A novel, highly-water-soluble apigenin derivative provides neuroprotection following ischemia in male rats by regulating the ERK/Nrf2/HO-1 pathway

COVID-19-Associated Sepsis: Potential Role of Phytochemicals as Functional Foods and Nutraceuticals

The acute manifestations of coronavirus disease 2019 (COVID-19) exhibit the hallmarks of sepsis-associated complications that reflect multiple organ failure. The inflammatory cytokine storm accompanied by an imbalance in the pro-inflammatory and anti-inflammatory host response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection leads to severe and critical septic shock. The sepsis signature in severely afflicted COVID-19 patients includes cellular reprogramming and organ dysfunction that leads to high mortality rates, emphasizing the importance of improved clinical care and advanced therapeutic interventions for sepsis associated with COVID-19. Phytochemicals of functional foods and nutraceutical importance have an incredible impact on the healthcare system, which includes the prevention and/or treatment of chronic diseases. Hence, in the present review, we aim to explore the pathogenesis of sepsis associated with COVID-19 that disrupts the physiological homeostasis of the body, resulting in severe organ damage. Furthermore, we have summarized the diverse pharmacological properties of some potent phytochemicals, which can be used as functional foods as well as nutraceuticals against sepsis-associated complications of SARS-CoV-2 infection. The phytochemicals explored in this article include quercetin, curcumin, luteolin, apigenin, resveratrol, and naringenin, which are the major phytoconstituents of our daily food intake. We have compiled the findings from various studies, including clinical trials in humans, to explore more into the therapeutic potential of each phytochemical against sepsis and COVID-19, which highlights their possible importance in sepsis-associated COVID-19 pathogenesis. We conclude that our review will open a new research avenue for exploring phytochemical-derived therapeutic agents for preventing or treating the life-threatening complications of sepsis associated with COVID-19.

Clarifying the mechanism of apigenin against blood-brain barrier disruption in ischemic stroke using systems pharmacology

Currently, recombinant tissue plasminogen activator (rtPA) is an effective therapy for ischemic stroke (IS). However, blood-brain barrier (BBB) disruption is a serious side effect of rtPA therapy and may lead to patients' death. The natural polyphenol apigenin has a good therapeutic effect on IS. Apigenin has potential BBB protection, but the mechanism by which it protects the BBB integrity is not clear. In this study, we used network pharmacology, bioinformatics, molecular docking and molecular dynamics simulation to reveal the mechanisms by which apigenin protects the BBB. Among the 146 targets of apigenin for the treatment of IS, 20 proteins were identified as core targets (e.g., MMP-9, TLR4, STAT3). Apigenin protects BBB integrity by inhibiting the activity of MMPs through anti-inflammation and anti-oxidative stress. These mechanisms included JAK/STAT, the toll-like receptor signaling pathway, and Nitrogen metabolism signaling pathways. The findings of this study contribute to a more comprehensive understanding of the mechanism of apigenin in the treatment of BBB disruption and provide ideas for the development of drugs to treat IS.

Use of Multivariate Analysis to Unravel the Differences between Two Chamomile Varieties and Their Anticancer and Antioxidant Activities

BACKGROUND

Plants from the Asteraceae family were commonly used to treat various diseases. The metabolomic profile of this family consisted of bioactive flavonoids and other phenolics. Chamomile is a member of the Asteraceae family. Jordanian and European chamomile are two varieties of Matricaria chamomilla (German chamomile), which were grown under different environmental conditions, were studied. Many examples of plant varieties with significant distinction in the secondary metabolite they afford have been described in the literature. Multivariate statistical analysis was employed to measure the depth of this variation in two chamomile varieties.

METHODS

From both types, crude extracts were prepared using solvents of different polarities and tested for their biological activity. The semipolar fraction of the European variety showed anticancer and antioxidant activity. Meanwhile, the semipolar fraction of the Jordanian type exhibited only antioxidant activity. Both extracts were fractionated, and then the biological activity was again assayed.

