Pterostilbene Exhibited the Anticancer Effect Against 1, 2-Dimethylhydrazine (DMH)-Induced Colorectal Cancer via Alteration of Oxidative Stress, Inflammation and Gut Microbiota

Colorectal cancer (CRC) is the third leading cause of cancer-related deaths worldwide. The current investigation aimed to assess the chemoprotective effects of pterostilbene against 1,2-dimethylhydrazine (DMH)-induced colorectal cancer in mice. An in-silico study was conducted to perform docking studies against nuclear factor kappa factor (NF-κB). CRC was induced in mice by administering DMH (20 mg/kg) subcutaneously, and the mice were subsequently administered various dosages of pterostilbene (5, 10, and 15 mg/kg). At the end of the study, various biochemical parameters, including inflammatory cytokines, inflammatory markers, and antioxidant enzymes, were examined. Additionally, the mice's stools were collected for the analysis of intestinal microbiota. A total of 5 hydrogen bonds were identified between NF-κB and pterostilbene using LigPlot+. Pterostilbene significantly (p < 0.001) reduced tumor incidence, tumor weight, and increased body weight. Pterostilbene significantly (p < 0.001) altered the levels of lipid peroxidation, reduced glutathione, superoxide dismutase, glutathione peroxidase, and catalase as well as the activity of both phase I and phase II enzymes. Furthermore, pterostilbene significantly (p < 0.001) decreased the levels of proinflammatory cytokines such as tumor necrosis factor-α, interleukin-6, interferon-γ, and interleukin-1β, while increasing the levels of anti-inflammatory cytokines like interleukin-4 and interleukin-10. Pterostilbene considerably suppressed the levels of cyclooxygenase-2 and prostaglandin E2, as well as inducible nitric oxide synthase and simultaneously elevated the levels of apoptosis-related parameters, including caspase-3, caspase-8, and caspase-9. Moreover, pterostilbene significantly reduced the abundance of Staphylococcus in the intestinal microbiota and enhanced the levels of beneficial bacteria, such as Bifidobacterium, Akkermansia, and Lactobacillus. Pterostilbene demonstrated a chemoprotective effect against CRC by effectively reducing oxidative stress, mitigating inflammatory responses, and inducing alterations in gut microbiota levels.

Pterostilbene Alleviates Dextran Sodium Sulfate (DSS)-Induced Intestinal Barrier Dysfunction Involving Suppression of a S100A8-TLR-4-NF-κB Signaling Cascade

Intestinal barrier hemostasis is the key to health. As a resveratrol analogue, pterostilbene (PT) has been reported to prevent dextran sodium sulfate (DSS)-induced intestinal barrier dysfunction mainly associated with the intestinal NF-κB signaling pathway. However, the exact underlying mechanisms are not yet well-defined yet. In this study, we performed RNA-sequencing analysis and unexpectedly found that alarmin S100A8 sensitively responded to DSS-induced intestinal injury. Accordingly, histologic assessments suggested that the high expression of S100A8 was accompanied by increased intestinal infiltration of macrophages, upregulated intestinal epithelial Toll-like receptor 4 (TLR-4), and activated NF-κB signaling pathway. Interestingly, the above phenomena were effectively counteracted upon the addition of PT. Furthermore, by using a coculture system of macrophage THP-1 cells and HT-29 colon cells, we identified macrophage-secreted S100A8 activated intestinal epithelial NF-κB signaling pathway through TLR-4. Taken together, these findings suggested that PT ameliorated DSS-induced intestinal barrier injury through suppression of the macrophage S100A8-intestinal epithelial TLR-4-NF-κB signaling cascade.

