Luteolin Inhibits Fibrillary β-Amyloid1-40-Induced Inflammation in a Human Blood-Brain Barrier Model by Suppressing the p38 MAPK-Mediated NF-κB Signaling Pathways

Taming neuroinflammation in Alzheimer's disease: The protective role of phytochemicals through the gut-brain axis

Alzheimer's disease (AD) is a progressive degenerative neurological condition characterized by cognitive decline, primarily affecting memory and logical thinking, attributed to amyloid-β plaques and tau protein tangles in the brain, leading to neuronal loss and brain atrophy. Neuroinflammation, a hallmark of AD, involves the activation of microglia and astrocytes in response to pathological changes, potentially exacerbating neuronal damage. The gut-brain axis is a bidirectional communication pathway between the gastrointestinal and central nervous systems, crucial for maintaining brain health. Phytochemicals, natural compounds found in plants with antioxidant and anti-inflammatory properties, such as flavonoids, curcumin, resveratrol, and quercetin, have emerged as potential modulators of this axis, suggesting implications for AD prevention. Intake of phytochemicals influences the gut microbial composition and its metabolites, thereby impacting neuroinflammation and oxidative stress in the brain. Consumption of phytochemical-rich foods may promote a healthy gut microbiota, fostering the production of anti-inflammatory and neuroprotective substances. Early dietary incorporation of phytochemicals offers a non-invasive strategy for modulating the gut-brain axis and potentially reducing AD risk or delaying its onset. The exploration of interventions targeting the gut-brain axis through phytochemical intake represents a promising avenue for the development of preventive or therapeutic strategies against AD initiation and progression.

Luteolin for neurodegenerative diseases: a review

Neurodegenerative diseases such as Parkinson's disease, Alzheimer's disease, Huntington's disease, and multiple sclerosis affect millions of people around the world. In addition to age, which is a key factor contributing to the development of all neurodegenerative diseases, genetic and environmental components are also important risk factors. Current methods of treating neurodegenerative diseases are mostly symptomatic and do not eliminate the cause of the disease. Many studies focus on searching for natural substances with neuroprotective properties that could be used as an adjuvant therapy in the inhibition of the neurodegeneration process. These compounds include flavonoids, such as luteolin, showing significant anti-inflammatory, antioxidant, and neuroprotective activity. Increasing evidence suggests that luteolin may confer protection against neurodegeneration. In this review, we summarize the scientific reports from preclinical in vitro and in vivo studies regarding the beneficial effects of luteolin in neurodegenerative diseases. Luteolin was studied most extensively in various models of Alzheimer's disease but there are also several reports showing its neuroprotective effects in models of Parkinson's disease. Though very limited, studies on possible protective effects of luteolin against Huntington's disease and multiple sclerosis are also discussed here. Overall, although preclinical studies show the potential benefits of luteolin in neurodegenerative disorders, clinical evidence on its therapeutic efficacy is still deficient.

Luteolin: A promising multifunctional natural flavonoid for human diseases

Natural products are closely associated with human health. Luteolin (LUT), a flavonoid polyphenolic compound, is widely found in fruits, vegetables, flowers, and herbs. It is noteworthy that LUT exhibits a variety of beneficial pharmacological properties and holds significant potential for clinical applications, particularly in antitumor, anti-convulsion, diabetes control, anti-inflammatory, neuroprotection, anti-oxidation, anti-cardiovascular, and other aspects. The potential mechanism of action has been partially elucidated, including the mediation of NF-κB, toll-like receptor, MAPK, Wnt/β-catenin, PI3K/Akt, AMPK/mTOR, and Nrf-2, among others. The review that aimed to comprehensively consolidate essential information on natural sources, pharmacological effects, therapeutic and preventive potential, as well as potential mechanisms of LUT. The objective is to establish a theoretical basis for the continued development and application of LUT.

The potential neuroprotective of luteolin against acetamiprid-induced neurotoxicity in the rat cerebral cortex

Acetamiprid is a class of neuroactive insecticides widely used to control insect pests. The current study aimed to investigate the potential neuroprotective effects of luteolin against acetamiprid-induced neurotoxicity in the rat cerebral cortex. Four equal groups of adult male rats (10 in each): control, acetamiprid (40 mg/kg for 28 days), luteolin (50 mg/kg for 28 days), and acetamiprid+luteolin cotreatment were used. Acetamiprid was shown to alter the oxidative state by increasing oxidant levels [nitric oxide (NO) and malondialdehyde (MDA)] and decreasing antioxidants [glutathione (GSH), glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD), and catalase-(CAT)], with increased activity of nuclear factor erythroid 2-related factor 2-(Nrf2). Likewise, acetamiprid increases the inflammatory response, as evidenced by increased interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and nuclear factor kappa B-(NF-κB). In contrast, the treatment with luteolin brought these markers back to levels close to normal, showing that it protects neurocytes from oxidative damage and the neuroinflammation effects of acetamiprid-induced inflammation. Luteolin also demonstrated a neuroprotective role via the modulation of acetylcholinesterase (AChE) activity in the cerebral cortex tissue. Histopathology showed severe neurodegenerative changes, and apoptotic cells were seen in the acetamiprid-induced cerebral cortex layer, which was evident by increased protein expression levels of Bax and caspase-3 and decreased Bcl-2 levels. Histochemistry confirmed the neuronal degeneration, as proven by the change in neurocyte colour from brown to black when stained with a silver stain. Luteolin may have a neuroprotective effect against biochemical and histopathological changes induced by acetamiprid in the rat cerebral cortex.

Polyphenols Targeting MAP Kinase Signaling Pathway in Neurological Diseases: Understanding Molecular Mechanisms and Therapeutic Targets

Polyphenols are a class of secondary metabolic products found in plants that have been extensively studied for how well they regulate biological processes, such as the proliferation of cells, autophagy, and apoptosis. The mitogen-activated protein kinase (MAPK)-mediated signaling cascade is currently identified as a crucial pro-inflammatory pathway that plays a significant role in the development of neuroinflammation. This process has been shown to contribute to the pathogenesis of several neurological conditions, such as Alzheimer's disease (AD), Parkinson's disease (PD), CNS damage, and cerebral ischemia. Getting enough polyphenols through eating habits has resulted in mitigating the effects of oxidative stress (OS) and lowering the susceptibility to associated neurodegenerative disorders, including but not limited to multiple sclerosis (MS), AD, stroke, and PD. Polyphenols possess significant promise in dealing with the root cause of neurological conditions by modulating multiple therapeutic targets simultaneously, thereby attenuating their complicated physiology. Several polyphenolic substances have demonstrated beneficial results in various studies and are presently undergoing clinical investigation to treat neurological diseases (NDs). The objective of this review is to provide a comprehensive summary of the different aspects of the MAPK pathway involved in neurological conditions, along with an appraisal of the progress made in using polyphenols to regulate the MAPK signaling system to facilitate the management of NDs.

Development of dietary small molecules as multi-targeting treatment strategies for Alzheimer's disease

Cognitive dysfunction can occur both in normal aging and age-related neurological disorders, such as mild cognitive impairment and Alzheimer's disease (AD). These disorders have few treatment options due to side effects and limited efficacy. New approaches to slow cognitive decline are urgently needed. Dietary interventions (nutraceuticals) have received considerable attention because they exhibit strong neuroprotective properties and may help prevent or minimize AD symptoms. Biological aging is driven by a series of interrelated mechanisms, including oxidative stress, neuroinflammation, neuronal apoptosis, and autophagy, which function through various signaling pathways. Recent clinical and preclinical studies have shown that dietary small molecules derived from natural sources, including flavonoids, carotenoids, and polyphenolic acids, can modulate oxidative damage, cognitive impairments, mitochondrial dysfunction, neuroinflammation, neuronal apoptosis, autophagy dysregulation, and gut microbiota dysbiosis. This paper reviews research on different dietary small molecules and their bioactive constituents in the treatment of AD. Additionally, the chemical structure, effective dose, and specific molecular mechanisms of action are comprehensively explored. This paper also discusses the advantages of using nanotechnology-based drug delivery, which significantly enhances oral bioavailability, safety, and therapeutic effect, and lowers the risk of adverse effects. These agents have considerable potential as novel and safe therapeutic agents that can prevent and combat age-related AD.

Biomaterials-based anti-inflammatory treatment strategies for Alzheimer's disease

The current therapeutic drugs for Alzheimer's disease only improve symptoms, they do not delay disease progression. Therefore, there is an urgent need for new effective drugs. The underlying pathogenic factors of Alzheimer's disease are not clear, but neuroinflammation can link various hypotheses of Alzheimer's disease; hence, targeting neuroinflammation may be a new hope for Alzheimer's disease treatment. Inhibiting inflammation can restore neuronal function, promote neuroregeneration, reduce the pathological burden of Alzheimer's disease, and improve or even reverse symptoms of Alzheimer's disease. This review focuses on the relationship between inflammation and various pathological hypotheses of Alzheimer's disease; reports the mechanisms and characteristics of small-molecule drugs (e.g., nonsteroidal anti-inflammatory drugs, neurosteroids, and plant extracts); macromolecule drugs (e.g., peptides, proteins, and gene therapeutics); and nanocarriers (e.g., lipid-based nanoparticles, polymeric nanoparticles, nanoemulsions, and inorganic nanoparticles) in the treatment of Alzheimer's disease. The review also makes recommendations for the prospective development of anti-inflammatory strategies based on nanocarriers for the treatment of Alzheimer's disease.

