Inhibitory effects of resveratrol and pterostilbene on human colon cancer cells: a side-by-side comparison

The Inhibitory Effects of the Natural Stilbene Piceatannol on Lactate Transport In Vitro Mediated by Monocarboxylate Transporters

SCOPE

Lactate, a signaling molecule and energy source, crosses membranes through monocarboxylate transporters (MCTs). MCT1 and MCT4 are potential cancer drug targets due to their role in metabolic reprogramming of cancer cells. Stilbenes, plant secondary metabolites found in several food sources, have anticancer effects, though their mechanisms of action are not well understood. This study links the anticancer activity of natural stilbenes to tumor cell lactate metabolism.

METHODS AND RESULTS

The impact of resveratrol, pinostilbene, pterostilbene, rhapontigenin, and piceatannol on lactate transport is studied using a fluorescence resonance energy transfer (FRET)-based lactate sensor. The viability and migration of cells expressing MCT1 or MCT4 are also evaluated. Piceatannol inhibits MCT1 effectively at low micromolar concentrations, with less effect on MCT4. All stilbenes significantly reduce cell viability and migration.

CONCLUSIONS

These findings indicate that both MCTs are stilbene targets, with piceatannol highlighted as a cost-effective, low-toxicity compound for studying MCTs in cancer, providing a new mechanism of action of the therapeutic and nutraceutical effects of natural polyphenols. This enriches the understanding of dietary polyphenols in cancer prevention and therapy.

Stilbenoid derivatives as potent inhibitors of HIF-1α-centric cancer metabolism under hypoxia

Hypoxia-inducible factor (HIF)-1α is a crucial transcription factor associated with cancer metabolism and is regarded as a potent anticancer therapeutic strategy within the hypoxic microenvironment of cancer. In this study, stilbenoid derivatives were designed, synthesized, and assessed for their capacity to inhibit HIF-1α-associated cancer metabolism and evaluated for inhibition of cancer cell viability and HIF activation. Through the structure-activity relationship studies, compound 28e was identified as the most potent derivative. Specifically, under the hypoxic condition, 28e reduced the accumulation of HIF-1α protein and the expression of its target genes related to glucose metabolism without affecting the expression of HIF-1α mRNA. Furthermore, 28e inhibited glucose uptake, glycolytic metabolism, and mitochondrial respiration, decreasing cellular ATP production under hypoxic conditions. In addition, 28e displayed significant anti-tumor effects and effectively suppressed the accumulation of HIF-1α protein in tumor tissue in vivo xenograft model. These findings suggest that our stilbenoid derivatives exert their anticancer effects by targeting HIF-1α-centered cancer metabolism under hypoxic conditions.

Pterostilbene upregulates MICA/B via the PI3K/AKT signaling pathway to enhance the capability of natural killer cells to kill cervical cancer cells

Natural killer (NK) cells are triggered by the innate immune response in the tumor microenvironment. The extensive set of stimulating and inhibiting receptors mediates the target recognition of NK cells, and controls the strength of the effector reaction countering specific targeted cells. Yet, lacking major MHC (histocompatibility complex) MICA/B class I chain-related proteins on the membrane of tumor cells results in the failure of NK cell recognition and ability to resist NK cell destruction. Searching databases and molecular docking suggested that in cervical cancer, pterostilbene (3,5-dimethoxy-40-hydroxystilbene; PTS) in Vaccinium corymbosum extract could constrain PI3K/AKT signaling and improving the MICA/B expression. In flow cytometry, MTT assay, viability/cytotoxicity assay, and colony development assays, PTS reduced the development of cervical cancer cells and increased apoptosis. The quantitative real-time PCR (qRT-PCR) and a Western blot indicate that PTS controlled the cytolytic action of NK cells in tumor cells via increasing the MICA/B expression, thus modifying the anti-tumor immune response in cervical cancer.

Molecular Dynamics Simulations of Selected Amorphous Stilbenoids and Their Amorphous Solid Dispersions with Poly(Vinylpyrrolidone)

Amorphous solid dispersions (ASDs) are one of the promising strategies to improve the solubility and dissolution rate of poorly soluble compounds. In this study, Molecular Dynamics simulations were used to investigate the interactions between three selected stilbenoids with important biological activity (resveratrol, pinostilbene and pterostilbene) and poly(vinylpyrrolidone). The analysis of the pair distribution functions and hydrogen bond distributions reveals a significant weakening of the hydrogen bond network of the stilbenoids in ASDs compared to the pure (no polymer) amorphous systems. This is accompanied by an increase in the mobility of the stilbenoid molecules in the ASDs, both in the translational dynamics determined from the molecular mean square displacements, and in the molecular reorientations followed by analysing several torsional distributions.

Cigarette smoke induces epithelial-to-mesenchymal transition, stemness, and metastasis in lung adenocarcinoma cells via upregulated RUNX-2/galectin-3 pathway

AIMS

An elevated level of galectin-3, a carbohydrate-binding lectin implicated in tumorigenesis, metastasis, and epithelial-mesenchymal transition (EMT), has been found in cigarette smokers. However, the regulation of its expression and role in the pathogenesis of CS-induced EMT and lung cancer metastasis is unclear. Here, we have investigated the mechanism of CS-induced and galectin-3-mediated EMT in airway epithelial cells (AECs).

MAIN METHODS

A549 adenocarcinoma cells and primary small airway epithelial cells cultured on an air-liquid interface (ALI) were exposed to cigarette smoke extract (CSE), and MTT, trypan blue, migration, invasion, tumor spheroid and colony formation assays were performed to assess EMT phenotype. Immunoblotting was performed to assess EMT and stemness markers and other regulatory proteins.

KEY FINDINGS

CSE exposure affected cell survival and morphology, migration, invasion, and clonogenicity of AECs, which were concomitant with an increase in the expression of EMT markers, galectin-3, and runt-related transcription factor-2 (RUNX-2), an osteogenic transcription factor and upstream regulator of galectin-3. Chemical inhibition or silencing of RUNX-2 downregulated galectin-3 and modulated EMT marker expression, migration, invasion, and clonogenicity in CSE-exposed AECs. Recombinant human galectin-3 also induced EMT and stemness-associated changes in the AECs, and GB1107, a galectin-3 inhibitor, ameliorated these changes. Further, CSE-induced intracellular ROS enabled an increase in RUNX-2 and galectin-3 expression, which were reversed by n-acetyl-cysteine.

