High-throughput screening for amyloid-β binding natural small-molecules based on the combinational use of biolayer interferometry and UHPLC−DAD-Q/TOF-MS/MS

Phyto-nanotechnology: A novel beneficial strategy for Alzheimer's disease therapy

Alzheimer's disease, a neurodegenerative condition, is characterized by the slow and progressive deterioration of the cognitive functions of geriatric patients. It occurs due to exacerbation of neurons in the brain, indicated by loss of memory, mood instability, and even death. The aggregation of amyloid β protein and neurofibrillary tangles-atypical forms of tau protein is the major cause of this disease. Phytoconstituents have been frequently employed in treating Alzheimer's disease. These natural compounds act through different molecular mechanisms to treat the disease. However, their potential in Alzheimer's disease therapy may be limited due to poor blood-brain barrier permeability, off-target effects, low bioavailability, etc. In recent times, nanotechnology has gained attraction to overcome these challenges. This article focuses on the potential phytoconstituents for Alzheimer's disease treatment and the associated limitations. Moreover, it highlights various nanoformulation strategies employed to penetrate the blood-brain barrier effectively, avoid side effects, improve bioavailability, and target specificity in treating Alzheimer's disease. The integration of nanotechnology with plant-derived compounds has the potential to revolutionize the therapeutic landscape for Alzheimer's disease.

Thonningianin A from Penthorum chinense Pursh as a targeted inhibitor of Alzheimer's disease-related β-amyloid and Tau proteins

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by complex pathogenesis mechanisms. Among these, β-amyloid plaques and hyperphosphorylated Tau protein tangles have been identified as significant contributors to neuronal damage. This study investigates thonningianin A (TA) from Penthorum chinense Pursh (PCP) as a potential inhibitor targeting these pivotal proteins in AD progression. The inhibitory potential of PCP and TA on Aβ fibrillization was initially investigated. Subsequently, ultra-high performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry and biolayer interferometry were employed to determine TA's affinity for both Aβ and Tau. The inhibitory effects of TA on the levels and cytotoxicity of AD-related proteins were then assessed. In 3xTg-AD mice, the therapeutic potential of TA was evaluated. Additionally, the molecular interactions between TA and either Aβ or Tau were explored using molecular docking. We found that PCP-total ethanol extract and TA significantly inhibited Aβ fibrillization. Additionally, TA demonstrated strong affinity to Aβ and Tau, reduced levels of amyloid precursor protein and Tau, and alleviated mitochondrial distress in PC-12 cells. In 3xTg-AD mice, TA improved cognition, reduced Aβ and Tau pathology, and strengthened neurons. Moreover, molecular analyses revealed efficient binding of TA to Aβ and Tau. In conclusion, TA, derived from PCP, shows significant neuroprotection against AD proteins, highlighting its potential as an anti-AD drug candidate.

Screening bioactive compounds from Fangji Huangqi decoction for treating rheumatoid arthritis via COX-2 magnetic ligand fishing combined with in vivo validation

ETHNOPHARMACOLOGICAL RELEVANCE

Fangji Huangqi Decoction (FHD) is a classical Chinese compound formula for treating rheumatoid arthritis (RA) with satisfactory effects. FHD is reputed for its ability to tonify qi with strengthening exterior, and dispel wind while removing dampness, but its mechanisms and bioactive compounds for treating RA remain unclear.

AIM OF THE STUDY

The aim of this study was to explore the key target and bioactive compounds that were responsible for FHD-mediated improvements in RA.

MATERIALS AND METHODS

Using network pharmacology, we discovered that cyclooxygenase-2 (COX-2) was the key target of FHD against RA. We utilized a ligand fishing technique with COX-2 immobilized magnetic beads to recognize the bioactive components that act on COX-2. Then we carried out an in vitro assay of COX-2 enzyme inhibition and in vivo assay of carrageenan-induced inflammation and collagen-induced arthritis (CIA) to validate the bioactive effects of these captured ingredients. In the CIA assay, micro-CT, hematoxylin‒eosin staining and safranin-O/fast green staining were employed to assess the influence of the captured ligand on bone damage, pathological injury and cartilage destruction, respectively. Immunohistochemistry (IHC) and enzyme-linked immunosorbent assays (ELISAs) were used to detect the expression of COX-2 target in the ankle joint. interleukin-6 (IL-6) levels in the serum were also detected by ELISA. Molecular docking was used to reveal the binding mechanism of the COX-2 protein and the captured ligand.

RESULTS

Eleven ligands, including tetrandrine, fangchinoline, cyclanoline, licochalcone B, ononin, calycosin and liquiritin, were specifically bound to the COX-2 protein, as determined by ultrahigh-performance liquid chromatography-mass spectrometry (UPLC-MS), seven of which were present at high levels. One ligand, tetrandrine, not only had a great inhibitory effect on COX-2 enzyme activity but also significantly reduced carrageenan-induced inflammation. In the CIA assay, middle- and high-dose tetrandrine (25 and 50 mg/kg) had effects comparable to those of FHD and celecoxib on ameliorating RA symptoms in CIA mice via the COX-2 target. Furthermore, compared with the low-dose tetrandrine group (12.5 mg/kg), the FHD group exhibited significantly lower arthritis index scores and serum IL-6 expression, although the content of tetrandrine in FHD extract solution was approximately 0.1% of that in the low-dose tetrandrine group.