Luteolin: Nature's promising warrior against Alzheimer's and Parkinson's disease

Neurodegenerative disorders (NDs) are defined as the slow loss of a group of neurons that are particularly sensitive. Due to the intricate pathophysiological processes underlying neurodegeneration, no cure exists for these conditions despite the extensive research and advances in our knowledge of the onset and course of NDs. Hence, there is a medical need for the creation of a novel therapeutic approach for NDs. By focusing on numerous signaling pathways, some natural substances derived from medicinal herbs and foods have demonstrated potent activity in treating various NDs. In this context, flavonoids have recently attracted increased popularity and research attention because of their alleged beneficial effects on health. By acting as antioxidant substances, nutritional supplements made up of flavonoids have been found to lessen the extent of NDs like Alzheimer's disease (AD) and Parkinson's disease (PD). Luteolin is a flavone that possesses potent antioxidant and anti-inflammatory properties. As a consequence, luteolin has emerged as an option for treatment with therapeutic effects on many brain disorders. More research has focused on luteolin's diverse biological targets as well as diverse signaling pathways, implying its potential medicinal properties in several NDs. This review emphasizes the possible use of luteolin as a drug of choice for the treatment as well as the management of AD and PD. In addition, this review recommends that further research should be carried out on luteolin as a potential treatment for AD and PD alongside a focus on mechanisms and clinical studies.

Investigating the Underlying Mechanisms of Ardisia japonica Extract's Anti-Blood-Stasis Effect via Metabolomics and Network Pharmacology

OBJECTIVE

Our study aims to assess Ardisia japonica (AJ)'s anti-blood-stasis effect and its underlying action mechanisms.

METHODS

The primary components of AJ were determined using liquid chromatography-mass spectrometry (LC-MS). The blood stasis model was used to investigate the anti-blood-stasis effect of AJ extract. The underlying mechanisms of AJ against blood stasis were investigated via network pharmacology, molecular docking, and plasma non-targeted metabolomics.

RESULTS

In total, 94 compounds were identified from an aqueous extract of AJ, including terpenoids, phenylpropanoids, alkaloids, and fatty acyl compounds. In rats with blood stasis, AJ reduced the area of stasis, decreased the inflammatory reaction in the liver and lungs of rats, lowered the plasma viscosity, increased the index of erythrocyte deformability, and decreased the index of erythrocyte aggregation, suggesting that AJ has an anti-blood-stasis effect. Different metabolites were identified via plasma untargeted metabolomics, and it was found that AJ exerts its anti-blood-stasis effect by reducing inflammatory responses through the cysteine and methionine metabolism, linolenic acid metabolism, and sphingolipid metabolism. For the effect of AJ on blood stasis syndrome, the main active ingredients predicted via network pharmacology include sinensetin, galanin, isorhamnetin, kaempferol, wogonin, quercetin, and bergenin, and their targets were TP53, HSP90AA1, VEGFA, AKT1, EGFR, and PIK3CA that were mainly enriched in the PI3K/AKT and MAPK signaling pathways, which modulate the inflammatory response. Molecular docking was also performed, and the binding energies of these seven compounds to six proteins were less than -5, indicating that the chemical components bind to the target proteins.

CONCLUSIONS

This study suggests AJ effectively prevents blood stasis by reducing inflammation.

Comprehensive Review of Nutraceuticals against Cognitive Decline Associated with Alzheimer's Disease

Nowadays, nutraceuticals are being incorporated into functional foods or used as supplements with nonpharmacological approaches in the prevention and management of several illnesses, including age-related conditions and chronic neurodegenerative diseases. Nutraceuticals are apt for preventing and treating such disorders because of their nontoxic, non-habit-forming, and efficient bioactivities for promoting neurological well-being due to their ability to influence cellular processes such as neurogenesis, synaptogenesis, synaptic transmission, neuro-inflammation, oxidative stress, cell death modulation, and neuronal survival. The capacity of nutraceuticals to modify all of these processes reveals the potential to develop food-based strategies to aid brain development and enhance brain function, prevent and ameliorate neurodegeneration, and possibly reverse the cognitive impairment observed in Alzheimer's disease, the most predominant form of dementia in the elderly. The current review summarizes the experimental evidence of the neuroprotective capacity of nutraceuticals against Alzheimer's disease, describing their mechanisms of action and the in vitro and in vivo models applied to evaluate their neuroprotective potential.

"Lifting Yang to Dredging Du Meridian Manipulation" acupuncture alleviates cerebral ischemia-reperfusion injury by mediating the NF-κB pathway

BACKGROUND

Ischemic stroke is a permanent neurological impairment resulting from the narrowing or blockage of blood vessels in the brain. The effectiveness of "Lifting Yang to Dredging Du Meridian Manipulation" (LYDD) acupuncture in clinical treatment of ischemic stroke patients has been well-established. Nevertheless, its mechanism is still uncertain.

METHODS

MCAO/R rat models at different time points of reperfusion (24, 36, 48 and 72 h) were constructed, and LYDD acupuncture treatment was performed. Zea-Longa score and TTC staining were used for assessing neurological impairment and cerebral infarct in rats, respectively. The pathological changes of cerebral tissue in each group were observed by HE and Nissl's staining. Cerebral tissue from each group was subjected to RNA-seq, and differentially expressed genes (DEGs) were performed for GO and KEGG enrichment analysis, and hub gene was identified based on the String database and MCODE algorithm.

RESULTS

LYDD acupuncture treatment significantly reduced Zea-Longa score, dry-wet weight ratio, infarct area, inflammatory factor levels (IL-1β and TNF-α), cerebral lesions, number of Nissl body and neuronal apoptosis in the MCAO/R model at different time points of reperfusion. A total of 3518 DEGs were identified in the MCAO/R model compared to the control group, and 3461 DEGs were present in the treatment group compared to the MCAO/R model, and they may be implicated in neurotransmitter transmission, synaptic membrane potential, cell junctions, inflammatory response, immune response, cell cycle, and ECM. The expression trends of BIRC3, LTBR, PLCG2, TLR4 and TRADD mRNAs in the Hub gene were consistent with the RNA-seq results, and LYDD acupuncture treatment significantly inhibited MCAO/R-induced p65 nuclear translocation.

CONCLUSIONS

LYDD acupuncture ameliorates cerebral ischemia-reperfusion injury by inhibiting NF-κB pathway activity.

Therapeutic targeting of Ras/Raf/MAPK pathway by natural products: A systematic and mechanistic approach for neurodegeneration

BACKGROUND

Multiple dysregulated pathways are behind the pathogenesis of neurodegenerative diseases (NDDs); however, the crucial targets are still unknown. Oxidative stress, apoptosis, autophagy, and inflammation are the most dominant pathways that strongly influence neurodegeneration. In this way, targeting the Ras/Raf/mitogen-activated protein kinases (MAPKs) pathway appears to be a developing strategy for combating NDDs like Parkinson's disease, Alzheimer's disease, stroke, aging, and other NDDs. Accordingly, plant secondary metabolites have shown promising potentials for the simultaneous modulation of the Ras/Raf/MAPKs pathway and play an essential role in NDDs. MAPKs include p38 MAPK, extracellular signal-regulated kinase 1/2 (ERK 1/2), and c-Jun N-terminal kinase (JNK), which are important molecular players in neurodegeneration. Ras/Raf, which is located the upstream of MAPK pathway influences the initiation and progression of neurodegeneration and is regulated by natural products.

PURPOSE

Thus, the present study aimed to investigate the neuroprotective roles of plant- and marine-derived secondary metabolites against several NDDs through the modulation of the Ras/Raf/MAPK signaling pathway.

STUDY DESIGN AND METHODS

A systematic and comprehensive review was performed to highlight the modulatory roles of natural products on the Ras/Raf/MAPK signaling pathway in NDDs, according to the PRISMA guideline, using scholarly electronic databases, including PubMed, Scopus, and Web of Sciences. Associated reference lists were also searched for the literature review.

RESULTS

From a total of 1495 results, finally 107 articles were included in the present study. The results show that several natural compounds such as alkaloid, phenolic, terpenoids, and nanoformulation were shown to have modulatory effects on the Ras/Raf/MAPKs pathway.

CONCLUSION

Natural products are promising multi-targeted agents with on NDDs through Ras/Raf/MAPKs pathway. Nevertheless, additional and complementary studies are necessary to check its efficacy and potential side effects.

