Natural dietary anti-cancer chemopreventive compounds: redox-mediated differential signaling mechanisms in cytoprotection of normal cells versus cytotoxicity in tumor cells

Derrischalcone suppresses cholangiocarcinoma cells through targeting ROS-mediated mitochondrial cell death, Akt/mTOR, and FAK pathways

Chemotherapy is a palliative treatment for unresectable patients with cholangiocarcinoma (CCA). However, drug resistance is a major cause of the failure of this treatment. Derrischalcone (DC), a novel chalcone isolated from Derris indica fruit, has been shown pharmacologically active; though, the effect of DC on CCA is unknown. The present study investigated the cytotoxic, antiproliferative, anti-migration, and anti-invasion effects and underlying mechanisms of DC on CCA KKU-M156 and KKU-100 cells. Cytotoxicity and apoptosis were evaluated by acridine orange and ethidium bromide fluorescent staining. Reactive oxygen species (ROS) was measured by dihydroethidium assay. Cell proliferation and reproductive cell death were assessed by sulforhodamine B staining and colony-forming assay. Migration and invasion were determined by wound healing and transwell chamber assays. Protein expressions associated with cell death, proliferation, migration, and invasion were analyzed by western immunoblotting. We found that DC induced cytotoxicity and apoptosis in association with ROS formation and oxidative stress. Treatment with N-acetylcysteine suppressed ROS formation and attenuated DC-induced cytotoxic and apoptotic effects. DC increased the expression of p53, p21, Bax, and cytochrome c proteins in association with cell death. DC-induced antiproliferation, colony formation, anti-migration, and anti-invasion were associated with the suppression of Akt/mTOR/cyclin D1 and FAK signaling pathways. These findings suggest that the multi-targeting strategies with DC may be a novel treatment for cancer therapy.

Natural products targeting cancer stem cells: Implications for cancer chemoprevention and therapeutics

Cancer, being the leading cause of death in the globe, has been one of the major thrust areas of research worldwide. In a new paradigm about neoplastic transformations, the initiation and recurrence of disease is attributed to few mutated cells in bulk of tumor called cancer stem cells (CSCs). CSCs have capacity of self-renewal and differentiation, which are known for resistance to radio and chemotherapy leading to recurrence of the disease even after treatment. Most of traditional drugs implicated in cancer therapy targeting primary tumors have substantial toxicity to the physiological system and have not been efficient in targeting these CSCs leading to poor prognosis. Targeting these CSCs in bulk of tumor might be novel strategy for cancer chemoprevention and therapeutics. Diet-derived interventions and diverse natural products are known to target these CSCs and related signaling pathways, namely, Wnt, Notch, and Hedgehog pathways, which are implicated for CSC self-renewal. PRACTICAL APPLICATIONS: Cancer remains a global challenge even in this century. Poor prognosis, survival rate, and recurrence of the disease have been the major concerns in traditional cancer therapy regimes. Targeting cancer stem cells might be novel strategy for elimination and cure of the chronic disease as they are known to modulate all stages of carcinogenesis and responsible for recurrence and resistance to chemotherapy and radiotherapy. The evidence support that natural products might inhibit, delay, or reverse the process of tumorigenesis and modulate the different signaling pathways implicated for cancer stem cells self-renewal and differentiation. Natural products have minimal toxicity compared to traditional cancer therapy drugs since they have long been utilized in our food habits without any major side effects reported. Thus, targeting cancer stem cells with natural product might be a novel strategy for drug development in cancer chemoprevention and therapeutics.

Botanic Origin of Propolis Extract Powder Drives Contrasted Impact on Diabesity in High-Fat-Fed Mice

Propolis extracts are considered as nutraceutical products with potentialities towards obesity and comorbidities management. Nevertheless, propolis extracts composition is highly variable and depends on the botanic origin of plants used by the bees to produce propolis. This study aims to evaluate the differential effect of poplar propolis extract powder (PPEP), Baccharis propolis extract powder (BPEP), and/ or Dalbergia propolis extract powder (DPEP) on obesity and glucose homeostasis in high-fat-fed mice. PPEP supplementation reduced high-fat (HF)-mediated body weight gain, adiposity index, and improved glucose homeostasis in male C57Bl/6J mice that were submitted to a high-fat diet for 12 weeks, whereas BPEP, DPEP, or a mix of the three PEPs did not modify those parameters. Adipose tissue (AT) gene expression profiling highlighted an induction of mRNA related to lipid catabolism and an inhibition of mRNA coding for inflammatory markers. Several Nrf2 target genes, coding for antioxidant enzymes, were induced in AT under PPEP effect, but not by other PEP. Interestingly, representative PPEP polyphenols mediated the induction of Nrf2 target genes cell-autonomously in adipocytes, suggesting that this induction may be related to the specific polyphenol content of PPEP. Whereas PPEP supplementation has demonstrated a clear potential to blunt the onset of obesity and associated comorbidities, other PEPs (from Baccharis and Dalbergia) were inefficient to support their role in preventive nutrition.

(E)-N-(2-(3, 5-Dimethoxystyryl) phenyl) furan-2-carboxamide (BK3C231) induces cytoprotection in CCD18-Co human colon fibroblast cells through Nrf2/ARE pathway activation

Cytoprotection involving the nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) signaling pathway is an important preventive strategy for normal cells against carcinogenesis. In our previous study, the chemopreventive potential of (E)-N-(2-(3, 5-Dimethoxystyryl) phenyl) furan-2-carboxamide (BK3C231) has been elucidated through its cytoprotective effects against DNA and mitochondrial damages in the human colon fibroblast CCD-18Co cell model. Therefore this study aimed to investigate the molecular mechanisms underlying BK3C231-induced cytoprotection and the involvement of the Nrf2/ARE pathway. The cells were pretreated with BK3C231 before exposure to carcinogen 4-nitroquinoline N-oxide (4NQO). BK3C231 increased the protein expression and activity of cytoprotective enzymes namely NAD(P)H:quinone oxidoreductase 1 (NQO1), glutathione S-transferase (GST) and heme oxygenase-1 (HO-1), as well as restoring the expression of glutamate-cysteine ligase catalytic subunit (GCLC) back to the basal level. Furthermore, dissociation of Nrf2 from its inhibitory protein, Keap1, and ARE promoter activity were upregulated in cells pretreated with BK3C231. Taken together, our findings suggest that BK3C231 exerts cytoprotection by activating the Nrf2 signaling pathway which leads to ARE-mediated upregulation of cytoprotective proteins. This study provides new mechanistic insights into BK3C231 chemopreventive activities and highlights the importance of stilbene derivatives upon development as a potential chemopreventive agent.