CONCLUSIONS

Hence, we inferred that tetrandrine was the main bioactive component responsible for the effects of FHD against RA by suppressing the expression of the COX-2 protein and inhibiting the enzyme catalytic activity of COX-2. The reason for these effects may be that tetrandrine can interact with the residue Tyr385 of COX-2, the enzymatic catalytic site of COX-2 to transform arachidonic acid (AA) to prostaglandin E2 (PGE2), and thereby reduce the production of prostaglandins and inflammatory metabolites. Moreover, in addition to tetrandrine, FHD contains other compounds that could supplement the activity of tetrandrine when FHD was used to treat RA, which is manifested the "multi-component" characteristic of how Traditional Chinese Medicine formulas treat diseases.

Mitophagy and cGAS-STING crosstalk in neuroinflammation

Mitophagy, essential for mitochondrial health, selectively degrades damaged mitochondria. It is intricately linked to the cGAS-STING pathway, which is crucial for innate immunity. This pathway responds to mitochondrial DNA and is associated with cellular stress response. Our review explores the molecular details and regulatory mechanisms of mitophagy and the cGAS-STING pathway. We critically evaluate the literature demonstrating how dysfunctional mitophagy leads to neuroinflammatory conditions, primarily through the accumulation of damaged mitochondria, which activates the cGAS-STING pathway. This activation prompts the production of pro-inflammatory cytokines, exacerbating neuroinflammation. This review emphasizes the interaction between mitophagy and the cGAS-STING pathways. Effective mitophagy may suppress the cGAS-STING pathway, offering protection against neuroinflammation. Conversely, impaired mitophagy may activate the cGAS-STING pathway, leading to chronic neuroinflammation. Additionally, we explored how this interaction influences neurodegenerative disorders, suggesting a common mechanism underlying these diseases. In conclusion, there is a need for additional targeted research to unravel the complexities of mitophagy-cGAS-STING interactions and their role in neurodegeneration. This review highlights potential therapies targeting these pathways, potentially leading to new treatments for neuroinflammatory and neurodegenerative conditions. This synthesis enhances our understanding of the cellular and molecular foundations of neuroinflammation and opens new therapeutic avenues for neurodegenerative disease research.

Penthorum chinense Pursh inhibits ferroptosis in cellular and Caenorhabditis elegans models of Alzheimer's disease

BACKGROUND

Ferroptosis, a unique type of cell death triggered by iron-dependent lipid peroxidation, plays a critical role in the pathogenesis of Alzheimer's disease (AD), a debilitating condition marked by memory loss and cognitive impairment due to the accumulation of beta-amyloid (Aβ) and hyperphosphorylated Tau protein. Increasing evidence suggests that inhibitors of ferroptosis could be groundbreaking in the treatment of AD.

METHOD

In this study, we established in vitro ferroptosis using erastin-, RSL-3-, hemin-, and iFSP1-induced PC-12 cells. Using MTT along with Hoechst/PI staining, we assessed cell viability and death. To determine various aspects of ferroptosis, we employed fluorescence probes, including DCFDA, JC-1, C11 BODIPY, Mito-Tracker, and PGSK, to measure ROS production, mitochondrial membrane potential, lipid peroxidation, mitochondrial morphology, and intracellular iron levels. Additionally, Western blotting, biolayer interferometry technology, and shRNA were utilized to investigate the underlying molecular mechanisms. Furthermore, p-CAX APP Swe/Ind- and pRK5-EGFP-Tau P301L overexpressing PC-12 cells, along with Caenorhabditis elegans (C. elegans) strains CL4176, CL2331, and BR5270, were employed to examine ferroptosis in AD models.

RESULTS

Here, we conducted a screening of our natural medicine libraries and identified the ethanol extract of Penthorum chinense Pursh (PEE), particularly its ethyl acetate fraction (PEF), displayed inhibitory effects on ferroptosis in cells. Specifically, PEF inhibited the generation of ROS, lipid peroxidation, and intracellular iron levels. Furthermore, PEF demonstrated protective effects against H2O2-induced cell death, ROS production, and mitochondrial damage. Mechanistic investigations unveiled PEF's modulation of intracellular iron accumulation, GPX4 expression and activity, and FSP1 expression. In p-CAX APP Swe/Ind and pRK5-EGFP-Tau P301L overexpressing PC-12 cells, PEF significantly reduced cell death, as well as ROS and lipid peroxidase production. Moreover, PEF ameliorated paralysis and slowing rate in Aβ and Tau transgenic C. elegans models, while inhibiting ferroptosis, as evidenced by decreased DHE intensity, lipid peroxidation levels, iron accumulation, and expression of SOD-3 and gst-4.

CONCLUSION

Our findings highlight the suppressive effects of PEF on ferroptosis in AD cellular and C. elegans models. This study helps us better understand how ferroptosis affects AD and emphasizes the potential of PCP as a candidate for AD intervention.

Carpesii fructus extract exhibits neuroprotective effects in cellular and Caenorhabditis elegans models of Parkinson's disease

OBJECTIVE

Parkinson's disease (PD) is a debilitating neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons in the substantia nigra. Despite extensive research, no definitive cure or effective disease-modifying treatment for PD exists to date. Therefore, the identification of novel therapeutic agents with neuroprotective properties is of utmost importance. Here, we aimed to investigate the potential neuroprotective effects of Carpesii fructus extract (CFE) in both cellular and Caenorhabditis elegans (C. elegans) models of PD.