SIGNIFICANCE

These results provide a novel mechanistic insight into CSE-induced EMT via RUNX-2/galectin-3 axis mediated through ROS, which promoted EMT-associated changes, including invasion, migration, and stemness in AECs, which could be implicated in CS-induced lung cancer progression.

Pterostilbene-Mediated Inhibition of Cell Proliferation and Cell Death Induction in Amelanotic and Melanotic Melanoma

Melanoma is one of the fastest-growing cancers worldwide. Treatment of advanced melanoma is very difficult; therefore, there is growing interest in the identification of new therapeutic agents. Pterostilbene is a natural stilbene that has been found to have several pharmacological activities. The aim of this study was to evaluate the influence of pterostilbene on the proliferation and apoptosis of human melanoma cells. Proliferation of pterostilbene-treated amelanotic (C32) and melanotic (A2058) melanoma cells was determined by BRDU assay. Flow cytometric analyses were used to determine cell cycle progression, and further molecular investigations were performed using real-time RT-qPCR. The expression of the p21 protein and the DNA fragmentation assay were determined by the ELISA method. The results revealed that pterostilbene reduced the proliferation of both amelanotic and melanotic melanoma cells. Pterostilbene induced apoptosis in amelanotic C32 melanoma cells, and this effect was mediated by an increase in the expression of the BAX, CASP9, and CASP9 genes; induction of caspase 3 activity; and DNA degradation. Pterostilbene did not affect the activation of apoptosis in the A2058 cell line. It may be concluded that pterostilbene has anticancer potential against human melanoma cells; however, more studies are still needed to fully elucidate the effects of pterostilbene on amelanotic and melanotic melanoma cells.

Main Determinants Affecting the Antiproliferative Activity of Stilbenes and Their Gut Microbiota Metabolites in Colon Cancer Cells: A Structure-Activity Relationship Study

trans-Resveratrol can be catabolized by the gut microbiota to dihydroresveratrol, 3,4'-dihydroxy-trans-stilbene, lunularin, and 4-hydroxydibenzyl. These metabolites can reach relevant concentrations in the colon. However, not all individuals metabolize RSV equally, as it depends on their RSV gut microbiota metabotype (i.e., lunularin producers vs. non-producers). However, how this microbial metabolism affects the cancer chemopreventive activity of stilbenes and their microbial metabolites is poorly known. We investigated the structure-antiproliferative activity relationship of dietary stilbenes, their gut microbial metabolites, and various analogs in human cancer (Caco-2 and HT-29) and non-tumorigenic (CCD18-Co) colon cells. The antiproliferative IC₅₀ values of pterostilbene, oxy-resveratrol, piceatannol, resveratrol, dihydroresveratrol, lunularin, 3,4'-dihydroxy-trans-stilbene, pinosylvin, dihydropinosylvin, 4-hydroxy-trans-stilbene, 4-hydroxydibenzyl, 3-hydroxydibenzyl, and 4-trans-stilbenemethanol were calculated. IC₅₀ values were correlated with 34 molecular characteristics by bi- and multivariate analysis. Little or no activity on CCD18-Co was observed, while Caco-2 was more sensitive than HT-29, which was explained by their different capacities to metabolize the compounds. Caco-2 IC₅₀ values ranged from 11.4 ± 10.1 μM (4-hydroxy-trans-stilbene) to 73.9 ± 13.8 μM (dihydropinosylvin). In HT-29, the values ranged from 24.4 ± 11.3 μM (4-hydroxy-trans-stilbene) to 96.7 ± 6.7 μM (4-hydroxydibenzyl). At their IC₅₀, most compounds induced apoptosis and arrested the cell cycle at the S phase, pterostilbene at G₂/M, while 4-hydroxy-trans-stilbene and 3,4'-dihydroxy-trans-stilbene arrested at both phases. Higher Connolly values (larger size) hindered the antiproliferative activity, while a lower pKa1 enhanced the activity in Caco-2, and higher LogP values (more hydrophobicity) increased the activity in HT-29. Reducing the styrene double bond in stilbenes was the most critical feature in decreasing the antiproliferative activity. These results (i) suggest that gut microbiota metabolism determines the antiproliferative effects of dietary stilbenes. Therefore, RSV consumption might exert different effects in individuals depending on their gut microbiota metabotypes associated with RSV metabolism, and (ii) could help design customized drugs with a stilbenoid and (or) dibenzyl core against colorectal cancer.

Combination Anticancer Therapies Using Selected Phytochemicals

Cancer is still one of the most widespread diseases globally, it is considered a vital health challenge worldwide and one of the main barriers to long life expectancy. Due to the potential toxicity and lack of selectivity of conventional chemotherapeutic agents, discovering alternative treatments is a top priority. Plant-derived natural products have high potential in cancer treatment due to their multiple mechanisms of action, diversity in structure, availability in nature, and relatively low toxicity. In this review, the anticancer mechanisms of the most common phytochemicals were analyzed. Furthermore, a detailed discussion of the anticancer effect of combinations consisting of natural product or natural products with chemotherapeutic drugs was provided. This review should provide a strong platform for researchers and clinicians to improve basic and clinical research in the development of alternative anticancer medicines.

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.

Applications of resveratrol in the treatment of gastrointestinal cancer

Natural product compounds have lately attracted interest in the scientific community as a possible treatment for gastrointestinal (GI) cancer, due to their anti-inflammatory and anticancer properties. There are many preclinical, clinical, and epidemiological studies, suggesting that the consumption of polyphenol compounds, which are abundant in vegetables, grains, fruits, and pulses, may help to prevent various illnesses and disorders from developing, including several GI cancers. The development of GI malignancies follows a well-known path, in which normal gastrointestinal cells acquire abnormalities in their genetic composition, causing the cells to continuously proliferate, and metastasize to other sites, especially the brain and liver. Natural compounds with the ability to affect oncogenic pathways might be possible treatments for GI malignancies, and could easily be tested in clinical trials. Resveratrol is a non-flavonoid polyphenol and a natural stilbene, acting as a phytoestrogen with anti-cancer, cardioprotective, anti-oxidant, and anti-inflammatory properties. Resveratrol has been shown to overcome resistance mechanisms in cancer cells, and when combined with conventional anticancer drugs, could sensitize cancer cells to chemotherapy. Several new resveratrol analogs and nanostructured delivery vehicles with improved anti-GI cancer efficacy, absorption, and pharmacokinetic profiles have already been developed. This present review focuses on the in vitro and in vivo effects of resveratrol on GI cancers, as well as the underlying molecular mechanisms of action.