Epigenetics/Epigenomics and Prevention of Early Stages of Cancer by Isothiocyanates

Cancer is a complex disease and cancer development takes 10-50 years involving epigenetics. Evidence suggests that approximately 80% of human cancers are linked to environmental factors impinging upon genetics/epigenetics. Because advanced metastasized cancers are resistant to radiotherapy/chemotherapeutic drugs, cancer prevention by relatively nontoxic chemopreventive "epigenetic modifiers" involving epigenetics/epigenomics is logical. Isothiocyanates are relatively nontoxic at low nutritional and even higher pharmacologic doses, with good oral bioavailability, potent antioxidative stress/antiinflammatory activities, possess epigenetic-modifying properties, great anticancer efficacy in many in vitro cell culture and in vivo animal models. This review summarizes the latest advances on the role of epigenetics/epigenomics by isothiocyanates in prevention of skin, colon, lung, breast, and prostate cancers. The exact molecular mechanism how isothiocyanates modify the epigenetic/epigenomic machinery is unclear. We postulate "redox" processes would play important roles. In addition, isothiocyanates sulforaphane and phenethyl isothiocyanate, possess multifaceted molecular mechanisms would be considered as "general" cancer preventive agents not unlike chemotherapeutic agents like platinum-based or taxane-based drugs. Analogous to chemotherapeutic agents, the isothiocyanates would need to be used in combination with other nontoxic chemopreventive phytochemicals or drugs such as NSAIDs, 5-α-reductase/aromatase inhibitors targeting different signaling pathways would be logical for the prevention of progression of tumors to late advanced metastatic states.

New vistas in malignant mesothelioma: MicroRNA architecture and NRF2/MAPK signal transduction

Malignant mesothelioma (MM) is a cancer of the mesothelial lining of the pleura, peritoneum, pericardium and testes. The most common form is asbestos-linked MM that is etiologically linked to repeated asbestos exposure with a long latency period, although non-asbestos MM has also been reported. Late diagnosis, poor survival rates, lack of diagnostic and prognostic markers act as major impediments in the clinical management of MM. Despite advances in immune checkpoint inhibition and CAR T-cell-based therapies, MM which is of different histologic subtypes remains challenging to treat. We review microRNAs (miRNAs) and the miRNA interactome implicated in MM which can be useful as circulating miRNA biomarkers for early diagnosis of MM and as biomarkers for prognostication in MM. Further, we underscore the relevance of the NRF2/MAPK signal transduction pathway that has been implicated in MM which may be useful as druggable targets or as biomarkers of predictive response. In addition, since MM is driven partly by inflammation, we elucidate chemopreventive phytochemicals that are beneficial in MM, either via crosstalk with the NRF2/MAPK pathway or via concerted anticancer mechanisms, and may be of benefit as adjuvants in chemotherapy. Taken together, a multifactorial approach comprising identification of miRNA target hubs and NRF2/MAPK biomarkers along with appropriately designed clinical trials may enable early detection and faster intervention in MM translating into better patient outcomes for this aggressive cancer.

Poplar Propolis Ethanolic Extract Reduces Body Weight Gain and Glucose Metabolism Disruption in High-Fat Diet-Fed Mice

SCOPE

Current evidence supports the beneficial effect of polyphenols on the management of obesity and associated comorbidities. This is the case for propolis, a polyphenol-rich substance produced by bees. The aim of the present study is to evaluate the effect of a poplar propolis ethanolic extract (PPEE) on obesity and glucose homeostasis, and to unveil its putative molecular mechanisms of action.

METHODS AND RESULTS

Male high-fat (HF) diet-fed mice are administered PPEE for 12 weeks. PPEE supplementation reduces the HF-mediated adiposity index, adipocyte hypertrophy, and body weight gain. It also improves HOMA-IR and fasting glucose levels. Gene expression profiling of adipose tissue (AT) shows an induction of mRNA related to lipid catabolism and mitochondrial biogenesis and inhibition of mRNA coding for inflammatory markers. Interestingly, several Nrf2-target genes are induced in AT following administration of PPEE. The ability of PPEE to induce the expression of Nrf2-target genes is studied in adipocytes. PPEE is found to transactivate the Nrf2 response element and the Nrf2 DNA-binding, suggesting that part of the effect of PPEE can be mediated by Nrf2.

CONCLUSION

PPEE supplementation may represent an interesting preventive strategy to tackle the onset of obesity and associated metabolic disorders.

Extra-Virgin Olive Oil from Apulian Cultivars and Intestinal Inflammation

Inflammatory bowel disease (IBD) is a multifactorial intestinal disorder characterized by chronic intestinal inflammation. The etiology of IBD is still unclear, although genetic, environmental and host factors have been associated to the disease. Extra-virgin olive oil (EVO) is a central component of the Mediterranean diet and it decreases chronic inflammation by interfering with arachidonic acid and NF-κB signaling pathways. Specifically, the different components of EVO are able to confer advantages in terms of health in their site of action. For instance, oleic acid displays a protective effect in liver dysfunction and gut inflammation, whereas phenolic compounds protect colon cells against oxidative damage and improve the symptoms of chronic inflammation in IBD. Given the biological properties of EVO, we investigated whether its administration is able to confer protection in a mouse model of dextrane sodium sulfate (DSS)-induced colitis. Four EVO cultivars from the Apulian Region of Italy, namely Ogliarola (Cima di Bitonto), Coratina, Peranzana and Cima di Mola, respectively, were used. Administration of EVO resulted in reduced body weight loss in our colitis model. Furthermore, mice treated with Ogliarola, Coratina and Cima di Mola EVO displayed a reduction of rectal bleeding and IL-1β, TGFβ, IL-6 gene expression levels. Furthermore, Ogliarola, Coratina and Peranzana EVO administration ameliorated intestinal permeability and histopathological features of inflammation. Our data further validate the well-known positive effects of EVO supplementation in promoting human health and suggest the bona fide contribution of EVO in preventing onset and reducing progression of intestinal inflammation.