METHODS

The neuroprotective effect of CFE in H2O2- or 6-OHDA-induced PC-12 cells and α-synuclein-overexpressing PC-12 cells were investigated by determining the cell viability, mitochondrial damage, reactive oxygen species (ROS) production, apoptosis, and α-synuclein expression. In NL5901, BZ555, and N2 worms, the expression of α-synuclein, motive ability, the viability of dopaminergic neurons, lifespan, and aging-related phenotypes were investigated. The signaling pathway was detected by Western blotting and validated by employing small inhibitors and RNAi bacteria.

RESULTS

In cellular models of PD, CFE significantly attenuated H2O2- or 6-OHDA-induced toxicity, as evidenced by increased cell viability and reduced apoptosis rate. In addition, CFE treatment suppressed ROS generation and restored mitochondrial membrane potential, highlighting its potential as a mitochondrial protective agent. Furthermore, CFE reduced the expression of α-synuclein in wide type (WT)-, A53T-, A30P-, or E46K-α-synuclein-overexpressing PC-12 cells. Our further findings reveal that CFE administration reduced α-synuclein expression and improved its induced locomotor deficits in NL5901 worms, protected dopaminergic neurons against 6-OHDA-induced degeneration in BZ555 worms, extended lifespan, delayed aging-related phenotypes, and enhanced the ability of stress resistance in N2 worms. Mechanistic studies suggest that the neuroprotective effects of CFE may involve the modulation of the MAPK signaling pathway, including ERK, JNK, and p38, whereas the interference of these pathways attenuated the neuroprotective effect of CFE in vitro and in vivo.

CONCLUSION

Overall, our study highlights the potential therapeutic value of CFE as a neuroprotective agent in the context of PD. Furthermore, elucidation of the active compounds of CFE will provide valuable insights for the development of novel therapeutic strategies for PD.

Classic Famous Prescription Kai-Xin-San Ameliorates Alzheimer's Disease via the Wnt/β-Catenin Signaling Pathway

Kai-Xin-San (KXS) is a classic famous prescription composed of Polygalae Radix, Ginseng Radix et Rhizoma, Acori Tatarinowii Rhizoma, and Poria. Clinically, KXS is effective in treating amnesia and regulating cognitive dysfunction of Alzheimer's disease (AD), whereas its mechanism of action is still unclear. In this study, the AD model rats were established by combining intraperitoneal injection of D-galactose (150 mg/kg/day) and intracerebral injection of Aβ25-35 (10 μL) to investigate the meliorative effect of KXS on AD and explore its mechanism. After 1-month KXS treatment, Morris water maze test showed that different doses of KXS all improved the cognitive impairment of AD rats. The results of hematoxylin and eosin staining, Nissl staining, and Tunnel staining showed that the neuron injury in the hippocampal CA1 region of the AD rats was markedly improved after KXS treatment. Concurrently, KXS reversed the levels of biochemical indexes of AD rats. Furthermore, the protein expressions of Wnt1 and β-catenin in KXS groups were remarkably increased, while the expressions of Bax and caspase-3 were significantly decreased. Besides, KXS-medicated serum reduced the levels of tumor necrosis factor-α, interleukin-1β, and reactive oxygen species and regulated the protein expressions of β-catenin, glycogen synthase kinase-3β (GSK-3β), p-GSK-3β, Bax, and caspase-3 in Aβ25-35-induced pheochromocytoma cells. Most importantly, this effect was attenuated by the Wnt inhibitor IWR-1. Our results suggest that KXS improves cognitive and memory function of AD rats, and its neuroprotective mechanism may be mediated through the Wnt/β-catenin signaling pathway.

Quercetin, a Flavonoid with Great Pharmacological Capacity

Quercetin is a flavonoid with a low molecular weight that belongs to the human diet's phenolic phytochemicals and nonenergy constituents. Quercetin has a potent antioxidant capacity, being able to capture reactive oxygen species (ROS), reactive nitrogen species (RNS), and reactive chlorine species (ROC), which act as reducing agents by chelating transition-metal ions. Its structure has five functional hydroxyl groups, which work as electron donors and are responsible for capturing free radicals. In addition to its antioxidant capacity, different pharmacological properties of quercetin have been described, such as carcinostatic properties; antiviral, antihypertensive, and anti-inflammatory properties; the ability to protect low-density lipoprotein (LDL) oxidation, and the ability to inhibit angiogenesis; these are developed in this review.

Preparation and application of UPLC silica microsphere stationary phase:A review

In this review, microspheres for ultra-performance liquid chromatography (UPLC) were reviewed in accordance with the literature in recent years. As people's demands for chromatography are becoming more and more sophisticated, the preparation and application of UPLC stationary phases have become the focus of researchers in this field. This new analytical separation science not only maintains the practicality and principle of high-performance liquid chromatography (HPLC), but also improves the step function of chromatographic performance. The review presents the morphology of four types of sub-2 μm silica microspheres that have been used in UPLC, including non-porous silica microspheres (NPSMs), mesoporous silica microspheres (MPSMs), hollow silica microspheres (HSMs) and core-shell silica microspheres (CSSMs). The preparation, pore control and modification methods of different microspheres are introduced in the review, and then the applications of UPLC in drug analysis and separation, environmental monitoring, and separation of macromolecular proteins was presented. Finally, a brief overview of the existing challenges in the preparation of sub-2 μm microspheres, which required further research and development, was given.