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.

Pterostilbene Promotes Mean Lifespan in Both Male and Female Drosophila Melanogaster Modulating Different Proteins in the Two Sexes

Aging is a multifactorial phenomenon characterized by degenerative processes closely connected to oxidative damage and chronic inflammation. Recently, many studies have shown that natural bioactive compounds are useful in delaying the aging process. In this work, we studied the effects of an in vivo supplementation of the stilbenoid pterostilbene on lifespan extension in Drosophila melanogaster. We found that the average lifespan of flies of both sexes was increased by pterostilbene supplementation with a higher effect in females. The expression of longevity related genes (Sir2, Foxo, and Notch) was increased in both sexes but with different patterns. Pterostilbene counteracted oxidative stress induced by ethanol and paraquat and up-regulated the antioxidant enzymes Ho e Trxr-1 in male but not in female flies. On the other hand, pterostilbene decreased the inflammatory mediators dome and egr only in female flies. Proteomic analysis revealed that pterostilbene modulates 113 proteins in male flies and only 9 in females. Only one of these proteins was modulated by pterostilbene in both sexes: vacuolar H[+] ATPase 68 kDa subunit 2 (Vha68-2) that was strongly down-regulated. These findings suggest a potential role of pterostilbene in increasing lifespan both in male and female flies by mechanisms that seem to be different in the two sexes, highlighting the need to conduct nutraceutical supplementation studies on males and females separately in order to give more reliable results.

Resveratrol and Immune Cells: A Link to Improve Human Health

The use of polyphenols as adjuvants in lowering risk factors for various debilitating diseases has been investigated in recent years due to their possible antioxidant action. Polyphenols represent a fascinating and relatively new subject of research in nutraceuticals and nutrition, with interest rapidly expanding since they can help maintain health by controlling metabolism, weight, chronic diseases, and cell proliferation. Resveratrol is a phenolic compound found mostly in the pulp, peels, seeds, and stems of red grapes. It has a wide variety of biological actions that can be used to prevent the beginning of various diseases or manage their symptoms. Resveratrol can influence multiple inflammatory and non-inflammatory responses, protecting organs and tissues, thanks to its interaction with immune cells and its activity on SIRT1. This compound has anti-inflammatory, antioxidant, anti-apoptotic, neuroprotective, cardioprotective, anticancer, and antiviral properties, making it a potential adjunct to traditional pharmaceutical therapy in public health. This review aims to provide a comprehensive analysis of resveratrol in terms of active biological effects and mechanism of action in modifying the immune cellular response to promote human psychophysical health.

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.

Mechanism of Pterostilbene-Induced Cell Death in HT-29 Colon Cancer Cells

Pterostilbene is a dietary phytochemical that has been found to possess several biological activities, such as antioxidant and anti-inflammatory. Recent studies have shown that it exhibits the hallmark characteristics of an anticancer agent. The aim of the study was to investigate the anticancer activity of pterostilbene against HT-29 human colon cancer cells, focusing on its influence on cell growth, differentiation, and the ability of this stilbene to induce cell death. To clarify the mechanism of pterostilbene activity against colon cancer cells, changes in the expression of several genes and proteins that are directly related to cell proliferation, signal transduction pathways, apoptosis, and autophagy were also evaluated. Cell growth and proliferation of cells exposed to pterostilbene (5-100 µM) were determined by SRB and BRDU assays. Flow cytometric analyses were used for cell cycle progression. Further molecular investigations were performed using quantitative real-time RT-PCR. The expression of the signaling proteins studied was determined by the ELISA method. The results revealed that pterostilbene inhibited proliferation and induced the death of HT-29 colon cancer cells. Pterostilbene, depending on concentration, caused inhibition of proliferation, G1 cell arrest, and/or triggered apoptosis in HT-29 cells. These effects were mediated by the down-regulation of the STAT3 and AKT kinase pathways. It may be concluded that pterostilbene could be considered as a potential therapeutic option in the treatment of colon cancer in the future.

Inhibitory Effects of Pinostilbene on Adipogenesis in 3T3-L1 Adipocytes: A Study of Possible Mechanisms

Resveratrol is a phytoalexin with multiple bioactive properties, including antioxidative, neuroprotective, cardioprotective, and anticancer effects. However, resveratrol exhibits structural instability in response to UV irradiation, alkaline pH, and oxygen exposure. Thus, resveratrol derivatives have attracted considerable research interest. In this study, we aimed to evaluate the anti-adipogenic effects of pinostilbene hydrate (PH), a methylated resveratrol derivative, in 3T3-L1 cells. We also evaluated the mechanisms underlying the effects of PH on adipogenesis in 3T3-L1 adipocytes. Oil Red O staining, lipid accumulation assay, and triglyceride (TG) content assay revealed that PH significantly inhibited lipid and TG accumulation without cytotoxicity. In addition, we determined that PH decreased the expression of adipogenesis-related transcription factors, such as PPARγ, C/EBPα, SREBP-1c, and FABP4, and the phosphorylation of MAPK and protein kinase B (AKT). Moreover, PH attenuated the expression of CREB and C/EBPβ, while increasing the phosphorylation of AMPK and ACC, and decreasing the expression of fatty acid synthase and FABP4. Based on these results, we suggest that PH suppresses adipogenesis in 3T3-L1 cells via the activation of the AMPK signaling pathway and the inhibition of the MAPK and AKT insulin-dependent signaling pathways.

