Pharmacokinetics and tissue distribution of pterostilbene in the rat

Pterostilbene: a potential therapeutic agent for fibrotic diseases

Fibrosis is a prevailing pathology in chronic diseases and accounts for 45% of deaths in developed countries. This condition is primarily identified by the transformation of fibroblasts into myofibroblasts and the overproduction of extracellular matrix (ECM) by myofibroblasts. Pterostilbene (PTS) is a natural analogue of resveratrol and is most commonly found in blueberries. Research has shown that PTS exerts a wide range of pharmacological effects, such as antioxidant, anti-inflammatory, and anticancer effects. As a result, PTS has the potential to prevent and cure numerous diseases. Emerging evidence has indicated that PTS can alleviate myocardial fibrosis, renal fibrosis, pulmonary fibrosis, hepatic fibrosis, and colon fibrosis via the inhibition of inflammation, oxidative stress, and fibrogenesis effects in vivo and in vitro, and the potential mechanisms are linked to various pathways, including transforming growth factor-β1 (TGF-β1)/small mother against decapentaplegic proteins (Smads) signalling, the reactive oxygen species (ROS)-driven Pitx2c/mir-15b pathway, nuclear factor kappa B (NF-κB) signalling, Kelch-like epichlorohydrin-associated protein-1 (Keap-1)/NF-E2-related factor-2 (Nrf2) cascade, the NLR family pyridine structure domain 3 (NLRP3) pathway, the Janus kinase-2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) pathway, and the Src/STAT3 pathway. In this review, we comprehensively summarize the antifibrotic effects of PTS both in vivo and in vitro and the pharmacological mechanisms, pharmacokinetics, and toxicology of PTS and provide insights into and strategies for exploring promising agents for the treatment of fibrosis.

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.

Illustrate the distribution and metabolic regulatory effects of pterostilbene in cerebral ischemia-reperfusion rat brain by mass spectrometry imaging and spatial metabolomics

Pterostilbene is a promising molecule with superior pharmacological activities and pharmacokinetic characteristics compared to its structural analogue resveratrol, which could be used to treat ischemic stroke. However, its mechanism is still unclear. The cutting-edge air flow-assisted desorption electrospray ionization mass spectrometry imaging (AFADESI-MSI) and spatial metabolomics analysis were applied to investigate the distribution of pterostilbene in ischemic rat brain and the changes of related small molecule metabolic pathways to further explore the potential mechanisms of pterostilbene against cerebral ischemia-reperfusion injury. This research found that pterostilbene could significantly restore cerebral microcirculation blood flow, reduce infarct volume, improve neurological function and ameliorate neuronal damage in ischemic rats. Moreover, pterostilbene was widely and abundantly distributed in ischemic brain tissue, laying a solid foundation for the rescue of ischemic penumbra. Further study revealed that pterostilbene played a therapeutic role in restoring energy supply, rebalancing neurotransmitters, reducing abnormal polyamine accumulation and phospholipid metabolism. These findings offer an opportunity to illustrate novel mechanisms of pterostilbene in the treatment of cerebral ischemia/reperfusion injury resulting from 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.

Pterostilbene and Probiotic Complex in Chemoprevention of Putative Precursor Lesions for Colorectal Cancer in an Experimental Model of Intestinal Carcinogenesis with 1,2-Dimethylhydrazine

Dietary supplementation with pterostilbene (PS) and/or a probiotic (PRO) may ameliorate the intestinal microbiota in disease conditions. This study aims to evaluate PS and PRO for the chemoprevention of putative precursor lesions for colorectal cancer (CRC) in an experimental model of intestinal carcinogenesis with 1,2-dimethylhydrazine (1,2-DMH). Sixty male Wistar rats were equally divided into five groups: Sham, 1,2-DMH, 1,2-DMH + PS, 1,2-DMH + PRO, and 1,2-DMH + PS + PRO. PRO (5 × 10⁷/mL) was offered in water, and PS (300 ppm) was provided in the diet ad libitum. 1,2-DMH (20 mg/kg/week) was administered for 15 consecutive weeks. In the 25th week, proctocolectomy was conducted. PRO alone and PRO combined with PS were the best intervention strategies to improve experimental 1,2-DMH-induced CRC regarding several parameters of carcinogenesis. Our findings may contribute to the development of novel preventive strategies for CRC and may help to identify novel modulators of colon carcinogenesis.

Subacute oral toxicology and toxicokinetics of pterostilbene, a novel Top1/Tdp1 inhibiting anti-tumor reagent

This study evaluated the subacute toxicity and toxicokinetics of a potential anti-cancer drug candidate, pterostilbene, in rats. Animals were orally administered at two repeated doses of 200 and 500 mg/kg for 28 days. No mortality was observed during the 28 days of continuous administration of pterostilbene. Body weight and food consumption in each group increased steadily, while no significant difference was found. Liver weight in the 500 mg/kg female, but not male group increased with mild cytoplasmic vacuoles observed in histopathological study. Toxicokinetics was assessed by measuring plasma concentrations of pterostilbene on the first and 28th day of administration using UPLC-MS/MS. Toxicokinetic parameters showed that AUC_0-t significantly increased in all animals, while the increase in females was greater than males. System exposure of pterostilbene appeared to be linear within the administrated dose range. In conclusion, our findings suggested a minimal subacute toxicity profile of pterostilbene, which could strongly support further development of this compound as a novel anti-cancer agent.

Phase I Metabolism of Pterostilbene, a Dietary Resveratrol Derivative: Metabolite Identification, Species Differences, Isozyme Contribution, and Further Bioactivation

Pterostilbene (PTE), a dietary derivative of resveratrol, displayed pleiotropic health-promoting activities. This study aimed to explore the metabolic profiles and species differences of the phase I metabolism of PTE and to investigate subsequent detoxification after PTE bioactivation. PTE was found to be biotransformed to two pharmacologically active metabolites, pinostilbene and 3'-hydroxypterostilbene, in vivo and in vitro with substantial species differences. Human CYP1A2 was proved to be mainly responsible for the demethylation and 3'-hydroxylation of PTE, with its contribution to a demethylation of 94.5% and to a 3'-hydroxylation of 97.9%. An in vitro glutathione trapping experiment revealed the presence of an ortho-quinone intermediate formed by further oxidation of 3'-hydroxypterostilbene. Human glutathione S-transferase isoforms A2, T1, and A1 inactivated the ortho-quinone intermediate by catalyzing glutathione conjugation, implicating a potential protective pathway against PTE bioactivation-derived toxicity. Overall, this study provided a comprehensive view of PTE phase I metabolism and facilitated its further development as a promising nutraceutical.

