Salvianolic acid B attenuates mitochondrial stress against Aβ toxicity in primary cultured mouse neurons

Unveiling the impact of aging on BBB and Alzheimer's disease: Factors and therapeutic implications

Alzheimer's disease (AD) is a highly prevalent neurodegenerative condition that has devastating effects on individuals, often resulting in dementia. AD is primarily defined by the presence of extracellular plaques containing insoluble β-amyloid peptide (Aβ) and neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau protein (P-tau). In addition, individuals afflicted by these age-related illnesses experience a diminished state of health, which places significant financial strain on their loved ones. Several risk factors play a significant role in the development of AD. These factors include genetics, diet, smoking, certain diseases (such as cerebrovascular diseases, obesity, hypertension, and dyslipidemia), age, and alcohol consumption. Age-related factors are key contributors to the development of vascular-based neurodegenerative diseases such as AD. In general, the process of aging can lead to changes in the immune system's responses and can also initiate inflammation in the brain. The chronic inflammation and the inflammatory mediators found in the brain play a crucial role in the dysfunction of the blood-brain barrier (BBB). Furthermore, maintaining BBB integrity is of utmost importance in preventing a wide range of neurological disorders. Therefore, in this review, we discussed the role of age and its related factors in the breakdown of the blood-brain barrier and the development of AD. We also discussed the importance of different compounds, such as those with anti-aging properties, and other compounds that can help maintain the integrity of the blood-brain barrier in the prevention of AD. This review builds a strong correlation between age-related factors, degradation of the BBB, and its impact on AD.

Role of CD36 in central nervous system diseases

CD36 is a highly glycosylated integral membrane protein that belongs to the scavenger receptor class B family and regulates the pathological progress of metabolic diseases. CD36 was recently found to be widely expressed in various cell types in the nervous system, including endothelial cells, pericytes, astrocytes, and microglia. CD36 mediates a number of regulatory processes, such as endothelial dysfunction, oxidative stress, mitochondrial dysfunction, and inflammatory responses, which are involved in many central nervous system diseases, such as stroke, Alzheimer's disease, Parkinson's disease, and spinal cord injury. CD36 antagonists can suppress CD36 expression or prevent CD36 binding to its ligand, thereby achieving inhibition of CD36-mediated pathways or functions. Here, we reviewed the mechanisms of action of CD36 antagonists, such as Salvianolic acid B, tanshinone IIA, curcumin, sulfosuccinimidyl oleate, antioxidants, and small-molecule compounds. Moreover, we predicted the structures of binding sites between CD36 and antagonists. These sites can provide targets for more efficient and safer CD36 antagonists for the treatment of central nervous system diseases.

Extending dual-targeting upper-limit in liposomal delivery of lithospermic acid B for Alzheimer's mitochondrial revitalization

Mitochondrial dysfunction is a pivotal event in Alzheimer's disease (AD) pathogenesis. Lithospermic acid B (LA) has shown promise in safeguarding mitochondria, yet the underlying mechanism remains elusive. Here, we present evidence that LA rejuvenated AD-related mitochondrial pool by co-activating mitophagy and mitochondria biogenesis via PINK1/LC3B/P62 and PGC-1α/Nrf2. To advance in vivo application, hydrophilic LA was encapsulated in liposome (MT-LIP@LA) composed of D-mannosamine-cholesterol/DSPE-PEG2000-Tet1/lecithin (molar ratio, 3:0.3:10) for cascaded brain-neuron targeting. MT-LIP demonstrated 4.3-fold enhanced brain accumulation (2.57%dose/g-brain) than LIP (0.60%dose/g-brain) and precisely targeted neurons at AD lesion sites. Mechanism studies unraveled factors contributing to the preeminent brain targeting ability of MT-LIP: (1) high-density modified mannose efficiently binds to glucose transporter 1 (GLUT1) on blood-brain barrier (BBB); (2) prone to trafficking towards caveolin-Golgi pathway during transcytosis. This augmented therapeutic platform efficiently restored mitochondrial health, prevented neurodegeneration, and ameliorated memory deficits in 3 × Tg-AD transgenic mice. Our studies revealed the underlying pharmacological mechanism of LA and provided a concise but efficient platform for neuronal mitochondria quality control in vivo.