A cell-based assay system for activators of the environmental cell stress response

Improved health span and lifespan extension in a wide phylogenetic range of species is associated with the induction of the environmental cell stress response through a signalling pathway regulated by the transcription factor Nrf2. Phytochemicals which stimulate this response may form part of therapeutic interventions which stimulate endogenous cytoprotective mechanisms, thereby delaying the onset of age-related diseases and promoting healthy ageing in humans. In order to identify compounds that activate the Nrf2 pathway, a cell-based reporter system was established in HepG2 cells using a luciferase reporter gene under the control of the Nqo1 promoter. Sulforaphane, an isothiocyanate derived from cruciferous vegetables and a known activator of the Nrf2 pathway, was used to validate the reporter system. The transfected cell line HepG2 C1 was subsequently used to screen natural product libraries. Five compounds were identified as activating the bioluminescent reporter by greater than 5-fold. The two most potent compounds, MBC20 and MBC37, were further characterised and shown to stimulate endogenous cytoprotective gene and protein expression. The bioluminescent reporter system will allow rapid, in vitro identification of novel compounds that have the potential to improve health span through activation of the environmental stress response.

DNA methylome and transcriptome alterations and cancer prevention by triterpenoid ursolic acid in UVB-induced skin tumor in mice

Nonmelanoma skin cancers (NMSCs) are the most common type of skin cancers. Major risk factors for NMSCs include exposure to ultraviolet (UV) irradiation. Ursolic acid (UA) is a natural triterpenoid enriched in blueberries and herbal medicinal products, and possess anticancer activities. This study focuses on the impact of UA on epigenomic, genomic mechanisms and prevention of UVB-mediated NMSC. CpG methylome and RNA transcriptome alterations of early, promotion and late stages of UA treated on UVB-induced NMSC in SKH-1 hairless mice were conducted using CpG methyl-seq and RNA-seq. Samples were collected at weeks 2, 15, and 25, and integrated bioinformatic analyses were performed to identify key pathways and genes modified by UA against UVB-induced NMSC. Morphologically, UA significantly reduced NMSC tumor volume and tumor number. DNA methylome showed inflammatory pathways IL-8, NF-κB, and Nrf2 pathways were highly involved. Antioxidative stress master regulator Nrf2, cyclin D1, DNA damage, and anti-inflammatory pathways were induced by UA. Nrf2, cyclin D1, TNFrsf1b, and Mybl1 at early (2 weeks) and late (25 weeks) stages were identified and validated by quantitative polymerase chain reaction. In summary, integration of CpG methylome and RNA transcriptome studies show UA alters antioxidative, anti-inflammatory, and anticancer pathways in UVB-induced NMSC carcinogenesis. Particularly, UA appears to drive Nrf2 and its upstream/downstream genes, anti-inflammatory (at early stages) and cell cycle regulatory (both early and late stages) genes, of which might contribute to the overall chemopreventive effects of UVB-induced MNSC. This study may provide potential biomarkers/targets for chemoprevention of early stage of UVB-induced NMSC in human.

Medicinal Plants from Brazilian Cerrado: Antioxidant and Anticancer Potential and Protection against Chemotherapy Toxicity

The use of natural antioxidants in cancer therapy has increased: first, due to the potential of natural antioxidants to kill tumour cells and second, because of their capacity to protect healthy cells from the damage caused by chemotherapy. This review article discusses the antioxidant properties of extracts obtained from medicinal plants from the Brazilian Cerrado and the cell death profile induced by each of these extracts in malignant cells. Next, we describe the capacity of other medicinal plants from the Cerrado to protect against chemotherapy-induced cell toxicity. Finally, we focus on recent insights into the cell death profile induced by extracts from Cerrado plants and perspectives for future therapeutic approaches.

Oxygen Availability during Growth Modulates the Phytochemical Profile and the Chemo-Protective Properties of Spinach Juice

Fruits and vegetables are a good source of potentially biologically active compounds. Their regular consumption in the human diet can help reduce the risk of developing chronic diseases such as cardiovascular diseases and cancer. Plants produce additional chemical substances when subject to abiotic stress or infected by microorganisms. The phytochemical profile of spinach leaves (Spinacia oleracea L.), which is a vegetable with widely recognized health-promoting activity, has been affected by applying root hypoxic and re-oxygenation stress during plant growth. Leaf juice at different sampling times has been subject to liquid chromatography mass spectrometry (LC-MSn) analysis and tested on the human colorectal adenocarcinoma cell line HT29 by using the Comet assay. The cells were previously treated with H₂O₂ to simulate the presence of an oxidative stress (as in colon cancer condition) and the leaf juice application resulted in a significant antioxidant and protective in vitro effect. The duration of the hypoxic/re-oxygenation stress imposed on the plant reflects the antioxidant leaf juice content. After hypoxic stress (24 h) and reoxygenation (2 h), we show a decrease (50%) of the relative abundance of the principal identified antioxidant molecules but a higher antioxidant activity of the spinach juice on HT29 cells (20%). Data shows a complex relation between plant growing conditions and the modulation of secondary metabolites content in leaf juice that results in different chemo-protective activities in colon cancer cells.

Advances with support vector machines for novel drug discovery

INTRODUCTION

Novel drug discovery remains an enormous challenge, with various computer-aided drug design (CADD) approaches having been widely employed for this purpose. CADD, specifically the commonly used support vector machines (SVMs), can employ machine learning techniques. SVMs and their variations offer numerous drug discovery applications, which range from the classification of substances (as active or inactive) to the construction of regression models and the ranking/virtual screening of databased compounds. Areas covered: Herein, the authors consider some of the applications of SVMs in medicinal chemistry, illustrating their main advantages and disadvantages, as well as trends in their utilization, via the available published literature. The aim of this review is to provide an up-to-date review of the recent applications of SVMs in drug discovery as described by the literature, thereby highlighting their strengths, weaknesses, and future challenges. Expert opinion: Techniques based on SVMs are considered as powerful approaches in early drug discovery. The ability of SVMs to classify active or inactive compounds has enabled the prioritization of substances for virtual screening. Indeed, one of the main advantages of SVMs is related to their potential in the analysis of nonlinear problems. However, despite successes in employing SVMs, the challenges of improving accuracy remain.