Overview of Anti-Inflammatory and Anti-Nociceptive Effects of Polyphenols to Halt Osteoarthritis: From Preclinical Studies to New Clinical Insights

Knee osteoarthritis (OA) is one of the most multifactorial joint disorders in adults. It is characterized by degenerative and inflammatory processes that are responsible for joint destruction, pain and stiffness. Despite therapeutic advances, the search for alternative strategies to target inflammation and pain is still very challenging. In this regard, there is a growing body of evidence for the role of several bioactive dietary molecules (BDMs) in targeting inflammation and pain, with promising clinical results. BDMs may be valuable non-pharmaceutical solutions to treat and prevent the evolution of early OA to more severe phenotypes, overcoming the side effects of anti-inflammatory drugs. Among BDMs, polyphenols (PPs) are widely studied due to their abundance in several plants, together with their benefits in halting inflammation and pain. Despite their biological relevance, there are still many questionable aspects (biosafety, bioavailability, etc.) that hinder their clinical application. This review highlights the mechanisms of action and biological targets modulated by PPs, summarizes the data on their anti-inflammatory and anti-nociceptive effects in different preclinical in vitro and in vivo models of OA and underlines the gaps in the knowledge. Furthermore, this work reports the preliminary promising results of clinical studies on OA patients treated with PPs and discusses new perspectives to accelerate the translation of PPs treatment into the clinics.

A resveratrol derivative modulates TRH and TRH ‐like peptide expression throughout the brain and peripheral tissues of male rats

Introduction

Methods

Results

Conclusion

Improving the in vitro and in vivo bioavailability of pterostilbene using Yesso scallop gonad protein isolates-epigallocatechin gallate (EGCG) conjugate-based emulsions: effects of carrier oil

This study investigated the influence of carrier oils on the in vitro and in vivo bioavailability of PTE encapsulated in scallop gonad protein isolates (SGPIs)-epigallocatechin gallate (EGCG) conjugate stabilized emulsions. The SGPIs-EGCG stabilized emulsions were subjected to an in vitro simulated digestion, and the resulting corn oil and MCT micelles were used to evaluate the PTE transportation using the Caco-2 cell model. Both emulsions remarkably improved the bioaccessibility of PTE in the micelle phase. Nevertheless, corn oil emulsions increased trans-enterocyte transportation of PTE more efficiently than MCT emulsions. Furthermore, the maximum plasma concentrations of PTE and its metabolites in mice fed with PTE emulsions were prominently higher than those in mice fed with PTE solution, while the in vivo metabolic patterns of PTE in different oil-stabilized emulsions were different. Therefore, SGPIs-EGCG stabilized emulsions could enhance the bioavailability of PTE through controlled release, in which corn oil is more suitable than MCT.

Sexual Dimorphism in Brown Adipose Tissue Activation and White Adipose Tissue Browning

The present narrative review gathers the studies reported so far, addressing sex differences in the effects of cold exposure, feeding pattern and age on brown adipose tissue (BAT) thermogenesis and white adipose tissue (WAT) browning. In rodents, when exposed to decreasing temperatures, females activate thermogenesis earlier. Results obtained in humans go in the same line, although they do not provide results as solid as those obtained in rodents. Regarding the effects of overfeeding, interesting sex differences on BAT thermogenic capacity have been reported, and the greater or lower sensitivity of each sex to this dietary situation seems to be dependent on the type of feeding. In the case of energy restriction, females are more sensitive than males. In addition, sex differences have also been observed in thermogenesis changes induced by phenolic compound administration. During sexual development, an increase in BAT mass and BAT activity takes place. This phenomenon is greater in boys than in girls, probably due to its relation to muscle-mass growth. The opposite situation takes place during ageing, a lifespan period where thermogenic capacity declines, this being more acute in men than in women. Finally, the vast majority of the studies have reported a higher susceptibility to developing WAT browning amongst females. The scarcity of results highlights the need for further studies devoted to analysing this issue, in order to provide valuable information for a more personalised approach.

Gastrointestinal biotransformation and tissue distribution of pterostilbene after long-term dietary administration in mice

The metabolic fate of dietary compounds is closely related to their biological functions. Pterostilbene (PT) is a methylated stilbene found in many plant foods. Herein, we investigated gastrointestinal biotransformation and tissue distribution of PT in mice fed with 0.05% PT (w/w) for 5 weeks. PT and its major metabolites i.e. PT sulfate (PT-S), pinostilbene, pinostilbene sulfate, hydroxylated PT and hydroxylated PT sulfate were identified and quantified in the mucosa and content of the digestive tissues, blood, urine and vital organs. The results showed PT underwent demethylation, hydroxylation and conjugation in the small intestine, while the conjugated metabolites were largely deconjugated in the colon. Anaerobic fermentation with mouse cecal bacteria demonstrated the microbiota mediated deconjugation and demethylation of PT-S and PT, respectively. In conclusion, oral consumption of PT led to extensive biotransformation in mouse gastrointestinal tract and the metabolites of PT might play important roles in the bioactivity of PT.

Intravenous nicotinamide riboside elevates mouse skeletal muscle NAD+ without impacting respiratory capacity or insulin sensitivity

In clinical trials, oral supplementation with nicotinamide riboside (NR) fails to increase muscle mitochondrial respiratory capacity and insulin sensitivity but also does not increase muscle NAD⁺ levels. This study tests the feasibility of chronically elevating skeletal muscle NAD⁺ in mice and investigates the putative effects on mitochondrial respiratory capacity, insulin sensitivity, and gene expression. Accordingly, to improve bioavailability to skeletal muscle, we developed an experimental model for administering NR repeatedly through a jugular vein catheter. Mice on a Western diet were treated with various combinations of NR, pterostilbene (PT), and voluntary wheel running, but the metabolic effects of NR and PT treatment were modest. We conclude that the chronic elevation of skeletal muscle NAD⁺ by the intravenous injection of NR is possible but does not affect muscle respiratory capacity or insulin sensitivity in either sedentary or physically active mice. Our data have implications for NAD⁺ precursor supplementation regimens.