RESULTS

European and Jordanian chamomile fractions produced dicaffeoylquinic acid isomers exhibiting antioxidant capability. Additionally, Z-glucoferulic acid was produced from the European chamomile, demonstrating antioxidant activity. The European samples afforded two major compounds, chrysosplenetin and apigenin, that displayed anticancer activity.

CONCLUSIONS

Different environmental conditions between Jordanian and European chamomile affected the type of isolated compounds. Structure elucidation was performed with HPLC-MS coupled with dereplication techniques and 2D NMR experiments.

The KEAP1-NRF2 System and Neurodegenerative Diseases

Significance: Central nervous system (CNS) diseases are disorders of the brain and/or spinal cord and include neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and multiple sclerosis. Nuclear factor erythroid 2-related factor 2 (NRF2) is a transcription factor belonging to the cap-n-collar family that harbors a unique basic leucine zipper motif and plays as a master regulator of homeostatic responses. Recent Advances: Kelch-like ECH-associated protein 1 (KEAP1) is an adaptor of the Cullin3 (CUL3)-based ubiquitin E3 ligase that enhances the ubiquitylation of NRF2, which promotes the degradation of NRF2 to suppress its transcriptional activity in the absence of stress. Cysteine residues of KEAP1 are modified under stress conditions, and NRF2 degradation is attenuated, allowing it to accumulate and induce the expression of target genes. This regulatory system is referred to as the KEAP1-NRF2 system and plays a central role in protecting cells against various stresses. NRF2 also negatively regulates the expression of inflammatory cytokine and chemokine genes and suppresses pathological inflammation. As oxidative stress, inflammation, and proteostasis are known to contribute to neurodegenerative diseases, the KEAP1-NRF2 system is an attractive target for the treatment of these diseases. Critical Issues: In mouse models of neurodegenerative diseases, Nrf2 depletion exacerbates symptoms and enhances oxidative damage and inflammation in the CNS. In contrast, chemical or genetic NRF2 activation improves these symptoms. Indeed, the NRF2-activating chemical dimethyl fumarate is now widely used for the clinical treatment of MS. Future Directions: The KEAP1-NRF2 system is a promising therapeutic target for neurodegenerative diseases.

The KEAP1-NRF2 system and neurodegenerative diseases

Significance: Central nervous system (CNS) diseases are disorders of the brain and/or spinal cord and include neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). NF-E2-related factor 2 (NRF2) is a transcription factor belonging to the cap-n-collar (CNC) family that harbors a unique basic leucine zipper motif and plays as a master regulator of homeostatic responses. Recent Advances: Kelch-like ECH-associated protein 1 (KEAP1) is an adaptor of the Cullin3 (CUL3)-based ubiquitin E3 ligase that enhances the ubiquitylation of NRF2, which promotes the degradation of NRF2 to suppress its transcriptional activity in the absence of stress. Cysteine residues of KEAP1 are modified under stress conditions, and NRF2 degradation is attenuated, allowing it to accumulate and induce the expression of target genes. This regulatory system is referred to as the KEAP1-NRF2 system and plays a central role in protecting cells against various stresses. NRF2 also negatively regulates the expression of inflammatory cytokine and chemokine genes and suppresses pathological inflammation. As oxidative stress, inflammation, and proteostasis are known to contribute to neurodegenerative diseases, the KEAP1-NRF2 system is an attractive target for the treatment of these diseases. Critical Issues: In mouse models of neurodegenerative diseases, Nrf2 depletion exacerbates symptoms and enhances oxidative damage and inflammation in the CNS. In contrast, chemical or genetic NRF2 activation improves these symptoms. Indeed, the NRF2-activating chemical dimethyl fumarate (DMF) is now widely used for the clinical treatment of MS. Future Directions: The KEAP1-NRF2 system is a promising therapeutic target for neurodegenerative diseases.

