Orally administrated pterostilbene attenuates acute cerebral ischemia–reperfusion injury in a dose- and time-dependent manner in mice

Pterostilbene in the treatment of inflammatory and oncological diseases

Pterostilbene (PTS), a naturally occurring analog of resveratrol (RSV), has garnered significant attention due to its potential therapeutic effects in treating inflammatory and oncological diseases. This comprehensive review elucidates the pharmacological properties, mechanisms of action, and therapeutic potential of PTS. Various studies indicate that PTS exhibits anti-inflammatory, antioxidant, and antitumour properties, potentially making it a promising candidate for clinical applications. Its influence on regulatory pathways like NF-κB and PI3K/Akt underscores its diverse strategies in addressing diseases. Additionally, PTS showcases a favorable pharmacokinetic profile with better oral bioavailability compared to other stilbenoids, thus enhancing its therapeutic potential. Given these findings, there is an increased interest in incorporating PTS into treatment regimens for inflammatory and cancer-related conditions. However, more extensive clinical trials are imperative to establish its safety and efficacy in diverse patient populations.

URB597 exerts neuroprotective effects against transient brain ischemia injury in mice by regulating autophagic flux and necroptosis

Ischemic stroke is a leading cause of death and disability, and medical treatments for ischemic stroke are very limited. URB597 is a potent and selective inhibitor of fatty acid amide hydrolase (FAAH). However, the effect of URB597 on ischemic stroke and the underlying molecular mechanisms remain little known. In this study, focal cerebral ischemia was induced by transient middle cerebral artery occlusion in mice. Our results showed that URB597 dose-dependently improved neurological function and reduced brain infarct volume and brain edema 24 h after brain ischemia. The most effective dose was 1 mg/kg and the therapeutic time window was within 3 h after ischemic stroke. To further investigate the underlying mechanism, necroptosis and autophagy flux were detected by Western blot and/or immunofluorescence staining with or without chloroquine, an autophagic flux inhibitor. Our results showed that URB597 promoted autophagic flux and reduced neuronal necroptosis after brain ischemia and these effects could be abolished by chloroquine. In addition, we found that peroxisome proliferator-activated receptor α (PPARα) antagonist GW6471 partly abolished the effect of URB597 against brain ischemia and URB597 upregulated the expressions of PPARα. In conclusion, URB597 exerts a neuroprotective effect in a dose- and time-dependent manner, and this effect may be related to its restoration of autophagic flux and inhibition of neuronal necroptosis. PPARα is involved in the neuroprotective effect of URB597. This study provides novel evidence that URB597 may be a promising agent for the clinical treatment of ischemic stroke.

Pterostilbene as a Therapeutic Alternative for Central Nervous System Disorders: A Review of the Current Status and Perspectives

Neurological disorders are diverse, have complex causes, and often result in disability; yet, effective treatments remain scarce. The resveratrol derivative pterostilbene possesses numerous physiological activities that hold promise as a novel therapy for the central nervous system (CNS) disorders. This review aimed to summarize the protective mechanisms of pterostilbene in in vitro and in vivo models of CNS disorders and the pharmacokinetics and safety to assess its possible effects on CNS disorders. Available evidence supports the protective effects of pterostilbene in CNS disorders involving mechanisms such as antioxidant and anti-inflammatory activity, regulation of lipid metabolism and vascular smooth muscle cell proliferation, improvement of synaptic function and neurogenesis, induction of glioma cell cycle arrest, and inhibition of glioma cell migration and invasion. Studies have identified possible molecular targets and pathways for the protective actions of pterostilbene in CNS disorders including the AMPK/STAT3, Akt, NF-κB, MAPK, and ERK signaling pathways. The possible pharmacological effects and molecular pathways of pterostilbene in CNS disorders are critically discussed in this review. Future studies should aim to increase our understanding of pterostilbene in animal models and humans to further evaluate its role in CNS disorders and the detailed mechanisms.