Sulforaphane protects granulosa cells against oxidative stress via activation of NRF2-ARE pathway

Sulforaphane (SFN) has been considered as an indirect antioxidant and potential inducer of the Nrf2-ARE pathway. This study was conducted to investigate the protective role of SFN against oxidative stress in bovine granulosa cells (GCs). GCs were collected from antral follicles (4-8 mm) and cultured according to the experimental design where group 1 = control, group 2 = treated with SFN, group 3 = treated with hydrogen peroxide (H₂O₂), group 4 = pretreated with SFN and then with H₂O₂ (protective) and group 5 = treated with H₂O₂ followed by SFN treatment (rescuing). Results showed that SFN pretreatment significantly increases cell viability and reduces cytotoxicity in GCs under oxidative stress. Following H₂O₂ exposure, expression of NRF2 was found to be significantly increased (p < 0.05) in SFN-pretreated cells, while no significant differences were observed between group 3 and group 5, although the expression was significantly increased compared to the control group. Moreover, the relative abundance of the NRF2 downstream target antioxidant genes (CAT, PRDX1, SOD1 and TXN1) were higher (fold change ranged from 7 to 14, p < 0.05) in sulforaphane pretreated GCs. Low level of ROS and lipid accumulation and higher mitochondrial activity were observed in GCs pretreated with SFN, whereas no such changes were observed in GCs treated with SFN after exposure to oxidative stress (group 5). Thus, we suggest that SFN pretreatment effectively protects GCs against oxidative damage through the activation of the NRF2-ARE pathway, whereas addition of SFN during oxidative insult failed to rescue GCs.

Capsaicinoids improve consequences of physical activity

•

Capsaicinoids (CAPs) are active compounds in Capsicum fruits.

•

CAPs have anti-inflammatory and antioxidant properties.

•

CAPs with regular exercise may enhance lipid metabolism.

•

CAPs down-regulate muscle SREBP-1c, LXRs, ACLY, FAS in exercised rats.

The purpose of this study was to investigate the effects of capsaicinoids (CAPs) on lipid metabolism, inflammation, antioxidant status and the changes in gene products involved in these metabolic functions in exercised rats. A total of 28 male Wistar albino rats were randomly divided into four groups (n = 7) (i) No exercise and no CAPs, (ii) No exercise + CAPs (iii) Regular exercise, (iv) Regular exercise + CAPs. Rats were administered as 0.2 mg capsaicinoids from 10 mg/kg BW/day Capsimax^® daily for 8 weeks. A significant decrease in lactate and malondialdehyde (MDA) levels and increase in activities of antioxidant enzymes were observed in the combination of regular exercise and CAPs group (P < 0.0001). Regular exercise + CAPs treated rats had greater nuclear factor-E2-related factor-2 (Nrf2) and heme oxygenase-1 (HO-1) levels in muscle than regular exercise and no exercise rats (P < 0.001). Nevertheless, regular exercise + CAPs treated had lower nuclear factor kappa B (NF-κB) and IL-10 levels in muscle than regular exercise and control rats (P < 0.001). Muscle sterol regulatory element-binding protein 1c (SREBP-1c), liver X receptors (LXR), ATP citrate lyase (ACLY) and fatty acid synthase (FAS) levels in the regular exercise + CAPs group were lower than all groups (P < 0.05). However, muscle PPAR-γ level was higher in the regular exercise and CAPs alone than the no exercise rats. These results suggest CAPs with regular exercise may enhance lipid metabolism by regulation of gene products involved in lipid and antioxidant metabolism including SREBP-1c, PPAR-γ, and Nrf2 pathways in rats.

Chemoprevention with isothiocyanates - From bench to bedside

Isothiocyanates (ITCs) are naturally occurring hydrolization products from glucosinolates (GLSs) in brassicaceae and in epidemiological studies their intake has been weakly to moderately inversely correlated with the risk of colorectal cancer, prostate cancer and lung cancer. Numerous preclinical studies demonstrate chemopreventive mode of actions of ITCs, mainly related to a.) detoxification (induction of phase II enzymes), b.) anti-inflammatory properties by down-regulation of NFkappaB activity, c.) cyclin-mediated cell cycle arrest and d.) epigenetic modulation by inhibition of histone deacetylase activity. First prospective clinical trials were promising in patients with risk of prostate cancer recurrence. The glutathione-S-transferase gene expression seems to play a major role in the individual susceptibility towards ITCs. Safety issues are widely unclear and should be more addressed in future studies because ITCs can, in low concentrations, compromise the function of human immune cells and might impair genome stability.

The role of Nrf2-Keap1 axis in colorectal cancer, progression, and chemoresistance

Colorectal cancer is the third common cancer after lung and genital cancers worldwide with more than 1.2 million new cases diagnosed annually. Although extensive progress has been made in the treatment of colorectal cancer, finding novel targets for early diagnosis and effective treatment of these patients is an urgent need. Nuclear factor-erythroid 2-kelch-like ECH-associated protein 1 signaling pathway plays a key role in protecting cells from the damage of intracellular oxidative stress and extracellular oxidizing agents. Nuclear factor-erythroid 2 is a transcription factor that creates intracellular redox homeostasis via transcriptional activity and interaction with kelch-like ECH-associated protein 1. Furthermore, it contributes to survival and chemoresistance of colorectal cancer cells which is mediated by overexpression of cytoprotective and multidrug resistance genes. In this review, the dual role of nuclear factor-erythroid 2 signaling in induction of colorectal cancer cell survival and death as well as the possibility of targeting nuclear factor-erythroid 2-kelch-like ECH-associated protein 1 axis as an advanced strategy in prevention and effective treatment of colorectal cancer patients have been discussed.

Polyphenolic Phytochemicals in Cancer Prevention and Therapy: Bioavailability versus Bioefficacy

Natural polyphenols are organic chemicals which contain phenol units in their structures. They show antitumor properties. However, a key problem is their short half-life and low bioavailability under in vivo conditions. Still, definitively demonstrating the human benefits of isolated polyphenolic compounds (alone or in combination) using modern scientific methodology has proved challenging. The most common discrepancy between experimental and clinical observations is the use of nonphysiologically relevant concentrations of polyphenols in mechanistic studies. Thus, it remains highly controversial how applicable underlying mechanisms are with bioavailable concentrations and biological half-life. The present Perspective analyses proposed antitumor mechanisms, in vivo reported antitumor effects, and possible mechanisms that may explain discrepancies between bioavailability and bioefficacy. Polyphenol metabolism and possible toxic side effects are also considered. Our main conclusion emphasizes that these natural molecules (and their chemical derivatives) indeed can be very useful, not only as cancer chemopreventive agents but also in oncotherapy.

