Mechanisms of combined action of different chemopreventive dietary compounds

Pomegranate-mediated chemoprevention of experimental hepatocarcinogenesis involves Nrf2-regulated antioxidant mechanisms

Hepatocellular carcinoma (HCC), one of the most prevalent and lethal cancers, has shown an alarming rise in the USA. Without effective therapy for HCC, novel chemopreventive strategies may effectively circumvent the current morbidity and mortality. Oxidative stress predisposes to hepatocarcinogenesis and is the major driving force of HCC. Pomegranate, an ancient fruit, is gaining tremendous attention due to its powerful antioxidant properties. Here, we examined mechanism-based chemopreventive potential of a pomegranate emulsion (PE) against dietary carcinogen diethylnitrosamine (DENA)-induced rat hepatocarcinogenesis that mimics human HCC. PE treatment (1 or 10 g/kg), started 4 weeks prior to the DENA challenge and continued for 18 weeks thereafter, showed striking chemopreventive activity demonstrated by reduced incidence, number, multiplicity, size and volume of hepatic nodules, precursors of HCC. Both doses of PE significantly attenuated the number and area of γ-glutamyl transpeptidase-positive hepatic foci compared with the DENA control. PE also attenuated DENA-induced hepatic lipid peroxidation and protein oxidation. Mechanistic studies revealed that PE elevated gene expression of an array of hepatic antioxidant and carcinogen detoxifying enzymes in DENA-exposed animals. PE elevated protein and messenger RNA expression of the hepatic nuclear factor E2-related factor 2 (Nrf2). Our results provide substantial evidence, for the first time, that pomegranate constituents afford chemoprevention of hepatocarcinogenesis possibly through potent antioxidant activity achieved by upregulation of several housekeeping genes under the control of Nrf2 without toxicity. The outcome of this study strongly supports the development of pomegranate-derived products in the prevention and treatment of human HCC, which remains a devastating disease.

Lunasin-aspirin combination against NIH/3T3 cells transformation induced by chemical carcinogens

Carcinogenesis is a multistage process involving a number of molecular pathways sensitive to intervention. Chemoprevention is defined as the use of natural and/or synthetic substances to block, reverse, or retard the process of carcinogenesis. To achieve greater inhibitory effects on cancer cells, combination of two or more chemopreventive agents is commonly considered as a better preventive and/or therapeutic strategy. Lunasin is a promising cancer preventive peptide identified in soybean and other seeds. Its efficacy has been demonstrated by both in vitro and in vivo models. This peptide has been found to inhibit human breast cancer MDA-MB-231 cells proliferation, suppressing cell cycle progress and inducing cell apoptosis. Moreover, lunasin potentiates the effects on these cells of different synthetic and natural compounds, such as aspirin and anacardic acid. This study explored the role of lunasin, alone and in combination with aspirin and anacardic acid on cell proliferation and foci formation of transformed NIH/3T3 cells induced by chemical carcinogens 7,12-dimethylbenz[a]anthracene or 3-methylcholanthrene. The results revealed that lunasin, acting as a single agent, inhibits cell proliferation and foci formation. When combined with aspirin, these effects were significantly increased, indicating that this combination might be a promising strategy to prevent/treat cancer induced by chemical carcinogens.

Combined consumption of soy germ and tomato powders results in altered isoflavone and carotenoid bioavailability in rats

The efficacy of combinations of food for enhanced anticancer activity is of clinical interest, but there is limited information on the effect of combined consumption on bioactive bioavailability. Male Copenhagen rats consumed diets containing 10% tomato powder (TP), 2% soy germ (SG), neither, or a combination (TP+SG) for 25 weeks (n = 63) or 7 days (n = 24). After 7 days, serum carotenoids were significantly lower after TP+SG feeding compared to TP alone. After 25 weeks, the TP+SG group had significantly lower lycopene and β-carotene concentration in the testes, seminal vesicles, and ventral prostate compared to the TP group and significantly higher urinary isoflavone excretion compared to the SG group. These differences were not explained by mRNA expression of scavenger receptor class B type I, carotene 15,15'-monooxygenase I, carotene 9',10'-monooxygenase II, or activity of hepatic detoxification enzymes. The results suggest interactions between soy germ and tomato powder that enhance isoflavone absorption but reduce carotenoid bioavailability.