Effect of Pterostilbene, a Natural Derivative of Resveratrol, in the Treatment of Colorectal Cancer through Top1/Tdp1-Mediated DNA Repair Pathway

Topoisomerase 1 (Top1) inhibitor is an effective anticancer drug, but several factors limit its clinical application such as drug inactivation, tyrosyl-DNA phosphodiesterase 1 (Tdp1)-mediated tumor drug resistance, and its toxicity. Our previous study identified pterostilbene (PTE) and resveratrol (RE) to suppress these two proteins by binding to their active center. PTE and RE could inhibit the proliferation of various colorectal cancer cells, induce cell apoptosis, and make cell cycle stay in G2/M phase in vitro. PTE and RE could decrease Top1 and Tdp1 contents and mRNA expression in wild-type, constructed Tdp1 overexpressing CL187, Top1- or Tdp1- silenced CL187 cell lines. PTE exhibited excellent antitumor activity in subcutaneous CL187 transplantation model (TGI = 79.14 ± 2.85%, 200 mg/kg, i.p.) and orthotopic transplantation model (TGI = 76.57 ± 6.34%, 100 mg/kg, i.p.; TGI = 72.79 ± 4.06%, 500 mg/kg, i.g.) without significant toxicity. PTE had no significant inhibitory effect on non-tumor cell proliferation in vitro and would not induce damage to liver, kidney, and other major organs. Overall, PTE and RE can inhibit the activity of Top1 enzyme and inhibit the DNA damage repair pathway mediated by Top1/Tdp1, and can effectively inhibit colorectal cancer development with low toxicity, thus they have great potential to be developed into a new generation of anti-tumor drugs.

Chemopreventive effects of pterostilbene through p53 and cell cycle in mouse lung of squamous cell carcinoma model

Cell proliferation and cell death abnormalities are strongly linked to the development of cancer, including lung cancer. The purpose of this study was to investigate the effect of pterostilbene on cell proliferation and cell death via cell cycle arrest during the transition from G1 to S phase and the p53 pathway. A total of 24 female Balb/C mice were randomly categorized into four groups (n = 6): N-nitroso-tris-chloroethyl urea (NTCU) induced SCC of the lungs, vehicle control, low dose of 10 mg/kg PS + NTCU (PS10), and high dose of 50 mg/kg PS + NTCU (PS50). At week 26, all lungs were harvested for immunohistochemistry and Western blotting analysis. Ki-67 expression is significantly lower, while caspase-3 expression is significantly higher in PS10 and PS50 as compared to the NTCU (p < 0.05). There was a significant decrease in cyclin D1 and cyclin E2 protein expression in PS10 and PS50 when compared to the NTCU (p < 0.05). PS50 significantly increased p53, p21, and p27 protein expression when compared to NTCU (p < 0.05). Pterostilbene is a potential chemoprevention agent for lung SCC as it has the ability to upregulate the p53/p21 pathway, causing cell cycle arrest.

In vitro and in vivo combinatorial anticancer effects of oxaliplatin- and resveratrol-loaded N,O-carboxymethyl chitosan nanoparticles against colorectal cancer

BACKGROUND

Oxaliplatin (OXE) combined with other chemotherapy drugs against colorectal cancer had been reported in the literature before, however, the efficacy of oxaliplatin combined with natural compounds was elusive. In addition, the clinical bioactivity and therapeutic dose of antitumor drugs are severely limited due to poor targeting and side effects. NDDSs offers an excellent strategy to overcome the disadvantages of small molecule anticancer drugs.

METHODS

Here, we have prepared N,O-carboxymethyl chitosan Oxaliplatin nanoparticles (CMCS-OXE NPs) and N,O-carboxymethyl chitosan Resveratrol nanoparticles (CMCS-Res NPs) were prepared by ion crosslinking and emulsification crosslinking, respectively.

RESULTS

The results revealed that the CMCS-OXE NPs exhibited a high encapsulation efficiency (60%) with a size of approximately 190.0 nm, and the CMCS-Res NPs exhibited a high encapsulation efficiency (65%) with a size of approximately 164.2 nm. The treatment with both types of nanoparticles combined exhibited more significant anti-colon cancer activity than the free drugs or either type of nanoparticle alone. In the in vivo experiments, the inhibition efficiency of the combined nanoparticle treatment was much stronger than the free drugs or either type of nanoparticle alone.

CONCLUSIONS

Overall, combination of oxaliplatin and resveratrol into a nanoparticle-drug delivery systems (NDDSs) appears to be a promising strategy for colorectal cancer (CRC) therapy.

Toxicological Evaluation of Piceatannol, Pterostilbene, and ε-Viniferin for Their Potential Use in the Food Industry: A Review

The application of stilbenes in the food industry is being considered because of their biological activities. Piceatannol, pterostilbene and ε-viniferin have awakened the industry’s interest. However, before they can be commercialized, we must first guarantee their safety for consumers. The present work reviews the toxicological studies performed with these stilbenes. A wide variety of studies has demonstrated their cytotoxic effects in both cancer and non-cancerous cell lines. In contrast, although DNA damage was detected by some authors, in vitro genotoxic studies on the effects of piceatannol, pterostilbene, and ε-viniferin remain scarce. None of the three reviewed substances have been evaluated using the in vitro tests required by the European Food Safety Authority (EFSA) as the first step in genotoxicity testing. We did not find any study on the toxic effects of these stilbenes in vivo. Thus, more studies are needed to confirm their safe use before they can be authorized as additive in the food industry.

Phytostilbenes as agrochemicals: biosynthesis, bioactivity, metabolic engineering and biotechnology

Covering: 1976 to 2020. Although constituting a limited chemical family, phytostilbenes represent an emblematic group of molecules among natural compounds. Ever since their discovery as antifungal compounds in plants and their ascribed role in human health and disease, phytostilbenes have never ceased to arouse interest for researchers, leading to a huge development of the literature in this field. Owing to this, the number of references to this class of compounds has reached the tens of thousands. The objective of this article is thus to offer an overview of the different aspects of these compounds through a large bibliography analysis of more than 500 articles. All the aspects regarding phytostilbenes will be covered including their chemistry and biochemistry, regulation of their biosynthesis, biological activities in plants, molecular engineering of stilbene pathways in plants and microbes as well as their biotechnological production by plant cell systems.

Effects of the polysaccharide SPS-3-1 purified from Spirulina on barrier integrity and proliferation of Caco-2 cells

Following ultrasonication combined with a hot water extraction, a new type of bioactive polysaccharide, SPS-3-1, was purified from Spirulina using ultrafiltration centrifugation and gel filtration chromatography. The structure of SPS-3-1 was determined with high performance gel permeation chromatography, gas chromatography, periodate oxidation, fourier transform infrared spectroscopy, nuclear magnetic resonance, and atomic force microscopy performance. SPS-3-1 is a homogeneous β-pyran polysaccharide with 1 → 2, 1 → 3, and 1 → 4 glycosyl bonds, mainly composed of d-ribose, l-rhamnose, l-arabinose, l-foucose, and d-glucose. The molar ratio of these components is 1:0.70:1.03:2.1:6.59. The molecular weight of SPS-3-1 is 623.02 kDa. SPS-3-1 has a linear filament structure with a width of 34.132 nm and a height of 819.169 pm. We found that SPS-3-1 significantly enhanced transepithelial electrical resistance, a tight junction integrity marker, in a Caco-2 intestinal cell monolayer model. Analysis of the effect of SPS-3-1 on cell proliferation showed that SPS-3-1 inhibited the in vitro growth of Caco-2 and HepG2 cells with an IC₅₀ of 566.67 μg/mL and 1078.95 μg/mL, respectively.

