Discovery of Sulforaphane as a Potent BACE1 Inhibitor Based on Kinetics and Computational Studies

Microencapsulation of broccoli sulforaphane using whey and pea protein: in vitro dynamic gastrointestinal digestion and intestinal absorption by Caco-2-HT29-MTX-E12 cells

Sulforaphane, an organosulfur phytochemical, has been demonstrated to have significant anticancer potential in both in vitro and in vivo studies, exhibiting mechanisms of action that include inducing apoptosis, inhibiting cell proliferation, and modulating key signalling pathways involved in cancer development. However, its instability presents a major obstacle to its clinical application due to its limited bioavailability. This study aimed to improve the stability and thus the bioavailability of sulforaphane from broccoli by microencapsulation with whey (BW) and pea protein (BP) by freeze-drying. BW and BP were characterised by particle size measurement, colour, infrared spectroscopy, scanning electron microscopy, thermogravimetry, and differential scanning calorimetry. Dynamic in vitro gastrointestinal digestion was performed to measure sulforaphane bioaccessibility, in BP, BW and dried broccoli. A Caco-2-HT29-MTX-E12 intestinal absorption model was used to measure sulforaphane bioavailability. The in vitro dynamic gastrointestinal digestion revealed that sulforaphane bioaccessibility of BW was significantly higher (67.7 ± 1.2%) than BP (19.0 ± 2.2%) and dried broccoli (19.6 ± 10.4%) (p < 0.01). In addition, sulforaphane bioavailability of BW was also significantly greater (54.4 ± 4.0%) in comparison to BP (9.6 ± 1.2%) and dried broccoli (15.8 ± 2.2%) (p < 0.01). Microencapsulation of broccoli sulforaphane with whey protein significantly improved its in vitro bioaccessibility and bioavailability. This suggests that whey protein isolate could be a promising wall material to protect and stabilise sulforaphane for enhanced bioactivity and applications (such as nutraceutical formulations).

The role of isothiocyanate-rich plants and supplements in neuropsychiatric disorders: a review and update

Neuroinflammation in response to environmental stressors is an important common pathway in a number of neurological and psychiatric disorders. Responses to immune-mediated stress can lead to epigenetic changes and the development of neuropsychiatric disorders. Isothiocyanates (ITC) have shown promise in combating oxidative stress and inflammation in the nervous system as well as organ systems. While sulforaphane from broccoli is the most widely studied ITC for biomedical applications, ITC and their precursor glucosinolates are found in many species of cruciferous and other vegetables including moringa. In this review, we examine both clinical and pre-clinical studies of ITC on the amelioration of neuropsychiatric disorders (neurodevelopmental, neurodegenerative, and other) from 2018 to the present, including documentation of protocols for several ongoing clinical studies. During this time, there have been 16 clinical studies (9 randomized controlled trials), most of which reported on the effect of sulforaphane on autism spectrum disorder and schizophrenia. We also review over 80 preclinical studies examining ITC treatment of brain-related dysfunctions and disorders. The evidence to date reveals ITC have great potential for treating these conditions with minimal toxicity. The authors call for well-designed clinical trials to further the translation of these potent phytochemicals into therapeutic practice.

A novel effect of sulforaphane on promoting mouse granulosa cells proliferation via the NRF2-TKT pathway

INTRODUCTION

Granulosa cells (GCs) is essential for maintaining follicular development. Follicle-stimulating Hormone (FSH) has been demonstrated to effectively promote GCs proliferation, driving the establishment of various superovulation techniques for animal husbandry. However, these techniques face challenges, such as high costs, hormonal imbalances, and an increased risk of early ovarian dysfunction. Therefore, it is important to investigate new methods to improve GCs proliferation.

OBJECTIVES

This study aimed to investigate the effect of sulforaphane (SFN) on ovarian GCs proliferation and the underlying mechanisms.

METHODS

A comparative transcriptomic analysis of ovaries from the control, SFN, and FSH groups was conducted to identify the primary factors contributing to high proliferative capacity. The role of SFN in the regulation of cell proliferation has been examined in mouse ovarian GCs. Gene interference, overexpression, CUT&TAG technology, and transcriptome analyses were performed to elucidate the underlying mechanisms of the nuclear factor E2-related factor 2 (NRF2)-transketolase (TKT) axis in mediating GCs proliferation.