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A model was developed for daily intravenous NR injections

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Intravenous NR stably elevates NAD⁺ of skeletal muscle and adipose, but not liver

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Voluntary running and intravenous NR synergize to boost mouse skeletal muscle NAD⁺

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NR did not impact skeletal muscle insulin sensitivity or respiratory capacity

Multiple Mechanisms Converging on Transcription Factor EB Activation by the Natural Phenol Pterostilbene

Pterostilbene (Pt) is a potentially beneficial plant phenol. In contrast to many other natural compounds (including the more celebrated resveratrol), Pt concentrations producing significant effects in vitro can also be reached with relative ease in vivo. Here we focus on some of the mechanisms underlying its activity, those involved in the activation of transcription factor EB (TFEB). A set of processes leading to this outcome starts with the generation of ROS, attributed to the interaction of Pt with complex I of the mitochondrial respiratory chain, and spreads to involve Ca²⁺ mobilization from the ER/mitochondria pool, activation of CREB and AMPK, and inhibition of mTORC1. TFEB migration to the nucleus results in the upregulation of autophagy and lysosomal and mitochondrial biogenesis. Cells exposed to several μM levels of Pt experience a mitochondrial crisis, an indication for using low doses in therapeutic or nutraceutical applications. Pt afforded significant functional improvements in a zebrafish embryo model of ColVI-related myopathy, a pathology which also involves defective autophagy. Furthermore, long-term supplementation with Pt reduced body weight gain and increased transcription levels of Ppargc1a and Tfeb in a mouse model of diet-induced obesity. These in vivo findings strengthen the in vitro observations and highlight the therapeutic potential of this natural compound.

Assessment of the Antibacterial Mechanism of Pterostilbene against Bacillus cereus through Apoptosis-like Cell Death and Evaluation of Its Beneficial Effects on the Gut Microbiota

Foods contaminated by harmful substances such as bacteria and viruses have caused more than 200 kinds of diseases, ranging from diarrhea to cancer. Among them, Bacillus cereus (B. cereus) is a foodborne pathogen that commonly contaminates raw meat, fresh vegetables, rice, and uncooked food. The current chemical preservatives may have adverse effects on food and even human health. Therefore, natural antibacterial agents are sought after as alternative preservatives. Stilbene compounds, including pterostilbene (PT), pinostilbene (PS), and piceatannol (PIC), which have many health benefits and exhibit antibacterial activity, were tested against B. cereus. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of PT, PS, and PIC against B. cereus ranged from 25 to 100 μg/mL. From the time-kill curve assay, PT reduced B. cereus cell survival, increased intracellular reactive oxygen species (ROS), and induced apoptosis-like cell death (ALD) in a dose-dependent manner. The quantitative real-time polymerase chain reaction (qPCR) results confirmed that treatment with PT induced genetic changes related to ALD, such as an increase in RecA gene expression and a decrease in LexA gene expression. In addition, PT showed a beneficial effect on the gut microbiota that increased the abundance of Bacteroidetes and lowered the abundance of Firmicutes. Taken together, our results showed that PT has antibacterial effects against B. cereus via ALD and is beneficial for promoting healthy gut microbiota that is worthy for the development of antibacterial agents for the food industry.

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.

Activity of Pterostilbene Metabolites against Liver Steatosis in Cultured Hepatocytes

Pterostilbene is a dimethyl ether derivative of resveratrol, less metabolized than its analogue, due to the substitution of two hydroxyl groups with methoxyl groups. Nevertheless, the amounts of pterostilbene phase II metabolites found in plasma and tissues are higher than those of the parent compound. The first aim of this study was to assess whether pterostilbene-4′-O-glucuronide (PT-G) and pterostilbene-4′-O-sulfate (PT-S) were able to prevent triglyceride accumulation in AML12 (alpha mouse liver 12) hepatocytes. This being the case, we aimed to analyze the mechanisms involved in their effects. For this purpose, an in vitro model mimicking the hepatocyte situation in fatty liver was developed by incubating mouse AML12 hepatocytes with palmitic acid (PA). For cell treatments, hepatocytes were incubated with 1, 10 or 25 µM of pterostilbene, pterostilbene-4′-O-glucuronide or pterostilbene-4′-O-sulfate for 18 h. Triglycerides and cell viability were assessed by a commercial kit and crystal violet assay, respectively. Protein expression of enzymes and transporters involved in triglyceride metabolism was analyzed by immunoblot. The results showed for the first time the anti-steatotic effect of pterostilbene metabolites and thus, that they contribute to the preventive effect induced by pterostilbene on steatosis in in vivo models. This anti-steatotic effect is mainly due to the inhibition of de novo lipogenesis.

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.

The Polyphenol Pterostilbene Ameliorates the Myopathic Phenotype of Collagen VI Deficient Mice via Autophagy Induction

The induction of autophagy, the catabolic pathway by which damaged or unnecessary cellular components are subjected to lysosome-mediated degradation and recycling, is impaired in Collagen VI (COL6) null mice and COL6-related myopathies. This autophagic impairment causes an accumulation of dysfunctional mitochondria, which in turn leads to myofiber degeneration. Our previous work showed that reactivation of autophagy in COL6-related myopathies is beneficial for muscle structure and function both in the animal model and in patients. Here we show that pterostilbene (Pt)-a non-toxic polyphenol, chemically similar to resveratrol but with a higher bioavailability and metabolic stability-strongly promotes in vivo autophagic flux in the skeletal muscle of both wild-type and COL6 null mice. Reactivation of autophagy in COL6-deficient muscles was also paralleled by several beneficial effects, including significantly decreased incidence of spontaneous apoptosis, recovery of ultrastructural defects and muscle remodeling. These findings point at Pt as an effective autophagy-inducing nutraceutical for skeletal muscle with great potential in counteracting the major pathogenic hallmarks of COL6-related myopathies, a valuable feature that may be also beneficial in other muscle pathologies characterized by defective regulation of the autophagic machinery.

