Lupeol, a Plant-Derived Triterpenoid, Protects Mice Brains against Aβ-Induced Oxidative Stress and Neurodegeneration

A network pharmacology approach to reveal the key ingredients in Scrophulariae Radix (SR) and their effects against Alzheimer's disease

Background

Scrophulariae Radix (SR) is a commonly used medicinal plant. Alzheimer's disease (AD) is a neurodegenerative disease for which there is no effective treatment. This study aims to initially clarify the potential mechanism of SR in the treatment of AD based on network pharmacology and molecular docking techniques.

Methods

The principal components and corresponding protein targets of SR were conducted by HPLC analysis and searched on TCMSP. AD targets were searched on DrugBank, Chemogenomics, TTD, OMIM and GeneCards databases. The compound-target network was constructed by Cytoscape3.8.2. The intersection of compound target and disease target was obtained and the coincidence target was imported into STRING database to construct a PPI network. We further performed GO and KEGG enrichment analysis on the targets. Meanwhile, molecular docking study and cell experiments were approved for the core target and the active compound.

Results

Through multidatabase retrieval and integration, it was found that 17 components of SR could exert anti-AD effects against 40 targets. KEGG enrichment analysis indicated that Alzheimer's disease (hsa05010) was one of the most significant AD enrichment signalling pathways. Combined with the gene expression profile information in the AlzData database, 15 targets were found to be associated with tau or beta-amyloid protein (Aβ). GO analysis indicated that the primary molecular functions of SR in the treatment of AD were neurotransmitter receptor activity (GO:0007268), postsynaptic neurotransmitter receptor activity (GO:0070997), and acetylcholine receptor activity (GO:0050435). Moreover, we explored the anti-AD effects of SR extract and ursolic acid (UA) using SH-SY5Y cells. Treatment of SH-SY5Y cells with 20 μM UA significantly reduced the oxidative damage to these neuronal cells.

Conclusion

This study reveals the active ingredients and potential molecular mechanism of SR in the treatment of AD, and provides a theoretical basis for further basic research and clinical application.

Particulate organic emissions from incense-burning smoke: Chemical compositions and emission characteristics

Incense burning is a common practice in Asian cultures, releasing hazardous particulate organics. Inhaling incense smoke can result in adverse health effects, yet the molecular compositions of incense-burning organics have not been well investigated due to the lack of measurement of intermediate-volatility and semi-volatile organic compounds (I/SVOCs). To elucidate the detailed emission profile of incense-burning particles, we conducted a non-target measurement of organics emitted from incense combustion. Quartz filters were utilized to trap particles, and organics were analyzed by a comprehensive two-dimensional gas chromatography-mass spectrometer (GC × GC-MS) coupled with a thermal desorption system (TDS). To deal with the complex data obtained by GC × GC-MS, homologs are identified mainly by the combination of selected ion chromatograms (SICs) and retention indexes. SICs of 58, 60, 74, 91, and 97 were utilized to identify 2-ketones, acids, fatty acid methyl esters, fatty acid phenylmethyl esters, and alcohols, respectively. Phenolic compounds contribute the most to emission factors (EFs) among all chemical classes, taking up 24.5 % ± 6.5 % of the total EF (96.1 ± 43.1 μg g-1). These compounds are largely derived from the thermal degradation of lignin. Biomarkers like sugars (mainly levoglucosan), hopanes, and sterols are extensively detected in incense combustion fumes. Incense materials play a more important role in shaping emission profiles than incense forms. Our study provides a detailed emission profile of particulate organics emitted from incense burning across the full-volatility range, which can be used in the health risk assessments. The data processing procedure in this work could also benefit those with less experience in non-target analysis, especially GC × GC-MS data processing.