RESULTS

Our research revealed a previously unknown function of SFN, an isothiocyanate of plant origin that is prevalent in cruciferous vegetables, in facilitating the proliferation of mouse ovarian GCs. The efficacy of SFN in enhancing GCs proliferation is similar to that of FSH. At the mechanistic level, SFN promotes NRF2 to transport to the nucleus, which subsequently activates the key enzyme of the non-oxidative pentose phosphate pathway TKT. This activation is instrumental in generating ribose 5-phosphate, a critical precursor for amino acid and nucleotide biosynthesis that underpins the proliferation of GCs.

CONCLUSION

Collectively, our findings delineate a novel pathway by which SFN, through the NRF2-TKT axis, enhances the nucleotide pool and thereby supports the proliferation of mouse GCs, presenting novel avenues for exploration in reproductive biology and agricultural sciences.

Inhibition of Amyloid β Accumulation by Protease-Digested Whitebait (Shirasu) in a Murine Model of Alzheimer's Disease

The number of people with dementia is increasing annually worldwide. Alzheimer's disease (AD), which accounts for the highest percentage of dementia-causing diseases, remains difficult to cure, and prevention of its onset is important. We aimed to discover new AD-preventive ingredients and investigate the inhibitory effects of ten different species of seafood digests prepared by protease treatment on β-secretase 1 (BACE1) activity. Substantial inhibition of BACE1 activity was observed in five species of seafood, and protease-digested whitebait (WPD) showed the highest inhibitory effect among the ten marine samples. We further examined the potential of WPD as an AD preventive component using a familial AD strain (5xFAD) murine model. The intraperitoneal administration of WPD for 28 days substantially decreased the insoluble amyloid β1-42 content and the expression of glial fibrillary acidic protein, a marker of astrogliosis, in the cerebral cortex of the 5xFAD mice. These results strongly suggest that WPD is a novel functional food-derived ingredient with preventive effects against AD.

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.

Cellular Stress Response (Hormesis) in Response to Bioactive Nutraceuticals with Relevance to Alzheimer Disease

Significance: Alzheimer's disease (AD) is the most common form of dementia associated with aging. As the large Baby Boomer population ages, risk of developing AD increases significantly, and this portion of the population will increase significantly over the next several decades. Recent Advances: Research suggests that a delay in the age of onset by 5 years can dramatically decrease both the incidence and cost of AD. In this review, the role of nuclear factor erythroid 2-related factor 2 (Nrf2) in AD is examined in the context of heme oxygenase-1 (HO-1) and biliverdin reductase-A (BVR-A) and the beneficial potential of selected bioactive nutraceuticals. Critical Issues: Nrf2, a transcription factor that binds to enhancer sequences in antioxidant response elements (ARE) of DNA, is significantly decreased in AD brain. Downstream targets of Nrf2 include, among other proteins, HO-1. BVR-A is activated when biliverdin is produced. Both HO-1 and BVR-A also are oxidatively or nitrosatively modified in AD brain and in its earlier stage, amnestic mild cognitive impairment (MCI), contributing to the oxidative stress, altered insulin signaling, and cellular damage observed in the pathogenesis and progression of AD. Bioactive nutraceuticals exhibit anti-inflammatory, antioxidant, and neuroprotective properties and are potential topics of future clinical research. Specifically, ferulic acid ethyl ester, sulforaphane, epigallocatechin-3-gallate, and resveratrol target Nrf2 and have shown potential to delay the progression of AD in animal models and in some studies involving MCI patients. Future Directions: Understanding the regulation of Nrf2 and its downstream targets can potentially elucidate therapeutic options for delaying the progression of AD. Antioxid. Redox Signal. 38, 643-669.

Bioactive Natural Compounds for Therapeutic and Nutraceutical Applications in Neurodegeneration

Figure 1 summarizes the neuroprotective effects played by bioactive compounds examined in this Special Issue [...].

Targeting Nrf2/Keap1 signaling pathway by bioactive natural agents: Possible therapeutic strategy to combat liver disease

BACKGROUND

Nuclear factor erythroid 2-related factor (Nrf2), a stress-activated transcription factor, has been documented to induce a defense mechanism against oxidative stress damage, and growing evidence considers this signaling pathway a key pharmacological target for the treatment of liver diseases.

PURPOSE

The present review highlights the role of phytochemical compounds in activating Nrf2 and mitigate toxicant-induced stress on liver injury.