Browning Effects of a Chronic Pterostilbene Supplementation in Mice Fed a High-Fat Diet

Obesity and related comorbidities are a major health concern. The drugs used to treat these conditions are largely inadequate or dangerous, and a well-researched approach based on nutraceuticals would be highly useful. Pterostilbene (Pt), i.e., 3,5-dimethylresveratrol, has been reported to be effective in animal models of obesity, acting on different metabolic pathways. We investigate here its ability to induce browning of white adipose tissue. Pt (5 µM) was first tested on 3T3-L1 mature adipocytes, and then it was administered (352 µmol/kg/day) to mice fed an obesogenic high-fat diet (HFD) for 30 weeks, starting at weaning. In the cultured adipocytes, the treatment elicited a significant increase of the levels of Uncoupling Protein 1 (UCP1) protein—a key component of thermogenic, energy-dissipating beige/brown adipocytes. In vivo administration antagonized weight increase, more so in males than in females. Analysis of inguinal White Adipose Tissue (WAT) revealed a trend towards browning, with significantly increased transcription of several marker genes (Cidea, Ebf2, Pgc1α, PPARγ, Sirt1, and Tbx1) and an increase in UCP1 protein levels, which, however, did not achieve significance. Given the lack of known side effects of Pt, this study strengthens the candidacy of this natural phenol as an anti-obesity nutraceutical.

Anticonvulsant Activity of Pterostilbene in Zebrafish and Mouse Acute Seizure Tests

Pterostilbene (PTE), a natural dimethylated analog of resveratrol, possesses numerous health-beneficial properties. The ability of PTE to cross the blood–brain barrier raised the possibility that this compound may modulate central nervous system functions, including seizure activity. The aim of our study was to investigate the activity of PTE in the larval zebrafish pentylenetetrazole (PTZ) seizure assay and three acute seizure tests in mice, i.e., in the maximal electroshock seizure threshold (MEST), 6 Hz-induced psychomotor seizure threshold and intravenous (iv) PTZ tests. Additionally, potential antidepressant activity of PTE was estimated in the forced swim test in mice. The chimney test was used to determine the influence of PTE on motor coordination in mice, while its influence on neuromuscular strength was assessed in the grip strength test in mice. Locomotor activity was determined to verify the results from the forced swim test. PTE revealed an evident anticonvulsant effect both in zebrafish larvae (10 µM; 2 h-incubation) and mice (at doses of 100 and 200 mg/kg, intraperitoneally) but it did not exhibit antidepressant potential in the forced swim test. Furthermore, it did not cause any statistically significant changes in motor coordination, neuromuscular strength and locomotor activity in mice. In conclusion, our present findings demonstrate for the first time the anticonvulsant potential of PTE. The aforementioned results suggest that it might be employed in epilepsy treatment, however, further precise studies are required to verify its activity in other experimental seizure and epilepsy models and its precise mechanism of action should be determined.

Efficacy and tolerability of EH301 for amyotrophic lateral sclerosis: a randomized, double-blind, placebo-controlled human pilot study

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease, characterized by progressive loss of spinal and cortical motor neurons, leading to muscular atrophy, respiratory failure, and ultimately death. There is no known cure, and the clinical benefit of the two drugs approved to treat ALS remains unclear. Novel disease-modifying therapeutics that are able to modulate the disease course are desperately needed. Our objective was to evaluate the efficacy and tolerability of Elysium Health's candidate drug EH301 in people with ALS (PALS).

METHODS

This was a single-center, prospective, double-blind, randomized, placebo-controlled pilot study. Thirty-two PALS were recruited thanks to the collaboration of the Spanish Foundation for ALS Research (FUNDELA). Study participants were randomized to receive either EH301 or placebo and underwent evaluation for 4 months. Differences between EH301 and placebo-treated participants were evaluated based on standard clinical endpoints, including the revised ALS functional rating scale (ALSFRS-R), forced vital capacity (FVC), and the Medical Research Council (MRC) grading scale.

RESULTS

Compared to placebo, participants treated with EH301 demonstrated significant improvements in the ALSFRS-R score, pulmonary function, muscular strength, and in skeletal muscle/fat weight ratio. EH301 was shown to significantly slow the progression of ALS relative to placebo, and even showed improvements in several key outcome measures compared with baseline.

CONCLUSIONS

This study provides evidence in support of the disease-modifying effects of EH301 for the treatment of ALS.

Use of generally recognized as safe or dietary compounds to inhibit buprenorphine metabolism: potential to improve buprenorphine oral bioavailability

The present study evaluated the potential of five generally recognized as safe (GRAS) or dietary compounds (α-mangostin, chrysin, ginger extract, pterostilbene and silybin) to inhibit oxidative (CYP) and conjugative (UGT) metabolism using pooled human intestinal and liver microsomes. Buprenorphine was chosen as the model substrate as it is extensively metabolized by CYPs to norbuprenorphine and by UGTs to buprenorphine glucuronide. Chrysin, ginger extract, α-mangostin, pterostilbene and silybin were tested for their inhibition of the formation of norbuprenorphine or buprenorphine glucuronide in both intestinal and liver microsomes. Pterostilbene was the most potent inhibitor of norbuprenorphine formation in both intestinal and liver microsomes, with IC50 values of 1.3 and 0.8 μM, respectively, while α-mangostin and silybin most potently inhibited buprenorphine glucuronide formation. The equipotent combination of pterostilbene and ginger extract additively inhibited both pathways in intestinal microsomes. Since pterostilbene and ginger extract showed potent CYP and/or UGT inhibition of buprenorphine metabolism, their equipotent combination was tested to assess the presence of synergistic inhibition. However, because the combination showed additive inhibition, it was not used while performing IVIVE analysis. Based on quantitative in vitro-in vivo extrapolation, pterostilbene (21 mg oral dose) appeared to be most effective in improving the mean predicted Foral and AUC∞ PO of buprenorphine from 3 ± 2% and 340 ± 330 ng*min/ml to 75 ± 8% and 36,000 ± 25,000 ng*min/ml, respectively. At a 10-fold lower dose of pterostilbene, the predicted buprenorphine Foral approximated sublingual bioavailability (~35%) and showed a 2-4 fold reduction in the variability around the predicted AUC∞ PO of buprenorphine. These results demonstrate the feasibility of using various GRAS/dietary compounds to inhibit substantially the metabolism by CYP and UGT enzymes to achieve higher and less variable oral bioavailability. This inhibitor strategy may be useful for drugs suffering from low and variable oral bioavailability due to extensive presystemic oxidative and/or conjugative metabolism.

Protective effect of pterostilbene on concanavalin A-induced acute liver injury

Pterostilbene (PTE) is broadly found in berries and has antioxidant and anti-inflammatory properties.

