Walnut extract modulates activation of microglia through alteration in intracellular calcium concentration

Role of Network Pharmacology in Prediction of Mechanism of Neuroprotective Compounds

Network pharmacology is an emerging pioneering approach in the drug discovery process, which is used to predict the therapeutic mechanism of compounds using various bioinformatic tools and databases. Emerging studies have indicated the use of network pharmacological approaches in various research fields, particularly in the identification of possible mechanisms of herbal compounds/ayurvedic formulations in the management of various diseases. These techniques could also play an important role in the prediction of the possible mechanisms of neuroprotective compounds. The first part of the chapter includes an introduction on neuroprotective compounds based on literature. Further, network pharmacological approaches are briefly discussed. The use of network pharmacology in the prediction of the neuroprotective mechanism of compounds is discussed in detail with suitable examples. Finally, the chapter concludes with the current challenges and future prospectives.

Phytochemical Interactions with Calmodulin and Critical Calmodulin Binding Proteins Involved in Amyloidogenesis in Alzheimer's Disease

An increasing number of plant-based herbal treatments, dietary supplements, medical foods and nutraceuticals and their component phytochemicals are used as alternative treatments to prevent or slow the onset and progression of Alzheimer's disease. Their appeal stems from the fact that no current pharmaceutical or medical treatment can accomplish this. While a handful of pharmaceuticals are approved to treat Alzheimer's, none has been shown to prevent, significantly slow or stop the disease. As a result, many see the appeal of alternative plant-based treatments as an option. Here, we show that many phytochemicals proposed or used as Alzheimer's treatments share a common theme: they work via a calmodulin-mediated mode of action. Some phytochemicals bind to and inhibit calmodulin directly while others bind to and regulate calmodulin-binding proteins, including Aβ monomers and BACE1. Phytochemical binding to Aβ monomers can prevent the formation of Aβ oligomers. A limited number of phytochemicals are also known to stimulate calmodulin gene expression. The significance of these interactions to amyloidogenesis in Alzheimer's disease is reviewed.

Variations in Antioxidant Capacity, Oxidative Stability, and Physicochemical Quality Parameters of Walnut (Juglans regia) Oil with Roasting and Accelerated Storage Conditions

Walnut oil, like all vegetable oils, is chemically unstable because of the sensitivity of its unsaturated fatty acids to the oxidation phenomenon. This phenomenon is based on a succession of chemical reactions, under the influence of temperature or storage conditions, that always lead to a considerable change in the quality of the oil by promoting the oxidation of unsaturated fatty acids through the degradation of their C-C double bonds, leading to the formation of secondary oxidation products that reduce the nutritional values of the oil. This research examines the oxidative stability of roasted and unroasted cold-pressed walnut oils under accelerated storage conditions. The oxidative stability of both oils was evaluated using physicochemical parameters: chemical composition (fatty acids, phytosterols, and tocopherols), pigment content (chlorophyll and carotenoids), specific extinction coefficients (K₂₃₂ and K₂₇₀), and quality indicators (acid and peroxide value) as well as the evaluation of radical scavenging activity by the DPPH method. The changes in these parameters were evaluated within 60 days at 60 ± 2 °C. The results showed that the levels of total phytosterols, the parameters of the acid and peroxide value, K₂₃₂ and K₂₇₀, increased slightly for both oils as well as the total tocopherol content and the antioxidant activity affected by the roasting process. In contrast, the fatty acid profiles did not change considerably during the 60 days of our study. After two months of oil treatment at 60 °C, the studied oils still showed an excellent physicochemical profile, which allows us to conclude that these oils are stable and can withstand such conditions. This may be due to the considerable content of tocopherols (vitamin E), which acts as an antioxidant.

Recent Studies on Protective Effects of Walnuts against Neuroinflammation

Neuroinflammation plays a significant role in the aging process and the pathophysiology of neurodegenerative diseases, such as Alzheimer’s disease. Accordingly, possible therapeutic strategies aimed at anti-inflammatory effects may be beneficial to brain health. Walnut kernels contain large quantities of unsaturated fatty acids, peptides, and phenolic compounds that have anti-inflammatory effects. The long-term intake of walnuts has been found to improve cognitive function and memory in rats and humans. However, the modulatory effect of walnuts on neuroinflammation has received much less attention. This review focuses on the potential influence and main regulating mechanisms of walnuts and their active ingredients on neuroinflammation, including the regulation of microglia activation induced by amyloid β or lipopolysaccharides, inhibition of peripheral inflammation mediated by macrophages, reduction in oxidative stress by decreasing free radical levels and boosting antioxidant defenses, and control of gut microbes to maintain homeostasis. However, the majority of evidence of the beneficial effects of walnuts or their components on neuroinflammation and neurodegeneration comes from experimental work, whereas evidence from clinical studies on the beneficial effects is scarcer and less conclusive. This review aims to provide new insights into the neuroinflammation-regulating mechanisms and natural active ingredients of walnuts and the development of walnut-based functional foods for the alleviation of neurodegenerative diseases.