Anti-inflammatory Fucoidan-ConA oral insulin nanosystems for smart blood glucose regulation

The smart oral administration Insulin device has the potential to improve glycemic management. It can reduce the risk of hypoglycemia associated with exogenous Insulin (INS) therapy while also avoiding many of the disadvantages associated with subcutaneous injections. Furthermore, diabetes mellitus (DM) is an endocrine illness characterized by inflammation, and it is critical to minimize the amount of inflammatory markers in diabetic patients while maintaining average blood glucose. In this study, a responsive nanosystem vitamin B12-Fucoidan-Concanavalin A (VB12-FU-ConA NPs) with anti-inflammatory action was developed for smart oral delivery of Insulin. Con A has high sensitivity and strong specificity as a glucose-responsive material. Fucoidan has anti-inflammatory, immunomodulatory, and hypoglycemic functions, and it can bind to Con A to form a reversible complex. Under high glucose conditions, free glucose competitively binds to Con A, which swells the nanocarrier and promotes Insulin release. Furthermore, in the low pH environment of the gastrointestinal tract, positively charged VB12 and anionic fucoidan bind tightly to protect the Insulin wrapped in the carrier, and VB12 can also bind to intestinal epithelial factors to improve transit rate, thereby promoting INS absorption. In vitro tests showed that the release of nanoparticles in hyperglycemic solutions was significantly higher than the drug release in normoglycemic conditions. Oral delivery of the nanosystems dramatically lowered blood glucose levels in type I diabetic mice (T1DM) during in vivo pharmacodynamics, minimizing the risk of hypoglycemia. Blood glucose levels reached a minimum of 8.1 ± 0.4 mmol/L after 8 h. Administering the nanosystem orally notably decreased the serum levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in diabetic mice. The nano delivery system can be degraded and metabolized in the intestinal tract after being taken orally, demonstrating good biodegradability and biosafety. In conclusion, the present study showed that VB12-FU-ConA nanocarriers are expected to be a novel system for rationalizing blood glucose.

Enhanced Antioxidant and Neuroprotective Properties of Pterostilbene (Resveratrol Derivative) in Amorphous Solid Dispersions

In this study, amorphous solid dispersions (ASDs) of pterostilbene (PTR) with polyvinylpyrrolidone polymers (PVP K30 and VA64) were prepared through milling, affirming the amorphous dispersion of PTR via X-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC). Subsequent analysis of DSC thermograms, augmented using mathematical equations such as the Gordon-Taylor and Couchman-Karasz equations, facilitated the determination of predicted values for glass transition (Tg), PTR's miscibility with PVP, and the strength of PTR's interaction with the polymers. Fourier-transform infrared (FTIR) analysis validated interactions maintaining PTR's amorphous state and identified involved functional groups, namely, the 4'-OH and/or -CH groups of PTR and the C=O group of PVP. The study culminated in evaluating the impact of amorphization on water solubility, the release profile in pH 6.8, and in vitro permeability (PAMPA-GIT and BBB methods). In addition, it was determined how improving water solubility affects the increase in antioxidant (ABTS, DPPH, CUPRAC, and FRAP assays) and neuroprotective (inhibition of cholinesterases: AChE and BChE) properties. The apparent solubility of the pure PTR was ~4.0 µg·mL-1 and showed no activity in the considered assays. For obtained ASDs (PTR-PVP30/PTR-PVPVA64, respectively) improvements in apparent solubility (410.8 and 383.2 µg·mL-1), release profile, permeability, antioxidant properties (ABTS: IC50 = 52.37/52.99 μg·mL-1, DPPH: IC50 = 163.43/173.96 μg·mL-1, CUPRAC: IC0.5 = 122.27/129.59 μg·mL-1, FRAP: IC0.5 = 95.69/98.57 μg·mL-1), and neuroprotective effects (AChE: 39.1%/36.2%, BChE: 76.9%/73.2%) were confirmed.

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.

Oryza sativa L. Indica Seed Coat Ameliorated Concanavalin A-Induced Acute Hepatitis in Mice via MDM2/p53 and PKCα/MAPK1 Signaling Pathways