Effects of generally recognized as safe (GRAS) and dietary compounds on phenylephrine metabolism in LS180 human intestinal cells

Phenylephrine (PE) has low and variable oral bioavailability in humans, due in part to presystemic metabolism by sulfation. LS180 cells were used as a model of the human intestinal epithelium to examine phenylephrine metabolism and its inhibition by generally recognized as safe (GRAS) and dietary compounds. Curcumin, zingerone, resveratrol, guaiacol, pterostilbene and isoeugenol significantly inhibited phenylephrine disappearance, while vanillin, propylparaben and eugenol did not. However, when propylparaben was combined with either vanillin or eugenol, the phenylephrine disappearance was significantly inhibited. These data suggest that these compounds or combinations thereof may have potential to improve phenylephrine oral bioavailability.

Colon targeted beads loaded with pterostilbene: Formulation, optimization, characterization and in vivo evaluation

Background

Pterostilbene has a proven chemopreventive effect for colon carcinogenesis but suffers low bioavailability limitations and therefore unable to reach the colonic tissue.

Objective and methodology

To overcome the issue of low bioavailability, pterostilbene was formulated into an oral colon targeted beads by ionic gelation method using pectin and zinc acetate. Optimization was carried out by 2³ factorial design whereby the effect of pectin concentration (X₁), zinc acetate concentration (X₂) and pterostilbene:pectin ratio (X₃) were studied on entrapment efficiency (Y₁) and in vitro drug release till 24 h (Y₂). The optimized beads were characterized for shape and size, swelling and surface morphology. The optimized beads were uniformly coated with Eudragit S-100 using fluidized bed coater. Optimized coated beads were characterized for in vitro drug release till 24 h and surface morphology. Pharmacokinetic and organ distribution study were performed in rats to ascertain the release of pterostilbene in colon.

Results

The optimized formulation comprised of 2% w/v of pectin concentration (X₁), 2% w/v of zinc acetate concentration (X₂) and 1:4 of pterostilbene:pectin ratio (X₃), which showed a satisfactory entrapment efficiency (64.80%) and in vitro release (37.88%) till 24 h. The zinc pectinate beads exhibited sphericity, uniform size distribution, adequate swelling and rough surface. The optimized coated beads achieved 15% weight gain, displayed smooth surface and optimum drug release. Pterostilbene from optimized coated beads appeared in the plasma at 14 h and reached the C_max at 22 h (T_max), whereas plain pterostilbene exhibited T_max of 3 h.

Discussion and conclusion

Thus, larger distribution of pterostilbene was obtained in the colonic tissue compared to stomach and small intestinal tissues. Thus, delayed T_max and larger distribution of pterostilbene in colonic tissue confirmed the targeting of beads to colon.

Tumor-reducing effect of the clinically used drug clofazimine in a SCID mouse model of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) represents the most common form of pancreatic cancer with rising incidence in developing countries. Unfortunately, the overall 5-year survival rate is still less than 5%. The most frequent oncogenic mutations in PDAC are loss-of function mutations in p53 and gain-of-function mutations in KRAS. Here we show that clofazimine (Lamprene), a drug already used in the clinic for autoimmune diseases and leprosy, is able to efficiently kill in vitro five different PDAC cell lines harboring p53 mutations. We provide evidence that clofazimine induces apoptosis in PDAC cells with an EC₅₀ in the μM range via its specific inhibitory action on the potassium channel Kv1.3. Intraperitoneal injection of clofazimine resulted in its accumulation in the pancreas of mice 8 hours after administration. Using an orthotopic PDAC xenotransplantation model in SCID beige mouse, we show that clofazimine significantly and strongly reduced the primary tumor weight. Thus, our work identifies clofazimine as a promising therapeutic agent against PDAC and further highlights ion channels as possible oncological targets.

Targeting MTA1/HIF-1α signaling by pterostilbene in combination with histone deacetylase inhibitor attenuates prostate cancer progression

The metastasis‐associated protein 1(MTA1)/histone deacetylase (HDAC) unit is a cancer progression‐related epigenetic regulator, which is overexpressed in hormone‐refractory and metastatic prostate cancer (PCa). In our previous studies, we found a significantly increased MTA1 expression in a prostate‐specific Pten‐null mouse model. We also demonstrated that stilbenes, namely resveratrol and pterostilbene (Pter), affect MTA1/HDAC signaling, including deacetylation of tumor suppressors p53 and PTEN. In this study, we examined whether inhibition of MTA1/HDAC using combination of Pter and a clinically approved HDAC inhibitor, SAHA (suberoylanilide hydroxamic acid, vorinostat), which also downregulates MTA1, could block prostate tumor progression in vivo. We generated and utilized a luciferase reporter in a prostate‐specific Pten‐null mouse model (Pb‐Cre⁺; Pten^f/f; Rosa26^Luc/+) to evaluate the anticancer efficacy of Pter/SAHA combinatorial approach. Our data showed that Pter sensitized tumor cells to SAHA treatment resulting in inhibiting tumor growth and additional decline of tumor progression. These effects were dependent on the reduction of MTA1‐associated proangiogenic factors HIF‐1α, VEGF, and IL‐1β leading to decreased angiogenesis. In addition, treatment of PCa cell lines in vitro with combined Pter and low dose SAHA resulted in more potent inhibition of MTA1/HIF‐1α than by high dose SAHA alone. Our study provides preclinical evidence that Pter/SAHA combination treatment inhibits MTA1/HIF‐1α tumor‐promoting signaling in PCa. The beneficial outcome of combinatorial strategy using a natural agent and an approved drug for higher efficacy and less toxicity supports further development of MTA1‐targeted therapies in PCa.

Potent Inhibition of HIV-1 Replication in Resting CD4 T Cells by Resveratrol and Pterostilbene

HIV-1 infection of resting CD4 T cells plays a crucial and numerically dominant role during virus transmission at mucosal sites and during subsequent acute replication and T cell depletion. Resveratrol and pterostilbene are plant stilbenoids associated with several health-promoting benefits. Resveratrol has been shown to inhibit the replication of several viruses, including herpes simplex viruses 1 and 2, papillomaviruses, severe acute respiratory syndrome virus, and influenza virus. Alone, resveratrol does not inhibit HIV-1 infection of activated T cells, but it does synergize with nucleoside reverse transcriptase inhibitors in these cells to inhibit reverse transcription. Here, we demonstrate that resveratrol and pterostilbene completely block HIV-1 infection at a low micromolar dose in resting CD4 T cells, primarily at the reverse transcription step. The anti-HIV effect was fully reversed by exogenous deoxynucleosides and Vpx, an HIV-1 and simian immunodeficiency virus protein that increases deoxynucleoside triphosphate (dNTP) levels. These findings are consistent with the reported ability of resveratrol to inhibit ribonucleotide reductase and to lower dNTP levels in cells. This study supports the potential use of resveratrol, pterostilbene, or related compounds as adjuvants in anti-HIV preexposure prophylaxis (PrEP) formulations.