Tanshinone IIA, the key compound in Salvia miltiorrhiza, improves cognitive impairment by upregulating Aβ-degrading enzymes in APP/PS1 mice

In Alzheimer's disease (AD), amyloid-beta (Aβ) plays a crucial role in pathogenesis. Clearing Aβ from the brain is considered as a key therapeutic strategy. Previous studies indicated that Salvia miltiorrhiza (Danshen) could protect against AD. However, the main anti-AD components in Danshen and their specific mechanisms are not clear. In this study, pharmacological network analysis indicated that Tanshinone IIA (Tan IIA) was identified as the key active compound in Danshen contributing to protect against AD. Then, APP/PS1 double transgenic mice were employed to examine the neuroprotective effect of Tan IIA. APP/PS1 mice (age, 6 months) were administered (10 and 20 mg/kg) for 8 weeks. Tan IIA improved learning and anxiety behaviors in APP/PS1 mice. Furthermore, Tan IIA reduced oxidative stress, inhibited neuronal apoptosis, improved cholinergic nervous system and decreased endoplasmic reticulum stress in the brain of APP/PS1 mice. Moreover, Tan IIA treatment reduced the level of Aβ. Molecular docking result showed that Tan IIA might block AD by upregulating Aβ-degrading enzymes. Western blot results confirmed that the expressions of insulin degrading enzymes (IDE) and neprilysin (NEP) were significantly increased after Tan IIA treatment, which demonstrated that Tan IIA improved AD by increasing Aβ-degrading enzymes.

Salvianolic acid B ameliorates retinal deficits in an early-stage Alzheimer's disease mouse model through downregulating BACE1 and Aβ generation

Alzheimer's disease (AD) is a neurodegenerative disease with subtle onset, early diagnosis remains challenging. Accumulating evidence suggests that the emergence of retinal damage in AD precedes cognitive impairment, and may serve as a critical indicator for early diagnosis and disease progression. Salvianolic acid B (Sal B), a bioactive compound isolated from the traditional Chinese medicinal herb Salvia miltiorrhiza, has been shown promise in treating neurodegenerative diseases, such as AD and Parkinson's disease. In this study we investigated the therapeutic effects of Sal B on retinopathy in early-stage AD. One-month-old transgenic mice carrying five familial AD mutations (5×FAD) were treated with Sal B (20 mg·kg-1·d-1, i.g.) for 3 months. At the end of treatment, retinal function and structure were assessed, cognitive function was evaluated in Morris water maze test. We showed that 4-month-old 5×FAD mice displayed distinct structural and functional deficits in the retinas, which were significantly ameliorated by Sal B treatment. In contrast, untreated, 4-month-old 5×FAD mice did not exhibit cognitive impairment compared to wild-type mice. In SH-SY5Y-APP751 cells, we demonstrated that Sal B (10 μM) significantly decreased BACE1 expression and sorting into the Golgi apparatus, thereby reducing Aβ generation by inhibiting the β-cleavage of APP. Moreover, we found that Sal B effectively attenuated microglial activation and the associated inflammatory cytokine release induced by Aβ plaque deposition in the retinas of 5×FAD mice. Taken together, our results demonstrate that functional impairments in the retina occur before cognitive decline, suggesting that the retina is a valuable reference for early diagnosis of AD. Sal B ameliorates retinal deficits by regulating APP processing and Aβ generation in early AD, which is a potential therapeutic intervention for early AD treatment.

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.

