Antioxidant effects of curcumin in models of neurodegeneration, aging, oxidative and nitrosative stress: A review

The Pathology of Parkinson's Disease and Potential Benefit of Dietary Polyphenols

Parkinson's disease (PD) is a progressive neurodegenerative disorder that is characterized by a loss of dopaminergic neurons, leading to bradykinesia, rigidity, tremor at rest, and postural instability, as well as non-motor symptoms such as olfactory impairment, pain, autonomic dysfunction, impaired sleep, fatigue, and behavioral changes. The pathogenesis of PD is believed to involve oxidative stress, disruption to mitochondria, alterations to the protein α-synuclein, and neuroinflammatory processes. There is currently no cure for the disease. Polyphenols are secondary metabolites of plants, which have shown benefit in several experimental models of PD. Intake of polyphenols through diet is also associated with lower PD risk in humans. In this review, we provide an overview of the pathology of PD and the data supporting the potential neuroprotective capacity of increased polyphenols in the diet. Evidence suggests that the intake of dietary polyphenols may inhibit neurodegeneration and the progression of PD. Polyphenols appear to have a positive effect on the gut microbiome, which may decrease inflammation that contributes to the disease. Therefore, a diet rich in polyphenols may decrease the symptoms and increase quality of life in PD patients.

Effect of Herbal Medicinal Compounds on Alzheimer’s Disease Pathology in APP/PS1 Transgenic Mouse Model

The pathogenesis of Alzheimer’s disease (AD) is complex as various mechanisms interact with each other and, therefore, intervention from a single target is often ineffective. Many studies have shown that herbal medicines, such as curcumin, fisetin, icariin, and ginsenosides, have significant intervention effects on AD with different treatment mechanisms. Therefore, we have designed this study to know whether the combination of these herbal medicines can have an intervention effect on AD through multiple targets. Amyloid precursor protein/presenilin 1(APP/PS1) double transgenic AD mice were used to study the protective effects of a combination of curcumin, piperine, icariin, and ginsenosides, as well as a combination of fisetin, piperine, icariin, and ginsenosides, which were separately mixed into the feed. These herbal medicinal compounds (HMCs) lowered the serum lipid levels, reduced the Aβ oligomers, decreased the pS404-tau protein, as well as neurofibrillary tangles, and restored the reduction of synaptic protein levels and neuronal death of AD mice without causing toxicity to liver and kidneys. In this study, we found that HMCs have significant intervention against AD through multiple targets, providing a novel therapeutic idea for the prevention of AD.

Preparation of chitosan/curcumin nanoparticles based zein and potato starch composite films for Schizothorax prenati fillet preservation

The aim of this study was to develop a zein/potato starch (PS) film based on chitosan nanoparticles incorporated with curcumin (CCN). The CCN film was characterized for encapsulation efficiency, particle size, zeta potential, polydispersity index (PDI), relative release, and DPPH radical scavenging test. Our results showed that the CCN encapsulated effectively curcumin (CUR) (84.8% ± 1.1%) and presented with high oxidation resistance and relative release efficiency. The CCN/zein/PS composite films were round, smooth, and compact. We measured and compared the mechanical properties, oxygen permeability (OP), water vapor permeability (WVP), relative release efficiency, and DPPH radical scavenging properties of the composite films of different mass ratios. We observed that the composite film had good mechanical and barrier properties. Further, we evaluated the preservative efficacy of the composite film on Schizothorax prenati fillets by measuring pH, total volatile basic nitrogen (TVB-N), thiobarbituric acid-reactive substances (TBARS), hardness, microbial counts, organoleptic characteristics, and other fillet quality parameters. The CCN/zein/PS composite film delayed physicochemical changes in the Schizothorax prenati fillets and prolonged their shelf life by up to 15 days. In conclusion, our work shows that CCN/zein/PS composite film holds promise as a potential bioactive packaging material for Schizothorax prenati fillets.

Antioxidant Activity of Encapsulated Extracts and Bioactives from Natural Sources

The low water solubility and low bioavailability of natural bioactive substances such as polyphenols and flavonoids, either in pure form or extracts, are a major concern in the pharmaceutical field and even on the food development sector. Although encapsulation has demonstrated success in addressing these drawbacks, it is important to evaluate the antioxidant activity of the encapsulated compounds. This article reviews the encapsulation of bioactive compounds from natural sources focusing their antioxidant activity after encapsulation. Attention is given to the methods and wall materials used, and the antioxidant activity methodologies (classical in vitro techniques such as DPPH, ORAC, FRAP and others, as well as in vivo/ex vivo tests to evaluate endogenous antioxidant enzymes or oxidative stress) applied to assess the antioxidant capacity are also comprehensively summarized.