Resveratrol derivatives as a pharmacological tool

Prodrugs of resveratrol are under development. Among the long-term goals, still largely elusive, are (1) modulating physical properties (e.g., water-soluble derivatives bearing polyethylene glycol chains), (2) changing distribution in the body (e.g., galactosyl derivatives restricted to the intestinal lumen), (3) increasing absorption from the gastrointestinal tract (e.g., derivatives imitating the natural substrates of endogenous transporters), and (4) hindering phase II metabolism (e.g., temporarily blocking the hydroxyls), all contributing to (5) increasing bioavailability. The chemical bonds that have been tested for functionalization include carboxyester, acetal, and carbamate groups. A second approach, which can be combined with the first, seeks to reinforce or modify the biochemical activities of resveratrol by concentrating the compound at specific subcellular sites. An example is provided by mitochondria-targeted derivatives. These proved to be pro-oxidant and cytotoxic in vitro, selectively killing fast-growing and tumor cells when supplied in the low micromolar range. This suggests the possibility of anticancer applications.

Resveratrol and pterostilbene as a microRNA-mediated chemopreventive and therapeutic strategy in prostate cancer

Growing evidence indicates that deregulation of the epigenetic machinery comprising the microRNA (miRNA) network is a critical factor in the progression of various diseases, including cancer. Concurrently, dietary phytochemicals are being intensively studied for their miRNA-mediated health-beneficial properties, such as anti-inflammatory, cardioprotective, antioxidative, and anticancer properties. Available experimental data have suggested that dietary polyphenols may be effective miRNA-modulating chemopreventive and therapeutic agents. Moreover, noninvasive detection of changes in miRNA expression in liquid biopsies opens enormous possibilities for their clinical utilization as novel prognostic and predictive biomarkers. In our published studies, we identified resveratrol-regulated miRNA profiles in prostate cancer. Resveratrol downregulated the phosphatase and tensin homolog (PTEN)-targeting members of the oncogenic miR-17 family of miRNAs, which are overexpressed in prostate cancer. We have functionally validated the miRNA-mediated ability of resveratrol and its potent analog pterostilbene to rescue the tumor suppressor activity of PTEN in vitro and in vivo. Taken together, our findings implicate the use of resveratrol and its analogs as an attractive miRNA-mediated chemopreventive and therapeutic strategy in prostate cancer and the use of circulating miRNAs as potential predictive biomarkers for clinical development.

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.

Direct Pharmacological Targeting of a Mitochondrial Ion Channel Selectively Kills Tumor Cells In Vivo

The potassium channel Kv1.3 is highly expressed in the mitochondria of various cancerous cells. Here we show that direct inhibition of Kv1.3 using two mitochondria-targeted inhibitors alters mitochondrial function and leads to reactive oxygen species (ROS)-mediated death of even chemoresistant cells independently of p53 status. These inhibitors killed 98% of ex vivo primary chronic B-lymphocytic leukemia tumor cells while sparing healthy B cells. In orthotopic mouse models of melanoma and pancreatic ductal adenocarcinoma, the compounds reduced tumor size by more than 90% and 60%, respectively, while sparing immune and cardiac functions. Our work provides direct evidence that specific pharmacological targeting of a mitochondrial potassium channel can lead to ROS-mediated selective apoptosis of cancer cells in vivo, without causing significant side effects.

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.

Biological actions and molecular effects of resveratrol, pterostilbene, and 3'-hydroxypterostilbene

Stilbenes are a class of polyphenolic compounds, naturally found in a wide variety of dietary sources such as grapes, berries, peanuts, red wine, and some medicinal plants. There are several well-known stilbenes including trans-resveratrol, pterostilbene, and 3′-hydroxypterostilbene. The core chemical structure of stilbene compounds is 1,2-diphenylethylene. Recently, stilbenes have attracted extensive attention and interest due to their wide range of health-beneficial effects such as anti-inflammation, -carcinogenic, -diabetes, and -dyslipidemia activities. Moreover, accumulating in vitro and in vivo studies have reported that stilbene compounds act as inducers of multiple cell-death pathways such as apoptosis, cell cycle arrest, and autophagy for chemopreventive and chemotherapeutic agents in several types of cancer cells. The aim of this review is to highlight recent molecular findings and biological actions of trans-resveratrol, pterostilbene, and 3′-hydroxypterostilbene.

Resveratrol and pterostilbene epigenetically restore PTEN expression by targeting oncomiRs of the miR-17 family in prostate cancer

In recent years, not only has the role of miRNAs in cancer become increasingly clear but also their utilization as potential biomarkers and therapeutic targets has gained ground. Although the importance of dietary stilbenes such as resveratrol and pterostilbene as anti-cancer agents is well recognized, our understanding of their miRNA-targeting capabilities is still limited. In our previous study, we reported that resveratrol downregulates PTEN-targeting members of the oncogenic miR-17 family, which are overexpressed in prostate cancer. This study investigates the resveratrol and pterostilbene induced miRNA-mediated regulation of PTEN in prostate cancer. Here, we show that both compounds decrease the levels of endogenous as well as exogenously expressed miR-17, miR-20a and miR-106b thereby upregulating their target PTEN. Using functional luciferase reporter assays, we demonstrate that ectopically expressed miR-17, miR-20a and miR-106b directly target PTEN 3′UTR to reduce its expression, an effect rescued upon treatment with resveratrol and pterostilbene. Moreover, while stable lentiviral expression of miR-17/106a significantly decreased PTEN mRNA and protein levels and conferred survival advantage to the cells, resveratrol and more so pterostilbene was able to dramatically suppress these effects. Further, pterostilbene through downregulation of miR-17-5p and miR-106a-5p expression both in tumors and systemic circulation, rescued PTEN mRNA and protein levels leading to reduced tumor growth in vivo. Our findings implicate dietary stilbenes as an attractive miRNA-mediated chemopreventive and therapeutic strategy, and circulating miRNAs as potential chemopreventive and predictive biomarkers for clinical development in prostate cancer.