Pharmacological and Molecular Insight on the Cardioprotective Role of Apigenin

Apigenin is a naturally occurring dietary flavonoid found abundantly in fruits and vegetables. It possesses a wide range of biological properties that exert antioxidant, anti-inflammatory, anticancer, and antibacterial effects. These effects have been reported to be beneficial in the treatment of atherosclerosis, stroke, hypertension, ischemia/reperfusion-induced myocardial injury, and diabetic cardiomyopathy, and provide protection against drug-induced cardiotoxicity. These potential therapeutic effects advocate the exploration of the cardioprotective actions of apigenin. This review focuses on apigenin, and the possible pharmacological mechanisms involved in the protection against cardiovascular diseases. We further discuss its therapeutic uses and highlight its potential applications in the treatment of various cardiovascular disorders. Apigenin displays encouraging results, which may have implications in the development of novel strategies for the treatment of cardiovascular diseases. With the commercial availability of apigenin as a dietary supplement, the outcomes of preclinical studies may provide the investigational basis for future translational strategies evaluating the potential of apigenin in the treatment of cardiovascular disorders. Further preclinical and clinical investigations are required to characterize the safety and efficacy of apigenin and establish it as a nutraceutical as well as a therapeutic agent to be used alone or as an adjuvant with current drugs.

Efficient Synthesis and In Vitro Hypoglycemic Activity of Rare Apigenin Glycosylation Derivatives

Apigenin is a natural flavonoid with significant biological activity, but poor solubility in water and low bioavailability limits its use in the food and pharmaceutical industries. In this paper, apigenin-7-O-β-(6″-O)-d-glucoside (AG) and apigenin-7-O-β-(6″-O-succinyl)-d-glucoside (SAG), rare apigenin glycosyl and succinyl derivatives formed by the organic solvent-tolerant bacteria Bacillus licheniformis WNJ02 were used in a 10.0% DMSO (v/v) system. The water solubility of SAG was 174 times that of apigenin, which solved the application problem. In the biotransformation reaction, the conversion rate of apigenin (1.0 g/L) was 100% at 24 h, and the yield of SAG was 94.2%. Molecular docking showed that the hypoglycemic activity of apigenin, apigenin-7-glucosides (AG), and SAG was mediated by binding with amino acids of α-glucosidase. The molecular docking results were verified by an in vitro anti-α-glucosidase assay and glucose consumption assay of active compounds. SAG had significant anti-α-glucosidase activity, with an IC₅₀ of 0.485 mM and enhanced glucose consumption in HepG2 cells, which make it an excellent α-glucosidase inhibitor.

Curcumin inhibits cerebral ischaemia-reperfusion injury and cell apoptosis in rats through the ERK-CHOP-caspase-11 pathway

CONTEXT

Curcumin has a significant effect on cerebral ischaemia-reperfusion injury (CIRI). However, the underlying mechanism is less studied.

OBJECTIVE

This study investigates the role and mechanism of curcumin in CIRI.

MATERIALS AND METHODS

CIRI model Sprague-Dawley rats were divided into model, positive control and curcumin low/middle/high dose (50, 100 and 200 mg/kg/d) groups (n = 10 each). Drug intervention was administered by gavage once a day for 4 weeks. We calculated the neurobehavioural score and observed the cerebral infarct volume. Glial cytopathological changes were observed after haematoxylin-eosin staining. Apoptosis was detected by TUNEL (TdT mediated dUTP nick end labelling). Extracellular signal-regulated protein kinase (ERK), C/EBP-homologous protein (CHOP) and caspase-11 mRNA were detected by real-time PCR. Phosphorylated ERK (p-ERK), phosphorylated CHOP (p-CHOP) and caspase-11 were detected by Western blot. Superoxide dismutase (SOD) activity was detected by xanthine oxidation method; malondialdehyde (MDA) content by thiobarbituric acid colorimetry; and, glutathione (GSH) by spectrophotometry.

RESULTS

Compared with control, the neurobehavioural scores, neuronal apoptosis, MDA, IL-1β, IL-18, mRNAs and protein levels of ERK/p-ERK, CHOP/p-CHOP and caspase-11 in model group were significantly higher (p < 0.01). Compared with model, the positive control and medium/high dose curcumin groups were significantly lower (p < 0.01). However, SOD and GSH decreased significantly in model group but increased significantly in positive control and medium/high dose curcumin groups (p < 0.01). Moreover, curcumin significantly alleviated ischaemic state and neuroinflammation (p < 0.01).