Acute hepatitis (AH) is a common liver disease with an increasing number of patients each year, requiring the development of new treatments. Hence, our work aimed to evaluate the therapeutic effect of Oryza sativa L. indica (purple rice) seed coat on concanavalin A (ConA)-induced AH and further reveal its potential mechanisms. Purple rice seed coat extract (PRE) was extracted with hydrochloric acid ethanol and analyzed through a widely targeted components method. We evaluated the effects of PRE on AH through histopathological examination, liver function, gut microbiota composition, and the intestinal barrier. The potential targets of PRE on AH were predicted by bioinformatics. Western blotting, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay (TUNEL) staining, and corresponding kits were used to investigate PRE effects on predicting targets and associated signaling pathways in AH mice. In AH model mice, PRE treatment increased transformed mouse 3T3 cell double minute 2 (MDM2) expression to inhibit apoptosis; it also markedly downregulated protein kinase C alpha (PKCα), prostaglandin-endoperoxide synthase 1 (PTGS1), and mitogen-activated protein kinase 1 (MAPK1) activity to alleviate inflammation. Thus, PRE treatment also recovered the intestinal barrier, decreased the lipopolysaccharide (LPS) levels of plasma and the liver, enhanced liver function, and improved the composition of intestinal microbiota. In general, PRE targeting MDM2, PKCα, MAPK1, and PTGS1 ameliorated ConA-induced AH by attenuating inflammation and apoptosis, restoring the intestinal barrier, enhancing the liver function, and improving the gut microbiota, which revealed that the purple rice seed coat might hold possibilities as a therapeutic option for AH.

Induction of Sestrin2 by pterostilbene suppresses ethanol-triggered hepatocyte senescence by degrading CCN1 via p62-dependent selective autophagy

Hepatocyte senescence is a key event participating in the progression of alcoholic liver disease. Autophagy is a critical biological process that controls cell fates by affecting cell behaviors like senescence. Pterostilbene is a natural compound with hepatoprotective potential; however, its implication for alcoholic liver disease was not understood. This study was aimed to investigate the therapeutic effect of pterostilbene on alcoholic liver disease and elucidate the potential mechanism. Our results showed that pterostilbene alleviated ethanol-triggered hepatocyte damage and senescence. Intriguingly, pterostilbene decreased the protein abundance of cellular communication network factor 1 (CCN1) in ethanol-exposed hepatocytes, which was essential for pterostilbene to execute its anti-senescent function. In vivo studies verified the anti-senescent effect of pterostilbene on hepatocytes of alcohol-intoxicated mice. Pterostilbene also relieved senescence-associated secretory phenotype (SASP), redox imbalance, and steatosis by suppressing hepatic CCN1 expression. Mechanistically, pterostilbene-forced CCN1 reduction was dependent on posttranscriptional regulation via autophagy machinery but not transcriptional regulation. To be specific, pterostilbene restored autophagic flux in damaged hepatocytes and activated p62-mediated selective autophagy to recognize and lead CCN1 to autolysosomes for degradation. The protein abundance of Sestrin2 (SESN2), a core upstream modulator of autophagy pathway, was decreased in ethanol-administrated hepatocytes but rescued by co-treatment with pterostilbene. Induction of SESN2 protein by pterostilbene rescued ethanol-triggered autophagic dysfunction in hepatocytes, which then reduced senescence-associated markers, postponed hepatocyte senescence, and relieved alcohol-caused liver injury and inflammation. In conclusion, this work discovered a novel compound pterostilbene with therapeutic implications for alcoholic liver disease and uncover its underlying mechanism.

Amorphous Pterostilbene Delivery Systems Preparation-Innovative Approach to Preparation Optimization

The aim of our research was to improve the solubility and antioxidant activity of pterostilbene (PTR) by developing a novel amorphous solid dispersion (ASD) with Soluplus^® (SOL). DSC analysis and mathematical models were used to select the three appropriate PTR and SOL weight ratios. The amorphization process was carried out by a low-cost and green approach involving dry milling. An XRPD analysis confirmed the full amorphization of systems in 1:2 and 1:5 weight ratios. One glass transition (T_g) observed in DSC thermograms confirmed the complete miscibility of the systems. The mathematical models indicated strong heteronuclear interactions. SEM micrographs suggest dispersed PTR within the SOL matrix and a lack of PTR crystallinity, and showed that after the amorphization process, PTR-SOL systems had a smaller particle size and larger surface area compared with PTR and SOL. An FT-IR analysis confirmed that hydrogen bonds were responsible for stabilizing the amorphous dispersion. HPLC studies showed no decomposition of PTR after the milling process. PTR's apparent solubility and antioxidant activity after introduction into ASD increased compared to the pure compound. The amorphization process improved the apparent solubility by ~37-fold and ~28-fold for PTR-SOL, 1:2 and 1:5 w/w, respectively. The PTR-SOL 1:2 w/w system was preferred due to it having the best solubility and antioxidant activity (ABTS: IC₅₀ of 56.389 ± 0.151 µg·mL^-1 and CUPRAC: IC_0.5 of 82.52 ± 0.88 µg·mL^-1).