PPARα Inhibits Astrocyte Inflammation Activation by Restoring Autophagic Flux after Transient Brain Ischemia

Astrocyte inflammation activation is an important cause that hinders the recovery of motor function after cerebral ischemia. However, its molecular mechanism has not yet been clearly clarified. The peroxisome proliferator-activated receptor α (PPARα) is a ligand-activated nuclear transcriptional factor. This study aims to further clarify the role of PPARα in astrocyte inflammation activation after cerebral ischemia and to explore the underlying mechanism. Astrocyte activation was induced in an in vivo model by transient middle cerebral artery occlusion (tMCAO) in mice. The in vitro model was induced by an oxygen-glucose deprivation/reoxygenation (OGD/R) in a primary culture of mouse astrocyte. PPARα-deficient mice were used to observe the effects of PPARα on astrocyte activation and autophagic flux. Our results showed that PPARα was mainly expressed in activated astrocytes during the chronic phase of brain ischemia and PPARα dysfunction promoted astrocyte inflammatory activation. After cerebral ischemia, the expressions of LC3-II/I and p62 both increased. Autophagic vesicle accumulation was observed by electron microscopy in astrocytes, and the block of autophagic flux was indicated by an mRFP-GFP-LC3 adenovirus infection assay. A PPARα deficit aggravated the autophagic flux block, while PPARα activation preserved the lysosome function and restored autophagic flux in astrocytes after OGD/R. The autophagic flux blocker bafilomycin A1 and chloroquine antagonized the effect of the PPARα agonist on astrocyte activation inhibition. This study identifies a potentially novel function of PPARα in astrocyte autophagic flux and suggests a therapeutic target for the prevention and treatment of chronic brain ischemic injury.

Pterostilbene fluorescent probes as potential tools for targeting neurodegeneration in biological applications

Several epidemiological studies suggest that a diet rich in fruit and vegetables reduces the incidence of neurodegenerative diseases. Resveratrol (Res) and its dimethylated metabolite, pterostibene (Ptb), have been largely studied for their neuroprotective action. The clinical use of Res is limited because of its rapid metabolism and its poor bioavailability. Ptb with two methoxy groups and one hydroxyl group has a good membrane permeability, metabolic stability and higher in vivo bioavailability in comparison with Res. The metabolism and pharmacokinetics of Ptb are still sparse, probably due to the lack of tools that allow following the Ptb destiny both in living cells and in vivo. In this contest, we propose two Ptb fluorescent derivatives where Ptb has been functionalised by benzofurazan and rhodamine-B-isothiocyanate, compounds 1 and 2, respectively. Here, we report the synthesis, the optical and structural characterisation of 1 and 2, and, their putative cytotoxicity in two different cell lines.

SIRT1 Is Involved in the Neuroprotection of Pterostilbene Against Amyloid β 25-35-Induced Cognitive Deficits in Mice

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by amyloid-β (Aβ) deposits and neurofibrillary tangles. Pterostilbene (PTE), a bioactive component mainly in blueberries, is found to have neuroprotective properties. However, the specific underlying mechanisms of PTE in protecting AD remain unclear. Herein, we explored its effects on Aβ25-35-induced neuronal damage in vivo and in vitro and further compared the roles with its structural analog resveratrol (RES) in improving learning-memory deficits. We found that intragastric administration of PTE (40 mg/kg) displayed more effective neuroprotection on Aβ25-35-induced cognitive dysfunction assessed using the novel object test, Y-maze test, and Morris water maze test. Then, we found that PTE improved neuronal plasticity and alleviated neuronal loss both in vivo and in vitro. Additionally, PTE upregulated the expression of sirtuin-1 (SIRT1) and nuclear factor erythroid 2-related factor 2 (Nrf2) and the level of superoxide dismutase (SOD), and inhibited mitochondria-dependent apoptosis in the Aβ25-35-treated group. However, SIRT1 inhibitor EX527 reversed the neuroprotection and induced a drop in mitochondrial membrane potential in PTE-treated primary cortical neurons. Our data suggest that PTE's enhancing learning-memory ability and improving neuroplasticity might be related to inhibiting mitochondria-dependent apoptosis via the antioxidant effect regulated by SIRT1/Nrf2 in AD.