METHODS

A comprehensive search of published articles was carried out to focus on original publications related to Nrf2 activators against liver disease using various literature databases, including the scientific Databases of Science Direct, Web of Science, Pubmed, Google, EMBASE, and Scientific Information (SID).

RESULTS

Nrf2 activators exhibited promising effects in resisting a variety of liver diseases induced by different toxicants in preclinical experiments and in vitro studies by regulating cell proliferation and apoptosis as well as an antioxidant defense mechanism. We found that the phytochemical compounds, such as curcumin, naringenin, sulforaphane, diallyl disulfide, mangiferin, oleanolic acid, umbelliferone, daphnetin, quercetin, isorhamnetin-3-O-galactoside, hesperidin, diammonium glycyrrhizinate, corilagin, shikonin, farrerol, and chenpi, had the potential to improve the Nrf2-ARE signaling thereby combat hepatotoxicity.

CONCLUSION

Nrf2 activators may offer a novel potential strategy for the prevention and treatment of liver diseases. More extensive studies are essential to identify the underlying mechanisms and establish future therapeutic potentials of these signaling modulators. Further clinical trials are warranted to determine the safety and effectiveness of Nrf2 activators for hepatopathy.

Selected Class of Enamides Bearing Nitro Functionality as Dual-Acting with Highly Selective Monoamine Oxidase-B and BACE1 Inhibitors

A small series of nitro group-bearing enamides was designed, synthesized (NEA1–NEA5), and evaluated for their inhibitory profiles of monoamine oxidases (MAOs) and β-site amyloid precursor protein cleaving enzyme 1 (β-secretase, BACE1). Compounds NEA3 and NEA1 exhibited a more potent MAO-B inhibition (IC₅₀ value = 0.0092 and 0.016 µM, respectively) than the standards (IC₅₀ value = 0.11 and 0.14 µM, respectively, for lazabemide and pargyline). Moreover, NEA3 and NEA1 showed greater selectivity index (SI) values toward MAO-B over MAO-A (SI of >1652.2 and >2500.0, respectively). The inhibition and kinetics studies suggested that NEA3 and NEA1 are reversible and competitive inhibitors with K_i values of 0.013 ± 0.005 and 0.0049 ± 0.0002 µM, respectively, for MAO-B. In addition, both NEA3 and NEA1 showed efficient BACE1 inhibitions with IC₅₀ values of 8.02 ± 0.13 and 8.21 ± 0.03 µM better than the standard quercetin value (13.40 ± 0.04 µM). The parallel artificial membrane permeability assay (PAMPA) method demonstrated that all the synthesized derivatives can cross the blood–brain barrier (BBB) successfully. Docking analyses were performed by employing an induced-fit docking approach in the GLIDE module of Schrodinger, and the results were in agreement with their in vitro inhibitory activities. The present study resulted in the discovery of potent dual inhibitors toward MAO-B and BACE1, and these lead compounds can be fruitfully explored for the generation of newer, clinically active agents for the treatment of neurodegenerative disorders.

FBXW11 deletion alleviates Alzheimer's disease by reducing neuroinflammation and amyloid-β plaque formation via repression of ASK1 signaling

Alzheimer's disease (AD) is a neurodegenerative disease with a complicated pathogenesis. F-box and WD-40 domain protein 11 (FBXW11), as a component of the SCF (Skp1-Cul1-F-box) E3 ubiquitin ligase complex, regulates multiple different signaling pathways. However, the effects of FBXW11 on AD progression and the underlying mechanisms have not been studied. In this study, we found that FBXW11 expression was markedly increased in microglial cells stimulated by amyloid-β (Aβ). Immunofluorescence staining showed that FBXW11 was co-localized with Iba-1 in microglial cells, suggesting its potential in regulating neuroinflammation. Meanwhile, significantly elevated expression of FBXW11 was detected in hippocampus of AD mouse models. Then, our in vitro studies showed that FBXW11 deletion considerably ameliorated inflammatory response in Aβ-incubated microglial cells through suppressing nuclear transcription factor κB (NF-κB) signaling. We further found that FBXW11 physically interacted with apoptosis signal-regulating kinase 1 (ASK1) and promoted its ubiquitination, which led to the aberrant activation of NF-κB and mitogen-activated protein kinase (MAPK) signaling pathways. Importantly, promoting ASK1 significantly abolished the effects of FBXW11 knockdown to repress inflammation and MAPKs/NF-κB activation in Aβ-treated microglial cells. Subsequently, our in vivo experiments demonstrated that hippocampus-specific knockout of FBXW11 dramatically alleviated Aβ plaque load, neuronal death, and microglial activation in AD mice. Furthermore, hippocampal deficiency of FBXW11 markedly mitigated neuroinflammation in AD mice through restraining ASK1/MAPKs/NF-κB signaling, along with alleviated cognitive deficits. Together, our findings demonstrated that FBXW11 may be a functionally important mediator of ASK1 activation, which could be a novel molecular target for AD treatment.