Inducible nitric oxide synthase regulates macrophage polarization via the MAPK signals in concanavalin A-induced hepatitis

INTRODUCTION

Acute liver inflammatory reactions contribute to many health problems; thus, it is critical to understand the underlying pathogenic mechanisms of acute hepatitis. In this study, an experimental in vivo model of concanavalin A (ConA)-induced hepatitis was used.

MATERIALS AND METHODS

C57BL/6 (wild-type, WT) or inducible nitric oxide synthase-deficient (iNOS-/- ) mice were injected with PBS or 15 mg/kg ConA via tail vein. Detection of liver injury by histological examination and apoptosis, and flow cytometry to detect the effect of immune cells on liver injury.

RESULTS

iNOS-/-  mice had lower levels of the liver enzymes aspartate aminotransferase and alanine aminotransferase, suggesting that they were protected against ConA-induced pathological liver injury and that iNOS participated in the regulation of hepatitis. Furthermore, iNOS deficiency was found to lower CD86 expression and suppressed the messenger RNA levels of inflammatory factors in the liver. In vitro experiments also demonstrated that iNOS deficiency suppressed the sequential phosphorylation of the mitogen-activated protein kinase pathway cascade, thereby inhibiting the M1 polarization of macrophages and consequently suppressing the transcription of inflammation factors.

CONCLUSION

iNOS may contribute to ConA-induced inflammation by promoting the activation of proinflammatory macrophages.

Pterostilbene alleviates liver ischemia/reperfusion injury via PINK1-mediated mitophagy

Hepatic ischemia/reperfusion (I/R) injury contributes to morbidity and mortality during liver resection or transplantation, with limited effective treatments available. Here, we investigated the potential benefits and underlying mechanisms of pterostilbene (Pt), a natural component of blueberries and grapes, in preventing hepatic I/R injury. Male C57BL/6 mice subjected to partial warm hepatic I/R and human hepatocyte cell line L02 cells exposed to anoxia/reoxygenation (A/R) were used as in vivo and in vitro models, respectively. Our findings showed that pretreatment with Pt ameliorated hepatic I/R injury by improving liver histology, decreasing hepatocyte apoptosis, and reducing plasma ALT and AST levels. Likewise, cell apoptosis, mitochondrial membrane dysfunction, and mitochondrial ROS overproduction in L02 cells triggered by the A/R challenge in vitro were reduced due to Pt administration. Mechanistically, Pt treatment efficiently enhanced mitophagy and upregulated PINK1, Parkin, and LC3B expression. Notably, the protective effect of Pt was largely abrogated after cells were transfected with PINK1 siRNA. Moreover, Pt pretreatment promoted hepatocyte proliferation and liver regeneration in the late phase of hepatic I/R. In conclusion, our findings provide evidence that Pt exerts hepatoprotective effects in hepatic I/R injury by upregulating PINK1-mediated mitophagy.

Pterostilbene Coupled with Physical Exercise Effectively Mitigates Collagen-Induced Articular Synovial by Correcting the PI3K/Akt/NF-κB Signal Pathway

Studies have revealed that a novel anti-inflammatory mediator─maresin-1 (MaR1)─can reduce the level of inflammatory factors. There is evidence that physical exercise (PE) promotes the biosynthesis of MaR1, leading to the prevention of rheumatoid arthritis (RA). Previously, we have proven that resveratrol can mitigate the formation of RA. Pterostilbene (Pte) is an analogue of resveratrol, but it is around four times more bioavailable. Hence, we hypothesize that Pte could be more effective in preventing RA, in particular, when accompanied by moderate PE. Based on this hypothesis, we explored the preventive effect of Pte combined with PE on a bovine type II collagen (BIIC)-stimulated rat RA model and its underlying molecular mechanism. Compared with the BIIC-stimulated group, the serum content of MaR1 with continuous intervention of Pte plus PE for 8 weeks was significantly increased to 46.3 pg/mL from 7.2 pg/mL in BIIC-treated alone. Besides, the variation in the relative expression levels of p-NF-κB and p-Akt was reversed with the administration of Pte plus PE. More importantly, the in vitro results confirmed that the treatment of Pte plus MaR1 inhibited proliferation and apoptosis and promoted the autophagy of the interleukin (IL)-1β-stimulated primary rat synovial cells through the PI3K/Akt/NF-κB signal pathway. Collectively, the oral administration of Pte plus moderate PE helped to ameliorate the pathological process of RA by correcting the PI3K/Akt/NF-κB signal pathway.