Luteolin and chicoric acid synergistically inhibited inflammatory responses via inactivation of PI3K-Akt pathway and impairment of NF-κB translocation in LPS stimulated RAW 264.7 cells

Synergistic anti-inflammatory effects of luteolin and chicoric acid, two abundant constituents of the common dandelion (Taraxacum officinale Weber), were investigated in lipopolysaccharide (LPS) stimulated RAW 264.7 cells. Co-treatment with luteolin and chicoric acid synergistically reduced cellular concentrations of nitric oxide (NO) and prostaglandin E2 (PGE2) and also inhibited expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). In addition, co-treatment reduced the levels of proinflammatory cytokines, tumor necrosis factor (TNF)-α, and interleukin (IL)-1β. Both luteolin and chicoric acid suppressed oxidative stress, but they did not exhibit any synergistic activity. Luteolin and chicoric acid co-treatment inhibited phosphorylation of NF-κB and Akt, but had no effect on extracellular signal-regulated kinase (ERK), c-Jun NH2-terminal kinase (JNK), and p38. This anti-inflammatory signaling cascade coincides with that affected by luteolin treatment alone. These results suggest that luteolin plays a central role in ameliorating LPS-induced inflammatory cascades via inactivation of the NF-κB and Akt pathways, and that chicoric acid strengthens the anti-inflammatory activity of luteolin through NF-κB attenuation.

Synergistic growth inhibition of mouse skin tumors by pomegranate fruit extract and diallyl sulfide: evidence for inhibition of activated MAPKs/NF-κB and reduced cell proliferation

Limited outcomes from earlier chemopreventive studies have necessitated that some modifications be made to get better efficacy. It is proposed that cancer prevention is more feasible than treatment, and this could be achieved effortlessly with use of multiple agents competent of targeting multiple targets. This study was initiated to examine the chemopreventive efficacy of pomegranate fruit extract (PFE) and diallyl sulfide (DAS), alone and in combination, using 2-stage mouse skin tumorigenesis model. PFE and DAS alone delayed onset and tumor incidence by ∼55% and ∼45%, respectively, while their combination at low doses synergistically decreased tumor incidence more potentially (∼84%, p<0.01). In addition, regression in tumor volume was seen with continuous combinatorial treatment (p<0.01). Mechanistic studies revealed that this inhibition was associated with decreased expression of phosphorylated ERK1/2, JNK1 and activated NF-κB/p65, IKKα, IκBα phosphorylation and degradation in skin tissue/tumor. Histological and cell death analysis also confirmed that combined PFE and DAS inhibit cellular proliferation and markedly induce apoptosis than the single agents. Altogether, our results suggest that PFE and DAS in combination impart better suppressive activity than either of these agents alone and provide support that development of novel combination therapies/chemoprevention using dietary agents will be more beneficial against cancer.

Concurrent Sulforaphane and Eugenol Induces Differential Effects on Human Cervical Cancer Cells

Background. The concept of combination of chemoprevention holds great potential for cancer management as lower, clinically tolerable doses of individual agents could be achieved through therapeutic synergy. However, elucidation of their possible interactions—additive, synergistic, or antagonistic—must be thoroughly studied before considering for clinical use. Methods. To evaluate the effect of combination treatment of sulforaphane (SFN) and eugenol on HeLa cells, the authors performed cell viability assay, apoptosis assay, and reverse transcription polymerase chain reaction for gene expression analysis. Calculations of combination effects were expressed as a combination index (CI) with CI < 1, CI = 1, or CI > 1 representing synergism, additivity, or antagonism, respectively. Results. Simultaneous treatment with variable dose combinations of SFN and eugenol resulted in differential effects with an antagonistic effect at lower and synergistic at higher sub-lethal doses as reflected in cell cytotoxicity and apoptosis induction. Importantly, gemcitabine used in conjunction with the low- and high-dose combinations showed no significant cell death at lower doses suggesting that cell cytotoxicity is proportional to gemcitabine alone, whereas at higher sublethal doses of SFN and eugenol, it was found to act in a synergistic manner with gemcitabine. Furthermore, SFN and eugenol combinations at synergistic dose significantly downregulated the expression of Bcl-2, COX-2 and IL-β but not the antagonistic combinations. Conclusion. This study clearly indicates that 2 (or more) chemopreventive agents can act antagonistically or synergistically necessitating elucidation of possible mechanistic interactions for favorable and reliable outcomes of dietary components in the field of cancer prevention.