Effect of olive cultivar on bioaccessibility and antioxidant activity of phenolic fraction of virgin olive oil

AIM

This study aims to characterize the phenolic profile and antioxidant capacity of seven monovarietal virgin olive oils (VOOs) and evaluate their in vitro gastrointestinal stability.

METHODS

'Picual', 'Blanqueta', 'Sevillana', 'Habichuelero', and 'Chetoui' olive cultivars were selected for VOO extraction. The oils were subjected to in vitro digestion. The recovery index (RI) of phenolic compounds after each digestion step and the bioaccessibility index (BI) were evaluated. In addition, the antioxidant activity of the bioaccessible fraction (BF) of VOOs was determined by DPPH, ABTS, and ORAC assays, as well as by studying the intracellular reactive oxygen species in Caco-2 cells.

RESULTS

Differences were found in the composition of phenolic compounds in VOOs depending on cultivars. During the digestive process, important losses of phenolic compounds were observed between the buccal and duodenal steps, unlike HTy and Ty, which presented increased recovery due to the hydrolysis of secoiridoid derivatives. Differences in the bioaccessibility of phenolic compounds were found between varieties of VOOs. 'Sevillana' VOO had the highest total bioaccessibility (36%), followed by the 'Picual' (19%), 'Chetoui' (17%), 'Habichuelero' (10%), and 'Blanqueta' (8%) varieties. The BF of all the varieties of VOO showed similar radical ABTS scavenging capacity, 'Chetoui', and 'Blanqueta'-BF having the highest radical DPPH scavenging capacity, and 'Habichuelero' and 'Picual'-BF showing protective effects against the peroxyl radical measured by ORAC_FL assay. All VOO-BFs presented decreases in ROS levels in Caco-2 cells.

CONCLUSIONS

Our results suggest differences in the bioaccessibility of phenolics from diverse VOO varieties, which could lead to different biological properties. Therefore, this study represents a first step toward the development of novel dietary strategies focusing on the phenolic supplementation of different VOOs to preserve human health.

Capsaicinoids improve egg production by regulating ovary nuclear transcription factors against heat stress in quail

1. To examine the molecular mechanism of capsaicinoid supplementation from capsicum extract, laying Japanese quail (n = 180, 5 weeks old) were reared either at 22°C for 24 h/d (thermoneutral, TN) or at 34°C for 8 h/d (heat stress, HS) and fed on one of three diets containing 0, 25 or 50 mg of capsaicinoids per kilogram for 12 weeks (2 × 3 factorial arrangement). 2. The results revealed that exposure to HS decreased feed consumption by 10.7% and egg production by 13.6%, increased serum and ovary malondialdehyde (MDA) levels by 66.9% and 88.1%, respectively, and reduced ovary superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities by 28.3%, 48.7% and 43.8%, respectively. 3. There were magnifications in the ovary nuclear factor kappa-light-chain-enhancer of activated B cell (NF-κB) levels by 42.4% and suppressions in nuclear factor (erythroid-derived 2)-like 2 (Nrf2), protein kinase B (Akt) and haem-oxygenase 1 (HO-1) levels by 29.2%, 38.2% and 30.7%, respectively, in heat-stressed quail. 4. With increasing supplemental capsaicinoids, there were linear increases in egg production, antioxidant enzyme activity, linear decreases in ovary MDA and NF-κB levels and linear increases in ovary Nrf2, Akt and HO-1 levels at a greater extent in quail reared under TN condition than those reared under HS condition. Two-way treatment interactions showed that the degree of restorations in all response variables was more notable under the HS environment than under the TN environment as supplemental capsaicinoid level was increased. 5. In conclusion, capsaicinoid supplementation alleviates oxidative stress through regulating the ovary nuclear transcription factors in heat-stressed quail.

Esculetin induces antiproliferative and apoptotic response in pancreatic cancer cells by directly binding to KEAP1

BACKGROUND

A handful of studies have exploited antitumor potential of esculetin, a dihydroxy coumarine derivative; the targets to which it binds and the possible downstream mechanism for its cytotoxicity in cancer cells remain to be elucidated. Using pancreatic cancer cell lines as a model system, herein the study was initiated to check the efficacy of esculetin in inhibiting growth of these cancer cells, to decipher mechanism of its action and to predict its direct binding target protein.

METHODS

The cytotoxicity of esculetin was determined in PANC-1, MIA PaCa-2 and AsPC-1 cell lines; followed by an inspection of intracellular levels of ROS and its associated transcription factor, p65-NF-κB. The interaction between transcription factor, Nrf2 and its regulator KEAP1 was studied in the presence and absence of esculetin. The effect of Nrf2 on gene expression of antioxidant response element pathway was monitored by real time PCR. Thereafter, potential binding target of esculetin was predicted through molecular docking and then confirmed in vitro.

RESULTS

Esculetin treatment in all three pancreatic cancer cell lines resulted in significant growth inhibition with G1-phase cell cycle arrest and induction of mitochondrial dependent apoptosis through activation of caspases 3, 8 and 9. A notable decrease was observed in intracellular ROS and protein levels of p65-NF-κB in PANC-1 cells on esculetin treatment. Antioxidant response regulator Nrf2 has been reportedly involved in crosstalk with NF-κB. Interaction between Nrf2 and KEAP1 was found to be lost upon esculetin treatment in PANC-1 and MIA Paca-2 cells. Nuclear accumulation of Nrf2 and an upregulation of expression of Nrf2 regulated gene NQO1, observed on esculetin treatment in PANC-1 further supported the activation of Nrf2. To account for the loss of Nrf2-KEAP1 interaction on esculetin treatment, direct binding potential between esculetin and KEAP1 was depicted in silico using molecular docking studies. Pull down assay using esculetin conjugated sepharose beads confirmed the binding between esculetin and KEAP1.

CONCLUSIONS

We propose that esculetin binds to KEAP1 and inhibits its interaction with Nrf2 in pancreatic cancer cells. This thereby promotes nuclear accumulation of Nrf2 in PANC-1 cells that induces antiproliferative and apoptotic response possibly by attenuating NF-κB.