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

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

Pterostilbene, a Bioactive Component of Blueberries, Alleviates Renal Interstitial Fibrosis by Inhibiting Macrophage-Myofibroblast Transition

Pterostilbene (PTB) is a derivative of resveratrol present in grapes and blueberries. PTB is structurally similar to resveratrol, possessing properties such as being analgesic, anti-aging, antidiabetic, anti-inflammatory, anti-obesity, anti-oxidation, cholesterol-reductive, and neuroprotective. However, there have not been reports on the effect of PTB on macrophage-myofibroblast transition (MMT) induced fibrosis in kidney. In this study, we investigated the antifibrotic effects of PTB on the in vivo mouse unilateral ureteral obstruction (UUO) model and in vitro MMT cells. Kidneys subjected to UUO with PTB treatment were collected for the investigation of PTB mediating MMT derived renal interstitial fibrosis. We conducted kidney RNA-seq transcriptomes and TGF-[Formula: see text]1-induced bone marrow-derived macrophages assays to determine the mechanisms of PTB. We found that PTB treatment suppressed the interstitial fibrosis in UUO mice. PTB also attenuated the number of MMT cells in vivo and in vitro. The transcriptomic analysis showed that CXCL10 may play a central role in the process of PTB-treated renal fibrosis. The siRNA-mediated CXCL10 knockdown decreased the number of MMT cells in TGF-[Formula: see text]1-induced bone marrow-derived macrophages. Our results suggested that PTB attenuated renal interstitial fibrosis by mediating MMT by regulating transcriptional activity of CXCL10.

The protective effect of stilbenes resveratrol and pterostilbene individually and combined with mycotoxin citrinin in human adenocarcinoma HT-29 cell line in vitro

This study was focused to determine an individual and combined effect of mycotoxin citrinin (CIT) and two compounds of the stilbene family- resveratrol (RES) and his dimethyl ether analogue pterostilbene (PTE) which have many health benefits. As a model the human adenocarcinoma cell line HT-29 was used which may exhibits the properties of small intestine cells. Viability, plasma membrane integrity, lysosomal functionality, intracellular production of superoxide anions and superoxide dismutase activity were examined. The results indicate that concentrations of 50 and 100 μg/mL of the tested compounds were cytotoxic in mostly monitored parameters and probably caused apoptosis. HT-29 cells were more sensitive to PTE than to RES with a higher antioxidant effect of PTE than RES, which may be caused by its chemical structure. Both stilbenes at medium doses act as effective superoxide anions scavengers leading to reduction of oxidative stress and consequent cell damage. The nontoxic concentration of RES (25 µg/mL) protects the HT-29 cell line faced to the toxicity of CIT at 25 µg/mL by increasing viability of cells and by reducing the superoxide production induced by CIT concentrations of 12.5 µg/mL and 25 µg/mL.

Pterostilbene Suppresses both Cancer Cells and Cancer Stem-Like Cells in Cervical Cancer with Superior Bioavailability to Resveratrol

Increasing studies have reported that cancer stem cells (CSCs) play critical roles in therapeutic resistance, recurrence, and metastasis of tumors, including cervical cancer. Pterostilbene, a dimethylated derivative of resveratrol, is a plant polyphenol compound with potential chemopreventive activity. However, the therapeutic effect of pterostilbene against cervical CSCs remains unclear. In this study, we compared the anticancer effects of resveratrol and pterostilbene using both HeLa cervical cancer adherent and stem-like cells. Pterostilbene more effectively inhibited the growth and clonogenic survival, as well as metastatic ability of HeLa adherent cells than those of resveratrol. Moreover, the superior inhibitory effects of pterostilbene compared to resveratrol were associated with the enhanced activation of multiple mechanisms, including cell cycle arrest at S and G2/M phases, induction of ROS-mediated caspase-dependent apoptosis, and inhibition of matrix metalloproteinase (MMP)-2/-9 expression. Notably, pterostilbene exhibited a greater inhibitory effect on the tumorsphere-forming and migration abilities of HeLa cancer stem-like cells compared to resveratrol. This greater effect was achieved through more potent inhibition of the expression levels of stemness markers, such as CD133, Oct4, Sox2, and Nanog, as well as signal transducer and activator of transcription 3 signaling. These results suggest that pterostilbene might be a potential anticancer agent targeting both cancer cells and cancer stem-like cells of cervical cancer via the superior bioavailability to resveratrol.

Effects of phytochemicals on cellular signaling: reviewing their recent usage approaches

Most of the previous studies in last three decades report evidence of interactions between the different phytochemicals and the proteins involved in signal transduction pathways using in silico, in vitro, ex vivo, and in vivo analyses. However, extrapolation of these findings for clinical purposes has not been that fruitful. The efficacy of the phytochemicals in vivo studies is limited by parameters such as solubility, metabolic degradation, excretion, etc. Various approaches have now been devised to circumvent these limitations. Recently, chemical modification of the phytochemicals are demonstrated to reduce some of the limitations and improve their efficacy. Similar to traditional medicines several combinatorial phytochemical formulations have shown to be more efficient. Further, phytochemicals have been reported to be even more efficient in the form of nanoparticles. However, systematic evaluation of their efficacy, mode of action in pathway modulation, usage and associated challenges is required to be done. The present review begins with basic understanding of how signaling cascades regulate cellular response and the consequences of their dysregulation further summarizing the developments and problems associated with the dietary phytochemicals and also discuss recent approaches in strengthening these compounds in pharmacological applications. Only context relevant studies have been reviewed. Considering the limitations and scope of the article, authors do not claim inclusion of all the early and recent studies.