Pterostilbene attenuates RIPK3-dependent hepatocyte necroptosis in alcoholic liver disease via SIRT2-mediated NFATc4 deacetylation

Receptor-interacting protein kinase (RIPK) 3-dependent necroptosis plays a critical role in alcoholic liver disease. RIPK3 also facilitates steatosis, oxidative stress, and inflammation. Pterostilbene (PTS) has favorable hepatoprotective activities. The present study was aimed to reveal the therapeutic effects of PTS on ethanol-induced hepatocyte necroptosis and further illustrate possible molecular mechanisms. Human hepatocytes LO2 were incubated with 100 mM ethanol for 24 h to mimic alcoholic hepatocyte injury. Results showed that PTS at 20 μM reduced damage-associated molecular patterns (DAMPs) release, including IL-1α and high-mobility group box 1 (HMGB1), and blocked necroptotic signaling, evidenced by decreased RIPK1 and RIPK3 expression. Trypan blue staining visually showed that PTS reduced nonviable hepatocytes after ethanol exposure, which was counteracted by adenovirus-mediated ectopic overexpression of RIPK3 but not RIPK1. Besides, PTS inhibited ethanol-induced hepatocyte steatosis via restricting lipogenesis and enhancing lipolysis, decreased oxidative stress via rescuing mitochondrial membrane potential, reducing oxidative system, and enhancing antioxidant system, and relieved inflammation evidenced by decreased expression of proinflammatory factors. Notably, RIPK3 overexpression diminished these protective effects of PTS. Subsequent work indicated that PTS suppressed the expression and nuclear translocation of nuclear factor of activated T-cells 4 (NFATc4), an acetylated protein, in ethanol-exposed hepatocytes, while NFATc4 overexpression impaired the negative regulation of PTS on RIPK3 and DAMPs release. Further, PTS rescued sirtuin 2 (SIRT2) expression, and SIRT2 knockdown abrogated the inhibitory effects of PTS on nuclear translocation and acetylation status of NFATc4 in ethanol-incubated hepatocytes. In conclusion, PTS attenuated RIPK3-dependent hepatocyte necroptosis after ethanol exposure via SIRT2-mediated NFATc4 deacetylation.

Blueberry as an Attractive Functional Fruit to Prevent (Pre)Diabetes Progression

Prediabetes, a subclinical impairment between euglycemia and hyperglycemia, is a risk factor for the development of type 2 diabetes mellitus (T2DM) and associated micro- and macrovascular complications. Lifestyle therapy, the first-line treatment of prediabetes, includes physical exercise and dietary regimens enriched in phytochemicals with health-related properties. Blueberries (Vaccinium spp.), given their pleasant taste and great abundance in beneficial phytochemicals, have gained public interest all over the world. Along with a high antioxidant activity, this functional fruit is also well-recognized due to its hypoglycemic and insulin-sensitizing effects and has been recommended for overt T2DM management. Yet blueberries target several other pathophysiological traits, namely gut microbiota dysbiosis and hepatic dysmetabolism, that ensue when prediabetes begins and for which pharmacological interventions tend to be delayed. In this work, we revisited preclinical data from in vitro assays, animal models and human studies, aiming to disclose the potential mechanisms by which blueberries may be a fruitful source of phytochemicals able to prevent (pre)diabetes progression. Collectively, future efforts should focus on longer-term studies with standardized interventions and readouts, particularly in humans, that will hopefully bring more robust evidence and concrete guidance for blueberries' effective use in prediabetes.