Curcumin prevents muscle damage by regulating NF-κB and Nrf2 pathways and improves performance: an in vivo model

Purpose

Exercise (Ex) increases reactive oxygen species and impairs antioxidant defense systems. Recent data suggest that curcumin (CW) possesses peroxisome proliferator-activated receptor gamma activity and anti-inflammatory properties. Therefore, this study was designed to investigate the effects of CW supplementation on Ex performance, endurance, and changes in serum and muscle proteins in rats after exhaustive Ex.

Materials and methods

Twenty-eight (28) male Wistar rats (age: 8 weeks and body weight: 180±20 g) were divided into four treatment groups: 1) control (C; no Ex), 2) C + CW (no Ex + CW), 3) C + Ex, and 4) C + Ex + CW (Ex + CW). CW was administered as 100 mg/kg CurcuWin^®, providing 20 mg of curcuminoids daily for 6 weeks. A motor-driven rodent treadmill was used to carry out the Ex protocols. During a 5-day period, animals in chronic Ex groups were put through different regimens: day 1, 10 m/min for 10 minutes; day 2, 20 m/min for 10 minutes; day 3, 25 m/min for 10 minutes; day 4, 25 m/min for 20 minutes; and day 5, 25 m/min for 30 minutes. Animals were exercised at 25 m/min for 45 min/d for 5 d/wk for 6 weeks. Blood and muscle samples were analyzed for muscle markers, oxidative stress, and antioxidant markers.

Results

Lactate and muscle malondialdehyde levels decreased in the CW-treated groups (P<0.0001). However, activities of antioxidant enzyme levels increased in the CW-treated groups. Run to exhaustion (minutes) improved in the CW-treated groups. Muscle nuclear factor-κB (P<0.05) and heat shock protein 70 (P<0.05) levels were much lowered in the CW treated group followed by Ex group. In addition, muscle inhibitors of kappa B, peroxisome proliferator-activated receptor gamma coactivator 1-alpha, thioredoxin-1, sirtuin 1, nuclear factor (erythroid-derived 2)-like 2, and glucose transporter 4 protein levels in the Ex + CW group were higher than those in the control and Ex groups (P<0.05).

Conclusion

This study suggests that novel CW has the potential to help prevent muscle damage by regulating the nuclear factor-κB and nuclear factor (erythroid-derived 2)-like 2 pathways and improve the performance and nutritional values of CW.

Mesozeaxanthin Protects Retina from Oxidative Stress in a Rat Model

PURPOSE

Mesozeaxanthin (MZ) is able to protect against chronic and cumulative eye damage and neutralize free radicals produced by oxidative stress. The objective of the present study was to evaluate the protective potential of MZ against retinal oxidative damage and growth and transcription factors of the retina in rats fed with high-fat diet (HFD).

METHODS

Twenty-eight Sprague Dawley rats were randomly divided into the following 4 groups: (1) Control, (2) MZ (100 mg/kg bw/d), (3) HFD (42% of calories as fat), and (4) HFD+MZ (100 mg/kg bw/d) group rats were administered daily as supplement for 12 weeks.

RESULTS

Consumption of HFD was associated with hyperglycemia and oxidative stress as reflected by increased serum MDA concentration (P < 0.001). No measurable zeaxanthin (Z)+MZ and lutein (L) could be detected in the serum of control and HFD rats, whereas they were observed in the serum of MZ-administered rats. Retinal antioxidant enzyme [superoxide dismutase (SOD) and catalase (CAT)] activities were significantly decreased in the HFD group compared to the normal group (P < 0.01). However, retinal antioxidant enzymes were restored close to normal levels in HFD+MZ-treated rats (P < 0.05). The retina of rats fed with HFD had increased levels of vascular endothelial growth factor (VEGF), inducible nitric oxide (iNOS), intercellular adhesion molecule-1 (ICAM-1), and nuclear factor-kappa B (NF-κB) levels and decreased nuclear factor erythroid 2-related factor 2 (Nrf2) and heme-oxygenase 1(HO-1) levels compared to the healthy rat retina (P < 0.001). Rats treated with MZ partially alleviated the inflammation as reflected by suppressed VEGF, iNOS, ICAM, and NF-κB levels and increased Nrf2 and HO-1 levels in the retina of rats fed (P < 0.05).

CONCLUSIONS

Results from the present study suggest that MZ has protective effects on the retina and the ability to modulate oxidative stress of retina in rats fed an HFD by suppressing retinal lipid peroxidation and regulating growth and transcription factors.

Induction of Nrf2/ARE-mediated cytoprotective genes by red ginseng oil through ASK1-MKK4/7-JNK and p38 MAPK signaling pathways in HepG2 cells

BACKGROUND

The induction of cellular defensive genes such as phase II detoxifying and antioxidant enzymes is a highly effective strategy for protection against carcinogenesis as well as slowing cancer development. Transcription factor Nrf2 (nuclear factor E2-related factor 2) is responsible for activation of phase II enzymes induced by natural chemopreventive compounds.

METHODS

Red ginseng oil (RGO) was extracted using a supercritical CO₂ extraction system and chemical profile of RGO was investigated by GC/MS. Effects of RGO on regulation of the Nrf2/antioxidant response element (ARE) pathway were determined by ARE-luciferase assay, western blotting, and confocal microscopy.

RESULTS

The predominant components of RGO were 9,12-octadecadienoic acid (31.48%), bicyclo[10.1.0]tridec-1-ene (22.54%), and 22,23-dihydrostigmasterol (16.90%). RGO treatment significantly increased nuclear translocation of Nrf2 as well as ARE reporter gene activity, leading to upregulation of heme oxygenase-1 and NAD(P)H:quinone oxidoreductase 1. Phosphorylation of the upstream kinases such as apoptosis signal-regulating kinase (ASK)1, mitogen-activated protein kinase (MAPK) kinase (MKK)4/7, c-Jun N-terminal kinase (JNK), and p38 MAPK were enhanced by treatment with RGO. In addition, RGO-mediated Nrf2 expression and nuclear translocation was attenuated by JNK inhibitor SP600125 and p38 MAPK inhibitor SB202190.

CONCLUSION

RGO could be used as a potential chemopreventive agent, possibly by induction of Nrf2/ARE-mediated phase II enzymes via ASK1-MKK4/7-JNK and p38 MAPK signaling pathways.