Pre-Clinical Neuroprotective Evidences and Plausible Mechanisms of Sulforaphane in Alzheimer's Disease

Sulforaphane, a potent dietary bioactive agent obtainable from cruciferous vegetables, has been extensively studied for its effects in disease prevention and therapy. Sulforaphane potently induces transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated expression of detoxification, anti-oxidation, and immune system-modulating enzymes, and possibly acts as an anti-carcinogenic agent. Several clinical trials are in progress to study the effect of diverse types of cruciferous vegetables and sulforaphane on prostate cancer, breast cancer, lung cancer, atopic asthmatics, skin aging, dermatitis, obesity, etc. Recently, the protective effects of sulforaphane on brain health were also considerably studied, where the studies have further extended to several neurological diseases, including Alzheimer’s disease (AD), Parkinson’s disease, Huntington’s disease, amyotrophic lateral sclerosis, multiple sclerosis, autism spectrum disorder, and schizophrenia. Animal and cell studies that employ sulforaphane against memory impairment and AD-related pre-clinical biomarkers on amyloid-β, tau, inflammation, oxidative stress, and neurodegeneration are summarized, and plausible neuroprotective mechanisms of sulforaphane to help prevent AD are discussed. The increase in pre-clinical evidences consistently suggests that sulforaphane has a multi-faceted neuroprotective effect on AD pathophysiology. The anti-AD-like evidence of sulforaphane seen in cells and animals indicates the need to pursue sulforaphane research for relevant biomarkers in AD pre-symptomatic populations.

PERK Pathway and Neurodegenerative Disease: To Inhibit or to Activate?

With the extension of life span in recent decades, there is an increasing burden of late-onset neurodegenerative diseases, for which effective treatments are lacking. Neurodegenerative diseases include the widespread Alzheimer’s disease (AD) and Parkinson’s disease (PD), the less frequent Huntington’s disease (HD) and Amyotrophic Lateral Sclerosis (ALS) and also rare early-onset diseases linked to mutations that cause protein aggregation or loss of function in genes that maintain protein homeostasis. The difficulties in applying gene therapy approaches to tackle these diseases is drawing increasing attention to strategies that aim to inhibit cellular toxicity and restore homeostasis by intervening in cellular pathways. These include the unfolded protein response (UPR), activated in response to endoplasmic reticulum (ER) stress, a cellular affliction that is shared by these diseases. Special focus is turned to the PKR-like ER kinase (PERK) pathway of the UPR as a target for intervention. However, the complexity of the pathway and its ability to promote cell survival or death, depending on ER stress resolution, has led to some confusion in conflicting studies. Both inhibition and activation of the PERK pathway have been reported to be beneficial in disease models, although there are also some reports where they are counterproductive. Although with the current knowledge a definitive answer cannot be given on whether it is better to activate or to inhibit the pathway, the most encouraging strategies appear to rely on boosting some steps without compromising downstream recovery.

Efficacy of Sulforaphane in Neurodegenerative Diseases

Sulforaphane (SFN) is a phytocompound belonging to the isothiocyanate family. Although it was also found in seeds and mature plants, SFN is mainly present in sprouts of many cruciferous vegetables, including cabbage, broccoli, cauliflower, and Brussels sprouts. SFN is produced by the conversion of glucoraphanin through the enzyme myrosinase, which leads to the formation of this isothiocyanate. SFN is especially characterized by antioxidant, anti-inflammatory, and anti-apoptotic properties, and for this reason, it aroused the interest of researchers. The aim of this review is to summarize the experimental studies present on Pubmed that report the efficacy of SFN in the treatment of neurodegenerative disease, including Alzheimer’s disease (AD), Parkinson’s disease (PD), and multiple sclerosis (MS). Therefore, thanks to its beneficial effects, SFN could be useful as a supplement to counteracting neurodegenerative diseases.