Neuroprotective Phytochemicals in Experimental Ischemic Stroke: Mechanisms and Potential Clinical Applications

Ischemic stroke is a challenging disease with high mortality and disability rates, causing a great economic and social burden worldwide. During ischemic stroke, ionic imbalance and excitotoxicity, oxidative stress, and inflammation are developed in a relatively certain order, which then activate the cell death pathways directly or indirectly via the promotion of organelle dysfunction. Neuroprotection, a therapy that is aimed at inhibiting this damaging cascade, is therefore an important therapeutic strategy for ischemic stroke. Notably, phytochemicals showed great neuroprotective potential in preclinical research via various strategies including modulation of calcium levels and antiexcitotoxicity, antioxidation, anti-inflammation and BBB protection, mitochondrial protection and antiapoptosis, autophagy/mitophagy regulation, and regulation of neurotrophin release. In this review, we summarize the research works that report the neuroprotective activity of phytochemicals in the past 10 years and discuss the neuroprotective mechanisms and potential clinical applications of 148 phytochemicals that belong to the categories of flavonoids, stilbenoids, other phenols, terpenoids, and alkaloids. Among them, scutellarin, pinocembrin, puerarin, hydroxysafflor yellow A, salvianolic acids, rosmarinic acid, borneol, bilobalide, ginkgolides, ginsenoside Rd, and vinpocetine show great potential in clinical ischemic stroke treatment. This review will serve as a powerful reference for the screening of phytochemicals with potential clinical applications in ischemic stroke or the synthesis of new neuroprotective agents that take phytochemicals as leading compounds.

A Review of Plant Extracts and Plant-Derived Natural Compounds in the Prevention/Treatment of Neonatal Hypoxic-Ischemic Brain Injury

Neonatal hypoxic-ischemic (HI) brain injury is one of the major drawbacks of mortality and causes significant short/long-term neurological dysfunction in newborn infants worldwide. To date, due to multifunctional complex mechanisms of brain injury, there is no well-established effective strategy to completely provide neuroprotection. Although therapeutic hypothermia is the proven treatment for hypoxic-ischemic encephalopathy (HIE), it does not completely chang outcomes in severe forms of HIE. Therefore, there is a critical need for reviewing the effective therapeutic strategies to explore the protective agents and methods. In recent years, it is widely believed that there are neuroprotective possibilities of natural compounds extracted from plants against HIE. These natural agents with the anti-inflammatory, anti-oxidative, anti-apoptotic, and neurofunctional regulatory properties exhibit preventive or therapeutic effects against experimental neonatal HI brain damage. In this study, it was aimed to review the literature in scientific databases that investigate the neuroprotective effects of plant extracts/plant-derived compounds in experimental animal models of neonatal HI brain damage and their possible underlying molecular mechanisms of action.

Recent Advances in Synthesis, Bioactivity, and Pharmacokinetics of Pterostilbene, an Important Analog of Resveratrol

Pterostilbene is a natural 3,5-dimethoxy analog of resveratrol. This stilbene compound has a strong bioactivity and exists widely in Dalbergia and Vaccinium spp. Besides natural extraction, pterostilbene can be obtained by biosynthesis. Pterostilbene has become popular because of its remarkable pharmacological activities, such as anti-tumor, anti-oxidation, anti-inflammation, and neuroprotection. Pterostilbene can be rapidly absorbed and is widely distributed in tissues, but it does not seriously accumulate in the body. Pterostilbene can easily pass through the blood-brain barrier because of its low molecular weight and good liposolubility. In this review, the studies performed in the last three years on resources, synthesis, bioactivity, and pharmacokinetics of pterostilbene are summarized. This review focuses on the effects of pterostilbene on certain diseases to explore its targets, explain the possible mechanism, and look for potential therapeutic applications.

Pterostilbene administration improves the recovery potential of extremely low-frequency magnetic field in acute renal ischemia-reperfusion injury: an FTIR spectroscopic study

Renal ischemia-reperfusion (I/R) injury, one of the drastic outcomes of renal failure and organ transplantation, tends to deteriorate over time; therefore, noninvasive therapeutic strategies will avail the progression-free survival of the patients. Magnetic field has been proposed as a noninvasive treatment strategy; however, with recent scientific advances, many controversies have arisen regarding its efficacy. Pterostilbene, a natural analog of resveratrol, was documented to be effective in treatment of I/R injuries. This study aims to assess the acute therapeutic effects of combined extremely low-frequency magnetic field (ELF-MF) and pterostilbene treatment on renal I/R injury. After induction of renal I/R in Wistar rats, treatments of 50 Hz, 1 mT ELF-MF applied alone or in combination with pterostilbene were applied for 5 consecutive days. Kidney homogenates were analyzed by Fourier transform infrared spectroscopy. I/R injury resulted in an altered protein and lipid structure with the dominance of longer acyl chains; a slight decrease in lipid, protein, unsaturated lipid, and unsaturated/saturated lipid content; and an increase in membrane fluidity and lipid peroxidation in rat kidneys. Although ELF-MF treatment alone was not sufficient to restore all ischemia-induced alterations, the combined treatment strategy of pterostilbene administration in the presence of ELF-MF was successful and warrants further investigation.