Dietary Polyphenols as a Protection against Cognitive Decline: Evidence from Animal Experiments; Mechanisms and Limitations

Emerging evidence suggests that cognitive impairments may result from various factors, such as neuroinflammation, oxidative stress, mitochondrial damage, impaired neurogenesis, synaptic plasticity, blood-brain barrier (BBB) disruption, amyloid β protein (Aβ) deposition, and gut dysbiosis. Meanwhile, dietary polyphenol intake in a recommended dosage has been suggested to reverse cognitive dysfunction via various pathways. However, excessive intake of polyphenols could trigger unwanted adverse effects. Thus, this review aims to outline possible causes of cognitive impairments and how polyphenols alleviate memory loss via various pathways based on in vivo experimental studies. Thus, to identify potentially relevant articles, the keywords (1) nutritional polyphenol intervention NOT medicine AND neuron growth OR (2) dietary polyphenol AND neurogenesis AND memory impairment OR (3) polyphenol AND neuron regeneration AND memory deterioration (Boolean operators) were used in the Nature, PubMed, Scopus, and Wiley online libraries. Based on the inclusion and exclusion criteria, 36 research papers were selected to be further reviewed. The outcome of all the studies included supports the statement of appropriate dosage by taking into consideration gender differences, underlying conditions, lifestyle, and causative factors for cognitive decline, which will significantly boost memory power. Therefore, this review recapitulates the possible causes of cognitive decline, the mechanism of polyphenols involving various signaling pathways in modulating the memory, gut dysbiosis, endogenous antioxidants, bioavailability, dosage, and safety efficacy of polyphenols. Hence, this review is expected to provide a basic understanding of therapeutic development for cognitive impairments in the future.

The Flavonoid Rich Black Currant (Ribes nigrum) Ethanolic Gemmotherapy Extract Elicits Neuroprotective Effect by Preventing Microglial Body Swelling in Hippocampus and Reduces Serum TNF-α Level: Pilot Study

Many plant-derived flavonoids are known for their anti-neuroinflammatory and anti-neurodegenerative effects. The fruits and leaves of the black currant (BC, Ribes nigrum) contain these phytochemicals with therapeutic benefits. The current study presents a report on a standardized BC gemmotherapy extract (BC-GTE) that is prepared from fresh buds. It provides details about the phytoconstituent profile specific to the extract as well as the associated antioxidant and anti-neuroinflammatory properties. The reported BC-GTE was found to contain approximately 133 phytonutrients, making it unique in its composition. Furthermore, this is the first report to quantify the presence of significant flavonoids such as luteolin, quercetin, apigenin, and kaempferol. Drosophila melanogaster-based tests revealed no cytotoxic but nutritive effects. We also demonstrated that adult male Wistar rats, pretreated with the analyzed BC-GTE and assessed after lipopolysaccharide (LPS) injection, did not show any apparent increase in body size in the microglial cells located in the hippocampal CA1 region, while in control experiments, the activation of microglia was evident. Moreover, no elevated levels of serum-specific TNF-α were observed under the LPS-induced neuroinflammatory condition. The analyzed BC-GTE's specific flavonoid content, along with the experimental data based on an LPS-induced inflammatory model, suggest that it possesses anti-neuroinflammatory/neuroprotective properties. This indicates that the studied BC-GTE has the potential to be used as a GTE-based complementary therapeutic approach.

Crosstalk between phytochemicals and inflammatory signaling pathways

Novel bioactive constituents from natural sources are actively being investigated. The phytochemicals in these phenolic compounds are believed to have a variety of beneficial effects on human health. Several phenolic compounds have been found in plants. The antioxidant potential of phenols has been discussed in numerous studies along with their anti-inflammatory effects on pro-inflammatory cytokine, inducible cyclooxygenase-2, and nitric oxide synthase. Through current study, an attempt is made to outline and highlight a wide variety of inflammation-associated signaling pathways that have been modified by several natural compounds. These signaling pathways include nuclear factor-kappa B (NF-кB), activator protein (AP)-1, protein tyrosine kinases (PTKs), mitogen-activated protein kinases (MAPKs), nuclear factor erythroid 2-related factor 2 (Nrf2) transcription factors, tyrosine phosphatidylinositol 3-kinase (PI3K)/AKT, and the ubiquitin-proteasome system. In light of the influence of natural substances on signaling pathways, their impact on the production of inflammatory mediator is highlighted in this review.

Characteristics and pathogenesis of chemokines in the post-stroke stage

Chemokines, as small molecular proteins, play a crucial role in the immune and inflammatory responses after stroke. A large amount of evidence showed chemokines and their receptors were increasingly recognized as potential targets for stroke treatment, which were involved in the processing of neovascularization, neurogenesis, and neural network reconstruction. In this review, we summarized the characteristics of chemokine alterations throughout the post-stroke nerve repair phase to gain insight into the pathological mechanisms of chemokines and find effective therapeutic targets for stroke.

Application Potential of Luteolin in the Treatment of Viral Pneumonia

Aim of the Review. This study aims to summarize the therapeutic effect of luteolin on the pathogenesis of viral pneumonia, explore its absorption and metabolism in the human body, evaluate the possibility of luteolin as a drug to treat viral pneumonia, and provide a reference for future research. Materials and Methods. We searched MEDLINE/PubMed, Web of Science, China National Knowledge Infrastructure, and Google Scholar and collected research on luteolin in the treatment of viral pneumonia and related diseases since 2003. Then, we summarized the efficacy and potential of luteolin in directly inhibiting viral activity, limiting inflammatory storms, reducing pulmonary inflammation, and treating pneumonia complications. Results and Conclusion. Luteolin has the potential to treat viral pneumonia in multiple ways. Luteolin has a direct inhibitory effect on coronavirus, influenza virus, and respiratory syncytial virus. Luteolin can alleviate the inflammatory factor storm induced by multiple factors by inhibiting the function of macrophages or mast cells. Luteolin can reduce pulmonary inflammation, pulmonary edema, or pulmonary fibrosis induced by multiple factors. In addition, viral pneumonia may cause multisystem complications, while luteolin has extensive protective effects on the gastrointestinal system, cardiovascular system, and nervous system. However, due to the first-pass metabolism mediated by phase II enzymes, the bioavailability of oral luteolin is low. The bioavailability of luteolin can be improved, and its potential value can be further developed by changing the dosage form or route of administration.

Preparation and Evaluation of Amorphous Solid Dispersions for Enhancing Luteolin's Solubility in Simulated Saliva

Luteolin (LUT), a bioactive flavonoid, possesses various pharmacological properties, including antioxidant, antimicrobial, anti-allergic, cardio-protective, and anti-cancer activity. Among them, LUT's administration for the treatment of periodontal disease is very promising. However, its low water solubility magnifies the challenge of formulating LUT into an effective dosage form. In this vein, the aim of the present study examines the preparation of amorphous solid dispersions (ASD) for the solubility improvement of LUT in saliva. At first, the physicochemical properties of the active pharmaceutical ingredient (API) were studied before the selection of the most suitable ASD matrix/carrier. For this reason, six commonly used polymeric ASD matrix/carriers (namely, povidone, PVP; copovidone, coPVP; hydroxypropyl cellulose, HPC-SL; hydroxypropyl methyl cellulose acetate succinate, HPMC-AS; Eudragit^® RS, Eud-RS; and Soluplus^®, SOL) were screened via the film casting method, as to whether they could suspend the drug's recrystallization. The most promising matrix/carriers were then evaluated, based on their ability to inhibit LUT's precipitation after its solubilization, via the solvent shift method. Based on both screening methods, it was determined that PVP was the most promising matrix/carrier for the preparation of LUT's ASDs. Hence, in a further step, after the successful testing of components' miscibility, LUT-PVP ASDs were prepared via the solvent evaporation method. These systems (examined via powder X-ray diffractometry, pXRD) showed full API amorphization immediately after preparation and excellent physical stability (since they were stable after 3 months of storage). The study of LUT-PVP ASD's ATR-FTIR (Attenuated Total Reflectance-Fourier Transform Infrared) spectra demonstrated strong H-bonds between the molecules of the drug and the matrix/carrier, while molecular dynamics (MD) simulations were able to shed light on these drug-matrix/carrier interactions, at a molecular level. Finally, in vitro dissolution studies in simulated saliva proved that the prepared ASDs were able to significantly enhance LUT's dissolution profile. Hence, according to findings of the present work, the preparation of LUT-ASDs utilizing PVP as the polymeric matrix/carrier is regarded as a highly promising technique for the improvement of API's solubility in the oral cavity.

Luteolin alleviates inflammation and autophagy of hippocampus induced by cerebral ischemia/reperfusion by activating PPAR gamma in rats

Background

Luteolin, a flavonoid compound with anti-inflammatory activity, has been reported to alleviate cerebral ischemia/reperfusion (I/R) injury. However, its potential mechanism remains unclear.