A Triterpenoid Lupeol as an Antioxidant and Anti-Neuroinflammatory Agent: Impacts on Oxidative Stress in Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative disease illustrated by neuronal dysfunctions, leading to memory weaknesses and personality changes mostly in the aged population worldwide. The exact cause of AD is unclear, but numerous studies have addressed the involvement of oxidative stress (OS), induced by reactive oxygen species (ROS), to be one of the leading causes in developing AD. OS dysregulates the cellular homeostasis, causing abnormal protein and lipid metabolism. Nutrition plays a pivotal role in modulating the antioxidant system and decreases the neuronal ROS level, thus playing an important therapeutic role in neurodegenerative diseases, especially in AD. Hence, medicinal herbs and their extracts have received global attention as a commercial source of antioxidants Lupeol. Lupeol is a pentacyclic triterpenoid and has many biological functions. It is available in fruits, vegetables, and medicinal plants. It has shown effective antioxidant and anti-inflammatory properties, and higher blood-brain barrier permeability. Also, the binding and inhibitory potentials of Lupeol have been investigated and proved to be effective against certain receptor proteins and enzymes in AD studies by computational molecular docking approaches. Therefore, AD-related research has gained interest in investigating the therapeutic effects of Lupeol. However, despite its beneficial effects in AD, there is still a lack of research in Lupeol. Hence, we compiled in this analysis all preclinical research that looked at Lupeol as an antioxidant and anti-inflammatory agent for AD.

Recent Advances in the Study of Na+/K+-ATPase in Neurodegenerative Diseases

Na⁺/K⁺-ATPase (NKA), a large transmembrane protein, is expressed in the plasma membrane of most eukaryotic cells. It maintains resting membrane potential, cell volume and secondary transcellular transport of other ions and neurotransmitters. NKA consumes about half of the ATP molecules in the brain, which makes NKA highly sensitive to energy deficiency. Neurodegenerative diseases (NDDs) are a group of diseases characterized by chronic, progressive and irreversible neuronal loss in specific brain areas. The pathogenesis of NDDs is sophisticated, involving protein misfolding and aggregation, mitochondrial dysfunction and oxidative stress. The protective effect of NKA against NDDs has been emerging gradually in the past few decades. Hence, understanding the role of NKA in NDDs is critical for elucidating the underlying pathophysiology of NDDs and identifying new therapeutic targets. The present review focuses on the recent progress involving different aspects of NKA in cellular homeostasis to present in-depth understanding of this unique protein. Moreover, the essential roles of NKA in NDDs are discussed to provide a platform and bright future for the improvement of clinical research in NDDs.

Biogenic Selenium Nanoparticles Attenuate Aβ25-35-Induced Toxicity in PC12 Cells via Akt/CREB/BDNF Signaling Pathway

Deposition of aggregated amyloid beta (Aβ) protein is considered to be a major causative factor that is associated with the development of oxidative stress and neuroinflammation in the pathogenesis of Alzheimer's disease (AD). Selenium nanoparticles (SeNPs) have been experimentally using for treatment of neurological disease due to their low toxicity, high bioavailability, and multiple bioactivities. This study was conducted to investigate the protective effects of biogenic SeNPs by Lactobacillus casei ATCC 393 against Aβ_25-35-induced toxicity in PC12 cells and its association with oxidative stress and inflammation. The results showed that SeNPs had no cytotoxicity on PC12 cells. Moreover, SeNPs entered cells through cellular endocytosis, which effectively attenuated Aβ_25-35-induced toxicity in PC12 cells. In addition, compared with Aβ_25-35 model group, SeNP pretreatment significantly enhanced the antioxidant capacity, inhibited the overproduction of reactive oxygen species (ROS), effectively regulated the inflammatory response, decreased the activity of acetylcholinesterase, significantly reduced the expression level of caspase-1 and the ratio of Bcl-2/Bax, and upregulated the expression level of p53. Furthermore, compared with Aβ_25-35 model group, SeNPs effectively promoted the phosphorylation of Akt and cAMP-response element-binding protein (CREB), and upregulated the expression level of brain-derived neurotrophic factor (BDNF). In addition, the Akt inhibitor (AKT inhibitor VIII, AKTi-1/2) could reverse the protective effects of SeNPs on PC12 cells. The Akt agonist (SC79) had a similar effect on PC12 cells as that of SeNPs. Overall, this study demonstrated that biogenic SeNPs can effectively alleviate the Aβ_25-35-induced toxicity in PC12 cells via Akt/CREB/BDNF signaling pathway.