Targeting the Wnt/β-catenin pathway in neurodegenerative diseases: recent approaches and current challenges

INTRODUCTION

Wnt/β-catenin signaling is an evolutionarily conserved pathway having a crucial role in embryonic and adult life. Specifically, the Wnt/β-catenin axis is pivotal to the development and homeostasis of the nervous system, and its dysregulation has been associated with various neurological disorders, including neurodegenerative diseases. Therefore, this signaling pathway has been proposed as a potential therapeutic target against neurodegeneration.

AREAS COVERED

This review focuses on the role of Wnt/β-catenin pathway in the pathogenesis of neurodegenerative diseases, including Parkinson's, Alzheimer's Diseases and Amyotrophic Lateral Sclerosis. The evidence showing that defects in the signaling might be involved in the development of these diseases, and the pharmacological approaches tested so far, are discussed. The possibilities that this pathway offers in terms of new therapeutic opportunities are also considered.

EXPERT OPINION

The increasing interest paid to the role of Wnt/β-catenin pathway in the onset of neurodegenerative diseases demonstrates how targeting this signaling for therapeutic purposes could be a great opportunity for both neuroprotection and neurorepair. Without overlooking some licit concerns about drug safety and delivery to the brain, there is growing and more convincing evidence that restoring this signaling in neurodegenerative diseases may strongly increase the chance to develop disease-modifying treatments for these brain pathologies.

Cytotoxic effects of polystyrene nanoplastics with different surface functionalization on human HepG2 cells

Nanoplastics in the environment lead to the human exposure to these particles. However, the consequences of this exposure are not yet fully understood. Here, the cytotoxicity of polystyrene nanoparticles (PS-NPs) with a uniform size (50 nm) but distinct surface functionalization (pristine polystyrene, PS; carboxy and amino functionalized, PS-COOH and PS-NH₂, respectively), and at an exposure dosage of 10, 50 and 100 μg/mL, were assessed in the human hepatocellular carcinoma (HepG2) cell line. Although all PS-NPs could be internalized by the HepG2 cells, according to the fluorescent intensities, more of PS-COOH and PS-NH₂ than PS, accumulated in the cells. The cell viability was significantly affected in a positively dose-related manner. Functionalized PS-NPs exhibited greater inhibition of cell viability than PS, and the viability inhibition peaked (46%) at 100 μg/mL of PS-NH₂ exposure. Superoxide dismutase (SOD) activity was maximum when HepG2 cells were exposed to 10 μg/mL of PS-COOH (1.8 folds higher than that without PS-COOH exposure). The glutathione (GSH) content was maximum when the cells were treated with 50 μg/mL of PS (3.75 fold increase compared to untreated cells). Although the difference in inhibition of cell viability was not significant between PS-NH₂ and PS-COOH exposure, 100 μg/mL of PS-NH₂ exposure caused the most severe oxidative stress due to dramatically increased accumulation of malondialdehyde (MDA); however, a decrease in the antioxidants levels as the SOD activity and GSH content were also found. The results demonstrated that the cellular oxidative damage occurred and that the antioxidation enzymes may not be able to maintain the balance between the generation of oxidant species and the antioxidant defense. Consequently, 100 μg/mL of PS-NH₂ exposure triggered the destruction of antioxidant structures. This study defines the cytotoxic effects of PS-NPs on HepG2 cells and emphasizes the significance of investigating the cytotoxic outcomes of nanoplastics in humans.

Effect of Morning vs. Evening Turmeric Consumption on Urine Oxidative Stress Biomarkers in Obese, Middle-Aged Adults: A Feasibility Study

The circadian rhythm of biological systems is an important consideration in developing health interventions. The immune and oxidative defense systems exhibit circadian periodicity, with an anticipatory increase in activity coincident with the onset of the active period. Spice consumption is associated with enhanced oxidative defense. The objective of this study was to test the feasibility of a protocol, comparing the effects of morning vs. evening consumption of turmeric on urine markers of oxidative stress in obese, middle-aged adults. Using a within-sample design, participants received each of four clock time x treatment administrations, each separated by one week: morning turmeric; evening turmeric; morning control; evening control. Participants prepared for each lab visit by consuming a low-antioxidant diet for two days and fasting for 12 h. Urine was collected in the lab at baseline and one-hour post-meal and at home for the following five hours. The results showed that the processes were successful in executing the protocol and collecting the measurements and that participants understood and adhered to the instructions. The findings also revealed that the spice treatment did not elicit the expected antioxidant effect and that the six-hour post-treatment urine collection period did not detect differences in urine endpoints across treatments. This feasibility study revealed that modifications to the spice treatment and urine sampling timeline are needed before implementing a larger study.

