Naringin Protects against Tau Hyperphosphorylation in Aβ (25-35)-Injured PC12 Cells through Modulation of ER, PI3K/AKT, and GSK-3β Signaling Pathways

Basic approach on the protective effects of hesperidin and naringin in Alzheimer's disease

OBJECTIVES

Alzheimer's disease (AD) is a neurodegenerative disease characterized by cognitive impairment. This situation imposes a great burden on individuals, both economically and socially. Today, an effective method for treating the disease and protective approach to tau accumulation has not been developed yet. Studies have been conducted on the effects of hesperidin and naringin flavonoids found in citrus fruits on many diseases.

METHODS

In this review, the pathophysiology of AD is defined, and the effects of hesperidin and naringin on these factors are summarized.

RESULTS

Studies have shown that both components may potentially affect AD due to their antioxidative and anti-inflammatory properties. Based on these effects of the components, it has been shown that they may have ameliorative effects on Aβ, α-synuclein aggregation, tau pathology, and cognitive functions in the pathophysiology of AD.

DISCUSSION

There are studies suggesting that hesperidin and naringin may be effective in the prevention/treatment of AD. When these studies are examined, it is seen that more studies should be conducted on the subject.

Berberine improves cognitive impairment by alleviating brain atrophy and promoting white matter reorganization in diabetic db/db mice: a magnetic resonance imaging-based study

Diabetic cognitive impairment is a common complication in type 2 diabetes. Berberine (BBR) is an isoquinoline alkaloid that has been shown to have neuroprotective effects against diabetes. This study aimed to investigate the effect of BBR on the gray and white matter of the brain by using magnetic resonance imaging (MRI) and to explore the underlying mechanisms. The study used diabetic db/db mice and administered BBR (50 and 100 mg/kg) intragastrically for twelve weeks. Morris water maze was applied to examine cognitive function. T2-weighted imaging (T2WI) was performed to assess brain atrophy, and diffusion tensor imaging (DTI) combined with fiber tracking was conducted to monitor the structural integrity of the white matter, followed by histological immunostaining. Furthermore, the protein expressions of the phosphatidylinositol 3-kinase (PI3K)/ protein kinase B (AKT)/ glycogen synthase kinase-3β (GSK-3β) were detected. The results revealed that BBR significantly improved the spatial learning and memory of the db/db mice. T2WI exhibited ameliorated brain atrophy in the BBR-treated db/db mice, as evidenced by reduced ventricular volume accompanied by increased hippocampal volumes. DTI combined with fiber tracking revealed that BBR increased FA, fiber density and length in the corpus callosum/external capsule of the db/db mice. These imaging findings were confirmed by histological immunostaining. Notably, BBR significantly enhanced the protein levels of phosphorylated AKT at Ser473 and GSK-3β at Ser9. Collectively, this study demonstrated that BBR significantly improved the cognitive function of the diabetic db/db mice through ameliorating brain atrophy and promoting white matter reorganization via AKT/GSK-3β pathway.

Could protein phosphatase 2A and glycogen synthase kinase-3 beta be targeted by natural compounds to ameliorate Alzheimer's pathologies?

Alzheimer's disease (AD) is a progressive neurological disorder that impairs memory and cognitive abilities, primarily in the elderly. The burden of AD extends beyond patients, impacting families and caregivers due to the patients' reliance on assistance for daily tasks. The main features of the pathogenesis of AD are beta-amyloid plaques and neurofibrillary tangles (NFTs), that strongly correlate with oxidative stress and inflammation. NFTs result from misfolded and hyperphosphorylated tau proteins. Various studies have focused on tau phosphorylation, indicating protein phosphatase 2A (PP2A) as the primary tau phosphatase and glycogen synthase kinase-3 beta (GSK-3β) as the leading tau kinase. Experimental evidence suggests that inhibition of PP2A and increased GSK-3β activity contribute to neuroinflammation, oxidative stress, and cognitive impairment. Hence, targeting PP2A and GSK-3β with pharmacological approaches shows promise in treating AD. The use of natural compounds in the drug development for AD have been extensively studied for their antioxidant, anti-inflammatory, anti-cholinesterase, and neuroprotective properties, demonstrating therapeutic advantages in neurological diseases. Alongside the development of PP2A activator and GSK-3β inhibitor drugs, natural compounds are likely to have neuroprotective effects by increasing PP2A activity and decreasing GSK-3β levels. Therefore, based on the preclinical and clinical studies, the potential of PP2A and GSK-3β as therapeutic targets of natural compounds are highlighted in this review.

Regulatory mechanism and therapeutic potentials of naringin against inflammatory disorders

Naringin is a natural flavonoid with therapeutic properties found in citrus fruits and an active natural product from herbal plants. Naringin has become a focus of attention in recent years because of its ability to actively participate in the body's immune response and maintain the integrity of the immune barrier. This review aims to elucidate the mechanism of action and therapeutic efficacy of naringin in various inflammatory diseases and to provide a valuable reference for further research in this field. The review provided the chemical structure, bioavailability, pharmacological properties, and pharmacokinetics of naringin and found that naringin has good therapeutic potential for inflammatory diseases, exerting anti-inflammatory, anti-apoptotic, anti-oxidative stress, anti-ulcerative and detoxifying effects in the disease. Moreover, we found that the great advantage of naringin treatment is that it is safe and can even alleviate the toxic side effects associated with some of the other drugs, which may become a highlight of naringin research. Naringin, an active natural product, plays a significant role in systemic diseases' anti-inflammatory and antioxidant regulation through various signaling pathways and molecular mechanisms.

Investigating the Potential Anti-Alzheimer's Disease Mechanism of Marine Polyphenols: Insights from Network Pharmacology and Molecular Docking

Marine polyphenols, including eckol(EK), dieckol(DK), and 8,8'-bieckol(BK), have attracted attention as bioactive ingredients for preventing Alzheimer's disease (AD). Since AD is a multifactorial disorder, the present study aims to provide an unbiased elucidation of unexplored targets of AD mechanisms and a systematic prediction of effective preventive combinations of marine polyphenols. Based on the omics data between each compound and AD, a protein-protein interaction (PPI) network was constructed to predict potential hub genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed to provide further biological insights. In the PPI network of the top 10 hub genes, AKT1, SRC, EGFR, and ESR1 were common targets of EK and BK, whereas PTGS2 was a common target of DK and BK. GO and KEGG pathway analysis revealed that the overlapped genes between each compound and AD were mainly enriched in EGFR tyrosine kinase inhibitor resistance, the MAPK pathway, and the Rap1 and Ras pathways. Finally, docking validation showed stable binding between marine polyphenols and their top hub gene via the lowest binding energy and multiple interactions. The results expanded potential mechanisms and novel targets for AD, and also provided a system-level insight into the molecular targets of marine polyphenols against AD.