Characterization of Effectiveness in Concerted Ih Inhibition and IK(Ca) Stimulation by Pterostilbene (Trans-3,5-dimethoxy-4'-hydroxystilbene), a Stilbenoid

Pterostilbene (PTER), a natural dimethylated analog of resveratrol, has been demonstrated to produce anti-neoplastic or neuroprotective actions. However, how and whether this compound can entail any perturbations on ionic currents in electrically excitable cells remains unknown. In whole-cell current recordings, addition of PTER decreased the amplitude of macroscopic I_h during long-lasting hyperpolarization in GH₃ cells in a concentration-dependent manner, with an effective IC₅₀ value of 0.84 μM. Its presence also shifted the activation curve of I_h along the voltage axis to a more hyperpolarized potential, by 11 mV. PTER at a concentration greater than 10 μM could also suppress l-type Ca²⁺ and transient outward K⁺ currents in GH₃ cells. With the addition of PTER, I_K(Ca) amplitude was increased, with an EC₅₀ value of 2.23 μM. This increase in I_K(Ca) amplitude was attenuated by further addition of verruculogen, but not by tolbutamide or TRAM-39. Neither atropine nor nicotine, in the continued presence of PTER, modified the PTER-stimulated I_K(Ca). PTER (10 μM) slightly suppressed the amplitude of l-type Ca²⁺ current and transient outward K⁺ current. The presence of PTER (3 μM) was also effective at increasing the open-state probability of large-conductance Ca²⁺-activated K⁺ (BK_Ca) channels identified in hippocampal mHippoE-14 neurons; however, its inability to alter single-channel conductance was detected. Our study highlights evidence to show that PTER has the propensity to perturb ionic currents (e.g., I_h and I_K(Ca)), thereby influencing the functional activities of neurons, and neuroendocrine or endocrine cells.

Oleoylethanolamide inhibits glial activation via moudulating PPARα and promotes motor function recovery after brain ischemia

Glial activation and scar formation impede the neurological function recovery after cerebral ischemia. Oleoylethanolamide (OEA), a bioactive lipid mediator, shows neuroprotection against acute brain ischemia, however, its long-term effect, especially on glial scar formation, has not been characterized. In this research, we investigate the effect of OEA on glial activation and scar formation after cerebral ischemia in vitro and in vivo experiments. Glial scar formation in vitro model was induced by transforming growth factor β1 (TGF-β1) in C6 glial cell culture, and experiment model in vivo was induced by middle cerebral artery occlusion (MCAO) in mice. The protein expressions of the markers of glial activation (S100β, GFAP, or pSmads) and glial scar (neurocan) were detected by Western blot and/or immunofluorescence staining; To evaluate the role of PPARɑ in the effect of OEA on glial activation, the PPARɑ antagonist GW6471 was used. Behavior tests were used to assay the effect of OEA on motor function recovery 14 days after brain ischemia in mice. Our results show that OEA (10-50 μM) concentration-dependently inhibited the upregulation of S100β, GFAP, pSmads and neurocan induced by TGF-β1 in C6 glial cells. At the same time, OEA promoted the protein expression and nuclear transportation of PPARɑ in glial cells. PPARα antagonist GW6471 abolished the effect of OEA on glial activation. In addition, we found that delay administration of OEA inhibited the astrocyte activation and promoted the recovery of motor function after brain ischemia in mice. These results indicate that OEA may be developed into a new candidate for attenuating astrocytic scar formation and improving motor function after ischemic stroke.