Nanocurcumin: A Promising Candidate for Therapeutic Applications

Curcuma longa is an important medicinal plant and a spice in Asia. Curcumin (diferuloylmethane) is a hydrophobic bioactive ingredient found in a rhizome of the C. longa. It has drawn immense attention in recent years for its variety of biological and pharmacological action. However, its low water solubility, poor bioavailability, and rapid metabolism represent major drawbacks for its successful therapeutic applications. Hence, researchers have attempted to enhance the biological and pharmacological activity of curcumin and overcome its drawbacks by efficient delivery systems, particularly nanoencapsulation. Research efforts so far and data from the available literature have shown a satisfactory potential of nanorange formulations of curcumin (Nanocurcumin), it increases all the biological and pharmacological benefits of curcumin, which was not significantly possible earlier. For the synthesis of nanocurcumin, an array of techniques has been developed and each technique has its own advantages and individual characteristics. The two most popular and effective techniques are ionic gelation and antisolvent precipitation. So far, many curcumin nanoformulations have been developed to enhance curcumin delivery, thereby overcoming the low therapeutic effects. However, most of the nanoformulation of curcumin remained at the concept level evidence, thus, several questions and challenges still exist to recommend the nanocurcumin as a promising candidate for therapeutic applications. In this review, we discuss the different curcumin nanoformulation and nanocurcumin implications for different therapeutic applications as well as the status of ongoing clinical trials and patents. We also discuss the research gap and future research directions needed to propose curcumin as a promising therapeutic candidate.

Curcumin circumvent lactate-induced chemoresistance in hepatic cancer cells through modulation of hydroxycarboxylic acid receptor-1

Curcumin has been demonstrated to affect the chemoresistance in cancer cells of various origins. However, its ability to modulate lactate-induced chemoresistance remains unclear. The Present investigation demonstrates that curcumin inhibits the survival of HepG2 and HuT78 cells and can modulate chemo-susceptibility of HepG2 cells. Experimental simulation of simultaneous and pre-treatment suggest cooperatively between curcumin and anticancer drugs as well as the modulation of molecular regulators. Inhibition of glucose consumption, lactate production, extracellular acidity and augmented level of Nitric oxide were observed. DAPI staining revealed hyper condensation of chromatin in curcumin-treated HepG2 cells. Curcumin also diminished the lactate-induced chemoresistance against doxorubicin in hepatic cancer cells along with down regulation of lactate receptor (hydroxycarboxylic acid receptor-1; HCAR-1/GPR81). Alteration of the extracellular milieu along with inhibited expression of genes (hif-1α, ldh-a, mct-1, mdr-1 and stat-3) and proteins (HIF-1α and HCAR-1) are indicated to be involved in curcumin-induced reversal of chemoresistance in HepG2 cells. Findings of present investigation contribute to knowledge of curcumin mediated chemosensitization and its mechanism.

Effect of Curcumin on Protein Damage Induced by Rotenone in Dopaminergic PC12 Cells

Oxidative stress is considered to be a key factor of the pathogenesis of Parkinson's disease, a multifactorial neurodegenerative disorder characterized by reduced dopaminergic neurons in the substantia nigra pars compacta and accumulated protein aggregates. Rotenone is a worldwide-used pesticide that induces the most common features of Parkinson's by direct inhibition of the mitochondrial complex I. Rotenone-induced Parkinson's models, as well as brain tissues from Parkinson's patients, are characterized by the presence of both lipid peroxidation and protein oxidation markers resulting from the increased level of free radical species. Oxidation introduces several modifications in protein structure, including carbonylation and nitrotyrosine formation, which severely compromise cell function. Due to the link existing between oxidative stress and Parkinson's disease, antioxidant molecules could represent possible therapeutic tools for this disease. In this study, we evaluated the effect of curcumin, a natural compound known for its antioxidant properties, in dopaminergic PC12 cells treated with rotenone, a cell model of Parkinsonism. Our results demonstrate that the treatment of PC12 cells with rotenone causes severe protein damage, with formation of both carbonylated and nitrotyrosine-derived proteins, whereas curcumin (10 µM) co-exposure exerts protective effects by reducing the levels of oxidized proteins. Curcumin also promotes proteasome activation, abolishing the inhibitory effect exerted by rotenone on this degradative system.

Characterization and Dissolution Study of Micellar Curcumin-Spray Dried Powder for Oral Delivery

Introduction

Curcumin faces a major challenge in clinical use due to its poor aqueous solubility, which affects its bioavailability over oral use. The present study was carried out to overcome this problem.