Chitosan Oleate Coated Poly Lactic-Glycolic Acid (PLGA) Nanoparticles versus Chitosan Oleate Self-Assembled Polymeric Micelles, Loaded with Resveratrol

Chitosan oleate (CS-OA), a chitosan salt with amphiphilic properties, has demonstrated the ability to self-assemble in aqueous environment to give polymeric micelles useful to load poorly soluble drugs. More recently, CS-OA was proposed to stabilize nanoemulsions during the preparation by emulsification and solvent evaporation of poly lactic-glycolic acid (PLGA) nanoparticles (NPs) loaded with curcumin. Positive mucoadhesive behavior and internalization properties were demonstrated for these NPs attributable to the presence of positive charge at the NP surface. In the present paper, two CS-OA-based nanosystems, micelles and PLGA NPs, were compared with the aim of elucidating their physico-chemical characteristics, and especially their interaction with cell substrates. The two systems were loaded with resveratrol (RSV), a hydrophobic polyphenol endowed with anti-cancerogenic, anti-inflammatory, and heart/brain protective effects, but with low bioavailability mainly due to poor aqueous solubility. Calorimetric analysis and X-ray spectra demonstrated amorphization of RSV, confirming its affinity for hydrophobic domains of polymeric micelles and PLGA core of NPs. TGA decomposition patterns suggest higher stability of PLGA-NPs compared with polymeric micelles, that anyway resulted more stable than expected, considering the RSV release profiles, and the cell line interaction results.

DCZ0801, a novel compound, induces cell apoptosis and cell cycle arrest via MAPK pathway in multiple myeloma

Multiple myeloma (MM) is a refractory malignant hematological malignancy, and many therapeutic strategies have been developed to cure patients with MM. DCZ0801 is a compound that consists of oxophenamide and pterostilbene. The role of these compounds in hematological cancers such as MM has yet to be studied. In this study, we explored the potential mechanism of DCZ0801 action, its anti-tumor activity both in vitro and in vivo on MM. This study was carried out via cell cycle proliferation assay, apoptotic analysis, western blot analysis, and examination of xenotransplantation model of tumors. The in vitro studies revealed that DCZ0801 could inhibit cell proliferation and induce apoptosis by regulating both caspase-dependent and mitogen-activated protein kinase signaling pathways, inducing S-phase arrest of the cell cycle related to downregulation of CDK2, cyclin-A2, and CDC25A protein expression. The in vivo studies showed that DCZ0801 could significantly reduce the size of the tumors in nude mice. Our results demonstrated that DCZ0801 may emerge as the new therapeutic option for the patient with MM.

Dietary Polyphenols, Resveratrol and Pterostilbene Exhibit Antitumor Activity on an HPV E6-Positive Cervical Cancer Model: An in vitro and in vivo Analysis

Human papilloma virus (HPV)-induced cervical cancer is one of the most frequent cancers in women residing in underdeveloped countries. Natural compounds like polyphenols continue to be of scientific interest as non-toxic effective alternative treatments. Our previous work showed the efficacy of two polyphenols, resveratrol, and pterostilbene on human HeLa cells. Here we explored the in vitro anti-cancer activity and in vivo anti-tumor potential of these two structurally similar compounds on HPV oncogene E6 and E7 positive murine TC1 cells. In vitro analysis confirmed the cytotoxic potential of both resveratrol and pterostilbene compounds with each having a low IC₅₀ value and each showing the ability to downregulate viral oncogene E6. Further in vivo studies on TC1 tumors developing in mice indicated that treatment with either resveratrol or pterostilbene can significantly inhibit tumor development, with both compounds capable of downregulating E6 and VEGF tumor protein levels. Interestingly, the decrease in tumor size in pterostilbene was associated with tumor cell apoptosis, as indicated by an upregulation of activated caspase-3 whereas in resveratrol-treated mice it was accompanied by arrest of cell cycle, as indicated by a downregulation of PCNA. Thus, resveratrol and pterostilbene can serve as potential antineoplastic agents against HPV E6+ tumors and may suppress tumor growth via two different mechanisms.

Pterostilbene increases Fas expression in T-lymphoblastic leukemia cell lines

Treatment of acute lymphoblastic leukemia (ALL) has been promising in last decades, but side effects still persist and searching for the least toxic agents continue. Pterostilbene (PTE) is a natural compound with several anti-cancer and anti-oxidant properties. Fas, as a member of death inducing family of tumor necrosis factor (TNF) receptors with an intracellular death domain, can initiate the extrinsic apoptosis signaling pathway. Here after the half maximal inhibitory concentration (IC₅₀) determination in cell lines, we searched for PTE effects on Fas, both in mRNA and surface levels in two ALL cell lines, Jurkat and Molt-4. After harvesting cells in optimum situations, MTS assay was used to determine IC₅₀ concentrations. Real-time polymerase chain reaction (RT-PCR) and flow cytometry were performed for Fas mRNA and surface expression variations after exposure to PTE. The findings showed that PTE decreases cell viability with different extent in two ALL cell lines. In addition to inducing apoptosis, it can increase Fas in both gene and cell surface expression in the same concentrations. Pterostilbene as a natural anti-cancer agent can increase Fas expression both in mRNA and surface levels that results in apoptosis signal transduction improvement which sensitizes cells to apoptosis by immune effector cells. As a result, abnormal cells removal would be more efficiently with the minimum side effects on normal cells.

The inhibitory effect of Manuka honey on human colon cancer HCT-116 and LoVo cell growth. Part 2: Induction of oxidative stress, alteration of mitochondrial respiration and glycolysis, and suppression of metastatic ability

Despite its high content of phenolic compounds, the chemopreventive activity of Manuka honey (MH) is still elusive. The aim of the present work was to evaluate the effects of MH on oxidative stress, antioxidant enzymes, cellular metabolism and the metastatic ability in HCT-116 and LoVo cells, paying particular attention to the molecular mechanisms involved. We observed a strong induction of oxidative stress after MH treatment since it augmented the accumulation of reactive oxygen species and increased the damage to proteins, lipids and DNA. Furthermore, MH suppressed the Nrf2-dependent antioxidant enzyme expression (superoxide dismutase (SOD), catalase and heme oxygenase-1) and the activity of SOD, catalase, glutathione peroxidase and glutathione reductase. Cell metabolisms were markedly disrupted after MH treatment. It decreased maximal oxygen consumption and spare respiratory capacity, which could reduce the mitochondrial function that is correlated with cell survival potential. Simultaneously, MH decreased the extracellular acidification rate (glycolysis) of HCT-116 and LoVo cells. Furthermore, MH suppressed the p-AMPK/AMPK, PGC1α and SIRT1 activation, involved in the survival of HCT-116 and LoVo cells under metabolic stress conditions. Dose-dependently, MH reduced the migration and invasion (MMP-2 and MMP-9) ability, and concurrently regulated EMT-related markers (E cadherin, N cadherin, and β-catenin) in both cell types. The above findings indicate that MH induces HCT-116 and LoVo cell death partly by enhancing oxidative stress, as well as by regulating the energy metabolism in both aerobic and anaerobic pathways and suppressing the metastatic ability.