Functional Foods for Health: The Interrelated Antioxidant and Anti-Inflammatory Role of Fruits, Vegetables, Herbs, Spices and Cocoa in Humans

The health benefits of plant food-based diets could be related to both integrated antioxidant and antiinflammatory mechanisms exerted by a wide array of phytochemicals present in fruit, vegetables, herbs and spices. Therefore, there is mounting interest in identifying foods, food extracts and phytochemical formulations from plant sources which are able to efficiently modulate oxidative and inflammatory stress to prevent diet-related diseases. This paper reviews available evidence about the effect of supplementation with selected fruits, vegetables, herbs, spices and their extracts or galenic formulation on combined markers of redox and inflammatory status in humans.

Hormesis: Decoding Two Sides of the Same Coin

In the paradigm of drug administration, determining the correct dosage of a therapeutic is often a challenge. Several drugs have been noted to demonstrate contradictory effects per se at high and low doses. This duality in function of a drug at different concentrations is known as hormesis. Therefore, it becomes necessary to study these biphasic functions in order to understand the mechanistic basis of their effects. In this article, we focus on different molecules and pathways associated with diseases that possess a duality in their function and thus prove to be the seat of hormesis. In particular, we have highlighted the pathways and factors involved in the progression of cancer and how the biphasic behavior of the molecules involved can alter the manifestations of cancer. Because of the pragmatic role that it exhibits, the imminent need is to draw attention to the concept of hormesis. Herein, we also discuss different stressors that trigger hormesis and how stress-mediated responses increase the overall adaptive response of an individual to stress stimulus. We talk about common pathways through which cancer progresses (such as nuclear factor erythroid 2-related factor 2-Kelch-like ECH-associated protein 1 (Nrf2-Keap1), sirtuin-forkhead box O (SIRT-FOXO) and others), analyzing how diverse molecules associated with these pathways conform to hormesis.

Evaluation Of Potential Cytotoxic Effects Of Herbal Extracts

Herbal medicines have played an important role in treating different diseases since ancient times. Bioactive components of medicinal plants are a good starting point for discovering new drugs such as chemotherapeutics. Currently, there are four classes of plant-derived chemotherapeutic drugs used in clinical practice. However, to discover new potential cytotoxic molecules, the research effort on herbal extracts has not diminished. The aim of this review was to evaluate the chemical constituents of plants that possess cytotoxicity, the signalling pathways responsible for this effect, and the influence of solvent polarity on potential cytotoxic effect and to present the cytotoxic activity of selected herbal extracts. The polyphenolic, anthraquinon, diterpneoid, triterpenoid, flavonoid, betulinic acid and berberine content contributes to cytotoxicity of herbal extracts. The inhibitory effect on cancer cells viability could be a consequence of the non-apoptotic processes, such as cell cycle arrestment, and the apoptotic process in tumour cells through different signalling pathways. The influence of solvent polarity on potential cytotoxic effect of herbal extracts should not be ignored. In general, the best cytotoxic activity was found in nonpolar and moderately polar herbal extracts. The herbal extract with IC50 below 30 μg/ml could be considered a very strong cytotoxic agent. Considering that many antitumor drugs have been discovered from natural products, further research on plants and plant-derived chemicals may result in the discovery of potent anticancer agents.

Down-regulation of lipocalin 2 suppresses the growth of human lung adenocarcinoma through oxidative stress involving Nrf2/HO-1 signaling

Lipocalin 2 (LCN2), a multifunctional secretory protein known as neutrophil gelatinase-associated lipocalin (NGAL), is expressed in a variety of cancers. However, little is known about the biological functions of NGAL in the development of lung adenocarcinoma. In the present study, we primarily found that NGAL expression was up-regulated in human lung adenocarcinoma tissues. Additionally, depletion of NGAL expression decreased the ability of cell proliferation and induced cell apoptosis. Furthermore, with the addition of N-acetylcysteine, a scavenger of reactive oxygen species (ROS), it was found that NGAL depletion was sufficient to cause apoptosis of lung adenocarcinoma cells by generating ROS through the inhibition of the nuclear factor E2-related factor 2/heme oxygenase-1 anti-oxidant pathway. Finally, the effect of NGAL down-regulation on the growth of human lung adenocarcinoma was determined in BALB/c nude mice. These findings demonstrate that NGAL may be a potential therapy target for patients with lung adenocarcinoma.

Dietary indicaxanthin from cactus pear (Opuntia ficus-indicaL. Mill) fruit prevents eryptosis induced by oxysterols in a hypercholesterolaemia-relevant proportion and adhesion of human erythrocytes to endothelial cell layers

Toxic oxysterols in a hypercholesterolaemia-relevant proportion cause suicidal death of human erythrocytes or eryptosis. This process proceeds through early production of reactive oxygen species (ROS), release of prostaglandin (PGE2) and opening of PGE2-dependent Ca channels, membrane phosphatidylserine (PS) externalisation, and cell shrinkage. The present study was the first to reveal that a bioavailable phytochemical, indicaxanthin (Ind) from cactus pear fruit, in a concentration range (1·0–5·0 μM) consistent with its plasma level after a fruit meal, prevents PS externalisation and cell shrinkage in a dose-dependent manner when incubated with isolated healthy human erythrocytes exposed to an oxysterol mixture for 48 h. Dietary Ind inhibited ROS production, glutathione (GSH) depletion, PGE2 release and Ca2+entry. Ind alone did not modify the erythrocyte redox environment or affect other parameters.Ex vivospiking of normal human blood with the oxysterol mixture for 48 h induced eryptosis, resulting in the production of ROS and decreased levels of GSH, which was prevented by concurrent exposure to 5 μm-Ind. The adherence of eryptotic erythrocytes to the endothelium causes vascular tissue injury. Erythrocytes isolated from blood incubated with the oxysterol mixture plus 5 μm-Ind did not adhere to endothelial cell monolayers. Eryptotic erythrocytes may contribute to thrombotic complications in hypercholesterolaemia. Our findings suggest the positive effects of diets containing Ind on erythrocytes in hypercholesterolaemic subjects.