Mastic oil inhibits the metastatic phenotype of mouse lung adenocarcinoma cells

Mastic oil from Pistacia lentiscus variation chia, a natural combination of bioactive terpenes, has been shown to exert anti-tumor growth effects against a broad spectrum of cancers including mouse Lewis lung adenocarcinomas (LLC). However, no studies have addressed its anti-metastatic actions. In this study, we showed that treatment of LLC cells with mastic oil within a range of non-toxic concentrations (0.01–0.04% v/v): (a) abrogated their Matrigel invasion and migration capabilities in transwell assays; (b) reduced the levels of secreted MMP-2; (c) restricted phorbol ester-induced actin remodeling and (d) limited the length of neo-vessel networks in tumor microenvironment in the model of chick embryo chorioallantoic membrane. Moreover, exposure of LLC and endothelial cells to mastic oil impaired their adhesive interactions in a co-culture assay and reduced the expression of key adhesion molecules by endothelial cells upon their stimulation with tumor necrosis factor-alpha. Overall, this study provides novel evidence supporting a multipotent role for mastic oil in prevention of crucial processes related to cancer metastasis.

Relative validity of fruit and vegetable intake estimated from an FFQ, using carotenoid and flavonoid biomarkers and the method of triads

The aim of the present study was to validate the intakes of fruit, juice and vegetables from an FFQ. In sub-study I (n 147), intakes from the FFQ were evaluated against 7 d weighed food records (WR) and plasma carotenoid concentrations, whereas in sub-study II (n 85), the intakes were evaluated against plasma carotenoid concentrations and amounts of flavonoids in 24 h urine samples. Relative validity was evaluated by comparing median intakes, estimating correlation coefficients and validity coefficients using the method of triads. In sub-study I, we observed no significant difference in daily median fruit intake between the FFQ and the WR, whereas the intake of vegetables was higher from the FFQ than from the WR. The correlations between intakes from the FFQ and the WR ranged from 0·31 to 0·58. In sub-study II, the intakes of fruit and vegetables correlated significantly with plasma carotenoid concentrations and urinary flavonoids. The validity coefficients for the intakes of fruit and vegetables from the FFQ ranged from 0·61 to 0·88 in sub-study I and from 0·60 to 0·94 in sub-study II. In summary, based on the associations observed between intakes from the FFQ and the biomarkers and the FFQ validity coefficients, the FFQ was found valid and suitable for ranking individuals according to their usual intake of fruit, juice and vegetables.

Anthocyanin-rich black currant extract suppresses the growth of human hepatocellular carcinoma cells

Dietary antioxidants, such as anthocyanins, are helpful in the prevention and control of various diseases by counteracting the imbalance of oxidative and antioxidative factors in the living systems. Black currant (Ribes nigrum L., Grossulariaceae) is known to contain high amounts of anthocyanins (250 mg/100 g fresh fruit). Black currant fruits have been used in Asian and European traditional medicine for the treatment of a variety of diseases. Black currant extract has recently been found to be the second most effective amongst nine different berry extracts studied for their free radical scavenging activity. Constituents present in black currant juice have been found to exert a number of health-promoting effects, including immunomodulatory, antimicrobial and antiinflammatory actions, inhibition of low-density lipoprotein, and reduction of cardiovascular diseases. Although antioxidant and antiinflammatory effects of black currant juice could be of value in preventing and treating oxidative stress- and inflammation-driven cancers, no experimental evidence is available to now. The objective of the present study was to evaluate the potential antiproliferative effects of black currant fruit skin extract against HepG2 human liver cancer cells. The aqueous extract yielded an anthocyanin-rich fraction with cyanidin-3-O-rutinoside as one of the major anthocyanins. This fraction exhibited a potent cytotoxic effect on HepG2 cells and this effect was more pronounced than that of delphinidin and cyanidin, two major aglycones of anthocyanins present in black currant. Our results indicate, for the first time, that black currant skin containing an anthocyanin-rich fraction inhibits the proliferation of liver cancer cells, possibly due to additive as well as synergistic effects. This product could be useful in the prevention and treatment of human hepatocellular carcinoma.