Methods

The binding activity of luteolin to peroxisome proliferator-activated receptor gamma (PPARγ) was calculated via molecular docking analysis. Rats were subjected to middle cerebral artery occlusion and reperfusion (MCAO/R). After reperfusion, vehicle, 25 mg/kg/d luteolin, 50 mg/kg/d luteolin, 10 mg/kg/d pioglitazone, 50 mg/kg/d luteolin combined with 10 mg/kg/d T0070907 (PPARγ inhibitor) were immediately orally treatment for 7 days. ELISA, TTC staining, H&E staining, immunohistochemistry, immunofluorescence and transmission electron microscope methods were performed to evaluate the inflammation and autophagy in damaged hippocampal region. The PPARγ, light chain 3 (LC3) B-II/LC3B-I and p-nuclear factor-κB (NF-κB) p65 proteins expression levels in damaged hippocampal region were analyzed.

Results

Luteolin showed good PPARγ activity according to docking score (score = − 8.2). Luteolin treatment downregulated the infarct area and the pro-inflammatory cytokines levels caused by MCAO/R injury. Moreover, luteolin administration ameliorated neuroinflammation and autophagy in damaged hippocampal region. Pioglitazone plays protective roles similar to luteolin. T0070907 concealed the neuroprotective roles of 50 mg/kg/d luteolin.

Conclusions

Luteolin exerts neuroprotective roles against inflammation and autophagy of hippocampus induced by cerebral I/R by activating PPARγ in rats.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03652-8.

Luteolin reduces fear, anxiety, and depression in rats with post-traumatic stress disorder

Exposure to severe stress can lead to the development of neuropsychiatric disorders, including post-traumatic stress disorder (PTSD). The cause of PTSD is dysregulation of the hypothalamic–pituitary–adrenal (HPA) axis and an imbalance of monoamines. Fruits and vegetables contain large amounts of luteolin (LU; 3′,4′,5,7-tetrahydroxylflavone), which has various pharmacological activities such as anti-inflammatory, antioxidant, and anti-allergic effects. We investigated the effects of LU on fear, depression, and anxiety following monoamine imbalance and hyperactivation of the HPA axis in rats exposed to single prolonged stress (SPS). Male rats were dosed with LU (10 and 20 mg/kg) once daily for 14 days after exposure to SPS. Administration of LU reduced fear freezing responses to extinction recall and depression- and anxiety-like behaviors, and suppressed increases in plasma corticosterone and adrenocorticotropic hormone levels. Also, administration of LU restored the increased norepinephrine and decreased serotonin levels in the structures within the fear circuit, medial prefrontal cortex, and hippocampus. Our results showed that administration of LU improved freezing behavior according in a situation-dependent manner, and showed anti-depressant and anxiolytic effects. Thus, LU may be a useful therapeutic agent to prevent traumatic stress such as PTSD.

Luteolin Phosphate Derivatives Generated by Cultivating Bacillus subtilis var. Natto BCRC 80517 with Luteolin

Luteolin (LUT), a plant-derived flavone, exhibits various bioactivities; however, the poor aqueous solubility hampers its applications. Here, we revealed bioconversion of LUT by Bacillus subtilis BCRC 80517, yielding three water-soluble phosphate conjugates. These derivatives were identified as luteolin 4'-O-phosphate (L4'P), luteolin 3'-O-phosphate (L3'P), and luteolin 7-O-phosphate (L7P) by LC-ESI-MS/MS and NMR. Besides, we found that Bacillus subtilis BCRC 80517 was able to convert different levels of LUT but showed a limited conversion rate. By observing bacterial morphology with transmission electron microscopy and confocal fluorescence microscopy, we found that LUT disrupted the bacterial membrane integrity, which explained the incomplete conversion. Additionally, we revealed a spontaneous intramolecular transesterification of L4'P to L3'P, the thermodynamically more stable form, under acidic conditions and proposed the possible mechanism involving a cyclic phosphate as the intermediate. This study provides insight into development of a potent structural modification strategy to enhance the solubility of LUT through biophosphorylation.

The Peptide/Antibody-Based Surface Decoration of Calcium Phosphate Nanoparticles Carrying siRNA Influences the p65 NF-κB Protein Expression in Inflamed Cells In Vitro

Earlier studies with nanoparticles carrying siRNA were restricted to investigating the inhibition of target-specific protein expression, while almost ignoring effects related to the nanoparticle composition. Here, we demonstrate how the design and surface decoration of nanoparticles impact the p65 nuclear factor-kappa B (NF-κB) protein expression in inflamed leucocytes and endothelial cells in vitro. We prepared silica-coated calcium phosphate nanoparticles carrying encapsulated siRNA against p65 NF-κB and surface-decorated with peptides or antibodies. We show that RGD-decorated nanoparticles are efficient in down-regulating p65 NF-κB protein expression in endothelial cells as a result of an enhanced specific cellular binding and subsequent uptake of nanoparticles. In contrast, nanoparticles decorated with IgG (whether specific or not for CD69) are efficient in down-regulating p65 NF-κB protein expression in T-cells, but not in B-cells. Thus, an optimized nanoparticle decoration with xenogenic IgG may stimulate a specific cellular uptake. In summary, the composition of siRNA-loaded calcium phosphate nanoparticles can either weaken or stimulate p65 NF-κB protein expression in targeted inflamed leucocytes and endothelial cells. In general, unveiling such interactions may be very useful for the future design of anti-p65 siRNA-based nanomedicines for treatment of inflammation-associated diseases.

Resveratrol ameliorates iron overload induced liver fibrosis in mice by regulating iron homeostasis

This study is intended to explore the protective effects of resveratrol (RES) on iron overload-induced liver fibrosis and its mechanism. Iron dextran (50 mg/kg) was injected intraperitoneally in all groups except the control group. Mice in the L-RES, M-RES and H-RES groups were gavaged with RES solution at 25, 50 mg/kg and 100 mg/kg, respectively, 4 h before injection of iron dextran every day; mice in the deferoxamine (DFO) group were injected with DFO intraperitoneally (100 mg/kg); mice in the control group received isovolumetric saline. After seven weeks of RES administration, serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) activities and liver hydroxyproline (Hyp) levels were reduced; the malondialdehyde (MDA) activities decreased and the levels of superoxide dismutase (SOD) and glutathione (GSH) were raised. Hematoxylin and eosin (H&E), Prussian, and Masson staining indicated that RES treatment could improve cell damage and reduce hepatic iron deposition and collagen deposition in iron-overload mice. The expression of Bcl-2 was increased, the expression levels of Bax and caspase-3 were decreased under RES treatment. Moreover, RES reduced the expression of hepcidin, ferritin (Ft), divalent metal transporter-1 (DMT-1), transferrin receptor-2 (TFR-2), and raised the expression of ferroprotein-1 (FPN-1). In conclusion, RES could ameliorate iron overload-induced liver fibrosis, and the potential mechanisms may be related to antioxidant, anti-inflammatory, anti-apoptotic, and more importantly, regulation of iron homeostasis by reducing iron uptake and increasing iron export.

E. Gaafar P, Mousa MR, Fayez AM, Elsheikh MA. Novel Luteolin-Loaded Chitosan Decorated Nanoparticles for Brain-Targeting Delivery in a Sporadic Alzheimer's Disease Mouse Model: Focus on Antioxidant, Anti-Inflammatory, and Amyloidogenic Pathways

Preparation and evaluation of a non-invasive intranasal luteolin delivery for the management of cognitive dysfunction in Alzheimer's disease (AD) using novel chitosan decorated nanoparticles. Development of luteolin-loaded chitosomes was followed by full in vitro characterization. In vivo efficacy was evaluated using a sporadic Alzheimer's disease (SAD) animal model via intracerebroventricular injection of 3 mg/kg streptozotocin (ICV-STZ). Treatment groups of luteolin suspension and chitosomes (50 mg/kg) were then intranasally administered after 5 h of ICV-STZ followed by everyday administration for 21 consecutive days. Behavioral, histological, immunohistochemical, and biochemical studies were conducted. Chitosomes yielded promising quality attributes in terms of particle size (PS) (412.8 ± 3.28 nm), polydispersity index (PDI) (0.378 ± 0.07), Zeta potential (ZP) (37.4 ± 2.13 mv), and percentage entrapment efficiency (EE%) (86.6 ± 2.05%). Behavioral findings showed obvious improvement in the acquisition of short-term and long-term spatial memory. Furthermore, histological evaluation revealed an increased neuronal survival rate with a reduction in the number of amyloid plaques. Biochemical results showed improved antioxidant effects and reduced pro-inflammatory mediators' levels. In addition, a suppression by half was observed in the levels of both Aβ aggregation and hyperphosphorylated-tau protein in comparison to the model control group which in turn confirmed the capability of luteolin-loaded chitosomes (LUT-CHS) in attenuating the pathological changes of AD. The prepared nanoparticles are considered a promising safe, effective, and non-invasive nanodelivery system that improves cognitive function in SAD albino mice as opposed to luteolin suspension.