DISCUSSION AND CONCLUSIONS

Curcumin may alleviate CIRI through ERK-CHOP-caspase-11 pathway. Our results may provide new insights into the pathogenesis of CIRI, and contribute to the development of treatment strategies for CIRI.

A Review on Therapeutic Potential of Natural Phytocompounds for Stroke

Stroke is a serious condition that results from an occlusion of blood vessels that leads to brain damage. Globally, it is the second highest cause of death, and deaths from strokes are higher in older people than in the young. There is a higher rate of cases in urban areas compared to rural due to lifestyle, food, and pollution. There is no effective single medicine for the treatment of stroke due to the multiple causes of strokes. Thrombolytic agents, such as alteplase, are the main treatment for thrombolysis, while multiple types of surgeries, such ascraniotomy, thrombectomy, carotid endarterectomy, and hydrocephalus, can be performed for various forms of stroke. In this review, we discuss some promising phytocompounds, such as flavone C-glycoside (apigenin-8-C-β-D-glucopyranoside), eriodictyol, rosamirinic acid, 6″-O-succinylapigenin, and allicin, that show effectiveness against stroke. Future study paths are given, as well as suggestions for expanding the use of medicinal plants and their formulations for stroke prevention.

Probiotic as a Potential Gut Microbiome Modifier for Stroke Treatment: A Systematic Scoping Review of In Vitro and In Vivo Studies

BACKGROUND

Pharmacologic and non-pharmacologic treatments for stroke are essential but can be costly or harmful, whereas probiotics are a promising alternative. This scoping review aimed to synthesize the in vitro and in vivo evidence of probiotics on stroke-related neurological, biochemical, and histochemical outcomes.

METHODS

A systematic review was conducted in PubMed, Embase, and Cochrane Central Register of Clinical Trials (CENTRAL) up to 7 May 2021. Titles and abstracts were screened and assessed by two independent reviewers. The initial screening criteria aimed to include studies using probiotics, prebiotics, and symbiotics both in vitro and in vivo for the prevention and/or treatment of stroke.

RESULTS

Of 6293 articles, 4990 passed the initial screen after excluding duplication articles, of which 36 theme-related full texts were assessed and 13 were included in this review. No in vitro studies passed the criteria to be included in this review. Probiotics can ameliorate neurological deficits and show their anti-inflammation and anti-oxidative properties. Decreased loss of cerebral volume and inhibition of neuronal apoptosis were revealed in histopathological evidence.

CONCLUSIONS

There are potential cognitive benefits of probiotic supplementation, especially among animal models, on decreasing cerebral volume, increasing neurological score, and decreasing the inflammatory response. However, further investigation is needed to validate these conclusions in various populations.

Apigenin attenuates molecular, biochemical, and histopathological changes associated with renal impairments induced by gentamicin exposure in rats

Gentamicin (GM) is an aminoglycoside antibiotic used to treat bacterial infections. However, its application is accompanied by renal impairments. Apigenin is a flavonoid found in many edible plants with potent therapeutic values. This study was designed to elucidate the therapeutic effects of apigenin on GM-induced nephrotoxicity. Animals were injected orally with three different doses of apigenin (5 mg kg-1 day-1, 10 mg kg-1 day-1, and 20 mg kg-1 day-1). Apigenin administration abolished the alterations in the kidney index and serum levels of kidney-specific functions markers, namely blood urea nitrogen and creatinine, and KIM-1, NGAL, and cystatin C following GM exposure. Additionally, apigenin increased levels of enzymatic (glutathione reductase, glutathione peroxidase, superoxide dismutase, and catalase) and non-enzymatic antioxidant proteins (reduced glutathione) and decreased levels of lipid peroxide, nitric oxide, and downregulated nitric oxide synthase-2 in the kidney tissue following GM administration. At the molecular scope, apigenin administration was found to upregulate the mRNA expression of Nfe2l2 and Hmox1 in the kidney tissue. Moreover, apigenin administration suppressed renal inflammation and apoptosis by decreasing levels of interleukin-1β, tumor necrosis factor-alpha, nuclear factor kappa-B, Bax, and caspase-3, while increasing B-cell lymphoma-2 compared with those in GM-administered group. The recorded data suggests that apigenin treatment could be used to alleviate renal impairments associated with GM administration.