Pterostilbene inhibits reactive oxygen species production and apoptosis in primary spinal cord neurons by activating autophagy via the mechanistic target of rapamycin signaling pathway

Autophagy is an important self-adaptive mechanism that is involved in inhibiting reactive oxygen species (ROS) in spinal cord neurons. Pterostilbene, a natural plant extract, has been demonstrated to possess antioxidant effects; however, it has not yet been investigated whether pterostilbene could activate autophagy and protect spinal cord neurons from oxidative stress. In the present study, primary spinal cord neurons of Sprague Dawley rats were cultured. Cell counting kit‑8 analysis was used to detect cytotoxicity of pterostilbene. Cells were treated with various doses of pterostilbene for 24 and 48 h, respectively, and H2O2 was used to induce ROS production. Western blot analysis was performed to assess the protein expression of microtubule‑associated protein 1 light chain 3 (LC3)‑II, Beclin‑1, p62, p‑p70S6K and p‑mechanistic target of rapamycin (mTOR). Furthermore, the green fluorescent protein (GFP)‑LC3 assay was used to detect the level of autophagy level and activation mechanism. 2',7'‑Dichlorofluorescin diacetate and MitoSOX Red staining were used to detect ROS production, and Terminal deoxynucleotidyl‑transferase‑mediated dUTP nick end labelling assay was used to analyze apoptosis percentage. ATG5 small interfering (si)RNA transfection was used to analyze the involvement of autophagy. A dose‑dependent increase in the expression of LC3‑II and Beclin‑1, as well as the p62 decline, were observed in the pterostilbene‑treated neurons; however, p‑p70S6K and p‑mTOR expression was inhibited by pterostilbene. Pterostilbene increased the expression of LC3‑II in H2O2‑treated cells, and GFP‑LC3 analysis demonstrated an increased number of autophagosomes. Furthermore, pterostilbene significantly inhibited the ROS production and apoptosis induced by H2O2; however, ATG5 siRNA transfection significantly reversed the protection of pterostilbene. These results indicate that pterostilbene may inhibit the ROS production and apoptosis in spinal cord neurons by activating autophagy via the mTOR signaling pathway.

SIRT1 activation by pterostilbene attenuates the skeletal muscle oxidative stress injury and mitochondrial dysfunction induced by ischemia reperfusion injury

Ischemia reperfusion (IR) injury is harmful to skeletal muscles and causes mitochondrial oxidative stress. Pterostilbene (PTE), an analogue of resveratrol, has organic protective effects against oxidative stress. However, no studies have investigated whether PTE can protect against IR-related skeletal muscular injury. In this study, we sought to evaluate the protective effect of PTE against IR-related skeletal muscle injury and to determine the mechanisms in this process. Male Sprague-Dawley rats were pretreated with PTE for a week and then underwent limb IR surgery. The IR injury induced segmental necrosis and apoptosis, myofilament disintegration, thicker interstitial spaces, and inflammatory cell infiltration. Furthermore, mitochondrial respiratory chain activity in the muscular tissue was inhibited, methane dicarboxylic aldehyde concentration and myeloperoxidase activity were up-regulated, and superoxide dismutase was down-regulated after IR. However, these effects were significantly inhibited by PTE in a dose-dependent manner. The mechanism underlying IR injury is attributed to the down-regulation of silent information regulator 1 (SIRT1)-FOXO1/p53 pathway and the increase of the Bax/Bcl2 ratio, Cleaved poly ADP-ribose polymerase 1, Cleaved Caspase 3, which can be reversed with PTE. Furthermore, EX527, an SIRT1 inhibitor, counteracted the protective effects of PTE on IR-related muscle injury. In conclusion, PTE has protective properties against IR injury of the skeletal muscles. The mechanism of this protective effect depends on the activation of the SIRT1-FOXO1/p53 signaling pathway and the decrease of the apoptotic ratio in skeletal muscle cells.

Goreisan Prevents Brain Edema after Cerebral Ischemic Stroke by Inhibiting Aquaporin 4 Upregulation in Mice

BACKGROUND

Aquaporin 4 (AQP4) is a water-selective transport protein expressed in astrocytes throughout the central nervous system. AQP4 level increases after cerebral ischemia and results in ischemic brain edema. Brain edema markedly influences mortality and motor function by elevating intracranial pressure that leads to secondary brain damage. Therefore, AQP4 is an important target to improve brain edema after cerebral ischemia. The Japanese herbal Kampo medicine, goreisan, is known to inhibit AQP4 activity. Here, we investigated whether goreisan prevents induction of brain edema by cerebral ischemia via AQP4 using 4-hour middle cerebral artery occlusion (4h MCAO) mice.