Targeting Protein Aggregates with Natural Products: An Optional Strategy for Neurodegenerative Diseases

Protein aggregation is one of the hallmarks of aging and aging-related diseases, especially for the neurodegenerative diseases (NDs) such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), Amyotrophic lateral sclerosis (ALS), and others. In these diseases, many pathogenic proteins, such as amyloid-β, tau, α-Syn, Htt, and FUS, form aggregates that disrupt the normal physiological function of cells and lead to associated neuronal lesions. Protein aggregates in NDs are widely recognized as one of the important targets for the treatment of these diseases. Natural products, with their diverse biological activities and rich medical history, represent a great treasure trove for the development of therapeutic strategies to combat disease. A number of in vitro and in vivo studies have shown that natural products, by virtue of their complex molecular scaffolds that specifically bind to pathogenic proteins and their aggregates, can inhibit the formation of aggregates, disrupt the structure of aggregates and destabilize them, thereby alleviating conditions associated with NDs. Here, we systematically reviewed studies using natural products to improve disease-related symptoms by reducing or inhibiting the formation of five pathogenic protein aggregates associated with NDs. This information should provide valuable insights into new directions and ideas for the treatment of neurodegenerative diseases.

Alternative Pharmacological Strategies for the Treatment of Alzheimer's Disease: Focus on Neuromodulator Function

Alzheimer's disease (AD) is a neurodegenerative disorder, comprising 70% of dementia diagnoses worldwide and affecting 1 in 9 people over the age of 65. However, the majority of its treatments, which predominantly target the cholinergic system, remain insufficient at reversing pathology and act simply to slow the inevitable progression of the disease. The most recent neurotransmitter-targeting drug for AD was approved in 2003, strongly suggesting that targeting neurotransmitter systems alone is unlikely to be sufficient, and that research into alternate treatment avenues is urgently required. Neuromodulators are substances released by neurons which influence neurotransmitter release and signal transmission across synapses. Neuromodulators including neuropeptides, hormones, neurotrophins, ATP and metal ions display altered function in AD, which underlies aberrant neuronal activity and pathology. However, research into how the manipulation of neuromodulators may be useful in the treatment of AD is relatively understudied. Combining neuromodulator targeting with more novel methods of drug delivery, such as the use of multi-targeted directed ligands, combinatorial drugs and encapsulated nanoparticle delivery systems, may help to overcome limitations of conventional treatments. These include difficulty crossing the blood-brain-barrier and the exertion of effects on a single target only. This review aims to highlight the ways in which neuromodulator functions are altered in AD and investigate how future therapies targeting such substances, which act upstream to classical neurotransmitter systems, may be of potential therapeutic benefit in the sustained search for more effective treatments.

Salvianolic acid B protects against MPP+-induced neuronal injury via repressing oxidative stress and restoring mitochondrial function

Maintaining normal conditions in the mitochondria and repressing oxidative stress has emerged as a crucial therapeutic strategy to ameliorate neuron damage in Parkinson's disease. Salvianolic acid B (SalB) is a polyphenolic compound isolated from Salvia miltiorrhiza, which has been prescribed for various biological properties, including antioxidative stress, anti-inflammation and neuroprotection in pathological conditions. Previously, SalB was reported to be of benefit in slowing Parkinson's disease pathology, but whether the neuroprotective role of SalB is associated with a mitochondrial protective action is still elusive. Here we aimed to explore the effects of SalB on mitochondrial function in Parkinson's disease to uncover the underlying cellular mechanisms. The results showed that SalB significantly alleviated 1-methyl-4-phenylpyridinium (MPP+)-induced mitochondrial disruption in line with ameliorated oxidative injury, which is evidenced by inhibited mitochondrial membrane potential collapse, reduced reactive oxygen species (ROS) generation, increased expression of NAD(P)H: quinone oxidoreductase, and enhanced mitochondrial biosynthesis - the upregulation of nuclear respiratory factor 1 and mitochondrial transcription factor A expressions. Mechanistically, SalB not only increased AMP-activated protein kinase (AMPK) activation and sirtuin3 mRNA and protein levels, but also attenuated ROS-triggered neuroinflammation by downregulating the expressions of NOD-like receptor family pyrin domain containing 3, caspase-1 and Interleukin-1β (IL-1β). In conclusion, these in-vitro findings, for the first time, demonstrate that SalB offers protection against MPP+-induced neuronal injury via upregulating sirtuin3 expression and activating the AMPK signaling to restore mitochondrial function.