Methods

An amorphous micellar curcumin-spray dried powder (MC-SDP) with self-assembled casein was prepared by the addition of sucrose as a protectant. The dry powder of curcumin-loaded micelles was obtained by a spray-drying technique in the presence of sucrose as a protectant. The MC-SDP in the form of dry powder was further developed into tablets to investigate the dissolution profile. The physical properties of preformed powder were characterized by differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Quantitative analysis in the form of solutions was analyzed by high-performance liquid chromatography (HPLC).

Results

The physical properties demonstrated that MC-SDP varies from dented to smoother surfaces as a function of sucrose. Furthermore, melting transitions of curcumin in the form of MC-SDP were broadened in all sample mixtures, as observed in the DTA thermogram. The XRD spectra showed that the sharp and very intense peaks of single curcumin crystalline structure no longer existed in all MC-SDP forms, indicating that the mixtures were amorphous. Moreover, a further dissolution study of MC-SDP showed a significant increase of drug dissolved with the presence of sucrose, where >80% of curcumin from MC-SDP was dissolved within 30 min.

Conclusion

The study demonstrated the manufacture of micellar spray-dried powder that would contribute to the development of oral delivery of curcumin.

Neuroinflammation: An overview of neurodegenerative and metabolic diseases and of biotechnological studies

Neuroinflammation is an important factor contributing to cognitive impairment and neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), Amyotrophic lateral sclerosis (ALS), ischemic injury, and multiple sclerosis (MS). These diseases are characterized by inexorable progressive injury of neuron cells, and loss of motor or cognitive functions. Microglia, which are the resident macrophages in the brain, play an important role in both physiological and pathological conditions. In this review, we provide an updated discussion on the role of ROS and metabolic disease in the pathological mechanisms of activation of the microglial cells and release of cytotoxins, leading to the neurodegenerative process. In addition, we also discuss in vivo models, such as zebrafish and Caenorhabditis elegans, and provide new insights into therapeutics bioinspired by neuropeptides from venomous animals, supporting high throughput drug screening in the near future, searching for a complementary approach to elucidating crucial mechanisms associated with neurodegenerative disorders.

Role of curcumin and its nanoformulations in neurotherapeutics: A comprehensive review

Curcumin, a dietary polyphenol and major constituent of Curcuma longa (Zingiberaceae), is extensively used as a spice in Asian countries. For ages, turmeric has been used in traditional medicine systems to treat various diseases, which was possible because of its anti-inflammatory, antioxidant, anticancerous, antiepileptic, antidepressant, immunomodulatory, neuroprotective, antiapoptotic, and antiproliferative effects. Curcumin has potent antioxidant, anti-inflammatory, antiapoptotic, neurotrophic activities, which support its plausible neuroprotective effects in neurodegenerative disease. However, there is limited information available regarding the clinical efficacy of curcumin in neurodegenerative cases. The low oral bioavailability of curcumin may be speculated as a plausible factor that limits its effects in humans. Therefore, utilization of several approaches for the enhancement of bioavailability may improve clinical outcomes. Furthermore, the use of nanotechnology and a targeted drug delivery system may improve the bioavailability of curcumin. The present review is designed to summarize the molecular mechanisms pertaining to the neuroprotective effects of curcumin and its nanoformulations.

Evaluation of Antioxidant Activity of Spice-Derived Phytochemicals Using Zebrafish

Various dietary phytochemicals seem to display antioxidant activity through the NF-E2-related factor 2 (Nrf2) pathway. However, few studies have demonstrated its antioxidant effect and Nrf2 dependency at the animal level. We constructed a zebrafish-based assay system to analyze the in vivo antioxidant activity of phytochemicals and examined the activity of 10 phytochemicals derived from spices, using this system as a pilot study. Hydrogen peroxide and arsenite were used as oxidative stressors, and Nrf2 dependency was genetically analyzed using an Nrf2-mutant zebrafish line. The activities of curcumin, diallyl trisulfide and quercetin were involved in the reduction of hydrogen peroxide toxicity, while those of cinnamaldehyde, isoeugenol and 6-(methylsulfinyl)hexyl isothiocyanate were involved in the reduction of arsenite toxicity. The antioxidant activities of these phytochemicals were all Nrf2 dependent, with the exception of cinnamaldehyde, which showed strong antioxidant effects even in Nrf2-mutant zebrafish. In summary, we succeeded in constructing an assay system to evaluate the in vivo antioxidant activity of various phytochemicals using zebrafish larvae. Using this system, we found that each spice-derived phytochemical has its own specific property and mechanism of antioxidant action.