Neuroprotective Effects of Nicotinamide against MPTP-Induced Parkinson's Disease in Mice: Impact on Oxidative Stress, Neuroinflammation, Nrf2/HO-1 and TLR4 Signaling Pathways

Nicotinamide (NAM) is the amide form of niacin and an important precursor of nicotinamide adenine dinucleotide (NAD), which is needed for energy metabolism and cellular functions. Additionally, it has shown neuroprotective properties in several neurodegenerative diseases. Herein, we sought to investigate the potential protective mechanisms of NAM in an intraperitoneal (i.p) 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease (PD) mouse model (wild-type mice (C57BL/6N), eight weeks old, average body weight 25-30 g). The study had four groups (n = 10 per group): control, MPTP (30 mg/kg i.p. for 5 days), MPTP treated with NAM (500 mg/kg, i.p for 10 days) and control treated with NAM. Our study showed that MPTP increased the expression of α-synuclein 2.5-fold, decreased tyrosine hydroxylase (TH) 0.5-fold and dopamine transporters (DAT) levels up to 0.5-fold in the striatum and substantia nigra pars compacta (SNpc), and impaired motor function. However, NAM treatment significantly reversed these PD-like pathologies. Furthermore, NAM treatment reduced oxidative stress by increasing the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) between 0.5- and 1.0-fold. Lastly, NAM treatment regulated neuroinflammation by reducing Toll-like receptor 4 (TLR-4), phosphorylated nuclear factor-κB, tumor (p-NFκB), and cyclooxygenase-2 (COX-2) levels by 0.5- to 2-fold in the PD mouse brain. Overall, these findings suggest that NAM exhibits neuroprotective properties and may be an effective therapeutic agent for PD.

Mechanistic Insights into the Neuroprotective Potential of Sacred Ficus Trees

Ficus religiosa (Bo tree or sacred fig) and Ficus benghalensis (Indian banyan) are of immense spiritual and therapeutic importance. Various parts of these trees have been investigated for their antioxidant, antimicrobial, anticonvulsant, antidiabetic, anti-inflammatory, analgesic, hepatoprotective, dermoprotective, and nephroprotective properties. Previous reviews of Ficus mostly discussed traditional usages, photochemistry, and pharmacological activities, though comprehensive reviews of the neuroprotective potential of these Ficus species extracts and/or their important phytocompounds are lacking. The interesting phytocompounds from these trees include many bengalenosides, carotenoids, flavonoids (leucopelargonidin-3-O-β-d-glucopyranoside, leucopelargonidin-3-O-α-l-rhamnopyranoside, lupeol, cetyl behenate, and α-amyrin acetate), flavonols (kaempferol, quercetin, myricetin), leucocyanidin, phytosterols (bergapten, bergaptol, lanosterol, β-sitosterol, stigmasterol), terpenes (α-thujene, α-pinene, β-pinene, α-terpinene, limonene, β-ocimene, β-bourbonene, β-caryophyllene, α-trans-bergamotene, α-copaene, aromadendrene, α-humulene, alloaromadendrene, germacrene, γ-cadinene, and δ-cadinene), and diverse polyphenols (tannin, wax, saponin, leucoanthocyanin), contributing significantly to their pharmacological effects, ranging from antimicrobial action to neuroprotection. This review presents extensive mechanistic insights into the neuroprotective potential, especially important phytochemicals from F. religiosa and F. benghalensis. Owing to the complex pathophysiology of neurodegenerative disorders (NDDs), the currently existing drugs merely alleviate the symptoms. Hence, bioactive compounds with potent neuroprotective effects through a multitarget approach would be of great interest in developing pharmacophores for the treatment of NDDs.

The Influence of Solvent and Extraction Time on Yield and Chemical Selectivity of Cuticular Waxes from Quercus suber Leaves

The cuticular lipid compounds, usually named cuticular waxes, present in the cuticular layering of Quercus suber adult leaves were extracted with solvents of different polarities (n-hexane, dichloromethane and acetone) and analysed by GC–MS. Q. suber leaves have a substantial cuticular wax layer (2.8% of leaf mass and 239 μg/cm2), composed predominantly by terpenes (43–63% of all compounds), followed by aliphatic long chain molecules, mainly fatty acids, and by smaller amounts of aliphatic alcohols and n-alkanes. The major identified compound was lupeol (1.2% of leaves in n-hexane extract). The recovery and composition of cuticular lipids depended on the solvent and extraction time. The non-polar or weak polar solvents n-hexane and dichloromethane extracted similar lipid yields (77% and 86% of the total extract, respectively) while acetone solubilised other cellular compounds, namely sugars, with the lipid compounds representing 43% of the total extract. For cuticular lipids extraction, solvents with a low polarity such as n-hexane are the more suitable with an adequate extraction duration, e.g., n-hexane with a minimum extraction of 3 h.