Dexmedetomidine Alleviates Neuropathic Pain via the TRPC6-p38 MAPK Pathway in the Dorsal Root Ganglia of Rats

Purpose

Neuropathic pain is a chronic intractable disease characterized by allodynia and hyperalgesia. Effective treatments are unavailable because of the complicated mechanisms of neuropathic pain. Transient receptor potential canonical 6 (TRPC6) is a nonselective calcium (Ca2+)-channel protein related to hyperalgesia. Dexmedetomidine (Dex) is an alpha-2 (α2) adrenoreceptor agonist that mediates intracellular Ca2+ levels to alleviate pain. However, the relationship between TRPC6 and Dex is currently unclear. We speculated that the α2 receptor agonist would be closely linked to the TRPC6 channel. We aimed to investigate whether Dex relieves neuropathic pain by the TRPC6 pathway in the dorsal root ganglia (DRG).

Methods

The chronic constriction injury (CCI) model was established in male rats, and we evaluated the mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL). The expression of TRPC6 and Iba-1 in the DRG were analyzed using quantitative real-time polymerase chain reaction, Western blot, and immunofluorescence assay. The levels of inflammatory cytokines were measured using an enzyme-linked immunosorbent assay.

Results

Compared with the CCI normal saline group, both the MWT and TWL were significantly improved after 7 days of Dex administration. Results demonstrated that TRPC6 expression was increased in the DRG following CCI but was suppressed by Dex. In addition, multiple administrations of Dex inhibited the phosphorylation level of p38 mitogen-activated protein kinase and the upregulation of neuroinflammatory factors.

Conclusion

The results of this study demonstrated that Dex exhibits anti-nociceptive and anti-inflammatory properties in a neuropathic pain model. Moreover, our findings of the CCI model suggested that Dex has an inhibitory effect on TRPC6 expression in the DRG by decreasing the phosphorylation level of p38 in the DRG.

Juglans regia L. extract promotes osteogenesis of human bone marrow mesenchymal stem cells through BMP2/Smad/Runx2 and Wnt/β-catenin pathways

Background

The present study investigates the effects of Juglans regia L. (walnut, JRL) leaves extract on osteogenesis of human bone marrow mesenchymal stem cells (hBMSCs).

Methods

hBMSCs were incubated with different concentrations of JRL extract (10, 20, 40, or 80 μM). Cell proliferation was evaluated by Cell Counting Kit-8 assay (CCK-8) assay. ALP activity and Alizarin Red staining were used to assess the osteogenesis of BMSCs. Western blot was performed to measure the levels of proteins.

Results

Our results showed all concentrations of JRL extract had no significant effect on cell proliferation. JRL extract concentration-dependently promoted osteoblastic differentiation and cell autophagy of hBMSCs, characterized by the increased expression of pro-osteogenic markers alkaline phosphatase (ALP), osteocalcin (BGLAP), osterin, and osteoprotegerin (OPG) and autophagy marker proteins (LC3II, Beclin-1, and p62). Furthermore, JRL extract stimulated the activation BMP2/Smad/Runx2 and Wnt/β-catenin signaling pathways in hBMSCs, which play key roles in osteogenesis differentiation. Meanwhile, BMP inhibitor (Noggin) and Wnt antagonist Dickkopf-1 (DKK1) both reversed the increases of BGLAP, osterin, and OPG expression induced by JRL extract.

Conclusions

Our findings indicate that JRL extract regulated osteogenic differentiation and cell autophagy of hBMSCs through the BMP2/Smad/Runx2 and Wnt/β-catenin pathways.