Curcumin's Nanomedicine Formulations for Therapeutic Application in Neurological Diseases

The brain is the body's control center, so when a disease affects it, the outcomes are devastating. Alzheimer's and Parkinson's disease, and multiple sclerosis are brain diseases that cause a large number of human deaths worldwide. Curcumin has demonstrated beneficial effects on brain health through several mechanisms such as antioxidant, amyloid β-binding, anti-inflammatory, tau inhibition, metal chelation, neurogenesis activity, and synaptogenesis promotion. The therapeutic limitation of curcumin is its bioavailability, and to address this problem, new nanoformulations are being developed. The present review aims to summarize the general bioactivity of curcumin in neurological disorders, how functional molecules are extracted, and the different types of nanoformulations available.

Curcumin Protects against White Matter Injury through NF-κB and Nrf2 Cross Talk

Inflammation and oxidative stress play a central role in the pathogenesis of white matter injury (WMI). Curcumin (Cur), a polyphenolic compound, exhibits anti-inflammatory and anti-oxidant effects on several conditions. The objective of this study was to investigate neuroprotective effects of Cur on WMI and explore its underlying mechanisms of action. Sprague-Dawley rats were subjected to the removal of white matter from the dorsal column of the spinal cord. Dorsal columns were randomly divided into three groups: Sham (Ringer's solution bubbled with 95% O₂ and 5% CO₂), hypoxia (Hyp; Ringer's solution bubbled with 95% N₂ and 5% CO₂ for 1 h), and Cur-treated (Hyp+Cur; Ringer's solution bubbled with 95% N₂ and 5% CO₂ for 1 h in the presence of 50 μM Cur). For NF-κB inhibition experiments, dorsal columns were incubated with 50 μM BAY 11-7082 (BAY) for 30 min in 95% O₂ and 5% CO₂ prior to 1-h incubation with 50 μM Cur in 95% N₂ and 5% CO₂. Our data show that Cur inhibited hypoxia-induced HIF1-α expression and tissue damage by demonstrating the improved morphology of astrocytes and remarkable reduction in vacuolation. Cur also inhibited the hypoxia-induced upregulation of glial fibrillary acidic protein (GFAP) and neurofilament-H (NF-H) after hypoxia and downregulated the expression of pro-inflammatory cytokines such as tumor necrosis factor alpha (TNF-α) and interleukin 1 (IL-1). Terminal dexynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-assay analysis showed that Cur effectively attenuated apoptosis in white matter. In addition, we demonstrated that Cur exerted its neuroprotective effect through cross talk between nuclear factor kappa-light-chain-enhancer of activated B (NF-κB) and nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathways. In conclusion, our results indicate that treatment with Cur inhibited the hypoxia, inflammation and apoptosis associated with WMI. Further, the Nrf-2 pathway inhibits NF-κB activation by preventing IkB degradation and increasing HO-1 expression, which in turn reduces reactive oxygen species (ROS) and as a result NF-κB activation is suppressed. Similarly, NF-κB-mediated transcription reduces Nrf2 activation by reducing anti-oxidant response element (ARE) gene and free CREB binding protein by competing with Nrf2 for CBP thus inhibiting the Nrf-2 activation.

Cur2004-8, a synthetic curcumin derivative, extends lifespan and modulates age-related physiological changes in Caenorhabditis elegans

Curcumin, a compound found in Indian yellow curry, is known to possess various biological activities, including anti-oxidant, anti-inflammatory, and anti-cancer activities. Cur2004-8 is a synthetic curcumin derivative having symmetrical bis-alkynyl pyridines that shows a strong anti-angiogenic activity. In the present study, we examined the effect of dietary supplementation with Cur2004-8 on response to environmental stresses and aging using Caenorhabditis elegans as a model system. Dietary intervention with Cur2004-8 significantly increased resistance of C. elegans to oxidative stress. Its anti-oxidative-stress effect was greater than curcumin. However, response of C. elegans to heat stress or ultraviolet irradiation was not significantly affected by Cur2004-8. Next, we examined the effect of Cur2004-8 on aging. Cur2004-8 significantly extended both mean and maximum lifespan, accompanying a shift in time-course distribution of progeny production. Age-related decline in motility was also delayed by supplementation with Cur2004-8. In addition, Cur2004-8 prevented amyloid-beta-induced toxicity in Alzheimer's disease model animals which required a forkhead box (FOXO) transcription factor DAF-16. Dietary supplementation with Cur2004-8 also reversed the increase of mortality observed in worms treated with high-glucose-diet. These results suggest that Cur2004-8 has higher anti-oxidant and anti-aging activities than curcumin. It can be used for the development of novel anti-aging product.