Neuroprotective Effect of Luteolin-7-O-Glucoside against 6-OHDA-Induced Damage in Undifferentiated and RA-Differentiated SH-SY5Y Cells

Luteolin is one of the most common flavonoids present in edible plants and its potential benefits to the central nervous system include decrease of microglia activation, neuronal damage and high antioxidant properties. The aim of this research was to evaluate the neuroprotective, antioxidant and anti-inflammatory activities of luteolin-7-O-glucoside (Lut7). Undifferentiated and retinoic acid (RA)-differentiated SH-SY5Y cells were pretreated with Lut7 and incubated with 6-hydroxydopamine (6-OHDA). Cytotoxic and neuroprotective effects were determined by MTT assay. Antioxidant capacity was determined by DPPH, FRAP, and ORAC assays. ROS production, mitochondrial membrane potential (ΔΨm), Caspase–3 activity, acetylcholinesterase inhibition (AChEI) and nuclear damage were also determined in SH-SY5Y cells. TNF-α, IL-6 and IL-10 release were evaluated in LPS-induced RAW264.7 cells by ELISA. In undifferentiated SH-SY5Y cells, Lut7 increased cell viability after 24 h, while in RA-differentiated SH-SY5Y cells, Lut7 increased cell viability after 24 and 48 h. Lut7 showed a high antioxidant activity when compared with synthetic antioxidants. In undifferentiated cells, Lut7 prevented mitochondrial membrane depolarization induced by 6-OHDA treatment, decreased Caspase-3 and AChE activity, and inhibited nuclear condensation and fragmentation. In LPS-stimulated RAW264.7 cells, Lut7 treatment reduced TNF-α levels and increased IL-10 levels after 3 and 24 h, respectively. In summary, the results suggest that Lut7 has neuroprotective effects, thus, further studies should be considered to validate its pharmacological potential in more complex models, aiming the treatment of neurodegenerative diseases.

A Brain-Targeted Approach to Ameliorate Memory Disorders in a Sporadic Alzheimer's Disease Mouse Model via Intranasal Luteolin-Loaded Nanobilosomes

Impaired memory and cognitive function are the main features of Alzheimer's disease (AD). Unfortunately, currently available treatments cannot cure or delay AD progression. Moreover, the blood-brain barrier hampers effective delivery of treatment to the brain. Therefore, we aimed to evaluate the impact of intranasally delivered luteolin on AD using bile-salt-based nano-vesicles (bilosomes). Different bilosomes were prepared using 23-factorial design. The variables were defined by the concentration of surfactant, the molar ratio of cholesterol:phospholipid, and the concentration of bile salt. Results demonstrated optimized luteolin-loaded bilosomes with particle size (153.2 ± 0.98 nm), zeta potential (-42.8 ± 0.24 mV), entrapment efficiency% (70.4 ± 0.77%), and % drug released after 8 h (80.0 ± 1.10%). In vivo experiments were conducted on an AD mouse model via intracerebroventricular injection of 3 mg/kg streptozotocin. We conducted behavioral, biochemical marker, histological, and immune histochemistry assays after administering a luteolin suspension or luteolin bilosomes (50 mg/kg) intranasally for 21 consecutive days. Luteolin bilosomes improved short-term and long-term spatial memory. They also exhibited antioxidant properties and reduced levels of proinflammatory mediators. They also suppressed both amyloid β aggregation and hyperphosphorylated Tau protein levels in the hippocampus. In conclusion, luteolin bilosomes are an effective, safe, and non-invasive approach with superior cognitive function capabilities compared to luteolin suspension.

Effects of Natural Polyphenols on Oxidative Stress-Mediated Blood–Brain Barrier Dysfunction

The blood-brain barrier (BBB), which consists mainly of brain microvascular endothelial cells and astrocytes connected by tight junctions (TJs) and adhesion molecules (AMs), maintains the homeostatic balance between brain parenchyma and extracellular fluid. Accumulating evidence shows that BBB dysfunction is a common feature of neurodegenerative diseases, including stroke, traumatic brain injury, and Alzheimer’s disease. Among the various pathological pathways of BBB dysfunction, reactive oxygen species (ROS) are known to play a key role in inducing BBB disruption mediated via TJ modification, AM induction, cytoskeletal reorganization, and matrix metalloproteinase activation. Thus, antioxidants have been suggested to exert beneficial effects on BBB dysfunction-associated brain diseases. In this review, we summarized the sources of ROS production in multiple cells that constitute or surround the BBB, such as BBB endothelial cells, astrocytes, microglia, and neutrophils. We also reviewed various pathological mechanisms by which BBB disruption is caused by ROS in these cells. Finally, we summarized the effects of various natural polyphenols on BBB dysfunction to suggest a therapeutic strategy for BBB disruption-related brain diseases.

Identification of miRNA and Their Regulatory Effects Induced by Total Flavonoids From Dracocephalum moldavica in the Treatment of Vascular Dementia

Vascular dementia (VaD) is a general term used to describe difficulties in memory, reasoning, judgment, and planning caused by a reduced blood flow to the brain and consequent brain damage, in which microRNAs (miRNAs) are involved. Dracocephalum moldavica L. (D. moldavica) is traditionally used in the treatment of cardiovascular diseases as well as VaD, but the biomolecular mechanisms underlying its therapeutic effect are obscure. In the present study, the molecular mechanisms involved in the treatment of VaD by the total flavonoids from Dracocephalum moldavica L. (TFDM) were explored by the identification of miRNA profiling using bioinformatics analysis and experimental verification. A total of 2,562 differentially expressed miRNAs (DEMs) and 3,522 differentially expressed genes (DEGs) were obtained from the GSE120584 and GSE122063 datasets, in which the gene functional enrichment and protein-protein interaction network of 93 core targets, originated from the intersection of the top DEM target genes and DEGs, were established for VaD gene profiling. One hundred and eighty-five targets interacting with 42 flavonoids in the TFDM were included in a compound-target network, subsequently found that they overlapped with potential targets for VaD. These 43 targets could be considered in the treatment of VaD by TFDM, and included CaMKII, MAPK, MAPT, PI3K, and KDR, closely associated with the vascular protective effect of TFDM, as well as anti-oxidative, anti-inflammatory, and anti-apoptotic properties. The subsequent analysis of the compound-target gene-miRNA network indicated that eight miRNAs that mediated 43 targets had a close interaction with TFDM, suggesting that the neuroprotective effects were principally due to kaempferol, apigenin, luteolin, and quercetin, which were mostly associated with the miR-3184-3p/ESR1, miR-6762-3p/CDK1, miR-6777-3p/ESRRA, and other related axes. Furthermore, the in vitro oxygen-glucose deprivation (OGD) model demonstrated that the dysregulation of miR-3184-3p and miR-6875-5p found by qRT-PCR was consistent with the changes in the bioinformatics analysis. TFDM and its active compounds involving tilianin, luteolin, and apigenin showed significant effects on the upregulation of miR-3184-3p and downregulation of miR-6875-5p in OGD-injured cells, in line with the improved cell viability. In conclusion, our findings revealed the underlying miRNA-target gene network and potential targets of TFDM in the treatment of VaD.

Exploring the Antiglioma Mechanisms of Luteolin Based on Network Pharmacology and Experimental Verification

Luteolin, a natural flavone compound, exists in a variety of fruits and vegetables, and its anticancer effect has been shown in many studies. However, its use in glioma treatment is hampered due to the fact that the underlying mechanism of action has not been fully explored. Therefore, we elucidated the potential antiglioma targets and pathways of luteolin systematically with the help of network pharmacology and molecular docking technology. The druggability of luteolin, including absorption, excretion, distribution, and metabolism, was assessed via the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP). The potential targets of luteolin and glioma were extracted from public databases, and the intersecting targets between luteolin and glioma were integrated and visualized by a Venn diagram. In addition, GO and KEGG pathway analysis was engaged in Metascape. The network of the luteolin-target-pathway was visualized by Cytoscape. Ultimately, the interactions between luteolin and predicted key targets were confirmed by Discovery studio software. According to the ADME results, luteolin shows great potential for development into a drug. 4860 glioma-associated targets and 280 targets of luteolin were identified, of which 205 were intersection targets. 6 core targets of luteolin against glioma, including AKT1, JUN, ALB, MAPK3, MAPK1, and TNF, were identified via PPI network analysis of which AKT1, JUN, ALB, MAPK1, and TNF harbor diagnostic value. The biological processes of luteolin are mainly involved in the response to inorganic substances, response to oxidative stress, and apoptotic signaling pathway. The essential pathways of luteolin against glioma involve pathways in cancer, the PI3K-Akt signaling pathway, the TNF signaling pathway, and more. Meanwhile, luteolin's interaction with six core targets was verified by molecular docking simulation and its antiglioma effect was verified by in vitro experiments. This study suggests that luteolin has a promising potential for development into a drug and, moreover, it displays preventive effects against glioma by targeting various genes and pathways.

