 3CL^pro, respectively. Our findings corroborated recent results reported on anti-SARS-CoV-2 in the literature.

CONCLUSION

This study revealed that amentoflavone, rubranoside B, savinin, psoralidin, hirsutenone, and papyriflavonol A are good drug candidate for the search of antibiotics against COVID-19.

The neuroprotective attribution of Ocimum basilicum: a review on the prevention and management of neurodegenerative disorders

Background

Bioactive principles from various natural resources including medicinal herbs have always played a crucial role in healthcare settings and increasingly became key players in drug discovery and development for many biopharmaceutical applications. Additionally, natural products (NPs) have immense arrangement of distinctive chemical structures with diverse functional groups that motivated numerous investigators including synthetic chemists to discover new therapeutic entities. Numerous pre-clinical investigations involving the animal models have evident the usefulness of these NPs against various human diseases including neurodegenerative disorders (NDs).

Main text

Ocimum basilicum Linn (O. basilicum L.), also known as sweet basil, is well practiced in traditional healthcare systems and has been used to treat various human illnesses, which include malaria, skin disease, diarrhea, bronchitis, dysentery, arthritis, eye diseases, and insect bites and emphasize the significance of the ethno-botanical approach as a potential source of novel drug leads With the growing interest in advanced techniques, herbal medicine and medicinal plants explorations are still considered to be a novel resource for new pharmacotherapeutic discovery and development. O. basilicum L and its bioactive principles including apigenin, eugenol, myretenal, β-sitosterol, luteolin, rosmarinic acid, carnosic acid, essential oil (EO)-rich phenolic compounds, and others like anthocyanins and flavones could be of therapeutic values in NDs by exhibiting their neuro-protective efficacy on various signaling pathways. The present comprehensive review collected various related information using the following searching engines such as PubMed, Science Direct, Google Scholar, etc. and focused mainly the English written documents. The search period comprised of last two decades until present.

Conclusion

Although these efficacious plant genera of prime importance and has potential medical and socioeconomic importance, yet the pivotal evidence for its neuroprotective potential in novel clinical trials remains lacking. However, with the available wealth of obtainable literature on this medicinal plant, which supports this review and concludes that O. basilicum L may function as a promising therapeutics for the treatment of NDs.

Natural product remedies for COVID-19: A focus on safety

Infection by the novel coronavirus SARS-CoV-2 causing the coronavirus disease (COVID-19), is currently a global pandemic with more than two million deaths to date. Though a number of vaccines have recently been approved against the virus, availability remains a big challenge, and also acceptance by most people has become a big debate. This review discusses possible/proposed natural product remedies and some major conventional treatment options used to manage the infection and, safety concerns on the use of unproven or unapproved health products against COVID-19. An extensive literature review indicated that the influx of unproven and unapproved health products in the global market are on the rise, leading to various forms of self- medication. To this effect, there have been warnings by the United States Food and Drug Administration and the World Health Organisation against the use of such products. Conventional drugs such as remdesivir, chloroquine/hydroxychloroquine and dexamethasone are the major proposed drugs that are currently undergoing clinical trials for the management of this disease. Efforts are being made globally in the search for possible therapeutics which may be the best way to eradicating this disease. Some countries have approved the use of natural products in the management of COVID-19, despite little or no clinical evidence on their efficacy and safety. Natural products may hold a great potential in the fight against COVID-19 but without detailed clinical trials, their potency against the virus and their safe use cannot be established. To attain this goal, extensive research followed by clinical studies are needed. Collaborative efforts between researchers, clinicians, governments and traditional medicinal practitioners in the search and development of safe and effective therapeutics from natural products for the treatment of COVID-19 could be a potential option.

Celastrol inhibits the proliferation and angiogenesis of high glucose-induced human retinal endothelial cells

Background

Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes. Celastrol plays a certain role in the improvement of various diabetes complications. Therefore, this study aimed to explore whether celastrol inhibited the proliferation and angiogenesis of high glucose (HG)-induced human retinal endothelial cells (hRECs) by down-regulating the HIF1/VEGF signaling pathway.