Pterostilbene Decreases the Antioxidant Defenses of Aggressive Cancer Cells In Vivo: A Physiological Glucocorticoids- and Nrf2-Dependent Mechanism

AIMS

Polyphenolic phytochemicals have anticancer properties. However, in mechanistic studies, lack of correlation with the bioavailable concentrations is a critical issue. Some reports had suggested that these molecules downregulate the stress response, which may affect growth and the antioxidant protection of malignant cells. Initially, we studied this potential underlying mechanism using different human melanomas (with genetic backgrounds correlating with most melanomas), growing in nude mice as xenografts, and pterostilbene (Pter, a natural dimethoxylated analog of resveratrol).

RESULTS

Intravenous administration of Pter decreased human melanoma growth in vivo. However, Pter, at levels measured within the tumors, did not affect melanoma growth in vitro. Pter inhibited pituitary production of the adrenocorticotropin hormone (ACTH), decreased plasma levels of corticosterone, and thereby downregulated the glucocorticoid receptor- and nuclear factor (erythroid-derived 2)-like 2 (Nrf2)-dependent antioxidant defense system in growing melanomas. Exogenous corticosterone or genetically induced Nrf2 overexpression in melanoma cells prevented the inhibition of tumor growth and decreased antioxidant defenses in these malignant cells. These effects and mechanisms were also found in mice bearing different human pancreatic cancers. Glutathione depletion (selected as an antimelanoma strategy) facilitated the complete elimination by chemotherapy of melanoma cells isolated from mice treated with Pter.

INNOVATION

Although bioavailability-related limitations may preclude direct anticancer effects in vivo, natural polyphenols may also interfere with the growth and defense of cancer cells by downregulating the pituitary gland-dependent ACTH synthesis.

CONCLUSIONS

Pter downregulates glucocorticoid production, thus decreasing the glucocorticoid receptor and Nrf2-dependent signaling/transcription and the antioxidant protection of melanoma and pancreatic cancer cells. Antioxid. Redox Signal. 24, 974-990.

Dietary pterostilbene is a novel MTA1-targeted chemopreventive and therapeutic agent in prostate cancer

Overexpression of the epigenetic modifier metastasis-associated protein 1 (MTA1) is associated with aggressive human prostate cancer. The purpose of this study was to determine MTA1- targeted chemopreventive and therapeutic efficacy of pterostilbene, a natural potent analog of resveratrol, in pre-clinical models of prostate cancer. Here, we show that high levels of MTA1 expression in Pten-loss prostate cooperate with key oncogenes, including c-Myc and Akt among others, to promote prostate cancer progression. Loss-of-function studies using human prostate cancer cells indicated direct involvement of MTA1 in inducing inflammation and epithelial-to-mesenchymal transition. Importantly, pharmacological inhibition of MTA1 by pterostilbene resulted in decreased proliferation and angiogenesis and increased apoptosis. This restrained prostatic intraepithelial neoplasia (PIN) formation in prostate-specific Pten heterozygous mice and reduced tumor development and progression in prostate-specific Pten-null mice. Our findings highlight MTA1 as a key upstream regulator of prostate tumorigenesis and cancer progression. More significantly, it offers pre-clinical proof for pterostilbene as a promising lead natural agent for MTA1-targeted chemopreventive and therapeutic strategy to curb prostate cancer.

Effects of polyphenols including curcuminoids, resveratrol, quercetin, pterostilbene, and hydroxypterostilbene on lymphocyte pro-inflammatory cytokine production of senior horses in vitro

Senior horses (aged ≥ 20 years) exhibit increased chronic, low-grade inflammation systemically, termed inflamm-aging. Inflammation is associated with many afflictions common to the horse, including laminitis and osteoarthritis, which are commonly treated with the non-steroidal anti-inflammatory drugs (NSAIDs) flunixin meglumine and phenylbutazone. Although these NSAIDs are effective in treating acute inflammatory problems, long-term treatment with NSAIDs can result in negative side effects. Thus, bioactive polyphenols including curcuminoids, resveratrol, quercetin, pterostilbene, and hydroxypterostilbene were investigated to determine their effectiveness as anti-inflammatory agents in vitro. Heparinized blood was collected via jugular venipuncture from senior horses (n = 6; mean age = 26 ± 2 years), and peripheral blood mononuclear cells (PBMC) were isolated using a Ficoll density gradient. PBMC were then incubated 22 h at 37°C, 5% CO2 with multiple concentrations (320, 160, 80, 40, 20, 10 μM) of all five polyphenols (curcuminoids, resveratrol, quercetin, pterostilbene, and hydroxypterostilbene), dissolved in DMSO to achieve the aforementioned concentrations. PBMC were stimulated the last 4h of the incubation period with phorbol 12-myristate 13-acetate (PMA)/ionomycin and Brefeldin A (BFA). A Vicell-XR counter evaluated cell viability following incubation. PBMC were stained intracellularly for interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α) and analyzed via flow cytometry. Data was analyzed by one-way analysis of variance (ANOVA). Viability of PBMC incubated with various compound concentrations were compared with PBMC incubated with DMSO alone (positive control) to determine at what concentration each compound caused cytotoxicity. The highest concentration at which cell viability did not significantly differ from the positive control was: 20 μM for curcuminoids, 40 μM for hydroxypterostilbene, 80 μM for pterostilbene, and 160 μM for quercetin and resveratrol. Flunixin meglumine and phenylbutazone were then evaluated within this range of optimal concentrations for the polyphenol compounds (160, 80, 40, 20 μM) to compare the polyphenols to NSAIDs at equivalent concentrations. The highest concentration at which viability did not significantly differ from the positive control was: 40 μM for flunixin meglumine and 160 μM for phenylbutazone. All five polyphenols and flunixin meglumine significantly decreased lymphocyte production of IFN-γ, while only hydroxypterostilbene, pterostilbene, quercetin, and resveratrol significantly reduced lymphocyte production of TNF-α compared to the positive control (p < 0.05). Polyphenols performed similarly to or more effectively than common NSAIDs in reducing lymphocyte production of inflammatory cytokines of the senior horse in vitro. This study therefore supports the further investigation of polyphenols to determine whether they may be effective anti-inflammatory treatments for chronic inflammation in the horse.