Distinct combinatorial effects of the plant polyphenols curcumin, carnosic acid, and silibinin on proliferation and apoptosis in acute myeloid leukemia cells

Acute myeloid leukemia (AML) is a malignancy without effective treatment for most patients. Here we demonstrate that combinations of the dietary plant polyphenols--curcumin and carnosic acid--at noncytotoxic concentrations of each agent, produced a synergistic antiproliferative effect and a massive apoptotic cell death in HL-60 and KG-1a human AML cells. In contrast, combinations of curcumin and another plant polyphenol silibinin had a predominantly additive cytostatic effect, without pronounced cytotoxicity. Neither polyphenol combination affected viability of normal human fibroblasts or proliferating and nonproliferating blood cells. Early stage of curcumin/carnosic acid-induced apoptosis was associated with cleavage (activation) of caspase-8, caspase-9, and caspase-3 and the proapoptotic protein Bid, but not with oxidative stress or altered levels of other Bcl-2 family proteins (Bcl-2, Bcl-xl, Mcl-1, Bax, and Bak). Inhibitors of caspase-8 and caspase-9 markedly attenuated apoptosis, indicating the involvement of both extrinsic and intrinsic apoptotic pathways. Caspase-8 inhibition abrogated Bid cleavage and strongly reduced caspase-9 activation, suggesting that the cross-talk mechanism mediated by caspase-8-dependent Bid cleavage can contribute to the activation of the intrinsic apoptotic pathway by curcumin + carnosic acid. Collectively, these results suggest a mechanistic basis for the potential use of dietary plant polyphenol combinations in the treatment and prevention of AML.

Intake of fruits and vegetables, and risk of endometrial cancer in the NIH-AARP Diet and Health Study

BACKGROUND

Fruits and vegetables contain a wide variety of phytochemicals which may have anti-carcinogenic effects. Although the results of case-control studies have suggested a possible protective effect of fruit and vegetable intake on the risk of endometrial carcinoma, few cohort studies have examined this association.

MATERIALS AND METHODS

We used data from the NIH-AARP Diet and Health Study to assess the association of fruit and vegetable consumption, as well as intake of specific botanical groupings of fruits and vegetables, with endometrial cancer risk among 112,088 women who completed a food-frequency questionnaire at baseline, in 1995-1996. During 8 years of follow-up 1142 incident cases of endometrial cancer were ascertained. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI).

RESULTS

After adjustment for covariates, HRs for the highest compared to the lowest quintile of total fruit and total vegetable intake were 1.30 (95% CI 1.04-1.61, P for trend 0.05) and 1.09 (95% CI 0.90-1.33, P for trend 0.55), respectively. No inverse associations were observed for intake of any of 13 botanical groupings of fruits and vegetables.

CONCLUSIONS

Results from this large prospective study do not support a protective role of a high intake of fruits or vegetables on the risk of endometrial cancer in older women.

Both common and specialty mushrooms inhibit adhesion molecule expression and in vitro binding of monocytes to human aortic endothelial cells in a pro-inflammatory environment

Background

Cardiovascular disease (CVD) is a leading cause of mortality in the United States as well as globally. Epidemiological studies show that regular fruit and vegetable consumption reduces CVD risk, in part, due to antioxidant activity and immunomodulation since oxidative stress and inflammation are features of atherogenesis. Accumulating evidence also shows that dietary fungi, viz., mushrooms, can protect against chronic disease by altering inflammatory environments such as those associated with CVD although most research has focused on specialty mushrooms. In this study, we tested the ability of both common and specialty mushrooms to inhibit cellular processes associated with CVD.