Methods

The viability and proliferation of hRECs treated with glucose, celastrol or dimethyloxallyl glycine (DMOG) were analyzed by MTT assay. The invasion and tube formation ability of hRECs treated with glucose, celastrol or DMOG were in turn detected by transwell assay and tube formation assay. The expression of HIF1α and VEGF in hRECs after indicated treatment was analyzed by Western blot analysis and RT-qPCR analysis and ICAM-1 expression in hRECs after indicated treatment was detected by immunofluorescence assay

Results

HG induction promoted the proliferation, invasion and tube formation ability and increased the expression of HIF-1α and VEGF of hRECs, which were gradually suppressed by celastrol changing from 0.5 to 2.0 μM. DMOG was regarded as a HIF1α agonist, which attenuated the effect of celastrol on HG-induced hRECs.

Conclusion

Celastrol inhibited the proliferation and angiogenesis of HG-induced hRECs by down-regulating the HIF1α/VEGF signaling pathway.

Celastrol Prevents Oxidative Stress Effects on FSHR, PAPP, and CYP19A1 Gene Expression in Cultured Human Granulosa-Lutein Cells

Regulation of oxidative stress (OS) is important to prevent damage to female reproductive physiology. While normal OS levels may have a regulatory role, high OS levels may negatively affect vital processes such as folliculogenesis or embryogenesis. The aim of this work was to study OS induced by glucose, a reactive oxygen species generator, or peroxynitrite, a reactive nitrogen species generator, in cultured human granulosa-lutein (hGL) cells from oocyte donors, analyzing expression of genes involved in oocyte maturation (FSHR, PAPP, and CYP19A1) and OS damage response (ALDH3A2). We also evaluated the effect of celastrol as an antioxidant. Our results showed that although both glucose and peroxynitrite produce OS increments in hGL cells, only peroxynitrite treatment increases ALDH3A2 and PAPP gene expression levels and decreases FSHR gene expression levels. Celastrol pre-treatment prevents this effect of peroxynitrite. Interestingly, when celastrol alone was added, we observed a reduction of the expression of all genes studied, which was independent of both OS inductors. In conclusion, regulation of OS imbalance by antioxidant substances such as celastrol may prevent negative effects of OS in female fertility. In addition to the antioxidant activity, celastrol may well have an independent role on regulation of gene expression in hGL cells.

The genome of Tripterygium wilfordii and characterization of the celastrol biosynthesis pathway

Tripterygium wilfordii is a vine from the Celastraceae family that is used in traditional Chinese medicine (TCM). The active ingredient, celastrol, is a friedelane-type pentacyclic triterpenoid with putative roles as an antitumor, immunosuppressive, and anti-obesity agent. Here, we report a reference genome assembly of T. wilfordii with high-quality annotation using a hybrid sequencing strategy. The total genome size obtained is 340.12 Mb, with a contig N50 value of 3.09 Mb. We successfully anchored 91.02% of sequences into 23 pseudochromosomes using high-throughput chromosome conformation capture (Hi–C) technology. The super-scaffold N50 value was 13.03 Mb. We also annotated 31,593 structural genes, with a repeat percentage of 44.31%. These data demonstrate that T. wilfordii diverged from Malpighiales species approximately 102.4 million years ago. By integrating genome, transcriptome and metabolite analyses, as well as in vivo and in vitro enzyme assays of two cytochrome P450 (CYP450) genes, TwCYP712K1 and TwCYP712K2, it is possible to investigate the second biosynthesis step of celastrol and demonstrate that this was derived from a common ancestor. These data provide insights and resources for further investigation of pathways related to celastrol, and valuable information to aid the conservation of resources, as well as understand the evolution of Celastrales.

Role of medicinal plants against neurodegenerative diseases

Diseases with a significant loss of neurons, structurally and functionally are termed as neurodegenerative diseases. Due to the present therapeutic interventions and progressive nature of diseases, a variety of side effects have risen up, thus leading the patients to go for an alternative medication. The role of medicinal plants in such cases has been beneficial because of their exhibition via different cellular and molecular mechanisms. Alleviation in inflammatory responses, suppression of the functionary aspect of pro-inflammatory cytokines like a tumor, improvement in antioxidative properties is among few neuroprotective mechanisms of traditional plants. Variation in transcription and transduction pathways play a vital role in the preventive measures of plants in such diseases. Neurodegenerative diseases are generally caused by depletion of proteins, oxidative and inflammatory stress, environmental changes and so on, with aging being the most important cause. Natural compounds can be used in order to treat neurodegenerative diseases Medicinal plants such as Ginseng, Withania somnifera, Bacopa monnieri, Ginkgo biloba, etc. are some of the medicinal plants for prevention of neurological symptoms. This review deals with the use of different medicinal plants for the prevention of neurodegenerative diseases.