Pterostilbene Ameliorates DSS-Induced Intestinal Epithelial Barrier Loss in Mice via Suppression of the NF-κB-Mediated MLCK-MLC Signaling Pathway

The integrity of the intestinal barrier is critical for homeostasis. In this study, we investigated the protective effect of pterostilbene (PTE) on the intestinal epithelium barrier. In vitro results of transepithelial electrical resistance (TEER) in Caco-2 cells indicated that PTE counteracted tumor necrosis factor α (TNFα)-induced barrier damage. In vivo PTE pretreatment markedly ameliorated intestinal barrier dysfunction induced by dextran sulfate sodium (DSS). Notably, intestinal epithelial tight junction (TJ) molecules were restored by PTE in mice exposed to DSS. The mechanism study revealed that PTE prevented myosin light-chain kinase (MLCK) from driving phosphorylation of MLC (p-MLC), which is crucial for maintaining intestinal TJ stability. Furthermore, PTE blunted translocation of NF-κB subunit p65 into the nucleus to downregulate MLCK expression and then to safeguard TJs and barrier integrity. These findings suggest that PTE protected the intestinal epithelial barrier through the NF-κB- MLCK/p-MLC signal pathway.

Pterostilbene modifies triglyceride metabolism in hepatic steatosis induced by high-fat high-fructose feeding: a comparison with its analog resveratrol

The use of phenolic compounds as a new therapeutic approach against NAFLD has emerged recently. In the present study, we aim to study the effect of pterostilbene in the prevention of liver steatosis developed as a consequence of high-fat (saturated) high-fructose feeding, by analysing the changes induced in metabolic pathways involved in triglyceride accumulation. Interestingly, a comparison with the anti-steatotic effect of its parent compound resveratrol will be made for the first time. Rats were distributed into 5 experimental groups and fed either a standard laboratory diet or a high-fat high-fructose diet supplemented with or without pterostilbene (15 or 30 mg per kg per d) or resveratrol (30 mg per kg per d) for 8 weeks. Serum triglyceride, cholesterol, NEFA and transaminase levels were quantified. Liver histological analysis was carried out by haematoxylin-eosin staining. Different pathways involved in liver triglyceride metabolism, including fatty acid synthesis, uptake and oxidation, triglyceride assembly and triglyceride release, were studied. Pterostilbene was shown to partially prevent high-fat high-fructose feeding induced liver steatosis in rats, demonstrating a dose-response pattern. In this dietary model, it acts mainly by reducing de novo lipogenesis and increasing triglyceride assembly and release. Improvement in mitochondrial functionality was also appreciated. At the same dose, the magnitude of pterostilbene and resveratrol induced effects, as well as the involved mechanisms of action, were similar.

Summary of Natural Products Ameliorate Concanavalin A-Induced Liver Injury: Structures, Sources, Pharmacological Effects, and Mechanisms of Action

Liver diseases represent a threat to human health and are a significant cause of mortality and morbidity worldwide. Autoimmune hepatitis (AIH) is a progressive and chronic hepatic inflammatory disease, which may lead to severe complications. Concanavalin A (Con A)-induced hepatic injury is regarded as an appropriate experimental model for investigating the pathology and mechanisms involved in liver injury mediated by immune cells as well as T cell-related liver disease. Despite the advances in modern medicine, the only available strategies to treat AIH, include the use of steroids either solely or with immunosuppressant drugs. Unfortunately, this currently available treatment is associated with significant side-effects. Therefore, there is an urgent need for safe and effective drugs to replace and/or supplement those in current use. Natural products have been utilized for treating liver disorders and have become a promising therapy for various liver disorders. In this review, the natural compounds and herbal formulations as well as extracts and/or fractions with protection against liver injury caused by Con A and the underlying possible mechanism(s) of action are reviewed. A total of 53 compounds from different structural classes are discussed and over 97 references are cited. The goal of this review is to attract the interest of pharmacologists, natural product researchers, and synthetic chemists for discovering novel drug candidates for treating immune-mediated liver injury.