Secondary Metabolites with Biomedical Applications from Plants of the Sarraceniaceae Family

Carnivorous plants have fascinated researchers and hobbyists for centuries because of their mode of nutrition which is unlike that of other plants. They are able to produce bioactive compounds used to attract, capture and digest prey but also as a defense mechanism against microorganisms and free radicals. The main purpose of this review is to provide an overview of the secondary metabolites with significant biological activity found in the Sarraceniaceae family. The review also underlines the necessity of future studies for the biochemical characterization of the less investigated species. Darlingtonia, Heliamphora and Sarracenia plants are rich in compounds with potential pharmaceutical and medical uses. These belong to several classes such as flavonoids, with flavonol glycosides being the most abundant, monoterpenes, triterpenes, sesquiterpenes, fatty acids, alkaloids and others. Some of them are well characterized in terms of chemical properties and biological activity and have widespread commercial applications. The review also discusses biological activity of whole extracts and commercially available products derived from Sarraceniaceae plants. In conclusion, this review underscores that Sarraceniaceae species contain numerous substances with the potential to advance health. Future perspectives should focus on the discovery of new molecules and increasing the production of known compounds using biotechnological methods.

Lupeol Treatment Attenuates Activation of Glial Cells and Oxidative-Stress-Mediated Neuropathology in Mouse Model of Traumatic Brain Injury

Traumatic brain injury (TBI) signifies a major cause of death and disability. TBI causes central nervous system (CNS) damage under a variety of mechanisms, including protein aggregation, mitochondrial dysfunction, oxidative stress, and neuroinflammation. Astrocytes and microglia, cells of the CNS, are considered the key players in initiating an inflammatory response after injury. Several evidence suggests that activation of astrocytes/microglia and ROS/LPO have the potential to cause more harmful effects in the pathological processes following traumatic brain injury (TBI). Previous studies have established that lupeol provides neuroprotection through modulation of inflammation, oxidative stress, and apoptosis in Aβ and LPS model and neurodegenerative disease. However, the effects of lupeol on apoptosis caused by inflammation and oxidative stress in TBI have not yet been investigated. Therefore, we explored the role of Lupeol on antiapoptosis, anti-inflammatory, and antioxidative stress and its potential mechanism following TBI. In these experiments, adult male mice were randomly divided into four groups: control, TBI, TBI+ Lupeol, and Sham group. Western blotting, immunofluorescence staining, and ROS/LPO assays were performed to investigate the role of lupeol against neuroinflammation, oxidative stress, and apoptosis. Lupeol treatment reversed TBI-induced behavioral and memory disturbances. Lupeol attenuated TBI-induced generation of reactive oxygen species/lipid per oxidation (ROS/LPO) and improved the antioxidant protein level, such as nuclear factor erythroid 2-related factor 2 (Nrf2) and heme-oxygenase 1 (HO-1) in the mouse brain. Similarly, our results indicated that lupeol treatment inhibited glial cell activation, p-NF-κB, and downstream signaling molecules, such as TNF-α, COX-2, and IL-1β, in the mouse cortex and hippocampus. Moreover, lupeol treatment also inhibited mitochondrial apoptotic signaling molecules, such as caspase-3, Bax, cytochrome-C, and reversed deregulated Bcl2 in TBI-treated mice. Overall, our study demonstrated that lupeol inhibits the activation of astrocytes/microglia and ROS/LPO that lead to oxidative stress, neuroinflammation, and apoptosis followed by TBI.

Molecular pharmacology and therapeutic advances of the pentacyclic triterpene lupeol

BACKGROUND

Plant triterpenoids are major sources of nutraceuticals that provide many health benefits to humans. Lupeol is one of the pentacyclic dietary triterpenoids commonly found in many fruits and vegetables, which is highly investigated for its pharmacological effect and benefit to human health.

PURPOSE

This systematic review critically discussed the potential pharmacological benefits of lupeol and its derivatives as evidenced by various cellular and animal model studies. To gain insight into the pharmacological effects of lupeol, the network pharmacological approach is applied. Pharmacokinetics and recent developments in nanotechnology-based approaches to targeted delivery of lupeol along with its safety use are also discussed.

METHODS

This study is dependent on the systematic and non-exhaustive literature survey for related research articles, papers, and books on the chemistry, pharmacological benefits, pharmacokinetics, and safety of lupeol published between 2011 and 2021. For online materials, the popular academic search engines viz. Google Scholar, PubMed, Science Direct, Scopus, ResearchGate, Springer, as well as official websites were explored with selected keywords.