The effect of nutmeg essential oil constituents on Novikoff hepatoma cell viability and communication through Cx43 gap junctions

Essential oils from plants are a potential source of molecules having anti-inflammatory, anticancer, cardiotropic, and other activities. However, most of these effects lack mechanistic explanations and structure-activity relationship testing. In the present study, we: 1) identified the nutmeg essential oil (NEO) composition; 2) using molecular docking, we determined the putative regulatory binding sites on the connexin 43 (Cx43) that is responsible for gap junction-dependent intercellular communication (GJIC) in the majority of tissues; 3) examined the effect of NEO and its three constituents - sabinene, α-pinene, and α-copaene - on GJ conductance and gating in Novikoff cells expressing endogenous Cx43; and 4) verified whether NEO effects on GJIC correlated with its action on Novikoff cell viability, proliferation, and colony formation capability. Our results revealed NEO and its constituents as potent and efficient Cx43 GJ inhibitors acting by slow gating mechanism. In addition, NEO reduced Novikoff hepatoma cell viability, proliferation, and colony formation capability; however, this was achieved at higher doses and was unrelated to its effects on GJIC.

Alzheimer's disease treatment: The share of herbal medicines

One of the most frequent forms of dementia in neurological disorders is Alzheimer's disease (AD). It is a chronic neurodegenerative disease characterized by impaired learning and memory. Pathological symptoms as extracellular amyloid-beta (Aβ) plaques and intracellular accumulation of neurofibrillary tangles occur in AD. Due to the aging of the population and increased prevalence of AD, discovery of new therapeutic agents with the highest effectiveness and fewer side effect seems to be necessary. Numerous synthetic medicines such as tacrine, donepezil, galantamine, rivastigmine, memantine, glutathione, ascorbic acid, ubiquinone, ibuprofen, and ladostigil are routinely used for reduction of the symptoms and prevention of disease progression. Nowadays, herbal medicines have attracted popular attention for numerous beneficial effects with little side effects. Lavandula angustifolia, Ginkgo biloba, Melissa officinalis, Crocus sativus, Ginseng, Salvia miltiorrhiza, and Magnolia officinalis have been widely used for relief of symptoms of some neurological disorders. This paper reviews the therapeutic effects of phytomedicines with prominent effects against various factors implicated in the emergence and progression of AD.

Celastrol inhibits intestinal lipid absorption by reprofiling the gut microbiota to attenuate high-fat diet-induced obesity

Celastrol, a compound extracted from traditional Chinese medicine, has been reported as a potent anti-obesity agent with controversial mechanisms. Here both C57BL/6J and leptin-deficient (ob/ob) mice fed a high-fat diet (HFD) displayed body weight loss after celastrol therapy, opposing the previous viewpoint that celastrol improves obesity by sensitizing leptin signaling. More importantly, celastrol downregulated lipid transporters in the intestine, increased lipid excretion in feces, and reduced body weight gain in HFD mice. Meanwhile, analysis of gut microbiota revealed that celastrol altered the gut microbiota composition in HFD-fed mice, and modulating gut microbiota by antibiotics or fecal microbiota transplantation blocked the celastrol effect on intestinal lipid transport and body weight gain, suggesting a critical role of the gut microbiota composition in mediating the anti-obesity role of celastrol under HFD. Together, the findings revealed that celastrol reduces intestinal lipid absorption to antagonize obesity by resetting the gut microbiota profile under HFD feeding.

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Celastrol reduced intestinal lipid transporters and lipids absorption

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Celastrol reset gut microbiota profile to modulate intestinal lipid transport

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Celastrol attenuated obesity in leptin-deficient (ob/ob) mice fed high fat diet