Poly (ADP-ribose) polymerase 1 and neurodegenerative diseases: Past, present, and future

Poly (ADP-ribose) polymerase 1 (PARP1) is a first responder that recognizes DNA damage and facilitates its repair. Neurodegenerative diseases, characterized by progressive neuron loss driven by various risk factors, including DNA damage, have increasingly shed light on the pivotal involvement of PARP1. During the early phases of neurodegenerative diseases, PARP1 experiences controlled activation to swiftly address mild DNA damage, thereby contributing to maintain brain homeostasis. However, in late stages, exacerbated PARP1 activation precipitated by severe DNA damage exacerbates the disease condition. Consequently, inhibition of PARP1 overactivation emerges as a promising therapeutic approach for neurodegenerative diseases. In this review, we comprehensively synthesize and explore the multifaceted role of PARP1 in neurodegenerative diseases, with a particular emphasis on its over-activation in the aggregation of misfolded proteins, dysfunction of the autophagy-lysosome pathway, mitochondrial dysfunction, neuroinflammation, and blood-brain barrier (BBB) injury. Additionally, we encapsulate the therapeutic applications and limitations intrinsic of PARP1 inhibitors, mainly including limited specificity, intricate pathway dynamics, constrained clinical translation, and the heterogeneity of patient cohorts. We also explore and discuss the potential synergistic implementation of these inhibitors alongside other agents targeting DNA damage cascades within neurodegenerative diseases. Simultaneously, we propose several recommendations for the utilization of PARP1 inhibitors within the realm of neurodegenerative disorders, encompassing factors like the disease-specific roles of PARP1, combinatorial therapeutic strategies, and personalized medical interventions. Lastly, the encompassing review presents a forward-looking perspective along with strategic recommendations that could guide future research endeavors in this field.

Baicalein promotes the microglia M2 polarization and suppresses apoptosis by targeting HMOX1/PDE4D to alleviate Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder that has quickly becoming one of the most expensive, lethal, and burdening diseases of this century. In the past twenty years, hundreds of drugs have been tested while only several have been authorized by FDA for AD treatment, hence, searching for candidate agent with therapeutic potential for AD is imminent. Controlling polarization direction of microglia is crucial in AD therapy. Recent research suggests that baicalein has potential to reduce neuroinflammation and prevent neurodegenerative diseases by affecting microglia, while the specific molecular mechanism of baicalein in regulating microglia in the treatment of AD is still unclear. In this study, we investigated how baicalein affected microglial polarization in AD and potential biological mechanisms. In cell experiments, it was verified that baicalein significantly shifted the BV-2 microglia phenotype from the pro-inflammatory M1 to the anti-inflammatory M2 phenotype, inhibited the microglial apoptosis and pro-inflammatory factors, promoted the microglial Aβ uptake and anti-inflammatory factors after LPS stimulated. In APP/PS1 mice, it was found that baicalein decreased the Aβ plaque deposition in brain, attenuated NLRP3 inflammasome activation and neuronal apoptosis in APP/PS1 mice. Furthermore, bioinformatics analysis and experiment validated that HMOX1 is a target of baicalein, and we elucidated that baicalein modulated the microglial polarization to inhibit neuroinflammation and neural injury through targeting on the HMOX1/PDE4D axis in AD. In conclusion, our findings indicate the therapeutic effect of baicalein for AD, and baicalein might serve a potential agent for AD treatment.

Stress-mediated aggregation of disease-associated proteins in amyloid bodies

The formation of protein aggregates is a hallmark of many neurodegenerative diseases and systemic amyloidoses. These disorders are associated with the fibrillation of a variety of proteins/peptides, which ultimately leads to cell toxicity and tissue damage. Understanding how amyloid aggregation occurs and developing compounds that impair this process is a major challenge in the health science community. Here, we demonstrate that pathogenic proteins associated with Alzheimer's disease, diabetes, AL/AA amyloidosis, and amyotrophic lateral sclerosis can aggregate within stress-inducible physiological amyloid-based structures, termed amyloid bodies (A-bodies). Using a limited collection of small molecule inhibitors, we found that diclofenac could repress amyloid aggregation of the β-amyloid (1-42) in a cellular setting, despite having no effect in the classic Thioflavin T (ThT) in vitro fibrillation assay. Mapping the mechanism of the diclofenac-mediated repression indicated that dysregulation of cyclooxygenases and the prostaglandin synthesis pathway was potentially responsible for this effect. Together, this work suggests that the A-body machinery may be linked to a subset of pathological amyloidosis, and highlights the utility of this model system in the identification of new small molecules that could treat these debilitating diseases.

Functional annotation map of natural compounds in traditional Chinese medicines library: TCMs with myocardial protection as a case

The chemical complexity of traditional Chinese medicines (TCMs) makes the active and functional annotation of natural compounds challenging. Herein, we developed the TCMs-Compounds Functional Annotation platform (TCMs-CFA) for large-scale predicting active compounds with potential mechanisms from TCM complex system, without isolating and activity testing every single compound one by one. The platform was established based on the integration of TCMs knowledge base, chemome profiling, and high-content imaging. It mainly included: (1) selection of herbal drugs of target based on TCMs knowledge base; (2) chemome profiling of TCMs extract library by LC‒MS; (3) cytological profiling of TCMs extract library by high-content cell-based imaging; (4) active compounds discovery by combining each mass signal and multi-parametric cell phenotypes; (5) construction of functional annotation map for predicting the potential mechanisms of lead compounds. In this stud TCMs with myocardial protection were applied as a case study, and validated for the feasibility and utility of the platform. Seven frequently used herbal drugs (Ginseng, etc.) were screened from 100,000 TCMs formulas for myocardial protection and subsequently prepared as a library of 700 extracts. By using TCMs-CFA platform, 81 lead compounds, including 10 novel bioactive ones, were quickly identified by correlating 8089 mass signals with 170,100 cytological parameters from an extract library. The TCMs-CFA platform described a new evidence-led tool for the rapid discovery process by data mining strategies, which is valuable for novel lead compounds from TCMs. All computations are done through Python and are publicly available on GitHub.