Occurrence, Bioavailability, Anti-inflammatory, and Anticancer Effects of Pterostilbene

Supplementation with natural compounds found in fruits and vegetables has long been associated with a reduced risk of several types of cancer. Pterostilbene is a natural stilbenoid and a dimethylated analogue of resveratrol which is found primarily in blueberries. Pterostilbene exhibits a range of pharmacological properties, particularly anti-inflammatory and anticancer effects. Due to two methoxy groups in its skeleton, pterostilbene is more lipophilic than resveratrol and thus possesses higher intestinal permeability and cellular uptake and enhanced stability. Moreover, pterostilbene exhibits less toxicity and fewer adverse effects, providing it with superior potential in cancer chemoprevention and chemotherapy applications. Numerous research studies have demonstrated that pterostilbene possesses detoxification activities, mediating the anti-inflammation response, regulating the cell cycle, augmenting apoptosis, enhancing autophagy, and inhibiting tumor angiogenesis, invasion, and metastasis by modulating signal transduction pathways which block multiple stages of carcinogenesis. In this review, we illustrate that pterostilbene is a natural compound having bioavailability. The extensive metabolism of pterostilbene will be discussed. We also summarize recent research on pterostilbene's anti-inflammatory and anticancer properties in the multistage carcinogenesis process and related molecular mechanism and conclude that it should contribute to improved cancer management.

Nobiletin Protects against Acute Liver Injury via Targeting c-Jun N-Terminal Kinase (JNK)-Induced Apoptosis of Hepatocytes

Acute liver injury resulting from several factors such as medication, food toxins, and herbal supplementation often leads to a severe health condition and makes treatment difficult; thereby, the prevention of acute liver injury remains a critical issue and is of great importance. In this study, we investigated the preventive effects of nobiletin (NOB) on a mouse model of concanavalin A (ConA)-induced acute liver injury. We observed that NOB (10 mg/kg) pretreatment of ConA-treated mice significantly lowered the levels of liver enzymes including alanine aminotransferase (ALT) and aspartate aminotransferase (AST), decreased the intracellular generation of reactive oxygen species (ROS), and suppressed the release of inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ). Pathological data suggested that pretreatment with NOB ameliorated ConA-induced liver damage by promoting proliferation and alleviating apoptosis of hepatocytes. Furthermore, significant suppression of the c-Jun-activating kinase (JNK) signal was also observed in NOB-pretreated liver tissues compared with that of ConA treatment only. In addition, an in vitro mechanism study confirmed that the addition of NOB protected hepatocytes via inhibition of JNK activation, manifesting that alleviation of JNK-induced apoptosis of hepatocytes is correlated with NOB protection in acute liver injury.

Pterostilbene prevents LPS-induced early pulmonary fibrosis by suppressing oxidative stress, inflammation and apoptosis in vivo

Early pulmonary fibrosis after acute lung injury leads to poor prognosis and high mortality. Pterostilbene (Pts), a bioactive component in blueberries, possesses anti-inflammatory, antioxidative and antifibrotic properties. However, the effects of Pts on lipopolysaccharide (LPS)-induced pulmonary fibrosis are still unknown. In our study, the Pts group showed lower lung injury and fibrosis scores, and lower levels of hydroxyproline and protein (collagen I and transforming growth factor-β) than the scores and levels in mice treated with LPS. MMP-1 was the degrading enzyme of collagen I and LPS caused the inhibition of MMP-1, disturbing the degradation of collagen. Additionally, Pts remarkably reversed the LPS-induced inhibition of interleukin-10 and the release of tumor necrosis factor-α, interleukin-6 and interleukin-1β. In terms of cellular pathways, Pts treatment ameliorated LPS-activated nuclear factor kappa B (NF-κB) and NOD-like receptor NLRP3 signaling. Besides, LPS-induced low levels of A20 could be activated by Pts. In addition, Pts treatment reversed the high levels of Caspase-3, poly ADP-ribose polymerase (PARP) and Bcl2-associated X protein (Bax) expression and the low levels of B cell lymphoma/lewkmia-2 (Bcl2) that had been induced by LPS. Moreover, oxidative stress is also involved in the pathogenesis of fibrosis. Our findings indicate that LPS injection triggered the production of myeloperoxidase (MPO) and malondialdehyde (MDA) and the depletion of superoxide dismutase (SOD) and glutathione (GSH), and that these effects were notably reversed by treatment with Pts. In addition, Pts induced the dissociation of Kelch-like epichlorohydrin-associated protein-1 (Keap-1) and NF-E2 related factor-2 (Nrf2) and the activation of downstream genes (heme oxygenase-1, NAD(P)H:quinine oxidoreductase, glutamate-cysteine ligase catalytic subunit and glutamate-cysteine ligase modifier). In conclusion, oxidative stress, apoptosis and inflammation are involved in early pulmonary fibrosis and Pts exerts a protective effect by activating Keap-1/Nrf2, inhibiting caspase-dependent A20/NF-κB and NLRP3 signaling pathways.