Beneficial effect of walnuts on vascular tone is associated with Akt signalling, voltage-dependent calcium channel LTCC and ATP-sensitive potassium channel Kv1.2

Consumption of walnuts is beneficial for cardiovascular health. To study walnut effects on proteins involved in vascular tone regulation, control and fructose-fed rats were subjected to walnut diet for 6 weeks. In contrast with increased energy intake and body mass gain, aortic protein level of L-type calcium channel alpha subunit was decreased and the level of SUR2B subunit of ATP-sensitive K + channel was increased in healthy rats subjected to walnuts, together with improved Akt phosphorylation. Upon the walnut diet in rats subjected to fructose overload, the rise in energy intake and body mass gain, was followed by an increase in blood insulin. Although SUR2B level was elevated, the level of sodium-calcium exchanger NCX1 and inducible nitric oxide synthase were reduced and increased, respectively. In summary, walnut consumption was accompanied with moderate beneficial vascular effect in healthy rats, while an effect of walnut in rats with metabolic disturbances was rather controversial.

Natural Products and Their Bioactive Compounds: Neuroprotective Potentials against Neurodegenerative Diseases

In recent years, natural products, which originate from plants, animals, and fungi, together with their bioactive compounds have been intensively explored and studied for their therapeutic potentials for various diseases such as cardiovascular, diabetes, hypertension, reproductive, cancer, and neurodegenerative diseases. Neurodegenerative diseases, including Alzheimer's disease, Huntington's disease, Parkinson's disease, and amyotrophic lateral sclerosis are characterized by the progressive dysfunction and loss of neuronal structure and function that resulted in the neuronal cell death. Since the multifactorial pathological mechanisms are associated with neurodegeneration, targeting multiple mechanisms of actions and neuroprotection approach, which involves preventing cell death and restoring the function to damaged neurons, could be promising strategies for the prevention and therapeutic of neurodegenerative diseases. Natural products have emerged as potential neuroprotective agents for the treatment of neurodegenerative diseases. This review focused on the therapeutic potential of natural products and their bioactive compounds to exert a neuroprotective effect on the pathologies of neurodegenerative diseases.

Plant-Based Dietary Patterns, Plant Foods, and Age-Related Cognitive Decline

The aging population is expanding, as is the prevalence of age-related cognitive decline (ARCD). Of the several risk factors that predict the onset and progression of ARCD, 2 important modifiable risk factors are diet and physical activity. Dietary patterns that emphasize plant foods can exert neuroprotective effects. In this comprehensive review, we examine studies in humans of plant-based dietary patterns and polyphenol-rich plant foods and their role in either preventing ARCD and/or improving cognitive function. As yet, there is no direct evidence to support the benefits of a vegetarian diet in preventing cognitive decline. However, there is emerging evidence for brain-health-promoting effects of several plant foods rich in polyphenols, anti-inflammatory dietary patterns, and plant-based dietary patterns such as the Mediterranean diet that include a variety of fruits, vegetables, legumes, nuts, and whole grains. The bioactive compounds present in these dietary patterns include antioxidant vitamins, polyphenols, other phytochemicals, and unsaturated fatty acids. In animal models these nutrients and non-nutrients have been shown to enhance neurogenesis, synaptic plasticity, and neuronal survival by reducing oxidative stress and neuroinflammation. In this review, we summarize the mounting evidence in favor of plant-centered dietary patterns, inclusive of polyphenol-rich foods for cognitive well-being. Randomized clinical trials support the role of plant foods (citrus fruits, grapes, berries, cocoa, nuts, green tea, and coffee) in improving specific domains of cognition, most notably frontal executive function. We also identify knowledge gaps and recommend future studies to identify whether plant-exclusive diets have an added cognitive advantage compared with plant-centered diets with fish and/or small amounts of animal foods.

A Comparative Review on the Extraction, Antioxidant Content and Antioxidant Potential of Different Parts of Walnut (Juglans regia L.) Fruit and Tree

As a valuable tree nut, walnut is a well-known member of the Juglandaceae family. The fruit is made up of an outer green shell cover or husk, the middle shell which must be cracked to release the kernel, a thin layer known as skin or the seed coat, and finally, the kernel or meat. The nutritional importance of walnut fruit is ascribed to its kernel. The shell and husk are burned as fuel or discarded away as waste products. In the past two decades, the evaluation of the phenolic content and antioxidant activity of different parts of walnut has received great interest. In this contribution, the recent reports on the extraction and quantification of phenolic content from each part of the walnut tree and fruit using different solvents were highlighted and comparatively reviewed. The current review paper also tries to describe the antioxidant content of phenolic extracts obtained from different parts of the walnut tree and fruit. Additionally, the antioxidant and antiradical activities of the prepared extracts have also been discussed.