Protective effects of Radix Stellariae extract against Alzheimer's disease via autophagy activation in Caenorhabditis elegans and cellular models

Enhancing the clearance of proteins associated with Alzheimer's disease (AD) emerges as a promising approach for AD therapeutics. This study explores the potential of Radix Stellariae, a traditional Chinese medicine, in treating AD. Utilizing transgenic C. elegans models of AD, we demonstrated that a 75% ethanol extract of Radix Stellariae (RSE) (at 50 µg/mL) effectively diminishes Aβ and Tau protein expression, and alleviates their induced impairments including paralysis, behavioral dysfunction, neurotoxicity, and ROS accumulation. Additionally, RSE enhances the stress resistance of C. elegans. Further investigations revealed that RSE promotes autophagy, a critical cellular process for protein degradation, in these models. We found that inhibiting autophagy-related genes negated the neuroprotective effects of RSE, suggesting a central role for autophagy in the actions of RSE. In PC-12 cells, we observed that RSE not only inhibited Aβ fibril formation but also promoted the degradation of AD-related proteins and reduced their cytotoxicity. Mechanistically, RSE was found to induce autophagy via modulating PI3K/AKT/mTOR and AMPK/mTOR signaling pathways. Importantly, inhibiting autophagy counteracted the beneficial effects of RSE on the clearance of AD-associated proteins. Moreover, we identified Dichotomine B, a β-carboline alkaloid, as a key active constituent of RSE in mitigating AD pathology in C. elegans at concentrations ranging from 50 to 1000 µM. Collectively, our study presents novel discoveries that RSE alleviates AD pathology and toxicity primarily by inducing autophagy, both in vivo and in vitro. These findings open up new avenues for exploring the therapeutic potential of RSE and its active component, Dichotomine B, in treating neurodegenerative diseases like AD.

High resolution micro-confocal Raman spectrometer-based photo-affinity microarray technology for the investigation of active ingredients - Target protein recognition strategy

Natural products has been used for the prevention and treatment of diseases for a long history. Research on the bioactive components from natural products and their interaction with target proteins are essential for drug discovery. However, studying the binding ability of natural products' active ingredients to target proteins is usually time-consuming and laborious due to their complex and diverse chemical structures. In this study, we have developed a high resolution micro-confocal Raman spectrometer-based photo-affinity microarray (HRMR-PM) technology for the investigation of active ingredients-target protein recognition strategy. The novel photo-affinity microarray was constructed by photo-cross-linking the small molecule with the photo-affinity group (4-[3-(Trifluoromethyl)-3H-diazirin-3-yl]benzoic acid, TAD) on the photo-affinity linker coated (PALC) slides under 365 nm ultraviolet irradiation. The small molecules on the microarrays with specific binding ability might immobilize target protein, which were characterized by high resolution micro-confocal Raman spectrometer. Using this method, more than a dozen components of Shenqi Jiangtang granules (SJG) were made into small molecule probe (SMP) microarrays. As a result, 8 of them had been identified to have α-glucosidase binding ability according to characteristic Raman shift at about 3060 cm^-1. These compounds were further verified by different small molecule-protein interaction analysis methods, including contact angle D-value, surface plasmon resonance (SPR) and molecular docking. The results showed that Ginsenosides Mb, Formononetin and Gomisin D exhibited the strongest binding ability. In conclusion, the HRMR-PM strategy for investigating the interaction between target proteins and small molecules has the advantages such as high throughput, low sample consumption and fast qualitative characterization. This strategy is universal which can be applied in the study of in vitro binding activity of various types of small molecules to target proteins.

Targeting autophagy to discover the Piper wallichii petroleum ether fraction exhibiting antiaging and anti-Alzheimer's disease effects in Caenorhabditis elegans

BACKGROUND

With population aging, the incidence of aging-related Alzheimer's disease (AD) is increasing, accompanied by decreased autophagy activity. At present, Caenorhabditis elegans (C. elegans) is widely employed to evaluate autophagy and in research on aging and aging-related diseases in vivo. To discover autophagy activators from natural medicines and investigate their therapeutic potential in antiaging and anti-AD effects, multiple C. elegans models related to autophagy, aging, and AD were used.

METHOD

In this study, we employed the DA2123 and BC12921 strains to discover potential autophagy inducers using a self-established natural medicine library. The antiaging effect was evaluated by determining the lifespan, motor ability, pumping rate, lipofuscin accumulation of worms, and resistance ability of worms under various stresses. In addition, the anti-AD effect was examined by detecting the paralysis rate, food-sensing behavior, and amyloid-β and Tau pathology in C. elegans. Moreover, RNAi technology was used to knock down the genes related to autophagy induction.

