3,6'-disinapoyl sucrose attenuates Aβ1-42 - induced neurotoxicity in Caenorhabditis elegans by enhancing antioxidation and regulating autophagy

Spectrum-effect relationship between HPLC fingerprints and antioxidant activity of Qi-Fu-Yin based on multiple statistical correlation analysis

INTRODUCTION

Qi-Fu-Yin has been used to treat Alzheimer's disease (AD) in China. Oxidative stress has been recognized as a factor in AD progress. To date, there is no quality control method to ensure batch-to-batch consistency of Qi-Fu-Yin, and the potential antioxidant compounds in Qi-Fu-Yin remain uncertain.

OBJECTIVES

The aim of this study is to identify the potential antioxidant compounds of Qi-Fu-Yin and establish quality control standards for Qi-Fu-Yin.

METHODS

High-performance liquid chromatography was used to establish and quantify the fingerprints of Qi-Fu-Yin from various batches. Ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UHPLC-Q-TOF/MS) was used to identify the common peaks. Bivariate correlation analysis, partial least squares regression analysis, and gray correlation analysis were used to establish the spectrum-effect relationship.

RESULTS

Forty-nine common peaks were determined through the establishment of fingerprints. Among them, 35 common peaks were preliminarily characterized. The multiple statistical correlation analysis methods identified six compounds as potential antioxidant constituents of Qi-Fu-Yin, and their antioxidant activities were validated in vitro. All six antioxidant compounds derived from two herbs. Therefore, three chemical index compounds derived from other three herbs were added to the quantitative analysis, while for two herbs, no peaks could be included. Eventually, six antioxidant constituents and three index compounds were quantitatively determined to provide a relatively comprehensive quality control for Qi-Fu-Yin.

CONCLUSIONS

The study elucidated the antioxidant substance basis of Qi-Fu-Yin and provided a relatively comprehensive approach for the assay of Qi-Fu-Yin, which is a promising advance in the quality control of Qi-Fu-Yin.

Ergosterol promotes neurite outgrowth, inhibits amyloid-beta synthesis, and extends longevity: In vitro neuroblastoma and in vivo Caenorhabditis elegans evidence

AIMS

Alzheimer's disease (AD), the most common neurodegenerative disorder associated with aging, is characterized by amyloid-β (Aβ) plaques in the hippocampus. Ergosterol, a mushroom sterol, exhibits neuroprotective activities; however, the underlying mechanisms of ergosterol in promoting neurite outgrowth and preventing Aβ-associated aging have never been investigated. We aim to determine the beneficial activities of ergosterol in neuronal cells and Caenorhabditis elegans (C. elegans).

MATERIALS AND METHODS

The neuritogenesis and molecular mechanisms of ergosterol were investigated in wild-type and Aβ precursor protein (APP)-overexpressing Neuro2a cells. The anti-amyloidosis properties of ergosterol were determined by evaluating in vitro Aβ production and the potential inhibition of Aβ-producing enzymes. Additionally, AD-associated transgenic C. elegans was utilized to investigate the in vivo attenuating effects of ergosterol.

KEY FINDINGS

Ergosterol promoted neurite outgrowth in Neuro2a cells through the upregulation of the transmembrane protein Teneurin-4 (Ten-4) mRNA and protein expressions, phosphorylation of the extracellular signal-regulated kinases (ERKs), activity of cAMP response element (CRE), and growth-associated protein-43 (GAP-43). Furthermore, ergosterol enhanced neurite outgrowth in transgenic Neuro2A cells overexpressing either the wild-type APP (Neuro2a-APPwt) or the Swedish mutant APP (Neuro2a-APPswe) through the Ten-4/ERK/CREB/GAP-43 signaling pathway. Interestingly, ergosterol inhibited Aβ synthesis in Neuro2a-APPwt cells. In silico analysis indicated that ergosterol can interact with the catalytic sites of β- and γ-secretases. In Aβ-overexpressing C. elegans, ergosterol decreased Aβ accumulation, increased chemotaxis behavior, and prolonged lifespan.

SIGNIFICANCE

Ergosterol is a potential candidate compound that might benefit AD patients by promoting neurite outgrowth, inhibiting Aβ synthesis, and enhancing longevity.