Ephedra sinica mitigates hepatic oxidative stress and inflammation via suppressing the TLR4/MyD88/NF-κB pathway in fipronil-treated rats

Ephedra sinica (ES) is a promising medicinal plant with a wide range of pharmacological aspects, including antioxidant and anti-inflammatory properties. Fipronil (FN) is a popularly used systemic insecticide in agriculture and veterinary applications. FN exposure can result in a variety of negative health consequences. The study aimed to explore the prophylactic effects of Ephedra sinica extract (ESE) against hepatotoxicity in FN-treated rats by following the TLR4/ MyD88/ NF-κB pathway. ESE was tested for polyphenolic and antioxidant activity. Forty rats were separated into four groups and given orally by FN (10 mg/kg B.W.) and/or ESE (150 mg/kg B.W.). Blood and tissue samples were collected at the end of the experiment and prepared for pathophysiological, gene expression, and pathological analysis. ESE showed strong antioxidant activity, as well as reduced levels of hepatic MDA and oxidative stress markers (H₂O₂, NO). Hepatic SOD and CAT activities were increased even further. Furthermore, in FN-treated rats, ESE improved liver functions (ALT, AST, ALP, and LDH) and recovered the lipid profile (Cho, TriG, HDL, and LDL). Moreover, by inhibiting TLR4/ MyD88/ NF-κB induction, ESE alleviated hepatic pathological changes and decreased FN-induced elevations of TNF-α, IL-6, and IL-1β mRNA/protein levels. These findings suggested that ESE mitigated FN-induced hepatotoxicity via combating oxidative stress and relieving inflammation.

Neuroprotective Potential of Mung Bean (Vigna radiata L.) Polyphenols in Alzheimer's Disease: A Review

Mung bean contains various neuroprotective polyphenols, so it might be a healthy food for Alzheimer's disease (AD) prevention. Totally, 19 major phenolic compounds were quantified in mung bean, including 10 phenolic acids and 9 flavonoids. After summarizing their contents and effective doses in rodent AD models, it was speculated that vitexin, isovitexin, sinapic acid, and ferulic acid might be the major bioactive compounds for mung bean-mediated neuroprotection. The mechanisms involved inhibition of β-amyloidogenesis, tau hyperphosphorylation, oxidative stress, and neuroinflammation, and promotion of autophagy and acetylcholinesterase enzyme activity. Notably, the neuroprotective phenolic profile in mung bean changed after germination, with decreased vitexin and isovitexin, and increased rutin, isoquercitrin, isorhamnetin, and caffeic acid detected. However, only studies of individual phenolic compounds in mung bean are published at present. Hence, further studies are needed to elucidate the neuroprotective activities and mechanisms of extractions of mung bean seeds and sprouts, and the synergism between different phenolic compounds.

Flavonoids with Potential Anti-Amyloidogenic Effects as Therapeutic Drugs for Treating Alzheimer's Disease

Alzheimer's disease (AD) is a central neurodegenerative disease generally among the elderly; it accounts for approximately 50-75%of total cases of dementia patients and poses a serious threat to physical and mental health. Currently available treatments for AD mainly relieves its symptoms, and effective therapy is urgently needed. Deposition of amyloid-β protein in the brain is an early and invariant neuropathological feature of AD. Currently the main efforts in developing anti-AD drugs focus on anti-amyloidogenic therapeutics that prevent amyloid-β production or aggregation and decrease the occurrence of neurotoxic events. The results of an increasing number of studies suggest that natural extracts and phytochemicals have a positive impact on brain aging. Flavonoids belong to the broad group of polyphenols and recent data indicate a favorable effect of flavonoids on brain aging. In this review, we collect relevant discoveries from 1999 to 2021, discuss 75 flavonoids that effectively influence AD pathogenesis, and summarize their functional mechanisms in detail. The data we have reviewed show that, these flavonoids belong to various subclasses, including flavone, flavanone, biflavone, etc. Our results provide a reference for further study of the effects of flavonoids on AD and the progress of anti-AD therapy.

Deciphering the Potential Neuroprotective Effects of Luteolin against Aβ1-42-Induced Alzheimer's Disease

The current study was undertaken to unveil the protective effects of Luteolin, a natural flavonoid, against amyloid-beta (Aβ₁–₄₂)-induced neuroinflammation, amyloidogenesis, and synaptic dysfunction in mice. For the development of an AD mouse model, amyloid-beta (Aβ₁–₄₂, 5 μL/5 min/mouse) oligomers were injected intracerebroventricularly (i.c.v.) into mice’s brain by using a stereotaxic frame. After that, the mice were treated with Luteolin for two weeks at a dose of 80 mg/kg/day. To monitor the biochemical changes, we conducted western blotting and immunofluorescence analysis. According to our findings, the infusion of amyloid-beta activated c-Jun N-terminal kinases (p-JNK), p38 mitogen-activated protein kinases, glial fibrillary acidic protein (GFAP), and ionized calcium adaptor molecule 1 (Iba-1) in the cortex and hippocampus of the experimental mice; these changes were significantly inhibited in Aβ₁–₄₂ + Luteolin-treated mice. Likewise, we also checked the expression of inflammatory markers, such as p-nuclear factor-kB p65 (p-NF-kB p65 (Ser536), tissue necrosis factor (TNF-α), and Interleukin1-β (IL-1β), in Aβ₁–₄₂-injected mice brain, which was attenuated in Aβ₁–₄₂ + Luteolin-treated mice brains. Further, we investigated the expression of pro- and anti-apoptotic cell death markers such as Bax, Bcl-2, Caspase-3, and Cox-2, which was significantly reduced in Aβ₁–₄₂ + Lut-treated mice brains compared to the brains of the Aβ-injected group. The results also indicated that with the administration of Aβ₁–₄₂, the expression levels of β-site amyloid precursor protein cleaving enzyme (BACE-1) and amyloid-beta (Aβ₁–₄₂) were significantly enhanced, while they were reduced in Aβ₁–₄₂ + Luteolin-treated mice. We also checked the expression of synaptic markers such as PSD-95 and SNAP-25, which was significantly enhanced in Aβ₁–₄₂ + Lut-treated mice. To unveil the underlying factors responsible for the protective effects of Luteolin against AD, we used a specific JNK inhibitor, which suggested that Luteolin reduced Aβ-associated neuroinflammation and neurodegeneration via inhibition of JNK. Collectively, our results indicate that Luteolin could serve as a novel therapeutic agent against AD-like pathological changes in mice.

A network pharmacological approach to investigate the pharmacological effects of CZ2HF decoction on Alzheimer's disease

Background

Alzheimer's disease (AD) is the most common type of dementia, which brings tremendous burden to the sufferers and society. However, ideal tactics are unavailable for AD. Our previous study has shown that CZ2HF, a Chinese herb preparation, mitigates cognitive impairment in AD rats; whereas, its detailed mechanism has not been elucidated.

Methods

Public databases were applied to collect and identify the chemical ingredients of eight herbs in CZ2HF. Criteria of absorption, distribution, metabolism, and excretion was used to screen oral bio-availability and drug-likeness. STITCH database and Therapeutic Target Database were applied to decipher the relationship between compounds and genes related to AD. Kyoto Encyclopedia of Genes and Genomes and Gene Ontology term analyses were used to identify the involved signaling pathways. Cytoscape was adopted to establish the networks The molecular docking was used to validate the interactions between the candidate compounds and their potential targets.

Results

914 compounds were identified in eight herbal medicines of CZ2HF. Among them, 9 compounds and 28 genes were highly involved in the pathologic process of AD. Furthermore, the mechanism of CZ2HF to AD was based on its anti-inflammatory effects mainly through lipopolysaccharide-mediated signaling pathway and TNF signaling pathway. Core genes in this network were TNF, ICAM1, MMP9 and IL-10.

Conclusion

This study predicts the active compounds in CZ2HF and uncovers their protein targets using holistic network pharmacology methods. It will provide a insight into the underlying mechanism of CZ2HF to AD from a multi-scale perspective.

Biphasic Effects of Blue Light Irradiation on Human Umbilical Vein Endothelial Cells

Blue light regulates biological function in various cells, such as proliferation, oxidative stress, and cell death. We employed blue light illumination on human umbilical vein endothelial cells utilizing a LED device at 453 nm wavelength and revealed a novel biphasic response on human umbilical vein endothelial cells (HUVECs). The results showed that low fluence blue light irradiation promoted the fundamental cell activities, including cell viability, migration and angiogenesis by activating the angiogenic pathways such as the VEGF signaling pathway. In contrast, high fluence illumination caused the opposite effect on those activities by upregulating pro-apoptotic signaling cascades like ferroptosis, necroptosis and the p53 signaling pathways. Our results provide an underlying insight into photobiomodulation by blue light and may help to implement potential treatment strategies for treating angiogenesis-dependent diseases.