Synthesis and antitumor activity of bis(hydroxymethyl)propionate analogs of pterostilbene in cisplatin-resistant human oral cancer cells

The aim of this study was to develop a new drug substance with low toxicity and effective inhibitory activity against cisplatin-resistant oral cancer. The naturally produced pterostilbene was selected as the lead compound for design and synthesis of a series of bis(hydroxymethyl)propionate-based prodrugs. All derivatives were screened for antiproliferative effects against the cisplatin-resistant oral squamous (CAR) cell line and the results indicated that several compounds demonstrated superior inhibitory activity compared with pterostilbene and resveratrol. Among them, the most promising compound, 12, was evaluated for in vivo antitumor activity in a CAR xenograft nude mouse model. Obvious antitumor activity was observed at the lowest oral dose (25 mg/kg/day). Increasing the dose of 12 to 100 mg/kg/day reduced the tumor size to 22% of the control group. Based on these findings as well as the extremely low toxicity seen in the in vivo studies, we believe that compound 12 could serve as a new lead for further development.

Biological Activities of Stilbenoids

Stilbenoids are a group of naturally occurring phenolic compounds found in various plant species. They share a common backbone structure known as stilbene, but differ in the nature and position of substituents. Stilbenoids are classified as phytoalexins, which are antimicrobial compounds produced de novo in plants to protect against fungal infection and toxins. In this review, the biological effects of stilbenoids such as resveratrol, pterostilbene, gnetol and piceatannol are discussed. Stilbenoids exert various biological activities ranging from cardioprotection, neuroprotection, anti-diabetic properties, depigmentation, anti-inflammation, cancer prevention and treatment. The results presented cover a myriad of models, from cell culture to animal studies as well as clinical human trials. Although positive results were obtained in most cell culture and animal studies, further human studies are needed to substantiate beneficial effects of stilbenoids. Resveratrol remains the most widely studied stilbenoid. However, there is limited information regarding the potential of less common stilbenoids. Therefore, further research is warranted to evaluate the salutary effects of various stilbenoids.

Resveratrol and Pterostilbene Exhibit Anticancer Properties Involving the Downregulation of HPV Oncoprotein E6 in Cervical Cancer Cells

Cervical cancer is one of the most common cancers in women living in developing countries. Due to a lack of affordable effective therapy, research into alternative anticancer compounds with low toxicity such as dietary polyphenols has continued. Our aim is to determine whether two structurally similar plant polyphenols, resveratrol and pterostilbene, exhibit anticancer and anti-HPV (Human papillomavirus) activity against cervical cancer cells. To determine anticancer activity, extensive in vitro analyses were performed. Anti-HPV activity, through measuring E6 protein levels, subsequent downstream p53 effects, and caspase-3 activation, were studied to understand a possible mechanism of action. Both polyphenols are effective agents in targeting cervical cancer cells, having low IC50 values in the µM range. They decrease clonogenic survival, reduce cell migration, arrest cells at the S-phase, and reduce the number of mitotic cells. These findings were significant, with pterostilbene often being more effective than resveratrol. Resveratrol and to a greater extent pterostilbene downregulates the HPV oncoprotein E6, induces caspase-3 activation, and upregulates p53 protein levels. Results point to a mechanism that may involve the downregulation of the HPV E6 oncoprotein, activation of apoptotic pathways, and re-establishment of functional p53 protein, with pterostilbene showing greater efficacy than resveratrol.

Metabolism and pharmacokinetics of resveratrol and pterostilbene

Beneficial properties of resveratrol and pterostilbene, a dimethyl ether analog of resveratrol, have attracted increasing interest in recent years. Resveratrol and pterostilbene exhibit many pharmacological similarities and both of them are generally considered to be safe for human consumption. Beyond the structural and general bioactivity similarities between them, large amounts of data are now available to reveal the metabolic fate and pharmacological differences between them. Pterostilbene was found to be more metabolically stable and usually exhibited stronger pharmacological activities than that of resveratrol. As a contribution to clarify and compare aspects like metabolic stability and pharmacokinetics of resveratrol and pterostilbene, as well as explain the pharmacological similarities and differences between them, this review presents and compares recent data on the metabolism and pharmacokinetics of resveratrol and pterostilbene. © 2018 BioFactors, 44(1):16-25, 2018.

Resveratrol reverses the Warburg effect by targeting the pyruvate dehydrogenase complex in colon cancer cells

Resveratrol (RES), a polyphenol found in natural foods, displays anti-oxidant, anti-inflammatory and anti-proliferative properties potentially beneficial in cancers, in particular in the prevention of tumor growth. However, the rapid metabolism of resveratrol strongly limits its bioavailability. The molecular mechanisms sustaining the potential biological activity of low doses of resveratrol has not been extensively studied and, thus, needs better characterization. Here, we show that resveratrol (10 µM, 48 hr) induces both a cell growth arrest and a metabolic reprogramming in colon cancer cells. Resveratrol modifies the lipidomic profile, increases oxidative capacities and decreases glycolysis, in association with a decreased pentose phosphate activity and an increased ATP production. Resveratrol targets the pyruvate dehydrogenase (PDH) complex, a key mitochondrial gatekeeper of energy metabolism, leading to an enhanced PDH activity. Calcium chelation, as well as the blockade of the mitochondrial calcium uniport, prevents the resveratrol-induced augmentation in oxidative capacities and the increased PDH activity suggesting that calcium might play a role in the metabolic shift. We further demonstrate that the inhibition of the CamKKB or the downstream AMPK pathway partly abolished the resveratrol-induced increase of glucose oxidation. This suggests that resveratrol might improve the oxidative capacities of cancer cells through the CamKKB/AMPK pathway.