RESULTS

We discovered that Piper wallichii extract (PE) and the petroleum ether fraction (PPF) activated autophagy in C. elegans, as evidenced by increased GFP-tagged LGG-1 foci and decreased GFP-p62 expression. In addition, PPF extended the lifespan and enhanced the healthspan of worms by increasing body bends and pumping rates, decreasing lipofuscin accumulation, and increasing resistance to oxidative, heat, and pathogenic stress. Moreover, PPF exhibited an anti-AD effect by decreasing the paralysis rate, improving the pumping rate and slowing rate, and alleviating Aβ and Tau pathology in AD worms. However, the feeding of RNAi bacteria targeting unc-51, bec-1, lgg-1, and vps-34 abolished the antiaging and anti-AD effects of PPF.

CONCLUSION

Piper wallichii may be a promising drug for antiaging and anti-AD. More future studies are also needed to identify autophagy inducers in Piper wallichii and clarify their molecular mechanisms.

Folium Hibisci Mutabilis extract, a potent autophagy enhancer, exhibits neuroprotective properties in multiple models of neurodegenerative diseases

BACKGROUND

Protein aggregates are considered key pathological features in neurodegenerative diseases (NDs). The induction of autophagy can effectively promote the clearance of ND-related misfolded proteins.

OBJECTIVE

In this study, we aimed to screen natural autophagy enhancers from traditional Chinese medicines (TCMs) presenting potent neuroprotective potential in multiple ND models.

METHODS

The autophagy enhancers were broadly screened in our established herbal extract library using the transgenic Caenorhabditis elegans (C. elegans) DA2123 strain. The neuroprotective effects of the identified autophagy enhancers were evaluated in multiple C. elegans ND models by measuring Aβ-, Tau-, α-synuclein-, and polyQ40-induced pathologies. In addition, PC-12 cells and 3 × Tg-AD mice were employed to further validate the neuroprotective ability of the identified autophagy enhancers, both in vitro and in vivo. Furthermore, RNAi bacteria and autophagy inhibitors were used to evaluate whether the observed effects of the identified autophagy enhancers were mediated by the autophagy-activated pathway.

RESULTS

The ethanol extract of Folium Hibisci Mutabilis (FHME) was found to significantly increase GFP::LGG-1-positive puncta in the DA2123 worms. FHME treatment markedly inhibited Aβ, α-synuclein, and polyQ40, as well as prolonging the lifespan and improving the behaviors of C. elegans, while siRNA targeting four key autophagy genes partly abrogated the protective roles of FHME in C. elegans. Additionally, FHME decreased the expression of AD-related proteins and restored cell viability in PC-12 cells, which were canceled by cotreatment with 3-methyladenine (3-MA) or bafilomycin A1 (Baf). Moreover, FHME ameliorated AD-like cognitive impairment and pathology, as well as activating autophagy in 3 × Tg-AD mice.

CONCLUSION

FHME was successfully screened from our natural product library as a potent autophagy enhancer that exhibits a neuroprotective effect in multiple ND models across species through the induction of autophagy. These findings offer a new and reliable strategy for screening autophagy inducers, as well as providing evidence that FHME may serve as a possible therapeutic agent for NDs.

Therapeutic potential of Polygala saponins in neurological diseases

BACKGROUND

There are many types of neurological diseases with complex etiologies. At present, most clinical drugs can only relieve symptoms but cannot cure these diseases. Radix Polygalae, a famous traditional Chinese medicine from the root of plants of the genus Polygala, has the traditional effect of treating insomnia, forgetfulness, and palpitation and improving intelligence and other symptoms of neurological diseases. Saponins are important bioactive components of plants of the genus Polygala and exhibit neuroprotective effects.

PURPOSE

This review aimed to summarize the traditional use of Polygala species and discuss the latest phytochemical, pharmacological, and toxicological findings, mainly with regard to Polygala saponins in the treatment of neurological disorders.

METHODS

Literature was searched and collected using databases, including PubMed, Science Direct, CNKI, and Google Scholar. The search terms used included "Polygala", "saponins", "neurological diseases", "Alzheimer's disease", "toxicity", etc., and combinations of these keywords. A total of 1202 papers were retrieved until August 2022, and we included 135 of these papers on traditional uses, phytochemistry, pharmacology, toxicology and other fields.

RESULTS

This literature review mainly reports on the traditional use of the Polygala genus and prescriptions containing Radix Polygalae in neurological diseases. Phytochemical studies have shown that plants of the genus Polygala mainly include saponins, flavonoids, oligosaccharide esters, alkaloids, coumarins, lignans, flavonoids, etc. Among them, saponins are the majority. Modern pharmacological studies have shown that Polygala saponins have neuroprotective effects on a variety of neurological diseases. Its mechanism of action involves autophagic degradation of misfolded proteins, anti-inflammatory, anti-apoptotic, antioxidative stress and so on. Toxicological studies have shown that Polygala saponins trigger gastrointestinal toxicity, and honey processing and glycosyl disruption of Polygala saponins can effectively ameliorate its gastrointestinal side effect.

CONCLUSION

Polygala saponins are the major bioactive components in plants of the genus Polygala that exhibit therapeutic potential in various neurological diseases. This review provides directions for the future study of Polygala saponins and references for the clinical use of prescriptions containing Radix Polygalae for the treatment of neurological diseases.