Shenqi Yizhi Granule attenuates Aβ1-42 induced cognitive dysfunction via inhibiting JAK2/STAT3 activated astrocyte reactivity

Shenqi Yizhi Granule (SYG), a modern preparation herbs based on the theory of traditional Chinese medicine, has been proved to be effective against Alzheimer's disease in clinical trials, APP/PS1 mice and 5XFAD transgenic mice. But the underlying mechanism remains ambiguous. Increasing evidence supports the crucial role of astrocyte reactivity in the pathogenesis of Alzheimer's disease (AD). In the present study, we attempt to explore the underlying mechanisms of SYG from astrocyte reactivity in Aβ_1-42-induced rat model of Alzheimer's disease. After SYG treatment, the impairment of learning and memory induced by Aβ_1-42 was significantly improved and the hippocampal neuron damages were alleviated. Additionally, the activity of glutamine synthetase and the concentration of glutamate, which might be involved in the cognitive dysfunctions, were outstandingly reduced. Meanwhile, the astrocyte reactivity was also remarkably inhibited. The expressions of JAK2 and STAT3, key proteins in the JAK2/STAT3 signaling pathway that is tightly associated with reactive astrocytes, were clearly attenuated, too. Collectively, our data demonstrate that SYG might exert protective effects on cognitive impairment induced by amyloid-β oligomers via inhibition of astrocyte reactivity regulated by the JAK2/STAT3 signaling pathway. It may be a potential therapeutic for cognitive dysfunctions in many neurological and psychiatric disorders such as Alzheimer's disease.

Natural products as pharmacological modulators of mitochondrial dysfunctions for the treatments of Alzheimer's disease: A comprehensive review

Alzheimer's disease (AD) is the most common progressive neurodegenerative disorder characterized by neuronal loss and cognitive impairment that harshly affect the elderly individuals. Currently, the available anti-AD pharmacological approaches are purely symptomatic to alleviate AD symptoms, and the curative effects of novel anti-AD drugs focused on Aβ target are disappointing. Hence, there is a tremendous need to adjust AD therapeutic targets and discover novel anti-AD agents. In AD, mitochondrial dysfunction gradually triggers neuronal death from different aspects and worsens the occurrence and progress of AD. Consequently, it has been proposed that the intervention of impaired mitochondria represents an attractive breakthrough point for AD treatments. Due to chemical diversity, poly-pharmacological activities, few adverse effects and multiple targeting, natural products (NPs) have been identified as a valuable treasure for drug discovery and development. Multiple lines of studies have scientifically proven that NPs display ameliorative benefits in AD treatment in relation to mitochondrial dysfunction. This review surveys the complicated implications for mitochondrial dysregulation and AD, and then summarizes the potentials of NPs and their underlying molecular mechanisms against AD via reducing or improving mitochondrial dysfunction. It is expected that this work may open the window to speed up the development of innovative anti-AD drugs originated from NPs and improve upcoming AD therapeutics.

Three salvianolic acids inhibit 2019-nCoV spike pseudovirus viropexis by binding to both its RBD and receptor ACE2

Since December 2019, the new coronavirus (also known as severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2, 2019-nCoV])-induced disease, COVID-19, has spread rapidly worldwide. Studies have reported that the traditional Chinese medicine Salvia miltiorrhiza possesses remarkable antiviral properties; however, the anti-coronaviral activity of its main components, salvianolic acid A (SAA), salvianolic acid B (SAB), and salvianolic acid C (SAC) is still debated. In this study, we used Cell Counting Kit-8 staining and flow cytometry to evaluate the toxicity of SAA, SAB, and SAC on ACE2 (angiotensin-converting enzyme 2) high-expressing HEK293T cells (ACE2^h cells). We found that SAA, SAB, and SAC had a minor effect on the viability of ACE2^h cells at concentrations below 100 μM. We further evaluated the binding capacity of SAA, SAB, and SAC to ACE2 and the spike protein of 2019-nCoV using molecular docking and surface plasmon resonance. They could bind to the receptor-binding domain (RBD) of the 2019-nCoV with a binding constant (K_D ) of (3.82 ± 0.43) e-6 M, (5.15 ± 0.64)e-7 M, and (2.19 ± 0.14)e-6 M; and bind to ACE2 with K_D (4.08 ± 0.61)e-7 M, (2.95 ± 0.78)e-7 M, and (7.32 ± 0.42)e-7 M, respectively. As a result, SAA, SAB, and SAC were determined to inhibit the entry of 2019-nCoV Spike pseudovirus with an EC₅₀ of 11.31, 6.22, and 10.14 μM on ACE2^h cells, respectively. In conclusion, our study revealed that three Salvianolic acids can inhibit the entry of 2019-nCoV spike pseudovirus into ACE2^h cells by binding to the RBD of the 2019-nCoV spike protein and ACE2 protein.