METHODS

Goreisan was orally administered at a dose of 500 mg/kg twice a day for 5 days before MCAO. AQP4 expression and motor coordination were measured by Western blotting and rotarod test, respectively.

RESULTS

Brain water content of 4h MCAO mice was significantly increased at 24 hours after MCAO. Treatment with goreisan significantly decreased both brain water content and AQP4 expression in the ischemic brain at 24 hours after MCAO. In addition, treatment with goreisan alleviated motor coordination deficits at 24 hours after MCAO.

CONCLUSIONS

The results of this study suggested that goreisan may be a useful new therapeutic option for ischemic brain edema.

Pterostilbene alleviates polymicrobial sepsis-induced liver injury: Possible role of SIRT1 signaling

Liver injury occurs frequently during sepsis. Pterostilbene (Pte), a natural dimethylated analog of resveratrol from blueberries, exerts anti-inflammatory and anti-apoptotic effects in various diseases. However, the role of Pte in sepsis-induced liver injury and its underlying mechanisms remain unknown. The current study aimed to evaluate the protective effects of Pte on sepsis-induced liver injury and its potential mechanisms. Sepsis was induced using cecal ligation and puncture (CLP) in C57BL/6 mice. Mice were administered Pte (5, 10, 15mg/kg, i.p.) at 0.5h, 2h, and 8h after CLP induction. The pathological changes of the liver were evaluated using hematoxylin and eosin (H&E) staining. The serum levels of alanine transaminase (ALT) and aspartate aminotransferase (AST) were measured. The levels of tumor necrosis factor-alpha (TNF-α), interleukin (IL-6), myeloperoxidase (MPO), p38 mitogen-activated protein kinase (p38MAPK), Bax, and B-cell lymphoma 2 (Bcl-2) were also evaluated. Pte treatment attenuated the CLP-induced liver injury, as evidenced by the attenuated histopathologic injuries and the decreased serum aminotransferase levels. Pte reduced the serum inflammatory cytokine (TNF-α and IL-6) levels and hepatic mRNA levels of TNF-α and IL-6. Pte also reduced MPO activity and p38MAPK activation in the liver. Additionally, Pte significantly inhibited Bax expression and increased Bcl-2 expression. Moreover, Pte increased the expression of sirtuin-1 (SIRT1) and reduced the expression of acetylated forkhead box O1 (Ac-FoxO1), acetylated Ac-p53, and acetylated nuclear factor-kappa beta (Ac-NF-κB). However, SIRT1 small interfering RNA (siRNA) abolished Pte's effects on the expression levels of those protein. Notably, Pte improved the survival rate in septic mice. In conclusion, Pte alleviates sepsis-induced liver injury by reducing inflammatory response and inhibiting hepatic apoptosis, and the potential mechanism is associated with SIRT1 signaling activation.

Bridging Type 2 Diabetes and Alzheimer's Disease: Assembling the Puzzle Pieces in the Quest for the Molecules With Therapeutic and Preventive Potential

Type 2 diabetes (T2D) and Alzheimer's disease (AD) are two age-related amyloid diseases that affect millions of people worldwide. Broadly supported by epidemiological data, the higher incidence of AD among type 2 diabetic patients led to the recognition of T2D as a tangible risk factor for the development of AD. Indeed, there is now growing evidence on brain structural and functional abnormalities arising from brain insulin resistance and deficiency, ultimately highlighting the need for new approaches capable of preventing the development of AD in type 2 diabetic patients. This review provides an update on overlapping pathophysiological mechanisms and pathways in T2D and AD, such as amyloidogenic events, oxidative stress, endothelial dysfunction, aberrant enzymatic activity, and even shared genetic background. These events will be presented as puzzle pieces put together, thus establishing potential therapeutic targets for drug discovery and development against T2D and diabetes-induced cognitive decline-a heavyweight contributor to the increasing incidence of dementia in developed countries. Hoping to pave the way in this direction, we will present some of the most promising and well-studied drug leads with potential against both pathologies, including their respective bioactivity reports, mechanisms of action, and structure-activity relationships.