Jiawei Kongsheng Zhenzhong Pill: marker compounds, absorption into the serum (rat), and Q-markers identified by UPLC-Q-TOF-MS/MS

Background: The Jiawei Kongsheng Zhenzhong pill (JKZP), a Chinese herbal prescription comprised of eight Chinese crude drugs, has been historically employed to treat neurological and psychological disorders. Nevertheless, the ambiguous material basis severely hindered its progress and application. Purpose: The current study aimed to establish a rapid analytical method for identifying the chemical components of the JKZP aqueous extract and the components absorbed into the rat serum to investigate the quality markers (Q-markers) responsible for the neuroprotective effects of JKZP. Methods: The qualitative detection of the chemical components, prototype components, and metabolites of the aqueous extracts of JKZP, as well as the serum samples of rats that were administered the drug, was performed using the ultra-performance liquid chromatography- quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS) technology. This analysis combined information from literature reports and database comparisons. Moreover, the study was conducted to anticipate the potential Q-markers for the neuroprotective effects of JKZP based on the "five principles" of Q-marker determination. Results: A total of 67 compounds and 111 serum components (comprising 33 prototypes and 78 metabolites) were detected and identified. Combining the principles of quality transmission and traceability, compound compatibility environment, component specificity, effectiveness, and measurability, the study predicted that five key compounds, namely, senkyunolide H, danshensu, echinacoside, loganin, and 3,6'-disinapoyl sucrose, may serve as potential pharmacological bases for the neuroprotective effects of JKZP. Conclusion: To summarize, the UPLC-Q-TOF-MS/MS technique can be employed to rapidly and accurately identify compounds in JKZP. Five active compounds have been predicted to be the Q-markers for the neuroprotective effects of JKZP. This discovery serves as a reference for improving quality, advancing further research and development, and utilizing Chinese herbal prescriptions.

Research on the quality markers of antioxidant activity of Kai-Xin-San based on the spectrum-effect relationship

Background: Kai-Xin-San (KXS) is one of the classic famous traditional Chinese medicine prescriptions for amnesia, which has been applied for thousands of years. Modern pharmacological research has found that KXS has significant therapeutic efficacy on nervous system diseases, which is related to its antioxidant activity. However, the antioxidant material basis and quality markers (Q-makers) of KXS have not been studied. Objective: The objective of this study is to explore the Q-makers of antioxidant activity of KXS based on spectrum-effect relationship. Methods: Specifically, the metabolites in KXS extracts were identified by UPLC-Q-Exactive Orbitrap MS/MS. The fingerprint profile of KXS extracts were established by high-performance liquid chromatography (HPLC) and seven common peaks were identified. Meanwhile, 2, 2-diphenyl-1-picrylhydrazyl (DPPH) test was used to evaluate the free radical scavenging ability of KXS. The spectrum-effect relationship between its HPLC fingerprint and DPPH free radical scavenging activity was preliminarily examined by the Pearson correlation analysis, grey relation analysis (GRA), and orthogonal partial least squares discrimination analysis (OPLS-DA). Further, the antioxidant effect of KXS and its Q-makers were validated through human neuroblastoma (SH-SY5Y) cells experiment. Results: The results showed that 103 metabolites were identified from KXS, and the similarity values between HPLC fingerprint of twelve batches of KXS were greater than 0.900. At the same time, the results of Pearson correlation analysis showed that the peaks 8, 1, 14, 17, 18, 24, 16, 21, 15, 13, 6, 5, and 3 from KXS were positively correlated with the scavenging activity values of DPPH. Combined with the results of GRA and OPLS-DA, peaks 1, 3, 5 (Sibiricose A6), 6, 13 (Ginsenoside Rg1), 15, and 24 in the fingerprints were screen out as the potential Q-makers of KXS for antioxidant effect. Besides, the results of CCK-8 assay showed that KXS and its Q-makers remarkably reduced the oxidative damage of SH-SY5Y cells caused by H2O2. However, the antioxidant activity of KXS was decreased significantly after Q-makers were knocked out. Conclusion: In conclusion, the metabolites in KXS were successfully identified by UPLC-Q-Exactive Orbitrap MS/MS, and the Q-makers of KXS for antioxidant effect was analyzed based on the spectrum-effect relationship. These results are beneficial to clarify the antioxidant material basis of KXS and provide the quality control standards for new KXS products development.