Merging the Multi-Target Effects of Phytochemicals in Neurodegeneration: From Oxidative Stress to Protein Aggregation and Inflammation

Wide experimental evidence has been provided in the last decade concerning the neuroprotective effects of phytochemicals in a variety of neurodegenerative disorders. Generally, the neuroprotective effects of bioactive compounds belonging to different phytochemical classes are attributed to antioxidant, anti-aggregation, and anti-inflammatory activity along with the restoration of mitochondrial homeostasis and targeting alterations of cell-clearing systems. Far from being independent, these multi-target effects represent interconnected events that are commonly implicated in the pathogenesis of most neurodegenerative diseases, independently of etiology, nosography, and the specific misfolded proteins being involved. Nonetheless, the increasing amount of data applying to a variety of neurodegenerative disorders joined with the multiple effects exerted by the wide variety of plant-derived neuroprotective agents may rather confound the reader. The present review is an attempt to provide a general guideline about the most relevant mechanisms through which naturally occurring agents may counteract neurodegeneration. With such an aim, we focus on some popular phytochemical classes and bioactive compounds as representative examples to design a sort of main highway aimed at deciphering the most relevant protective mechanisms which make phytochemicals potentially useful in counteracting neurodegeneration. In this frame, we emphasize the potential role of the cell-clearing machinery as a kernel in the antioxidant, anti-aggregation, anti-inflammatory, and mitochondrial protecting effects of phytochemicals.

ATP synthase and Alzheimer's disease: putting a spin on the mitochondrial hypothesis

It is estimated that over 44 million people across the globe have dementia, and half of these cases are believed to be Alzheimer’s disease (AD). As the proportion of the global population which is over the age 60 increases so will the number of individuals living with AD. This will result in ever-increasing demands on healthcare systems and the economy. AD can be either sporadic or familial, but both present with similar pathobiology and symptoms. Three prominent theories about the cause of AD are the amyloid, tau and mitochondrial hypotheses. The mitochondrial hypothesis focuses on mitochondrial dysfunction in AD, however little attention has been given to the potential dysfunction of the mitochondrial ATP synthase in AD. ATP synthase is a proton pump which harnesses the chemical potential energy of the proton gradient across the inner mitochondrial membrane (IMM), generated by the electron transport chain (ETC), in order to produce the cellular energy currency ATP. This review presents the evidence accumulated so far that demonstrates dysfunction of ATP synthase in AD, before highlighting two potential pharmacological interventions which may modulate ATP synthase.

Salvianolic Acid B improves cognitive impairment by inhibiting neuroinflammation and decreasing Aβ level in Porphyromonas gingivalis-infected mice

Amyloid-β (Aβ) accumulation is one of the main pathological hallmarks of Alzheimer’s disease (AD). Porphyromonas gingivalis (P. gingivalis), the pathogen of chronic periodontitis, could cause Aβ accumulation and was identified in the brain of AD patients. Salvianolic Acid B (SalB) has been proven to have the neuroprotective effect. Whether SalB could protect against P. gingivalis-induced cognitive impairment is still unknown. In this study, a P. gingivalis-infected mouse model was employed to study the neuroprotective role of SalB. The results showed that SalB (20 and 40 mg/kg) treatment for 4 weeks could shorten the escape latency and improve the percentage of spontaneous alternation in the P. gingivalis-infected mice. SalB inhibited the levels of reactive oxygen species and malondialdehyde, while increased the levels of antioxidative enzymes (superoxide dismutase and glutathione peroxidase). SalB decreased the levels of IL-1β and IL-6, increased the mRNA levels of bdnf and ngf in the brain of P. gingivalis-infected mice. In addition, SalB obviously decreased the level of Aβ. SalB elevated the protein expression of ADAM10, while downregulated BACE1 and PS1. SalB increased the protein expression of LRP1, while decreased RAGE. In conclusion, SalB could improve cognitive impairment by inhibiting neuroinflammation and decreasing Aβ level in P. gingivalis-infected mice.