New Insights into Oxidative Damage and Iron Associated Impairment in Traumatic Brain Injury

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Traumatic Brain Injury is considered one of the most prevalent causes of death around the world; more than seventy millions of individuals sustain the condition per year. The consequences of traumatic brain injury on brain tissue are complex and multifactorial, hence, the current palliative treatments are limited to improve patients’ quality of life. The subsequent hemorrhage caused by trauma and the ongoing oxidative process generated by biochemical disturbances in the in the brain tissue may increase iron levels and reactive oxygen species. The relationship between oxidative damage and the traumatic brain injury is well known, for that reason, diminishing factors that potentiate the production of reactive oxygen species have a promissory therapeutic use. Iron chelators are molecules capable of scavenging the oxidative damage from the brain tissue and are currently in use for ironoverload- derived diseases.

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Here, we show an updated overview of the underlying mechanisms of the oxidative damage after traumatic brain injury. Later, we introduced the potential use of iron chelators as neuroprotective compounds for traumatic brain injury, highlighting the action mechanisms of iron chelators and their current clinical applications.

Restoration of Autophagic Flux Rescues Oxidative Damage and Mitochondrial Dysfunction to Protect against Intervertebral Disc Degeneration

Oxidative stress-induced mitochondrial dysfunction and nucleus pulposus (NP) cell apoptosis play crucial roles in the development of intervertebral disc degeneration (IDD). Increasing studies have shown that interventions targeting impaired autophagic flux can maintain cellular homeostasis by relieving oxidative damage. Here, we investigated the effect of curcumin (CUR), a known autophagy activator, on IDD in vitro and in vivo. CUR suppressed tert-butyl hydroperoxide- (TBHP-) induced oxidative stress and mitochondrial dysfunction and thereby inhibited human NP cell apoptosis, senescence, and ECM degradation. CUR treatment induced autophagy and enhanced autophagic flux in an AMPK/mTOR/ULK1-dependent manner. Notably, CUR alleviated TBHP-induced interruption of autophagosome-lysosome fusion and impairment of lysosomal function and thus contributed to the restoration of blocked autophagic clearance. These protective effects of CUR in TBHP-stimulated human NP cells resembled the effects produced by the autophagy inducer rapamycin, but the effects were partially eliminated by 3-methyladenine- and compound C-mediated inhibition of autophagy initiation or chloroquine-mediated obstruction of autophagic flux. Lastly, CUR also exerted a protective effect against puncture-induced IDD progression in vivo. Our results showed that suppression of excessive ROS production and mitochondrial dysfunction through enhancement of autophagy coupled with restoration of autophagic flux ameliorated TBHP-induced human NP cell apoptosis, senescence, and ECM degradation. Thus, maintenance of the proper functioning of autophagy represents a promising therapeutic strategy for IDD, and CUR might serve as an effective therapeutic agent for IDD.

Mangiferin glycethosomes as a new potential adjuvant for the treatment of psoriasis

Mangiferin, a natural compound isolated from Mangifera indica L, was incorporated in glycerosomes, ethosomes and alternatively in glycerol-ethanol phospholipid vesicles (glycethosomes). Actually, only glycethosomes were able to stably incorporate the mangiferin that was loaded at increasing concentrations (2, 4, 6, 8 mg/mL). The morphology, size distribution, rheological properties, surface charge and entrapment efficiency of prepared vesicles were deeply measured. All vesicles were mainly spherical, oligolamellar, small in size (~145 nm) and negatively charged (~-40 mV), as confirmed by cryo-TEM observation and dynamic laser light scattering measurements. The higher concentration of mangiferin (8 mg/mL) allowed an increase of vesicle mean diameter up to ~288 nm. The entrapment efficiency was inversely proportional to the amount of loaded mangiferin. In vitro studies performed by using human abdominal skin, underlined that, the dose-dependent ability of vesicles to promote mangiferin retention in epidermis. In addition, glycethosomes were highly biocompatible and showed a strong ability to protect in vitro the fibroblasts against damages induced by hydrogen peroxide. In vivo results underlined the superior ability of mangiferin loaded glycethosomes respect to the mangiferin dispersion to promote the heal of the wound induced by TPA, confirming their potential application for the treatment of psoriasis or other skin disorders.