Bioconversion of stilbenes in genetically engineered root and cell cultures of tobacco

It is currently possible to transfer a biosynthetic pathway from a plant to another organism. This system has been exploited to transfer the metabolic richness of certain plant species to other plants or even to more simple metabolic organisms such as yeast or bacteria for the production of high added value plant compounds. Another application is to bioconvert substrates into scarcer or biologically more interesting compounds, such as piceatannol and pterostilbene. These two resveratrol-derived stilbenes, which have very promising pharmacological activities, are found in plants only in small amounts. By transferring the human cytochrome P450 hydroxylase 1B1 (HsCYP1B1) gene to tobacco hairy roots and cell cultures, we developed a system able to bioconvert exogenous t-resveratrol into piceatannol in quantities near to mg L-1. Similarly, after heterologous expression of resveratrol O-methyltransferase from Vitis vinifera (VvROMT) in tobacco hairy roots, the exogenous t-resveratrol was bioconverted into pterostilbene. We also observed that both bioconversions can take place in tobacco wild type hairy roots (pRiA4, without any transgene), showing that unspecific tobacco P450 hydroxylases and methyltransferases can perform the bioconversion of t-resveratrol to give the target compounds, albeit at a lower rate than transgenic roots.

Podophyllotoxin–pterostilbene fused conjugates as potential multifunctional antineoplastic agents against human uveal melanoma cells

Conjugate B1 showed potential multifunctional antineoplastic activity against human uveal melanoma cells.

Identification of terpenoids from Rubus corchorifolius L. f. leaves and their anti-proliferative effects on human cancer cells

Two novel and four known terpenoids were isolated and identified fromRubus corchorifoliusL. f. leaves. Two exhibited strong inhibitory effects on HCT116 human colon cancer cells, causing cell cycle arrest and apoptosis.

Pterostilbene induces apoptosis and cell cycle arrest in diffuse large B-cell lymphoma cells

Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma (NHL). Pterostilbene, a natural dimethylated analog of resveratrol, has been shown to possess diverse pharmacological activities, including anti-inflammatory, antioxidant and anticancer properties. However, to the best of our knowledge, there has been no study of the effects of pterostilbene upon hematological malignancies. Herein, we report the antitumor activity and mechanism of pterostilbene against DLBCL cells both in vitro and in vivo. We found that pterostilbene treatment resulted in a dose-dependent inhibition of cell viability. In addition, pterostilbene exhibited a strong cytotoxic effect, as evidenced not only by reductions of mitochondrial membrane potential (MMP) but also by increases in cellular apoptotic index and reactive oxygen species (ROS) levels, leading to arrest in the S-phase of the cell cycle. Furthermore, pterostilbene treatment directly up-regulated p-p38MAPK and down-regulated p-ERK1/2. In vivo, intravenous administration of pterostilbene inhibited tumor development in xenograft mouse models. Overall, the results suggested that pterostilbene is a potential anti-cancer pharmaceutical against human DLBCL by a mechanism involving the suppression of ERK1/2 and activation of p38MAPK signaling pathways.

Stereoisomers of Astaxanthin Inhibit Human Colon Cancer Cell Growth by Inducing G2/M Cell Cycle Arrest and Apoptosis

Astaxanthin (AST) is a xanthophyll carotenoid with potential protective effects against carcinogenesis. Different stereoisomers of AST (ASTs) exist in a variety of food sources. Due to limited information on the bioactivities of ASTs, the present study investigated the inhibitory effects of ASTs on HCT116 and HT29 human colon cancer cells. ASTs investigated herein included 3S,3'S (S) from Haematococcus pluvialis, 3R,3'R (R) from Phaffia rhodozyma, and a statistical mixture (S: meso: R = 1:2:1) (M) from synthetic AST. Cell viability assay showed that ASTs all inhibited colon cancer cell growth in a time-dependent (24-72 h) and dose-dependent (4-16 μM) manner, and there was no significant difference among the IC₅₀ values of ASTs (p > 0.05). Flow cytometry analysis indicated that ASTs induced G2/M cell cycle arrest and cellular apoptosis in cancer cells. The cell cycle arrest caused by ASTs was associated with increases in the expression levels of p21^Cip1/Waf1, p27, and p53, as well as decreases in the levels of CDK4 and CDK6. Meanwhile, the apoptosis induced by ASTs was confirmed by activation of caspase-3 and PARP in the cancer cells. The results indicated that hydroxyl (OH) at C3 and C3' of terminal ring structure might not be the major factor that affects the anticancer activity of AST. This study revealed important information on the inhibitory effects of ASTs on human colon cancer cells, which provided a basis for using ASTs as chemopreventive agents for colon cancer.

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, Acetyl-Resveratrol, and Polydatin Exhibit Antigrowth Activity against 3D Cell Aggregates of the SKOV-3 and OVCAR-8 Ovarian Cancer Cell Lines

Resveratrol has aroused significant scientific interest as it has been claimed that it exhibits a spectrum of health benefits. These include effects as an anti-inflammatory and an antitumour compound. The purpose of this study was to investigate and compare any potential antigrowth effects of resveratrol and two of its derivatives, acetyl-resveratrol and polydatin, on 3D cell aggregates of the EGFR/Her-2 positive and negative ovarian cancer cell lines SKOV-3 and OVCAR-8, respectively. Results showed that resveratrol and acetyl-resveratrol reduced cell growth in the SKOV-3 and OVCAR-8 in a dose-dependant manner. The growth reduction was mediated by the induction of apoptosis via the cleavage of poly(ADP-ribose) polymerase (PARP-1). At lower concentrations, 5 and 10 µM, resveratrol, acetyl-resveratrol, and polydatin were less effective than higher concentrations, 50 and 100 µM. In SKOV-3 line, at higher concentrations, resveratrol and polydatin significantly reduced the phosphorylation of Her-2 and EGFR and the expression of Erk. Acetyl-resveratrol, on the other hand, did not change the activation of Her-2 and EGFR. Resveratrol, acetyl-resveratrol, and polydatin suppressed the secretion of VEGF in a dose-dependant fashion. In the OVCAR-8 cell line, resveratrol and acetyl-resveratrol at 5 and 10 µM increased the activation of Erk. Above these concentrations they decreased activation. Polydatin did not produce this effect. This study demonstrates that resveratrol and its derivatives may inhibit growth of 3D cell aggregates of ovarian cancer cell lines via different signalling molecules. Resveratrol and its derivatives, therefore, warrant further in vivo evaluation to assess their potential clinical utility.