Traditional Chinese Medicine: Role in Reducing β-Amyloid, Apoptosis, Autophagy, Neuroinflammation, Oxidative Stress, and Mitochondrial Dysfunction of Alzheimer's Disease

Alzheimer's disease (AD) is a progressive age-related neurodegenerative disease characterized by memory loss and cognitive impairment. The major characteristics of AD are amyloid β plaques, apoptosis, autophagy dysfunction, neuroinflammation, oxidative stress, and mitochondrial dysfunction. These are mostly used as the significant indicators for selecting the effects of potential drugs. It is imperative to explain AD pathogenesis and realize productive treatments. Although the currently used chemical drugs for clinical applications of AD are effective in managing the symptoms, they are inadequate to achieve anticipated preventive or therapeutic outcomes. There are new strategies for treating AD. Traditional Chinese Medicine (TCM) has accumulated thousands of years of experience in treating dementia. Nowadays, numerous modern pharmacological studies have verified the efficacy of many bioactive ingredients isolated from TCM for AD treatment. In this review, representative TCM for the treatment of AD are discussed, and among these herbal medicines, the Lamiaceae family accounts for the highest proportion. It is concluded that monomers and extracts from TCM have potential therapeutic effect for AD treatment.

Current Progress of Research on Neurodegenerative Diseases of Salvianolic Acid B

Salvia miltiorrhiza Bunge (Lamiaceae), one of the most commonly used traditional Chinese herbs, is widely used for the treatment of cardiovascular disease, cerebrovascular disease, Alzheimer's disease, and Parkinson's disease in clinical practice. Salvianolic acid B (Sal B, C₃₆H₃₀O₁₆, FW = 718.62) is the main water-soluble active ingredient of Salvia miltiorrhiza Bunge, which performs prophylactic and therapeutic activities against neurodegenerative diseases. So far, numerous studies have proved that multiple factors and mechanisms are involved in the pathological process of neurodegenerative diseases, including amyloid β (Aβ) aggregation and fibril formation, hyperphosphorylation of tau protein, neuroinflammation, oxidative-stress damage, mitochondrial dysfunction, and neuron apoptosis. This study is aimed at reviewing experimental studies and describing the possible mechanisms of Sal B on neurodegenerative diseases.

The effects of bioactive components from the rhizome of Salvia miltiorrhiza (Danshen) on the characteristics of Alzheimer's disease

Alzheimer's disease (AD) is a common human neurodegenerative disease, which is characterized by the progressive loss of memory and the cognitive impairment. Since the etiology of AD is still unknown, it is extremely difficult to develop the effective drugs for preventing or slowing the AD process. The major characteristics of AD such as amyloid β plaques, neurofibrillary tangles, mitochondrial dysfunction, and autophagy dysfunction are commonly used as the important indicators for evaluating the effects of potential candidate drugs. The rhizome of Salvia miltiorrhiza (known as 'Danshen' in Chinese), a famous traditional Chinese medicine, which is widely used for the treatment of hyperlipidemia, stroke, cardiovascular and cerebrovascular diseases. Increasing evidences suggest that the bioactive components of Danshen can improve cognitive deficits in mice, protect neuronal cells, reduce tau hyperphosylation, prevent amyloid-β fiber formation and disaggregation. Here we briefly summarize the studies regarding the effects of bioactive component from Danshen on those major characteristics of AD in preclinical studies, as well as explore the potential of these Danshen component in the treatment of AD.