Curcumin inhibits LPS-induced neuroinflammation by promoting microglial M2 polarization via TREM2/ TLR4/ NF-κB pathways in BV2 cells

Microglia mediate multiple facets of neuroinflammation, which plays a double-edged role in various brain diseases via distinct microglial phenotypes (deleterious M1 and neuroprotective M2). Therefore, the inhibition of overactivated inflammatory M1 microglia by switching to the protective M2 phenotype appears to be a potential therapeutic strategy in neuroinflammatory disorders. Curcumin has been shown to exhibit anti-inflammatory and neuroprotective activities. The present study investigated the potential effects of curcumin on microglial M1/M2 polarization and elucidated the possible molecular mechanisms of action in vitro. In this study, the BV2 microglial cell line was pretreated with different curcumin concentrations in the presence or absence of lipopolysaccharide (LPS) to assess the anti-inflammatory efficacy of curcumin based on the morphological and inflammatory changes. The cytotoxicity of curcumin for BV2 cells was evaluated using the CCK-8 assay. Further, the effect of curcumin concentrations on LPS-induced BV2 cells was studied. The morphological changes were observed using an optical microscope and immunofluorescent staining. Nitric oxide (NO) expression was determined using the Griess reagent. The expression of cytokines and inflammatory mediators was also measured by ELISA, qRT-PCR, flow cytometry, and immunofluorescence. Western blot analysis was used to determine the levels of triggering receptor expressed on myeloid cells 2 (TREM2), toll-like receptor 4 (TLR4), nuclear factor-kappa B (NF-κB) p65, p-NF-κB p65, IκB, and p-IκB expression. Results showed that curcumin concentrations less than 10 μM did not induce any detectable cytotoxicity but decreased BV2 cell viability up to 20 μM. Curcumin inhibited LPS-induced microglial activation. Curcumin treatment switched the M1 pro-inflammatory phenotype to the M2 anti-inflammatory phenotype by decreasing the expression of M1 markers (i.e., iNOS, IL-1β, IL-6, and CD16/32) and elevating the expression of M2 markers (i.e., arginase 1, IL-4, IL-10, and CD206). Interestingly, curcumin attenuated the activation of TLR4/NF-κB pathways and the downregulation of TREM2 expression in LPS-activated BV2 cells. Collectively, these results suggest that curcumin significantly alleviates LPS-induced inflammation by regulating microglial (M1/M2) polarization by reducing the imbalance of TREM2 and TLR4 and balancing the downstream NF-κB activation.

A Review of Dietary (Phyto)Nutrients for Glutathione Support

Glutathione is a tripeptide that plays a pivotal role in critical physiological processes resulting in effects relevant to diverse disease pathophysiology such as maintenance of redox balance, reduction of oxidative stress, enhancement of metabolic detoxification, and regulation of immune system function. The diverse roles of glutathione in physiology are relevant to a considerable body of evidence suggesting that glutathione status may be an important biomarker and treatment target in various chronic, age-related diseases. Yet, proper personalized balance in the individual is key as well as a better understanding of antioxidants and redox balance. Optimizing glutathione levels has been proposed as a strategy for health promotion and disease prevention, although clear, causal relationships between glutathione status and disease risk or treatment remain to be clarified. Nonetheless, human clinical research suggests that nutritional interventions, including amino acids, vitamins, minerals, phytochemicals, and foods can have important effects on circulating glutathione which may translate to clinical benefit. Importantly, genetic variation is a modifier of glutathione status and influences response to nutritional factors that impact glutathione levels. This narrative review explores clinical evidence for nutritional strategies that could be used to improve glutathione status.

Curcumin Protects Human Umbilical Vein Endothelial Cells against H2O2-Induced Cell Injury

Migraine is a prevalent neurological disorder which causes a huge economic burden on society. It is thought to be a neurovascular disease with oxidative stress might be involved. Curcumin, one of the major ingredients of turmeric, has potent antioxidative and anti-inflammatory properties, but whether it could be used as a potential treatment for migraine remains to be explored. In the present study, human umbilical vein endothelial cells (HUVECs) were pretreated with various concentrations of curcumin (0 μM, 10 μM, 20 μM, 30 μM, 40 μM, and 50 μM) for 12 h, thereby exposed to H₂O₂ (100 μM) for another 12 h. The viability of HUVECs was tested by the CCK-8 assay, and the activities of antioxidant enzymes including superoxide dismutase (SOD) and glutathione (GSH) were also examined. Intracellular reactive oxygen species (ROS) and malondialdehyde (MDA) were assayed to determine H₂O₂-induced oxidative stress. In addition, several cell death-related genes (p53, p21, Bax, and Bcl-2) were detected by PCR, and an apoptosis-related protein (caspase3) was evaluated by western blotting. Our results showed that curcumin improved the H₂O₂-induced decrease of cell viability and antioxidative enzyme activities and decreased the level of oxidative stress. As a conclusion, curcumin could mitigate H₂O₂-induced oxidative stress and cell death in HUVECs and may be a potential therapeutic drug for migraine.