Neurohormetic phytochemicals: An evolutionary-bioenergetic perspective

The impact of dietary factors on brain health and vulnerability to disease is increasingly appreciated. The results of epidemiological studies, and intervention trials in animal models suggest that diets rich in phytochemicals can enhance neuroplasticity and resistance to neurodegeneration. Here we describe how interactions of plants and animals during their co-evolution, and resulting reciprocal adaptations, have shaped the remarkable characteristics of phytochemicals and their effects on the physiology of animal cells in general, and neurons in particular. Survival advantages were conferred upon plants capable of producing noxious bitter-tasting chemicals, and on animals able to tolerate the phytochemicals and consume the plants as an energy source. The remarkably diverse array of phytochemicals present in modern fruits, vegetables spices, tea and coffee may have arisen, in part, from the acquisition of adaptive cellular stress responses and detoxification enzymes in animals that enabled them to consume plants containing potentially toxic chemicals. Interestingly, some of the same adaptive stress response mechanisms that protect neurons against noxious phytochemicals are also activated by dietary energy restriction and vigorous physical exertion, two environmental challenges that shaped brain evolution. In this perspective article, we describe some of the signaling pathways relevant to cellular energy metabolism that are modulated by 'neurohormetic phytochemicals' (potentially toxic chemicals produced by plants that have beneficial effects on animals when consumed in moderate amounts). We highlight the cellular bioenergetics-related sirtuin, adenosine monophosphate activated protein kinase (AMPK), mammalian target of rapamycin (mTOR) and insulin-like growth factor 1 (IGF-1) pathways. The inclusion of dietary neurohormetic phytochemicals in an overall program for brain health that also includes exercise and energy restriction may find applications in the prevention and treatment of a range of neurological disorders.

Biology-oriented development of novel lipophilic antioxidants with neuroprotective activity

Discovery of hydroxycinnamic acid derivatives with enhanced in lipophilicity, blood brain barrier permeability and neuroprotective potential.

Redox control of viral carcinogenesis: The human papillomavirus paradigm

BACKGROUND

Cervical cancer is the second most common neoplastic disease among women worldwide. The initiating event of such cancer is the infection with certain types of human papillomavirus (HPV), a very common condition in the general population. However, the majority of HPV infections is subclinical and transitory and is resolved spontaneously. Intriguingly, viral oncogene expression, although necessary, is not per se sufficient to promote cervical cancer and other factors are involved in the progression of infected cells to the full neoplastic phenotype. In this perspective it has been suggested that the redox balance and the oxidative stress (OS) may represent interesting and under-explored candidates as promoting factors in HPV-initiated carcinogenesis.

SCOPE OF THE REVIEW

The current review discusses the possible interplay between the viral mechanisms modulating cell homeostasis and redox sensitive mechanisms. Experimental data and indirect evidences are presented on the activity of viral dependent functions on i) the regulation of enzymes and compounds involved in OS; ii) the protection from oxidation of detoxifying/antiapoptotic enzymes and redox-sensitive transcription factors; iii) the suppression of apoptosis; and iv) the modulation of host microRNAs regulating genes associated with antioxidant defense.

MAJOR CONCLUSIONS

The resulting tangled scenario suggests that viral hosting cells adapt their metabolisms in order to support their growth and survival in the increasingly oxidant micro-environment associated with HPV tumor initiation and progression.

GENERAL SIGNIFICANCE

HPV can modulate the host cell redox homeostasis in order to favor infection and possibly tumor transformation. This article is part of a Special Issue entitled Redox regulation of differentiation and de-differentiation.

Cruciferous vegetables have variable effects on biomarkers of systemic inflammation in a randomized controlled trial in healthy young adults

BACKGROUND

Isothiocyanates in cruciferous vegetables modulate signaling pathways critical to carcinogenesis, including nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), a central regulator of inflammation. Glutathione S-transferase (GST) M1 and GSTT1 metabolize isothiocyanates; genetic variants may result in differences in biologic response.

OBJECTIVE

The objective of this study was to test whether consumption of cruciferous or cruciferous plus apiaceous vegetables altered serum concentrations of interleukin (IL)-6, IL-8, C-reactive protein (CRP), tumor necrosis factor (TNF) α, and soluble TNF receptor (sTNFR) I and II, and whether this response was GSTM1/GSTT1 genotype dependent.

METHODS

In a randomized crossover trial, healthy men (n = 32) and women (n = 31) aged 20-40 y consumed 4 14-d controlled diets: basal (vegetable-free), single-dose cruciferous (1xC) [7 g vegetables/kg body weight (BW)], double-dose cruciferous (2xC) (14 g/kg BW), and cruciferous plus apiaceous (carrot family) (1xC+A) vegetables (7 and 4 g/kg BW, respectively), with a 21-d washout period between each intervention. Urinary isothiocyanate excretion was also evaluated as a marker of systemic isothiocyanate exposure. Fasting morning blood and urine samples were collected on days 0 and 14 and analyzed.

RESULTS

IL-6 concentrations were significantly lower on day 14 of the 2xC and 1xC+A diets than with the basal diet [-19% (95% CI: -30%, -0.1%) and -20% (95% CI: -31%, -0.7%), respectively]. IL-8 concentrations were higher after the 1xC+A diet (+16%; 95% CI: 4.2%, 35.2%) than after the basal diet. There were no effects of diet on CRP, TNF-α, or sTNFRI or II. There were significant differences between GSTM1-null/GSTT1+ individuals for several biomarkers in response to 1xC+A compared with basal diets (CRP: -37.8%; 95% CI: -58.0%, -7.4%; IL-6: -48.6%; 95% CI: -49.6%, -12.0%; IL-8: 16.3%; 95% CI: 6.7%, 57.7%) and with the 2xC diet compared with the basal diet (IL-8: -33.2%; 95% CI: -43.0%, -1.4%; sTNFRI: -7.5%; 95% CI: -12.7%, -2.3%). There were no significant reductions in biomarker concentrations in response to diet among GSTM1+/GSTT1+ or GSTM1-null/GSTT1-null individuals. Twenty-four-hour urinary isothiocyanate excretion was not associated with any of the inflammation markers overall; however, IL-6 was inversely associated with total isothiocyanate excretion in GSTM1-null/GSTT1-null individuals (β = -0.12; 95% CI: -0.19, -0.05).

CONCLUSIONS

In this young, healthy population, consumption of cruciferous and apiaceous vegetables reduced circulating IL-6; however, results for other biomarkers of inflammation were not consistent.