Hesperidin ameliorates Amyloid-β toxicity and enhances oxidative stress resistance and lifespan of Caenorhabditis elegans through acr-16 mediated activation of the autophagy pathway

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease in aged populations. Aberrant amyloid-beta accumulation is a common pathological feature in AD patients. Dysfunction of autophagy and impairment of α7nAChR functioning are associated with enhanced amyloid-beta (Aβ) accumulation in AD patients. Hesperidin, a flavone glycoside found primarily in citrus species, is known to have anti-inflammatory, antioxidant, and neuroprotective effects. However, the underlying molecular mechanisms of hesperidin as an antiaging and anti-Aβ phytochemical were unclear. In this study, we found that hesperidin upregulates the acr-16 expression level in C. elegans as evidenced by increased GFP-tagged ACR-16 and GFP-tagged pmyo-3:ACR-16 expression in muscle and ventral nerve cord. Further, hesperidin upregulates the autophagy genes in wild-type N2, evident by increased GFP-tagged LGG-1 foci. However, hesperidin failed to upregulate the autophagy genes level in acr-16 mutant worms that suggests autophagy activation is mediated through acr-16. In addition, hesperidin showed antiaging and anti-oxidative effects, as evidenced by positive changes in different markers necessary for health span and lifespan. Additionally, hesperidin could upregulate acr-16 and autophagy genes (lgg-1 & bec-1) and ameliorates Aβ-induced toxicity as observed with reduce ROS accumulation, paralysis rate, and enhanced lifespan even in worms AD model CL4176 and CL2006 strain. Our finding suggests that hesperidin significantly enhances oxidative stress resistance, prolongs the lifespan, and protects against Aβ-induced toxicity in C. elegans. Thus, acr-16 mediated autophagy and antioxidation is associated with anti-aging and anti-Aβ effect of hesperidin.

Exploring the therapeutic potential of natural compounds for Alzheimer's disease: Mechanisms of action and pharmacological properties

Alzheimer's Disease (AD) is a global public health priority characterized by high mortality rates in adults and an increasing prevalence in aging populations worldwide. Despite significant advancements in comprehending the pathogenesis of AD since its initial report in 1907, there remains a lack of effective curative or preventive measures for the disease. In recent years, natural compounds sourced from diverse origins have garnered considerable attention as potential therapeutic agents for AD, owing to their anti-inflammatory, antioxidant, and neuroprotective properties. This review aims to consolidate the therapeutic effects of natural compounds on AD, specifically targeting the reduction of β-amyloid (Aβ) overproduction, anti-apoptosis, autophagy, neuroinflammation, oxidative stress, endoplasmic reticulum (ER) stress, and mitochondrial dysfunction. Notably, the identified compounds exhibiting these effects predominantly originate from plants. This review provides valuable insights into the potential of natural compounds as a reservoir of novel therapeutic agents for AD, thereby stimulating further research and contributing to the development of efficacious treatments for this devastating disease.

Synthesis of mannan oligosaccharide-sialic acid conjugates and its inhibition on Aβ42 aggregation

In this work, a mannan-oligosaccharide conjugate with sialic acid capable of perturbing Aβ42 aggregation was designed and synthesized. Mannan oligosaccharides with degree polymerization of 3-13 were obtained by stepwise hydrolysis of locust bean gum using β-mannanase and α-galactosidase, named as LBOS. The activated LBOS was further chemically conjugated with sialic acid (Sia, N-acetylneuraminic acid) by fluoro-mercapto chemical coupling to synthesize a conjugate LBOS-Sia, and then phosphorylated to obtain pLBOS-Sia. The successful synthesis of pLBOS-Sia was confirmed by infrared1 chromatography, mass spectrometry, and ¹H NMR. The soluble protein analysis, microscopic observation, thioflavin T-labeling, and circular dichroism spectroscopy revealed that both LBOS-Sia and pLBOS-Sia can inhibit Aβ42 aggregation. MTT assay showed that LBOS-Sia and pLBOS-Sia had no cytotoxicity to BV-2 cells, and could substantially reduce the release of pro-inflammatory factor TNF-α induced by Aβ42 in BV-2 cells, and inhibit the occurrence of neuroinflammation. In future, this novel structure of mannan oligosaccharide-sialic acid conjugate can be potentially used to for the development of glycoconjugates against AD targeting Aβ.

3,6'-Disinapoylsucrose alleviates the amyloid precursor protein and lipopolysaccharide induced cognitive dysfunction through upregulation of the TrkB/BDNF pathway

The aim of this study is to explore the effect and mechanism of 3,6'-disinapoylsucrose (DISS) on an Alzheimer's disease (AD) mice model induced by APPswe695 lentivirus (LV) and intraperitoneal injection of lipopolysaccharide (LPS). The results show that DISS improves cognitive ability, decreases the levels of IL-2, IL-6, IL-1β, and TNF-α, reduces the expression of NF-κB p65, and alleviates Aβ deposition and nerve cell damage. DISS can regulate tyrosine kinase B (TrkB)/brain-derived neurotrophic factor (BDNF) signaling in the hippocampus. In summary, DISS can significantly alleviate neuroinflammation, spatial learning and memory disorders in AD model mice.