Luteolin inhibits the proliferation, adhesion, migration and invasion of choroidal melanoma cells in vitro

Choroidal melanoma is a devastating disease that causes visual loss and a high mortality rate due to metastasis. Luteolin, a potential anticancer compound, is widely found in natural plants. The aim of this study was to evaluate the antiproliferative, antiadhesive, antimigratory and anti-invasive effects of luteolin on choroidal melanoma cells in vitro and to explore its potential mechanism. Cell counting kit-8 (CCK-8) assays, 5-ethynyl-2'-deoxyuridine (EdU) assays, Cell adhesion, migration, and invasion assays were performed to examine the inhibitory effects of luteolin on cell cell viability, proliferation, adhesion, migration and invasion capacities, respectively. Considering the correlation between Matrix metalloenzymes and tumor metastasis, Enzyme-linked immunosorbent assays (ELISAs) were used to assess matrix metalloproteases MMP-2 and MMP-9 secretion. Western blotting was performed to detect p-PI3K P85, Akt, and p-Akt protein expression. The cytoskeletal proteins vimentin were observed with cell immunofluorescence staining. Luteolin can inhibit OCM-1 cell proliferation, migration, invasion and adhesion and C918 cell proliferation, migration, and invasion through the PI3K/Akt signaling pathway. Therefore, Luteolin may have potential as a therapeutic medication for Choroidal melanoma.

Exploration of the hepatoprotective effect and mechanism of magnesium isoglycyrrhizinate in mice with arsenic trioxide‑induced acute liver injury

Arsenic trioxide (ATO)-induced hepatotoxicity limits the therapeutic effect of acute myelogenous leukemia treatment. Magnesium isoglycyrrhizinate (MgIG) is a natural compound extracted from licorice and a hepatoprotective drug used in liver injury. It exhibits anti-oxidant, anti-inflammatory and anti-apoptotic properties. The aim of the present study was to identify the protective action and underlying mechanism of MgIG against ATO-induced hepatotoxicity. A total of 50 mice were randomly divided into five groups (n=10/group): Control; ATO; MgIG and high- and low-dose MgIG + ATO. Following continuous administration of ATO for 7 days, the relative weight of the liver, liver enzyme, histological data, antioxidant enzymes, pro-inflammatory cytokines, cell apoptosis and changes in Kelch-like ECH-associated protein 1/nuclear factor erythroid 2-related factor 2 (Keap1-Nrf2) signaling pathway were observed. MgIG decreased liver injury, decreased the liver weight and liver index, inhibited oxidative stress and decreased the activity of glutathione, superoxide dismutase and catalase, production of reactive oxygen species and levels of pro-inflammatory cytokines, including IL-1β, IL-6 and TNF-α. Western blotting showed a decrease in Bax and caspase-3. There was decreased cleaved caspase-3 expression and increased Bcl-2 expression. MgIG notably activated ATO-mediated expression of Keap1 and Nrf2 in liver tissue. MgIG administration was an effective treatment to protect the liver from ATO-induced toxicity. MgIG maintained the level of Nrf2 in the liver and protected the antioxidative defense system to attenuate oxidative stress and prevent ATO-induced liver injury.

Protection against Alzheimer's disease by luteolin: Role of brain glucose regulation, anti-inflammatory activity, and the gut microbiota-liver-brain axis

Luteolin is a widely distributed flavone herbs and vegetables. It has anti-oxidant and anti-inflammatory activities and improves glucose metabolism by potentiating insulin sensitivity and improving β-cell function and mass. Alzheimer's disease (AD) is induced by the deposition of amyloid-beta (Aβ) in the hippocampus and the formation of neurotoxic Aβ plaques. The Aβ deposition is associated with increased formation of Aβ from amyloid precursor protein by up-regulation of β-secretase and β-site amyloid precursor protein-cleaving enzyme 1 (BACE1). Furthermore, Aβ accumulation is increased by brain insulin resistance. The impairment of insulin/IGF-1 signaling mainly in the hippocampus and brain insulin resistance is connected to signals originating in the liver and gut microbiota, known as the gut microbiota-liver-brain axis. This indicates that the changes in the production of short-chain fatty acids by the gut microbiota and pro-inflammatory cytokines can alter insulin resistance in the liver and brain. Luteolin is detected in the brain tissues after passing through the blood-brain barrier, where it can directly influence neuroinflammation and brain insulin resistance and modulate Aβ deposition. Luteolin (10-70 mg/kg bw for rodents) can modulate the systemic and brain insulin resistance, and it suppresses AD development directly, and it influences Aβ deposition by activation of the gut microbiota-liver-brain axis. In this review, we evaluate the potential of luteolin to mitigate two potential causes of AD, neuroinflammatory processes, and disruption of glucose metabolism in the brain. This review suggests that luteolin intake can enhance brain insulin resistance and neuroinflammation, directly and indirectly, to protect against the development of Alzheimer's-like disease, and the gut microbiota-liver-brain axis is mainly involved in the indirect pathway. However, most studies have been conducted in animal studies, and human clinical trials are needed.

Neuroinflammation in Alzheimer's disease and beneficial action of luteolin

Alzheimer's disease (AD), already the world's most common form of dementia, is projected to continue increasing in prevalence over the next several decades. The current lack of understanding of the pathogenesis of AD has hampered the development of effective treatments. Historically, AD research has been predicated on the amyloid cascade hypothesis (ACH), which attributes disease progression to the build-up of amyloid protein. However, multiple clinical studies of drugs interfering with ACH have failed to show any benefit demonstrating that AD etiology is more complex than previously thought. Here we review the current literature on the emerging key role of neuroinflammation, especially activation of microglia, in AD pathogenesis. Moreover, we provide compelling evidence that certain flavonoids, especially luteolin formulated in olive pomace oil together with hydroxytyrosol, offers a reasonable prophylactic treatment approach due to its many beneficial actions.

Dietary phytochemicals that influence gut microbiota: Roles and actions as anti-Alzheimer agents

The last decide has witnessed a growing research interest in the role of dietary phytochemicals in influencing the gut microbiota. On the other hand, recent evidence reveals that dietary phytochemicals exhibit properties of preventing and tackling symptoms of Alzheimer's disease, which is a neurodegenerative disease that has also been linked with the status of the gut microbiota over the last decade. Till now, little serious discussions, however, have been made to link recent understanding of Alzheimer's disease, dietary phytochemicals and the gut microbiota together and to review the roles played by phytochemicals in gut dysbiosis induced pathologies of Alzheimer's disease. Deciphering these connections can provide insights into the development and future use of dietary phytochemicals as anti-Alzheimer drug candidates. This review aims at presenting latest evidence in the modulating role of phytochemicals in the gut microbiota and its relevance to Alzheimer's disease and summarizing the mechanisms behind the modulative activities. Limitations of current research in this field and potential directions will also be discussed for future research on dietary phytochemicals as anti-Alzheimer agents.

CXC chemokine ligand 5 (CXCL5) disrupted the permeability of human brain microvascular endothelial cells via regulating p38 signal

The ischemia-reperfusion-induced damage in human brain microvascular endothelial cells (BMECs) is associated with disruption of the blood-brain barrier. CXC chemokine ligand 5 (CXCL5) is reported to be up-regulated in ischemic stroke. However, the detailed function of CXCL5 in this pathological process remains largely unclear. To further analyze the function of CXCL5 in ischemic stroke, an oxygen-glucose deprivation model on human BMECs was constructed to mimic the ischemic stroke condition in vitro. Cell proliferation was analyzed using a cell counting kit-8 (CCK-8) assay. Quantitative real-time polymerase chain reaction and western blot were utilized to determine gene expression. The barrier function of BMECs was assessed using a fluorescently labeled dextran assay and a trans-epithelial/endothelial electrical resistance (TEER) technique. The results indicated that CXCL5 antibody (anti-CXCL5) promoted the proliferation of model cells, whereas it reduced the permeability. Moreover, the TEER value of model cells was enhanced in the presence of anti-CXCL5. Therefore, these findings demonstrated that CXCL5 silencing attenuated the ischemic/hypoxic-induced injury in human BMECs. Importantly, human recombinant protein CXCL5 (Re-CXCL5) deeply disrupted the function of BMECs in the normoxic condition. Furthermore, the p38 inhibitor SB203580 significantly abolished the function of CXCL5 in model cells. More importantly, similar results were also obtained in BMECs under normoxic conditions in the presence of Re-CXCL5. These results indicated that CXCL5 might regulate the function of BMECs by mediating the p38 pathway. This investigation not only enhanced the understanding of the biological effect of CXCL5 in human BMECs under ischemic/hypoxic conditions but also indicated its potential value as a therapeutic target for ischemic-induced brain disease.

Potential of Medicinal Plants as Neuroprotective and Therapeutic Properties Against Amyloid-β-Related Toxicity, and Glutamate-Induced Excitotoxicity in Human Neural Cells

Alzheimer's disease (AD) and Parkinson's disease (PD) are notorious neurodegenerative diseases amongst the general population. Being age-associated diseases, the prevalence of AD and PD is forecasted to rapidly escalate with the progressive aging population of the world. These diseases are complex and multifactorial. Among different events, amyloid β peptide (Aβ) induced toxicity is a well-established pathway of neuronal cell death, which plays a vital function in AD. Glutamate, the major excitatory transmitter, acts as a neurotoxin when present in excess at the synapses; this latter mechanism is termed excitotoxicity. It is hypothesised that glutamate-induced excitotoxicity contributes to the pathogenesis of AD and PD. No cure for AD and PD is currently available and the currently approved drugs available to treat these diseases have limited effectiveness and pose adverse effects. Indeed, plants have been a major source for the discovery of novel pharmacologically active compounds for distinct pathological conditions. Diverse plant species employed for brain-related disorders in traditional medicine are being explored to determine the scientific rationale behind their uses. Herein, we present a comprehensive review of plants and their constituents that have shown promise in reversing the (i) amyloid-β -related toxicity in AD models and (ii) glutamate-induced excitotoxicity in AD and PD models. This review summarizes information regarding the phytochemistry, biological and cellular activities, and clinical trials of several plant species in view to provide adequate scientific baseline information that could be used in the drug development process, thereby providing effective leads for AD and PD.