Curcumin: Biological, Pharmaceutical, Nutraceutical, and Analytical Aspects

Turmeric is a curry spice that originated from India, which has attracted great interest in recent decades because it contains bioactive curcuminoids (curcumin, demethoxycurcumin, and bisdemethoxycurcumin). Curcumin (1,7-bis-(4-hydroxy-3-methoxyphenyl)-hepta-1,6-diene-3,5-dione), a lipophilic polyphenol may work as an anticancer, antibiotic, anti-inflammatory, and anti-aging agent as suggested by several in vitro, in vivo studies and clinical trials. However, poor aqueous solubility, bioavailability, and pharmacokinetic profiles limit curcumin’s therapeutic usage. To address these issues, several curcumin formulations have been developed. However, suboptimal sample preparation and analysis methodologies often hamper the accurate evaluation of bioactivities and their clinical efficacy. This review summarizes recent research on biological, pharmaceutical, and analytical aspects of the curcumin. Various formulation techniques and corresponding clinical trials and in vivo outcomes are discussed. A detailed comparison of different sample preparation (ultrasonic, pressurized liquid extraction, microwave, reflux) and analytical (FT-IR, FT-NIR, FT-Raman, UV, NMR, HPTLC, HPLC, and LC-MS/MS) methodologies used for the extraction and quantification of curcuminoids in different matrices, is presented. Application of optimal sample preparation, chromatographic separation, and detection methodologies will significantly improve the assessment of different formulations and biological activities of curcuminoids.

Lipoic Acid Synergizes with Antineoplastic Drugs in Colorectal Cancer by Targeting p53 for Proteasomal Degradation

Lipoic acid (LA) is a redox-active disulphide compound, which functions as a pivotal co-factor for mitochondrial oxidative decarboxylation. LA and chemical derivatives were shown to target mitochondria in cancer cells with altered energy metabolism, thereby inducing cell death. In this study, the impact of LA on the tumor suppressor protein p53 was analyzed in various colorectal cancer (CRC) cell lines, with a focus on the mechanisms driving p53 degradation. First, LA was demonstrated to trigger the depletion of both wildtype and mutant p53 protein in all CRC cells tested without influencing its gene expression and preceded LA-triggered cytotoxicity. Depletion of p53 coincided with a moderate, LA-dependent ROS production, but was not rescued by antioxidant treatment. LA induced the autophagy receptor p62 and differentially modulated autophagosome formation in CRC cells. However, p53 degradation was not mediated via autophagy as shown by chemical inhibition and genetic abrogation of autophagy. LA treatment also stabilized and activated the transcription factor Nrf2 in CRC cells, which was however dispensable for p53 degradation. Mechanistically, p53 was found to be readily ubiquitinylated and degraded by the proteasomal machinery following LA treatment, which did not involve the E3 ubiquitin ligase MDM2. Intriguingly, the combination of LA and anticancer drugs (doxorubicin, 5-fluorouracil) attenuated p53-mediated stabilization of p21 and resulted in synergistic killing in CRC cells in a p53-dependant manner.

Phytochemicals Bridging Autophagy Induction and Alpha-Synuclein Degradation in Parkinsonism

Among nutraceuticals, phytochemical-rich compounds represent a source of naturally-derived bioactive principles, which are extensively studied for potential beneficial effects in a variety of disorders ranging from cardiovascular and metabolic diseases to cancer and neurodegeneration. In the brain, phytochemicals produce a number of biological effects such as modulation of neurotransmitter activity, growth factor induction, antioxidant and anti-inflammatory activity, stem cell modulation/neurogenesis, regulation of mitochondrial homeostasis, and counteracting protein aggregation through modulation of protein-folding chaperones and the cell clearing systems autophagy and proteasome. In particular, the ability of phytochemicals in restoring proteostasis through autophagy induction took center stage in recent research on neurodegenerative disorders such as Parkinson’s disease (PD). Indeed, autophagy dysfunctions and α-syn aggregation represent two interdependent downstream biochemical events, which concur in the parkinsonian brain, and which are targeted by phytochemicals administration. Therefore, in the present review we discuss evidence about the autophagy-based neuroprotective effects of specific phytochemical-rich plants in experimental parkinsonism, with a special focus on their ability to counteract alpha-synuclein aggregation and toxicity. Although further studies are needed to confirm the autophagy-based effects of some phytochemicals in parkinsonism, the evidence discussed here suggests that rescuing autophagy through natural compounds may play a role in preserving dopamine (DA) neuron integrity by counteracting the aggregation, toxicity, and prion-like spreading of α-syn, which remains a hallmark of PD.