Biosynthesis and evaluation of a novel highly water-soluble quercetin glycoside derivative

Quercetin (1) was converted into quercetin 7-O-succinyl glucoside (2) by used Bacillus amyloliquefaciens FJ18 as a solvent-resistant whole-cell biocatalyst. The structure of the new compound was confirmed by LC-MS analysis and NMR spectroscopy. The water-solubility of this novel quercetin 7-O-succinyl glucoside (2) was approximately 1000 times higher than that of native quercetin (2). Quercetin (1) and quercetin 7-O-succinyl glucoside (2) exhibited significant DPPH scavenging capacity with IC₅₀ values of 23.55 and 36.05 µM, respectively. Both compounds showed moderate cytotoxic effects against the two human cancer cell lines (MCF-7 and HepG2) with IC₅₀ values ranging from 39.45-63.38 µM.

|Therapeutic and preventive effects of apigenin in cerebral ischemia: a review

APG can exert various protective effects against cerebral ischemia. Moreover, APG has shown a highly promising ability to prevent cerebral ischemia in terms of regulating blood glucose, blood pressure, lipids and gut microbes.

Bioactive Compounds in Oxidative Stress-Mediated Diseases: Targeting the NRF2/ARE Signaling Pathway and Epigenetic Regulation

Oxidative stress is a pathological condition occurring due to an imbalance between the oxidants and antioxidant defense systems in the body. Nuclear factor E2-related factor 2 (NRF2), encoded by the gene NFE2L2, is the master regulator of phase II antioxidant enzymes that protect against oxidative stress and inflammation. NRF2/ARE signaling has been considered as a promising target against oxidative stress-mediated diseases like diabetes, fibrosis, neurotoxicity, and cancer. The consumption of dietary phytochemicals acts as an effective modulator of NRF2/ARE in various acute and chronic diseases. In the present review, we discussed the role of NRF2 in diabetes, Alzheimer's disease (AD), Parkinson's disease (PD), cancer, and atherosclerosis. Additionally, we discussed the phytochemicals like curcumin, quercetin, resveratrol, epigallocatechin gallate, apigenin, sulforaphane, and ursolic acid that have effectively modified NRF2 signaling and prevented various diseases in both in vitro and in vivo models. Based on the literature, it is clear that dietary phytochemicals can prevent diseases by (1) blocking oxidative stress-inhibiting inflammatory mediators through inhibiting Keap1 or activating Nrf2 expression and its downstream targets in the nucleus, including HO-1, SOD, and CAT; (2) regulating NRF2 signaling by various kinases like GSK3beta, PI3/AKT, and MAPK; and (3) modifying epigenetic modulation, such as methylation, at the NRF2 promoter region; however, further investigation into other upstream signaling molecules like NRF2 and the effect of phytochemicals on them still need to be investigated in the near future.

Dietary nutrition for neurological disease therapy: Current status and future directions

Adequate food intake and relative abundance of dietary nutrients have undisputed effects on the brain function. There is now substantial evidence that dietary nutrition aids in the prevention and remediation of neurologic symptoms in diverse pathological conditions. The newly described influences of dietary factors on the alterations of mitochondrial dysfunction, epigenetic modification and neuroinflammation are important mechanisms that are responsible for the action of nutrients on the brain health. In this review, we discuss the state of evidence supporting that distinct dietary interventions including dietary supplement and dietary restriction have the ability to tackle neurological disorders using Alzheimer's disease, Parkinson's disease, stroke, epilepsy, traumatic brain injury, amyotrophic lateral sclerosis, Huntington's disease and multiple sclerosis as examples. Additionally, it is also highlighting that diverse potential mechanisms such as metabolic control, epigenetic modification, neuroinflammation and gut-brain axis are of utmost importance for nutrient supply to the risk of neurologic condition and therapeutic response. Finally, we also highlight the novel concept that dietary nutrient intervention reshapes metabolism-epigenetics-immunity cycle to remediate brain dysfunction. Targeting metabolism-epigenetics-immunity network will delineate a new blueprint for combating neurological weaknesses.