RESULTS

Lupeol has shown promising benefits in the management of cancer and many other human diseases such as diabetes, obesity, cardiovascular diseases, kidney and liver problems, skin diseases, and neurological disorders. The pharmacological effects of lupeol primarily rely on its capacity to revitalize the cellular antioxidant, anti-inflammatory and anti-apoptotic mechanisms. Network pharmacological approach revealed some prospective molecular targets and pathways and presented some significant information that could help explain the pharmacological effects of lupeol and its derivatives. Despite significant progress in molecular pharmacology, the clinical application of lupeol is limited due to poor bioavailability and insufficient knowledge on its mode of action. Structural modification and nanotechnology-guided targeted delivery of lupeol improve the bioavailability and bioactivity of lupeol.

CONCLUSION

The pentacyclic triterpene lupeol possesses numerous human health-benefiting properties. This review updates current knowledge and critically discusses the pharmacological effects and potential applications of lupeol and its derivatives in human health and diseases. Future studies are needed to evaluate the efficacies of lupeol and its derivatives in the management and pathobiology of human diseases.

Triterpenoids as Reactive Oxygen Species Modulators of Cell Fate

The triterpenoid natural products have played an important role in understanding mechanistic models of human diseases. These natural products are diverse, but many have been characterized as reactive oxygen species (ROS) modulators. ROS can regulate cell survival and function, which ultimately affects biological processes leading to disease. The triterpenoids offer an untapped source of creativity to generate tool compounds with high selectivity to regulate ROS. This brief Review highlights the diverse complexity by which these secondary metabolites induce many cell death modalities (apoptosis, autophagy, ferroptosis, etc.) that can affect various complex cell signaling pathways through ROS and ultimately lead to evading or accelerating cell death.

The Optimized Delivery of Triterpenes by Liposomal Nanoformulations: Overcoming the Challenges

The last decade has witnessed a sustained increase in the research development of modern-day chemo-therapeutics, especially for those used for high mortality rate pathologies. However, the therapeutic landscape is continuously changing as a result of the currently existing toxic side effects induced by a substantial range of drug classes. One growing research direction driven to mitigate such inconveniences has converged towards the study of natural molecules for their promising therapeutic potential. Triterpenes are one such class of compounds, intensively investigated for their therapeutic versatility. Although the pharmacological effects reported for several representatives of this class has come as a well-deserved encouragement, the pharmacokinetic profile of these molecules has turned out to be an unwelcomed disappointment. Nevertheless, the light at the end of the tunnel arrived with the development of nanotechnology, more specifically, the use of liposomes as drug delivery systems. Liposomes are easily synthesizable phospholipid-based vesicles, with highly tunable surfaces, that have the ability to transport both hydrophilic and lipophilic structures ensuring superior drug bioavailability at the action site as well as an increased selectivity. This study aims to report the results related to the development of different types of liposomes, used as targeted vectors for the delivery of various triterpenes of high pharmacological interest.

Biomarkers in Neurodegenerative Diseases

An increasing number of people are affected by various neurodegenerative diseases each year, impacting the quality of life of millions of people worldwide [...]

Herbal Mixture of Carthamus tinctorius L. Seed and Taraxacum coreanum Attenuates Amyloid Beta-Induced Cognitive Dysfunction In Vivo

Deposition of amyloid-beta (Aβ) in the aging brain has been often observed and is thought to be a pathological feature of Alzheimer’s disease. The use of natural products for disease prevention and treatment is gaining attention worldwide. Carthamus tinctorius L. seed and Taraxacum coreanum have been used as traditional medicines in Asian countries, where they have been reported to exert anti-inflammatory and anti-oxidative effects. It has been demonstrated that the combination of C. tinctorius L. seed and T. coreanum has an effect on cognitive enhancement, indicating a ratio of 5:5 synergistically enhancing learning and memory abilities in comparison with a single treatment. Here, we aimed to investigate the protective effect of C. tinctorius L. seed and T. coreanum mixture (CT) at different concentrations on cognition in Aβ_25-35-infused mice. CT-administered mice showed significant cognitive improvement in the T-maze, novel object recognition, and Morris water maze tests. Moreover, amyloidogenesis-related proteins, such as β-secretase and γ-secretase, were detected and their protein levels decreased after treatment with CT. Our study shows that CT attenuates cognitive dysfunction by improving learning and memory capability and regulating Aβ-related proteins in Aβ_25-35-injected mice. These findings suggest that CT might be a candidate for functional food on cognitive improvement.