Nobiletin Attenuates DSS-Induced Intestinal Barrier Damage through the HNF4α-Claudin-7 Signaling Pathway

The intestinal epithelium barrier functions to protect human bodies from damages such as harmful microorganisms, antigens, and toxins. In this study, we evaluated the protective effect and molecular mechanism of a dominant polymethoxyflavone nobiletin (NOB) from tangerine peels on intestinal epithelial integrity. The results from transepithelial electrical resistance (TEER) suggested that NOB pretreatment counteracts epithelial injury induced by inflammatory cytokines (TEER value in 48 h: vehicle, 135.6 ± 3.9 Ω/cm²; TNF-α + IL-1β, 90.7 ± 0.5 Ω/cm²; 10 μM NOB + TNF-α + IL-1β, 126.1 ± 0.8 Ω/cm²; 100 μM NOB + TNF-α + IL-1β, 125.3 ± 0.5 Ω/cm². P < 0.001). Clinical and pathological test results suggested that administration of NOB effectively alleviates intestinal barrier injury induced by dextran sulfate sodium (DSS) as evidenced by the length of colon villi on day 7 (control, 253.7 ± 4.8 μm, DSS 131.6 ± 4.6 μm, NOB + DSS, 234.5 ± 5.1 μm. P < 0.001). Interestingly, when screening tight junction molecules for intestinal barrier integrity, we observed that independent treatment with NOB sharply increased claudin-7 levels (ratio of claudin-7 over GAPDH: control, 1.0 ± 0.06; DSS, 0.02 ± 0.001; NOB + DSS, 0.3 ± 0.07. P < 0.001), which was previously suppressed upon DSS stimulation. Furthermore, hepatocyte nuclear factor 4α (HNF-4α) transcriptional regulation of claudin-7 contributed to intestinal barrier homeostasis. Therefore, our study suggests potential intestinal protective strategies based on polymethoxyflavones of aged tangerine peels.

Effects of Selected Resveratrol Analogues on Activation and Polarization of Lipopolysaccharide-Stimulated BV-2 Microglial Cells

Increasing health-promoting effects of resveratrol and its molecular structural analogues have been discovered, and the acting mechanism has been explored. However, the activity comparison of such compounds in targeting macrophage-related inflammation associated with neurodegenerative diseases remains untouched. In this study, we evaluated the activation and polarization transition of lipopolysaccharide (LPS)-stimulated BV-2 mouse microglial macrophages exposed to resveratrol (RES) and its analogues pterostilbene (PTE), oxyresveratrol (ORES), acetyl-trans-resveratrol (ARES), and trans-2,3,5,4'-tetrahydroxystilbene-2-O-glucopyranoside (TSG). At 10 μM, all of the five stilbene compounds have effectively suppressed the LPS-stimulated BV-2 cell release of proinflammatory mediators such as NO, TNF-α, iNOS, IL-1β, and IL-6. Mechanism study elucidated that they exert anti-inflammatory effects through MAPKs (ERK1/2, JNK, and p38) and NF-κB signaling pathways. Further investigation in treating BV-2 cells with resveratrol and its analogues revealed the reversal of LPS-induced phenotype molecules from M1 (iNOS, IL-1β, IL-6, and CD86) to M2 (Arg1, CD163, and IL-10) subtypes, manifesting that these five stilbenes suppressed inflammation through modulating the polarized phenotypes of BV-2 microglia. Most importantly, PTE demonstrated the most potent inhibitory activity among these five stilbene compounds. Therefore, this study not only highlights microglia-induced inflammatory responses as a potential therapeutic target but also suggests future insights in considering the options of nutraceutical development for resveratrol and its analogues.