Targeting microglial autophagic degradation of the NLRP3 inflammasome for identification of thonningianin A in Alzheimer’s disease

Background

NLRP3 inflammasome-mediated neuroinflammation plays a critical role in the pathogenesis and development of Alzheimer’s disease (AD). Microglial autophagic degradation not only decreases the deposits of extracellular Aβ fibrils but also inhibits the activation of NRLP3 inflammasome. Here, we aimed to identify the potent autophagy enhancers from Penthorum chinense Pursh (PCP) that alleviate the pathology of AD via inhibiting the NLRP3 inflammasome.

Methods

At first, autophagic activity-guided isolation was performed to identify the autophagy enhancers in PCP. Secondly, the autophagy effect was monitored by detecting LC3 protein expression using Western blotting and the average number of GFP-LC3 puncta per microglial cell using confocal microscopy. Then, the activation of NLRP3 inflammasome was measured by detecting the protein expression and transfected fluorescence intensity of NLRP3, ASC, and caspase-1, as well as the secretion of proinflammatory cytokines. Finally, the behavioral performance was evaluated by measuring the paralysis in C. elegans, and the cognitive function was tested by Morris water maze (MWM) in APP/PS1 mice.

Results

Four ellagitannin flavonoids, including pinocembrin-7-O-[4″,6″-hexahydroxydiphenoyl]-glucoside (PHG), pinocembrin-7-O-[3″-O-galloyl-4″,6″-hexahydroxydiphenoyl]-glucoside (PGHG), thonningianin A (TA), and thonningianin B (TB), were identified to be autophagy enhancers in PCP. Among these, TA exhibited the strongest autophagy induction effect, and the mechanistic study demonstrated that TA activated autophagy via the AMPK/ULK1 and Raf/MEK/ERK signaling pathways. In addition, TA effectively promoted the autophagic degradation of NLRP3 inflammasome in Aβ(1–42)-induced microglial cells and ameliorated neuronal damage via autophagy induction. In vivo, TA activated autophagy and improved behavioral symptoms in C. elegans. Furthermore, TA might penetrate the blood-brain barrier and could improve cognitive function and ameliorate the Aβ pathology and the NLRP3 inflammasome-mediated neuroinflammation via the AMPK/ULK1 and Raf/MEK/ERK signaling pathways in APP/PS1 mice.

Conclusion

We identified TA as a potent microglial autophagy enhancer in PCP that promotes the autophagic degradation of the NLRP3 inflammasome to alleviate the pathology of AD via the AMPK/ULK1 and Raf/MEK/ERK signaling pathways, which provides novel insights for TA in the treatment of AD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41232-022-00209-7.

A comprehensive review of Rubia cordifolia L.: Traditional uses, phytochemistry, pharmacological activities, and clinical applications

Rubia cordifolia (family: Rubiaceae) L (R. cordifolia) is a perennial botanical drug climbing vine. As the main part of the traditional Chinese medicine, the rhizome has a long history. A great number of literary studies have reported that it can be used for the improvement of blood circulation, hemostasis, activation of collaterals, etc. When it comes to the wide application of R. cordifolia in traditional medicine, we systematically review its traditional uses, phytochemistry and pharmacological effects. Literatures were systematically searched using several scientific databases, including China National Knowledge Infrastructure (CNKI), Baidu Scholar, PubMed, Web of Science, and other professional websites. Kew Botanical Garden and the iPlant were used for obtaining the scientific names and plant images of R. cordifolia. In addition, other information was also gathered from books including traditional Chinese herbal medicine, the Chinese Pharmacopoeia, and Chinese Materia Medica. So far, many prescriptions containing R. cordifolia have been widely used in the clinical treatment of abnormal uterine bleeding, primary dysmenorrhea and other gynecological diseases, allergic purpura, renal hemorrhage and other diseases. The phytochemistry studies have reported that more than 100 compounds are found in R. cordifolia, such as bicyclic peptides, terpenes, polysaccharides, trace elements, flavonoids, and quinones. Among them, quinones and peptides are the types of components with the highest contents in R. cordifolia. The modern pharmacological studies have revealed that R. cordifolia and its derived components have anti-tumor, anti-oxidative, anti-platelet aggregation, and anti-inflammatory effects. However, most studies are preclinical. The pharmacological mechanism of R. cordifolia has not been thoroughly studied. In addition, there are few pharmacokinetic and toxicity studies of R. cordifolia, therefore the clinical safety data for R. cordifolia is lacking. To sum up, this review for the first time summarizes a systemic and integrated traditional uses, chemical compositions, pharmacological actions and clinical applications of R. cordifolia, which provides the novel and full-scale insight for the drug development, medicinal value, and application of R. cordifolia in the future.

Galangin Exhibits Neuroprotective Effects in 6-OHDA-Induced Models of Parkinson’s Disease via the Nrf2/Keap1 Pathway