Role of Natural Stilbenes in the Prevention of Cancer

Natural stilbenes are an important group of nonflavonoid phytochemicals of polyphenolic structure characterized by the presence of a 1,2-diphenylethylene nucleus. Stilbenes have an extraordinary potential for the prevention and treatment of different diseases, including cancer, due to their antioxidant, cell death activation, and anti-inflammatory properties which associate with low toxicity under in vivo conditions. This review aims to discuss various approaches related to their mechanisms of action, pharmacological activities in animal models and humans, and potential chemoprevention in clinical studies. The biological activity of natural stilbenes is still incompletely understood. Furthermore, after administration to animals or humans, these molecules are rapidly metabolized. Thus pharmacokinetics and/or activities of the natural structures and their metabolites may be very different. Novel drug formulations have been postulated in order to improve stability and bioavailability, to minimize side effects, and to facilitate interaction with their domains in target proteins. These pharmacological improvements should lead stilbenes to become effective candidates as anticancer drugs.

Pterostilbene exerts an anti-inflammatory effect via regulating endoplasmic reticulum stress in endothelial cells

Pterostilbene (PT), an analog of resveratrol, exerts a potent anti-inflammatory effect. However, the protective effects of PT against inflammation in endothelial cells have not been elucidated. Previous studies have confirmed that endoplasmic reticulum stress (ERS) plays an important role in regulating the pathological process of endothelial cell inflammation. In this study, we explored the effect of PT on the tumor necrosis factor-α (TNF-α)-induced inflammatory response in human umbilical vein endothelial cells (HUVECs) and elaborated the role of ERS in this process. TNF-α treatment significantly upregulated the levels of inflammation-related molecules in cell culture media, increased the adhesion of monocytes to HUVECs, and enhanced the expression of the MMP9 and ICAM proteins in HUVECs. Additionally, TNF-α potently increased ERS-related protein levels, such as GRP78 and p-eIF2α. However, PT treatment reversed the increased production of inflammatory cytokines and the adhesion of monocytes to HUVECs, as well as reduced the TNF-α-induced effects exerted by ERS-related molecules. Furthermore, thapsigargin (THA), an ERS inducer, attenuated the protective effect of PT against TNF-α-induced inflammation and ERS in HUVECs. Additionally, the downregulation of ERS signaling using siRNA targeting eIF2α and IRE1 not only inhibited ERS-related molecules but also simulated the therapeutic effects of PT on TNF-α-induced inflammation. In summary, PT treatment potently attenuates inflammation in vascular endothelial cells, which at least partly depends on the reduction of ERS.

Amino Acid Carbamates As Prodrugs Of Resveratrol

Resveratrol (3, 5, 4′-trihydroxy-trans-stilbene), a plant polyphenol, has important drug-like properties, but its pharmacological exploitation in vivo is hindered by its rapid transformation via phase II conjugative metabolism. One approach to bypass this problem relies on prodrugs. We report here the synthesis, characterization, stability and in vivo pharmacokinetic behaviour of prodrugs of resveratrol in which the OH groups are engaged in an N-monosubstituted carbamate ester (-OC(O)NHR) linkage with a natural amino acid (Leu, Ile, Phe, Thr) to prevent conjugation and modulate the physicochemical properties of the molecule. We also report a convenient, high-yield protocol to obtain derivatives of this type. The new carbamate ester derivatives are stable at pH 1, while they undergo slow hydrolysis at physiological pH and hydrolyse with kinetics suitable for use in prodrugs in whole blood. After administration to rats by oral gavage the isoleucine-containing prodrug was significantly absorbed, and was present in the bloodstream as non-metabolized unaltered or partially deprotected species, demonstrating effective shielding from first-pass metabolism. We conclude that prodrugs based on the N-monosubstituted carbamate ester bond have the appropriate stability profile for the systemic delivery of phenolic compounds.

Epigenetic potential of resveratrol and analogs in preclinical models of prostate cancer

Lifestyle, particularly diet, is a risk factor for prostate cancer. Dietary polyphenols such as resveratrol possess anticancer properties and therefore have chemopreventive and therapeutic potential. Resveratrol has pleiotropic effects, exerting its biological activity through multiple pathways and targets, including those associated with cancer. Numerous studies have demonstrated the anticancer effects of resveratrol and, to a lesser extent, its analogs, in tissue culture, while in vivo observations are limited. Here, we provide a concise summary of our results on epigenetic mechanisms of resveratrol and analogs mediated through regulation of chromatin modifier metastasis-associated protein 1 (MTA1) and microRNAs (miRNAs), and highlight the anticancer effects of these compounds in preclinical models of prostate cancer. We suggest that the identified stilbene responsive mechanism-based biomarkers, such as MTA1 and oncogenic miRNAs, may become indicative of treatment efficacy in prostate cancer. Resveratrol analogs with better bioavailability, conferring superior pharmacological potencies and greater anticancer effects, may become stronger candidates for clinical development.

Topical treatment with pterostilbene, a natural phytoalexin, effectively protects hairless mice against UVB radiation-induced skin damage and carcinogenesis

The aim of our study was to investigate in the SKH-1 hairless mouse model the effect of pterostilbene (Pter), a natural dimethoxy analog of resveratrol (Resv), against procarcinogenic ultraviolet B radiation (UVB)-induced skin damage. Pter prevented acute UVB (360 mJ/cm(2))-induced increase in skin fold, thickness, and redness, as well as photoaging-associated skin wrinkling and hyperplasia. Pter, but not Resv, effectively prevented chronic UVB (180 mJ/cm(2), three doses/week for 6 months)-induced skin carcinogenesis (90% of Pter-treated mice did not develop skin carcinomas, whereas a large number of tumors were observed in all controls). This anticarcinogenic effect was associated with (a) maintenance of skin antioxidant defenses (i.e., glutathione (GSH) levels, catalase, superoxide, and GSH peroxidase activities) close to control values (untreated mice) and (b) an inhibition of UVB-induced oxidative damage (using as biomarkers 8-hydroxy-2'-deoxyguanosine, protein carbonyls, and isoprostanes). The molecular mechanism underlying the photoprotective effect elicited by Pter was further evaluated using HaCaT immortalized human keratinocytes and was shown to involve potential modulation of the Nrf2-dependent antioxidant response.