New natural amino acid-bearing prodrugs boost pterostilbene's oral pharmacokinetic and distribution profile

The biomedical effects of the natural phenol pterostilbene are of great interest but its bioavailability is negatively affected by the phenolic group in position 4' which is an ideal target for the conjugative enzymes of phase II metabolism. We report the synthesis and characterization of prodrugs in which the hydroxyl moiety is reversibly protected as a carbamate ester linked to the N-terminus of a natural amino acid. Prodrugs comprising amino acids with hydrophobic side chains were readily absorbed after intragastric administration to rats. The Area Under the Curve for pterostilbene in blood was optimal when prodrugs with isoleucine or β-alanine were used. The prodrug incorporating isoleucine was used for further studies to map distribution into major organs. When compared to pterostilbene itself, administration of the isoleucine prodrug afforded increased absorption, reduced metabolism and higher concentrations of pterostilbene, sustained for several hours, in most of the organs examined. Experiments using Caco-2 cells as an in vitro model for human intestinal absorption suggest that the prodrug could have promising absorption profiles also in humans; its uptake is partly due to passive diffusion, and partly mediated by H⁺-dependent transporters expressed on the apical membrane of enterocytes, such as PepT1 and OATP.

Pterostilbene attenuates high glucose-induced oxidative injury in hippocampal neuronal cells by activating nuclear factor erythroid 2-related factor 2

In the present study, neuroblastoma (SH-SY5Y) cells were used to investigate the mechanisms mediating the potential protective effects of pterostilbene (PTE) against mitochondrial metabolic impairment and oxidative stress induced by hyperglycemia for mimicking the diabetic encephalopathy. High glucose medium (100mM) decreased cellular viability after 24h incubation which was evidenced by: (i) reduced mitochondrial complex I and III activities; (ii) reduced mitochondrial cytochrome C; (iii) increased reactive oxygen species (ROS) generation; (iv) decreased mitochondrial membrane potential (ΔΨm); and (v) increased lactate dehydrogenase (LDH) levels. PTE (2.5, 5, and 10μM for 24h) was nontoxic and induced the nuclear transition of Nrf2. Pretreatment of PTE (2.5, 5, and 10μM for 2h) displayed a dose-dependently neuroprotective effect, as indicated by significantly prevented high glucose-induced loss of cellular viability, generation of ROS, reduced mitochondrial complex I and III activities, reduced mitochondrial cytochrome C, decreased ΔΨm, and increased LDH levels. Moreover, the levels of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and glutathione S-transferase (GST) were elevated after PTE treatment. In addition, the elevation of nuclear Nrf2 by PTE treatment (10μM for 2h) was abolished by Nrf2 siRNA. Importantly, Nrf2 siRNA induced the opposite changes in mitochondrial complex I and III activities, mitochondrial cytochrome C, reactive species generation, ΔΨm, and LDH. Overall, the present findings were the first to show that pterostilbene attenuated high glucose-induced central nervous system injury in vitro through the activation of Nrf2 signaling, displaying protective effects against mitochondrial dysfunction-derived oxidative stress.

Dietary Phytochemicals in Neuroimmunoaging: A New Therapeutic Possibility for Humans?

Although several efforts have been made in the search for genetic and epigenetic patterns linked to diseases, a comprehensive explanation of the mechanisms underlying pathological phenotypic plasticity is still far from being clarified. Oxidative stress and inflammation are two of the major triggers of the epigenetic alterations occurring in chronic pathologies, such as neurodegenerative diseases. In fact, over the last decade, remarkable progress has been made to realize that chronic, low-grade inflammation is one of the major risk factor underlying brain aging. Accumulated data strongly suggest that phytochemicals from fruits, vegetables, herbs, and spices may exert relevant immunomodulatory and/or anti-inflammatory activities in the context of brain aging. Starting by the evidence that a common denominator of aging and chronic degenerative diseases is represented by inflammation, and that several dietary phytochemicals are able to potentially interfere with and regulate the normal function of cells, in particular neuronal components, aim of this review is to summarize recent studies on neuroinflammaging processes and proofs indicating that specific phytochemicals may act as positive modulators of neuroinflammatory events. In addition, critical pathways involved in mediating phytochemicals effects on neuroinflammaging were discussed, exploring the real impact of these compounds in preserving brain health before the onset of symptoms leading to inflammatory neurodegeneration and cognitive decline.