Epigallocatechin gallate-derived carbonized polymer dots: A multifunctional scavenger targeting Alzheimer's β-amyloid plaques

The design of high-efficiency scavengers targeting β-amyloid protein (Aβ) plaques in the progress of Alzheimer's disease (AD) has been recognized as an effective way to prevent and treat AD. Herein, epigallocatechin gallate (EGCG)-derived carbonized polymer dots (E-CPDs) were synthesized for the first time via a hydrothermal method using EGCG, an Aβ inhibitor, as one of the raw materials. The inhibitory efficiency and fluorescent property of E-CPDs were elegantly modulated by adjusting the molar ratio of EGCG to nitrogen-containing dopant, o-phenylenediamine (oPD), and 75E-CPDs fabricated with 75 mM EGCG and 50 mM oPD showed the highest inhibitory capability. The multifunctionality of 75E-CPDs on inhibition of Aβ fibrillization, Aβ fibrils disaggregation, amyloid fluorescent detection, and intracellular reactive oxygen species scavenging was demonstrated. 75E-CPDs inhibited the formation of β-sheet-rich Aβ aggregates, alleviated Aβ-induced cytotoxicity of cultured cells from 47% to 15%, and prolonged the lifespan of AD nematodes by scavenging in vivo amyloid plaques, demonstrating much higher performance than either EGCG or EGCG-free carbon dots. Notably, 75E-CPDs could rapidly disaggregate Aβ fibrils on "second" scale, faster than any other disaggregating agents. The aromatic structure as well as hydroxyl and carboxyl groups existing on 75E-CPDs surface, which would interact with Aβ species via hydrogen bonding, electrostatic interactions, and hydrophobic interactions, played critical roles in their inhibition and disaggregation capabilities. This work reveals that potent CDs can be fabricated by using an Aβ inhibitor as the precursor, providing a new perspective for the design of multifunctional scavengers targeting amyloid plaques. STATEMENT OF SIGNIFICANCE: Alzheimer's disease (AD) is one of the top ten causes of death worldwide and seriously threatens human health. Recently, carbon nanomaterials have attracted much attention because of their good biocompatibility and capability in modulating Aβ aggregation via multiple interactions. This work has for the first time fabricated epigallocatechin gallate-derived carbonized polymer dots (E-CPDs) and revealed the multifunctional potency of E-CPDs on alleviating the multifaced symptoms associated with β-amyloid protein (Aβ) fibrillization in the progression of AD. Notably, E-CPDs exhibited enhanced fluorescence emission upon binding to Aβ fibrils, possessing potential as Aβ fluorescent probes. It is believed that this work would open a new horizon in the design of multifunctional carbon nanomaterials as a potent amyloid scavenger for AD theranostics.

Exendin-4 alleviates β-Amyloid peptide toxicity via DAF-16 in a Caenorhabditis elegans model of Alzheimer's disease

Epidemiological analyses indicate that type 2 diabetes mellitus (T2DM) is a risk factor for Alzheimer's disease (AD). They share common pathophysiological mechanisms. Thus, it has been increasingly suggested that several anti-T2DM drugs may have therapeutic potential in AD. Exendin-4, as a glucagon-like peptide-1 (GLP-1) receptor agonist, is an approved drug used to treat T2DM. In this research, the neuroprotective effect of Exendin-4 was investigated for the first time using transgenic Caenorhabditis elegans. Our results demonstrated that Exendin-4 attenuated the amyloid-β (1-42) (Aβ1-42) toxicity via multiple mechanisms, such as depressing its expression on protein and mRNA and reducing Aβ (1-42) accumulation. Exendin-4 at 0.5 mg/ml had been shown to extend life by 34.39% in CL4176 and delay the onset of paralysis in CL4176 and CL2006 which were increased by 8.18 and 8.02%, respectively. With the treatment of Exendin-4, the nuclear translocation of DAF-16 in the transgenic nematode TJ356 was enhanced. Superoxide dismutase-3 (SOD-3), as a downstream target gene regulated by DAF-16, was upregulated on mRNA level and activity. The reactive oxygen species (ROS) level was decreased. In contrast, we observed that the ability of Exendin-4 to regulate SOD was decreased in CL4176 worms with the DAF-16 gene silenced. The activity of SOD and the mRNA level of sod-3 were downregulated by 30.45 and 43.13%, respectively. Taken together, Exendin-4 attenuated Aβ (1-42) toxicity in the C. elegans model of AD via decreasing the expression and the accumulation of Aβ (1-42). Exendin-4 exhibited the ability of antioxidant stress through DAF-16. With continuous research, Exendin-4 would become a potential therapeutic strategy for treating AD.