Mechanistic insight into immunomodulatory effects of food-functioned plant secondary metabolites

Medicinally important plant-foods offer a balanced immune function, which is essential for protecting the body against antigenic invasion, mainly by microorganisms. Immunomodulators play pivotal roles in supporting immune function either suppressing or stimulating the immune system's response to invading pathogens. Among different immunomodulators, plant-based secondary metabolites have emerged as high potential not only for immune defense but also for cellular immunoresponsiveness. These natural immunomodulators can be developed into safer alternatives to the clinically used immunosuppressants and immunostimulant cytotoxic drugs which possess serious side effects. Many plants of different species have been reported to possess strong immunomodulating properties. The immunomodulatory effects of plant extracts and their bioactive metabolites have been suggested due to their diverse mechanisms of modulation of the complex immune system and their multifarious molecular targets. Phytochemicals such as alkaloids, flavonoids, terpenoids, carbohydrates and polyphenols have been reported as responsible for the immunomodulatory effects of several medicinal plants. This review illustrates the potent immunomodulatory effects of 65 plant secondary metabolites, including dietary compounds and their underlying mechanisms of action on cellular and humoral immune functions in in vitro and in vivo studies. The clinical potential of some of the compounds to be used for various immune-related disorders is highlighted.

Brain-Protective Mechanisms of Transcription Factor NRF2: Toward a Common Strategy for Neurodegenerative Diseases

Neurodegenerative diseases are characterized by the loss of homeostatic functions that control redox and energy metabolism, neuroinflammation, and proteostasis. The transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) is a master controller of these functions, and its overall activity is compromised during aging and in these diseases. However, NRF2 can be activated pharmacologically and is now being considered a common therapeutic target. Many gaps still exist in our knowledge of the specific role that NRF2 plays in specialized brain cell functions or how these cells respond to the hallmarks of these diseases. This review discusses the relevance of NRF2 to several hallmark features of neurodegenerative diseases and the current status of pharmacological activators that might pass through the blood-brain barrier and provide a disease-modifying effect. Expected final online publication date for the Annual Review of Pharmacology and Toxicology, Volume 62 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Hypoxia and brain aging: Neurodegeneration or neuroprotection?

The absolute reliance of the mammalian brain on oxygen to generate ATP renders it acutely vulnerable to hypoxia, whether at high altitude or in clinical settings of anemia or pulmonary disease. Hypoxia is pivotal to the pathogeneses of myriad neurological disorders, including Alzheimer's, Parkinson's and other age-related neurodegenerative diseases. Conversely, reduced environmental oxygen, e.g. sojourns or residing at high altitudes, may impart favorable effects on aging and mortality. Moreover, controlled hypoxia exposure may represent a treatment strategy for age-related neurological disorders. This review discusses evidence of hypoxia's beneficial vs. detrimental impacts on the aging brain and the molecular mechanisms that mediate these divergent effects. It draws upon an extensive literature search on the effects of hypoxia/altitude on brain aging, and detailed analysis of all identified studies directly comparing brain responses to hypoxia in young vs. aged humans or rodents. Special attention is directed toward the risks vs. benefits of hypoxia exposure to the elderly, and potential therapeutic applications of hypoxia for neurodegenerative diseases. Finally, important questions for future research are discussed.

Nicotinamide Ameliorates Amyloid Beta-Induced Oxidative Stress-Mediated Neuroinflammation and Neurodegeneration in Adult Mouse Brain