Activation of Nrf2 by Natural Bioactive Compounds: A Promising Approach for Stroke?

Stroke represents one of the main causes of disability and death worldwide. The pathological subtypes of stroke are ischemic stroke, the most frequent, and hemorrhagic stroke. Nrf2 is a transcription factor that regulates redox homeostasis. In stress conditions, Nrf2 translocates inside the nucleus and induces the transcription of enzymes involved in counteracting oxidative stress, endobiotic and xenobiotic metabolism, regulators of inflammation, and others. Different natural compounds, including food and plant-derived components, were shown to be able to activate Nrf2, mediating an antioxidant response. Some of these compounds were tested in stroke experimental models showing several beneficial actions. In this review, we focused on the studies that evidenced the positive effects of natural bioactive compounds in stroke experimental models through the activation of Nrf2 pathway. Interestingly, different natural compounds can activate Nrf2 through multiple pathways, inducing a strong antioxidant response associated with the beneficial effects against stroke. According to several studies, the combination of different bioactive compounds can lead to a better neuroprotection. In conclusion, natural bioactive compounds may represent new therapeutic strategies against stroke.

The antidepressant effects of apigenin are associated with the promotion of autophagy via the mTOR/AMPK/ULK1 pathway

The present study aimed to investigate whether apigenin elicits antidepressant effects in depressant‑like mice via the regulation of autophagy. The depressant‑like behaviors were established in a chronic restraint stress model. Male BALB/c mice were subjected to restraint stress for 6 h/day for a period of 21 days, and deficits in sucrose preference, tail suspension and forced swim tests were confirmed to be improved following oral apigenin. To investigate the underlining mechanisms, the hippocampal levels of p62 and microtubule‑associated protein light chain 3‑II/I (LC3‑II/I) were measured using western blot analysis. The expression levels of LC3‑II/I and p62 indicated that the significantly inhibited autophagy level induced by chronic restraint stress can be increased following apigenin treatment. Similar to the level of autophagy, the expression levels of adenosine monophosphate‑activated protein kinase (AMPK) and Unc‑51 like autophagy activating kinase‑1 were downregulated after chronic restraint stress stimulation and, subsequently upregulated following treatment with apigenin. Conversely, the levels of mammalian target of rapamycin (mTOR) were increased in chronic restraint stress mice and inhibited by apigenin. Collectively, the present findings indicated that apigenin potentially promotes autophagy via the AMPK/mTOR pathway and induces antidepressive effects in chronic restraint stress mice.

Crocin induces anti-ischemia in middle cerebral artery occlusion rats and inhibits autophagy by regulating the mammalian target of rapamycin

Crocin, an active compound found in Gardenia jasminoides Ellis, has been shown to possess neuron-protective properties, but its potential mechanisms of action still remain poorly understood. In this study, the anti-ischemic effect and underlying mechanism of action of crocin were investigated in male rats with right middle cerebral artery occlusion/reperfusion. Computed tomography and magnetic resonance imaging were used to evaluate the area of infarction 24 h after reperfusion. Neurological scores were employed to evaluate nerve injury. Direct 2,3,5-triphenyltetrazolium chloride staining was used to calculate the infarct ratio 120 h after reperfusion. Finally, HT22 cells and Western blot were used to study the underlying mechanisms. Crocin showed a decreased infarct volume and neurological score in vivo, while the expression of LC3-II/I and AMP-activated protein kinase was remarkably down-regulated with increased levels of p62 and mammalian target of rapamycin (mTOR) expression. However, rapamycin significantly inhibited mTOR, which can impact the anti-ischemic effect of crocin in vitro. These results suggest that crocin may elicit an anti-ischemic effect probably through the mTOR pathway.