Complementary Chinese Herbal Medicine Therapy Improves Survival in Patients With Pemphigus: A Retrospective Study From a Taiwan-Based Registry

Pemphigus is a life-threatening and skin-specific inflammatory autoimmune disease, characterized by intraepidermal blistering between the mucous membranes and skin. Chinese herbal medicine (CHM) has been used as an adjunct therapy for treating many diseases, including pemphigus. However, there are still limited studies in effects of CHM treatment in pemphigus, especially in Taiwan. To more comprehensively explore the effect of long-term CHM treatment on the overall mortality of pemphigus patients, we performed a retrospective analysis of 1,037 pemphigus patients identified from the Registry for Catastrophic Illness Patients database in Taiwan. Among them, 229 and 177 patients were defined as CHM users and non-users, respectively. CHM users were young, predominantly female, and had a lesser Charlson comorbidity index (CCI) than non-CHM users. After adjusting for age, sex, prednisolone use, and CCI, CHM users had a lower overall mortality risk than non-CHM users (multivariate model: hazard ratio (HR): 0.422, 95% confidence interval (CI): 0.242–0.735, p = 0.0023). The cumulative incidence of overall survival was significantly higher in CHM users than in non-users (p = 0.0025, log rank test). Association rule mining and network analysis showed that there was one main CHM cluster with Qi–Ju–Di–Huang–Wan (QJDHW), Dan–Shen (DanS; Radix Salviae miltiorrhizae; Salvia miltiorrhiza Bunge), Jia–Wei–Xiao–Yao-–San (JWXYS), Huang–Lian (HL; Rhizoma coptidis; Coptis chinensis Franch.), and Di–Gu–Pi (DGP; Cortex lycii; Lycium barbarum L.), while the second CHM cluster included Jin–Yin–Hua (JYH; Flos lonicerae; Lonicera hypoglauca Miq.) and Lian–Qiao (LQ; Fructus forsythiae; Forsythia suspensa (Thunb.) Vahl). In Taiwan, CHMs used as an adjunctive therapy reduced the overall mortality to approximately 20% among pemphigus patients after a follow-up of more than 6 years. A comprehensive CHM list may be useful in future clinical trials and further scientific investigations to improve the overall survival in these patients.

Resistance of nepetin and its analogs on the fibril formation of human islet amyloid polypeptide

The self-aggregation of human islet amyloid polypeptide (hIAPP) into toxic oligomers and fibrils is closely linked to the pathogenesis of type II diabetes mellitus. Inhibitors can resist hIAPP misfolding, and the resistance can be considered an alternative therapeutic strategy for this disease. Flavones have been applied in the field of diabetes research, however, the inhibition mechanism of many compounds on the fibril formation of related pathogenic peptides remains unclear. In this work, four flavones, namely, nepetin (1), genkwanin (2), luteolin (3), and apigenin (4), were used to impede the peptide aggregation of hIAPP and compared with that on Aβ protein, which is correlated with Alzheimer's disease. Results indicated that the four flavones effectively inhibited the aggregation of the two peptides and mostly dispersed the mature fibrils to monomers. The interactions of flavones with the two peptides demonstrated a spontaneous and exothermic reaction through predominant hydrophobic and hydrogen bonding interactions. The binding affinities of 1 and 3 were stronger than those of 2 and 4 possibly because of the difference in the substituent groups of these molecules. These flavones could also decrease membrane leakage and upregulate cell viability by reducing the formation of toxic oligomers. Moreover, the performance of these flavones in terms of binding affinity, cellular viability, and decreased oligomerization was better on hIAPP than on Aβ. This work offered valuable data about these flavones as prospective therapeutic agents against relevant diseases.

Bioavailability and Pharmaco-therapeutic Potential of Luteolin in Overcoming Alzheimer's Disease

Luteolin is a naturally occurring, yellow crystalline flavonoid found in numerous dietary supplements we frequently have in our meals. Studies in the last 2 decades have revealed its therapeutic potential to reduce the Alzheimer's disease (AD) symptoms in various in vitro and in vivo models. The anti-Alzheimer's potential of luteolin is attributed to its ability to suppress Aβ as well as tau aggregation or promote their disaggregation, down-regulate the expression of COX-2, NOS, MMP-9, TNF-α, interleukins and chemokines, reduce oxidative stress by scavenging ROS, modulate the activities of transcription factors CREB, cJun, Nrf-1, NF-κB, p38, p53, AP-1 and β-catenine and inhibiting the activities of various protein kinases. In several systems, luteolin has been described as a potent antioxidant and anti-inflammatory agent. In addition, we have also discussed about the bio-availability of the luteolin in the plasma. After being metabolized luteolin persists in plasma as glucuronides and sulphate-conjugates. Human clinical trials indicated no dose limiting toxicity when administered at a dose of 100 mg/day. Improvements in the formulations and drug delivery systems may further enhance the bioavailability and potency of luteolin. The current review describes in detail the data supporting these studies.

A Network Pharmacological Approach to Investigate the Mechanism of Action of Active Ingredients of Epimedii Herba and Their Potential Targets in Treatment of Alzheimer's Disease

Background

Epimedii Herba is a traditional Chinese herbal medicine used to treat central nervous system diseases such as Alzheimer’s disease in China. However, the pharmacological mechanism is unclear. To investigate the mechanisms of Epimedii Herba in the treatment of Alzheimer’s disease, we assessed effective compounds, corresponding targets, and related pathways of Epimedii Herba in the treatment of Alzheimer’s disease based on network pharmacology.

Material/Methods

The active components and targets of Epimedii Herba were obtained through the TCMSP database and the DrugBank database. The DisGeNET database and GeneCards database were used to search for Alzheimer’s disease targets. The common targets of components and disease were obtained by Wayne diagram. Gene ontology (GO) analysis and enrichment analysis of the Kyoto Encyclopedia of Genes and Genomes (KEGG) were performed using the DAVID database. The component-target-pathway interaction network model was constructed using Cytoscape software. Auto Duck Vina software was used for molecular docking to analyze the affinity of the key ingredients and the main targets.

Results

We screened 17 active ingredients and 27 key targets of Epimedii Herba in the treatment of Alzheimer’s disease, which were related to the HIF-1 signaling pathway, TNF signaling pathway, PI3K-Akt signaling pathway, NF-κB signaling pathway, VEGF signaling pathway, and sphingolipid signaling pathway.

Conclusions

Based on network pharmacology, the multi-component, multi-target, and multi-pathway characteristics of Epimedii Herba in the treatment of Alzheimer’s disease were explored. Our results provide new ideas for future pharmacological and experimental research on Epimedii Herba in the treatment of Alzheimer’s disease.

Luteolin protects against testicular injury induced by lead acetate by activating the Nrf2/HO-1 pathway

Lead (Pb) is a toxic heavy metal that is harmful to humans, especially male reproductive organs. Luteolin (LUT) is a naturally occurring flavonoid with numerous biological activities. Our aim was to investigate the possible reproprotective effect of LUT against testicular deficits induced by Pb intoxication. In the present study, 28 rats were distributed into 4 groups: control, LUT (50 mg/kg), lead acetate (PbAc, 20 mg/kg), and LUT + PbAc groups, in which rats were pre-treated with LUT 3 hr before PbAc injection. All animals were treated for 7 days. Oxidative stress, inflammatory and apoptotic markers along with histopathological changes have been examined using spectrophotometric, ELISA, real-time PCR, and histopathological methods. PbAc injection elevated Pb concentration in testicular tissue and decreased levels of sex hormones. PbAc intoxication exacerbated lipoperoxidation and nitric oxide formation, depleted superoxide dismutase, and catalase activities along with glutathione and its originated enzymes (glutathione peroxidase and glutathione reductase). At the molecular level, PbAc deactivated nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 in the testicular tissue. In addition, PbAc toxicity induced inflammatory and apoptotic cascades in testicular tissue as evidenced by the increased tumor necrosis factor-alpha, interleukin-1 beta, inducible nitric oxide synthase, Bax, and caspase 3, while Bcl-2 was declined. Histopathological examination of testicular tissue also revealed that PbAc caused degeneration alterations in spermatogenic cells, the spermatogenic epithelial cells were disconnected from the basement membrane, and the seminiferous tubules were vacuolated. Remarkably, pre-treatment with LUT minimized significantly the testicular damage induced by PbAc. Therefore, we conclude that LUT may have a beneficial effect against PbAc-induced testicular injury through preventing oxidative challenge, inflammation, and finally apoptosis.