Parkinson’s disease (PD) is the second most common neurodegenerative disease, and there is still no cure for it. PD is characterized by the degeneration of dopaminergic neurons, and oxidative stress has been considered an important pathological mechanism. Therefore, the discovery of antioxidants to alleviate the oxidative damage of dopaminergic neurons is a promising therapeutic strategy for PD. First, a network pharmacology approach was used, and nine common core targets of galangin and PD were screened, mainly involving cell aging, apoptosis, and cellular responses to hydrogen peroxide and hypoxia. In addition, the Gene Ontology (GO) function and pathway enrichment analysis of the Kyoto Encyclopedia of Genes and Genomes (KEGG) identified apoptosis, PI3K/Akt, and HIF-1 signaling pathways. Furthermore, the molecular docking results revealed a strong affinity between galangin and the NFE2L2/Nrf2 protein. To validate the above predictions, we employed 6-hydroxydopamine (6-OHDA) to induce neuronal death in HT22 cells and Caenorhabditis elegans (C. elegans). MTT, cell morphology observation, and Hoechst 33342-PI staining results showed that galangin significantly increased the viability of 6-OHDA-treated HT22 cells. In addition, galangin inhibited 6-OHDA-induced ROS generation and apoptosis in HT22 cells. Mechanistic studies demonstrated that galangin activates the Nrf2/Keap1 signaling pathway, as evidenced by the decreased protein expression of Keap1 and increased protein expression of Nrf2 and HO-1. In the 6-OHDA-induced PD model of C. elegans, galangin indeed inhibited the degeneration of dopaminergic neurons, improved behavioral ability, and decreased ROS generation. In conclusion, the current study is the first to show that galangin has the capacity to inhibit neuronal degeneration via the Nrf2/Keap1 pathway, suggesting that galangin is a possible PD treatment.

PC-12 Cell Line as a Neuronal Cell Model for Biosensing Applications

PC-12 cells have been widely used as a neuronal line study model in many biosensing devices, mainly due to the neurogenic characteristics acquired after differentiation, such as high level of secreted neurotransmitter, neuron morphology characterized by neurite outgrowth, and expression of ion and neurotransmitter receptors. For understanding the pathophysiology processes involved in brain disorders, PC-12 cell line is extensively assessed in neuroscience research, including studies on neurotoxicity, neuroprotection, or neurosecretion. Various analytical technologies have been developed to investigate physicochemical processes and the biosensors based on optical and electrochemical techniques, among others, have been at the forefront of this development. This article summarizes the application of different biosensors in PC-12 cell cultures and presents the modern approaches employed in neuronal networks biosensing.

Dietary Plant Polyphenols as the Potential Drugs in Neurodegenerative Diseases: Current Evidence, Advances, and Opportunities

Neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD), are characterized by the progressive degeneration of neurons. Although the etiology and pathogenesis of neurodegenerative diseases have been studied intensively, the mechanism is still in its infancy. In general, most neurodegenerative diseases share common molecular mechanisms, and multiple risks interact and promote the pathologic process of neurogenerative diseases. At present, most of the approved drugs only alleviate the clinical symptoms but fail to cure neurodegenerative diseases. Numerous studies indicate that dietary plant polyphenols are safe and exhibit potent neuroprotective effects in various neurodegenerative diseases. However, low bioavailability is the biggest obstacle for polyphenol that largely limits its adoption from evidence into clinical practice. In this review, we summarized the widely recognized mechanisms associated with neurodegenerative diseases, such as misfolded proteins, mitochondrial dysfunction, oxidative damage, and neuroinflammatory responses. In addition, we summarized the research advances about the neuroprotective effect of the most widely reported dietary plant polyphenols. Moreover, we discussed the current clinical study and application of polyphenols and the factors that result in low bioavailability, such as poor stability and low permeability across the blood-brain barrier (BBB). In the future, the improvement of absorption and stability, modification of structure and formulation, and the combination therapy will provide more opportunities from the laboratory into the clinic for polyphenols. Lastly, we hope that the present review will encourage further researches on natural dietary polyphenols in the treatment of neurodegenerative diseases.

Polygala saponins inhibit NLRP3 inflammasome-mediated neuroinflammation via SHP-2-Mediated mitophagy

Activation of the NLRP3 inflammasome and its mediated neuroinflammation are implicated in neurodegenerative diseases, while mitophagy negatively regulates NLRP3 inflammasome activation. SHP-2, a protein-tyrosine phosphatase, is critical for NLRP3 inflammasome regulation and inflammatory responses. In this study, we investigated whether triterpenoid saponins in Radix Polygalae inhibit the NLRP3 inflammasome via mitophagy induction. First, we isolated the active fraction (polygala saponins (PSS)) and identified 17 saponins by ultra-performance liquid chromatography coupled with diode-array detection and tandem quadrupole time-of-flight mass spectrometry (UHPLC-DAD-Q/TOF-MS). In microglial BV-2 cells, PSS induced mitophagy as evidenced by increased co-localization of LC3 and mitochondria, as well as an increased number of autophagic vacuoles surrounding the mitochondria. Furthermore, the mechanistic study found that PSS activated the AMPK/mTOR and PINK1/parkin signaling pathways via the upregulation of SHP-2. In Aβ(1-42)-, A53T-α-synuclein-, or Q74-induced BV-2 cells, PSS significantly inhibited NLRP3 inflammasome activation, which was attenuated by bafilomycin A1 (an autophagy inhibitor) and SHP099 (an SHP-2 inhibitor). In addition, the co-localization of LC3 and ASC revealed that PSS promoted the autophagic degradation of the NLRP3 inflammasome. Moreover, PSS decreased apoptosis in conditioned medium-induced PC-12 cells. In APP/PS1 mice, PSS improved cognitive function, ameliorated Aβ pathology, and inhibited neuronal death. Collectively, the present study, for the first time, shows that PSS inhibit the NLRP3 inflammasome via SHP-2-mediated mitophagy in vitro and in vivo, which strongly suggests the therapeutic potential of PSS in various neurodegenerative diseases.