Alzheimer’s disease (AD) is the most predominant age-related neurodegenerative disease, pathologically characterized by the accumulation of aggregates of amyloid beta Aβ_1–42 and tau hyperphosphorylation in the brain. It is considered to be the primary cause of cognitive dysfunction. The aggregation of Aβ_1–42 leads to neuronal inflammation and apoptosis. Since vitamins are basic dietary nutrients that organisms need for their growth, survival, and other metabolic functions, in this study, the underlying neuroprotective mechanism of nicotinamide (NAM) Vitamin B3 against Aβ_1–42 -induced neurotoxicity was investigated in mouse brains. Intracerebroventricular (i.c.v.) Aβ_1–42 injection elicited neuronal dysfunctions that led to memory impairment and neurodegeneration in mouse brains. After 24 h after Aβ_1–42 injection, the mice were treated with NAM (250 mg/kg intraperitoneally) for 1 week. For biochemical and Western blot studies, the mice were directly sacrificed, while for confocal and “immunohistochemical staining”, mice were perfused transcardially with 4% paraformaldehyde. Our biochemical, immunofluorescence, and immunohistochemical results showed that NAM can ameliorate neuronal inflammation and apoptosis by reducing oxidative stress through lowering malondialdehyde and 2,7-dichlorofluorescein levels in an Aβ_1–42-injected mouse brains, where the regulation of p-JNK further regulated inflammatory marker proteins (TNF-α, IL-1β, transcription factor NF-kB) and apoptotic marker proteins (Bax, caspase 3, PARP1). Furthermore, NAM + Aβ treatment for 1 week increased the amount of survival neurons and reduced neuronal cell death in Nissl staining. We also analyzed memory dysfunction via behavioral studies and the analysis showed that NAM could prevent Aβ_1–42 -induced memory deficits. Collectively, the results of this study suggest that NAM may be a potential preventive and therapeutic candidate for Aβ_1–42 -induced reactive oxygen species (ROS)-mediated neuroinflammation, neurodegeneration, and neurotoxicity in an adult mouse model.

Quinpirole-Mediated Regulation of Dopamine D2 Receptors Inhibits Glial Cell-Induced Neuroinflammation in Cortex and Striatum after Brain Injury

Brain injury is a significant risk factor for chronic gliosis and neurodegenerative diseases. Currently, no treatment is available for neuroinflammation caused by the action of glial cells following brain injury. In this study, we investigated the quinpirole-mediated activation of dopamine D2 receptors (D2R) in a mouse model of traumatic brain injury (TBI). We also investigated the neuroprotective effects of quinpirole (a D2R agonist) against glial cell-induced neuroinflammation secondary to TBI in adult mice. After the brain injury, we injected quinpirole into the TBI mice at a dose of 1 mg/kg daily intraperitoneally for 7 days. Our results showed suppression of D2R expression and deregulation of downstream signaling molecules in ipsilateral cortex and striatum after TBI on day 7. Quinpirole administration regulated D2R expression and significantly reduced glial cell-induced neuroinflammation via the D2R/Akt/glycogen synthase kinase 3 beta (GSK3-β) signaling pathway after TBI. Quinpirole treatment concomitantly attenuated increase in glial cells, neuronal apoptosis, synaptic dysfunction, and regulated proteins associated with the blood–brain barrier, together with the recovery of lesion volume in the TBI mouse model. Additionally, our in vitro results confirmed that quinpirole reversed the microglial condition media complex-mediated deleterious effects and regulated D2R levels in HT22 cells. This study showed that quinpirole administration after TBI reduced secondary brain injury-induced glial cell activation and neuroinflammation via regulation of the D2R/Akt/GSK3-β signaling pathways. Our study suggests that quinpirole may be a safe therapeutic agent against TBI-induced neurodegeneration.

Lupeol and its derivatives as anticancer and anti-inflammatory agents: Molecular mechanisms and therapeutic efficacy

Lupeol is a natural triterpenoid that widely exists in edible fruits and vegetables, and medicinal plants. In the last decade, a plethora of studies on the pharmacological activities of lupeol have been conducted and have demonstrated that lupeol possesses an extensive range of pharmacological activities such as anticancer, antioxidant, anti-inflammatory, and antimicrobial activities. Pharmacokinetic studies have indicated that absorption of lupeol by animals was rapid despite its nonpolar characteristics, and lupeol belongs to class II BCS (biopharmaceutics classification system) compounds. Moreover, the bioactivities of some isolated or synthesized lupeol derivatives have been investigated, and these results showed that, with modification to C-3 or C-19, some derivatives exhibit stronger activities, e.g., antiprotozoal or anticancer activity. This review aims to summarize the advances in pharmacological and pharmacokinetic studies of lupeol in the last decade with an emphasis on its anticancer and anti-inflammatory activities, as well as the research progress of lupeol derivatives thus far, to provide researchers with the latest information, point out the limitations of relevant research at the current stage and the aspects that should be strengthened in future research.