Neuroprotective actions of pterostilbene on hypoxic-ischemic brain damage in neonatal rats through upregulation of heme oxygenase-1

Neonatal hypoxic-ischemic (HI) brain damage causes acute mortality and morbidity in newborns and long-term neurological disorders in the survivors. Pterostilbene (PTE) is a natural compound possessing various biological and pharmacological activities. In the present study, we aimed to investigate the effect of PTE on neonatal HI brain damagein P7 rat model and to explore the possible mechanisms. Neonatal HI brain damage was induced in rat pups (P7). Prior to the induction of HI injury, PTE was injected with or without zinc protoporphyrin IX (ZnPP), an inhibitor of heme oxygenase-1 (HO-1). ZnPP was used to test whether abnormal changes of HO-1 expression were involved in the effect of PTE. The results showed that PTE exhibited excellent neuroprotective effects against neonatal HI brain injury, as evidenced by the decrease of brain infarct volume, brain edema, neurological score, and improvement in motor coordination motor deficit and working memory deficit. PTE pretreatment decreased the expression of several proinflammatory cytokines, including TNFα, IL-1β, IL-6, and key transcription factor p65 NF-κB, and reduced the number of TUNEL-stained neurons, indicating the inhibition of inflammation and programmed cell death. Moreover, PTE pretreatment decreased thiobarbituric acid reactive substances content, increased superoxide dismutase activity and decreased reactive oxygen species level, indicating that PTE played an important antioxidant role. Furthermore, ZnPP was able to inhibit PTE-induced suppression of oxidative stress, programmed cell death, inflammation and brain damage. In conclusion, PTE pretreatment prevented HI-induced brain injury in newborns through HO-1-mediated reduction of oxidative stress, programmed cell death, and inflammation, and final improvement of histological and functional injury. Overall, the data that obtained in rat model provide novel insights into the pathogenesis of neonatal HI brain injury and may be translational to human clinical intervention for HI-associated brain injury in newborns.

Activation of the c-Met Pathway Mobilizes an Inflammatory Network in the Brain Microenvironment to Promote Brain Metastasis of Breast Cancer

Brain metastasis is one of the chief causes of mortality in breast cancer patients, but the mechanisms that drive this process remain poorly understood. Here, we report that brain metastatic cells expressing high levels of c-Met promote the metastatic process via inflammatory cytokine upregulation and vascular reprogramming. Activated c-Met signaling promoted adhesion of tumor cells to brain endothelial cells and enhanced neovascularization by inducing the secretion of IL8 and CXCL1. Additionally, stimulation of IL1β secretion by activation of c-Met induced tumor-associated astrocytes to secrete the c-Met ligand HGF. Thus, a feed-forward mechanism of cytokine release initiated and sustained by c-Met fed a vicious cycle that generated a favorable microenvironment for metastatic cells. Reinforcing our results, we found that pterostilbene, a compound that penetrates the blood-brain barrier, could suppress brain metastasis by targeting c-Met signaling. These findings suggest a potential utility of this natural compound for chemoprevention. Cancer Res; 76(17); 4970-80. ©2016 AACR.

Piceatannol and Other Wine Stilbenes: A Pool of Inhibitors against α-Synuclein Aggregation and Cytotoxicity

The aggregation of α-synuclein is one on the key pathogenic events in Parkinson’s disease. In the present study, we investigated the inhibitory capacities of stilbenes against α-synuclein aggregation and toxicity. Thioflavin T fluorescence, transmission electronic microscopy, and SDS-PAGE analysis were performed to investigate the inhibitory effects of three stilbenes against α-synuclein aggregation: piceatannol, ampelopsin A, and isohopeaphenol. Lipid vesicle permeabilization assays were performed to screen stilbenes for protection against membrane damage induced by aggregated α-synuclein. The viability of PC12 cells was examined using an MTT assay to assess the preventive effects of stilbenes against α-synuclein-induced toxicity. Piceatannol inhibited the formation of α synuclein fibrils and was able to destabilize preformed filaments. It seems to induce the formation of small soluble complexes protecting membranes against α-synuclein-induced damage. Finally, piceatannol protected cells against α-synuclein-induced toxicity. The oligomers tested (ampelopsin A and hopeaphenol) were less active.