Methods

Human aortic endothelial cells (HAEC) were incubated overnight with control media with dimethylsulfoxide (DMSO) vehicle (1% v/v) or containing DMSO extracts of whole dehydrated mushrooms (0.1 mg/mL), which included Agaricus bisporus (white button and crimini), Lentinula edodes (shiitake), Pleurotus ostreatus (oyster), and Grifola frondosa (maitake). Monolayers were subsequently washed and incubated with medium alone or containing the pro-inflammatory cytokine IL-1β (5 ng/mL) for 6 h to upregulate pro-atherosclerotic adhesion molecules (AM). AM expression was assayed by ELISA and binding of U937 human monocytes pre-loaded with fluorescent dye was determined.

Results

White button mushrooms consistently reduced (p < 0.05) VCAM-1, ICAM-1, and E-selectin-1 expression, whereas other test mushrooms significantly modulated AM expression singly, collectively, or combinatorially. All mushrooms, however, significantly reduced binding of monocytes to both quiescent and cytokine-stimulated monolayers.

Conclusion

These data provide evidence that dietary mushrooms can inhibit cellular processes such as adhesion molecule expression and ultimate binding of monocytes to the endothelium under pro-inflammatory conditions, which are associated with CVD. As a result, these findings support the notion that dietary mushrooms can be protective against CVD.

On the natural chemoprevention of cancer

Cancer is a complex disease to treat and the treatments have not progressed significantly in the last few years. Alternative strategies such as chemoprevention are being investigated. Proof of concept of chemoprevention has been shown with the non-steroidal anti-inflammatory drugs (NSAIDs); however there is significantly more interest in plant and naturally available compounds for chemoprevention. A number of different naturally occurring chemical compounds are reviewed here for their potential benefits and the pathways which they may target, in particular the polyamine pathway.

Dietary components related to N-nitroso compound formation: a prospective study of adult glioma

BACKGROUND

N-nitroso compounds (NOC) are found in processed meat and are formed endogenously from intake of nitrite and nitrate. Endogenous NOC formation is antagonized by nitrosation inhibitors in fruit and vegetables (e.g., vitamin C) and promoted by heme in red meat. It has been hypothesized that a diet resulting in high exposure to NOCs increases adult glioma risk.

METHODS

Using proportional hazards models, we tested this hypothesis among 545,770 participants in the prospective NIH-AARP Diet and Health Study, which assessed dietary intake at baseline (1995-1996) with a comprehensive food frequency questionnaire, and at ages 12 to 13 years with an abbreviated food frequency questionnaire.

RESULTS

During follow-up through 2003, 585 participants were diagnosed with glioma. We found no significant trends in glioma risk for consumption of processed or red meat, nitrate, or vitamin C or E. We found significant positive trends for nitrite intake from plant sources (hazard ratio for quintile 5 versus quintile 1, 1.59; 95% confidence interval, 1.20-2.10; P for trend = 0.028) and, unexpectedly, for fruit and vegetable intake (hazard ratio, 1.42; 95% confidence interval, 1.08-1.86; P for trend = 0.0081). Examination of interactions between dietary intakes (e.g., nitrite and vitamin C) and a limited analysis of diet at ages 12 to 13 years provided no support for the NOC hypothesis.

CONCLUSIONS

Our results suggest that consumption of processed or red meat, nitrite, or nitrate does not increase adult glioma risk, and that consumption of fruit and vegetables, vitamin C, or vitamin E does not reduce risk.

IMPACT

Our results, in agreement with the only previous prospective analysis, cast doubt on the NOC hypothesis in relation to dietary intake and adult glioma risk.

Polyphenolic compounds from Salvia species protect cellular DNA from oxidation and stimulate DNA repair in cultured human cells

DNA damage can lead to carcinogenesis if replication proceeds without proper repair. This study evaluated the effects of the water extracts of three Salvia sp., Salvia officinalis (SO), Salvia fruticosa (SF), and Salvia lavandulifolia (SL), and of the major phenolic constituents, rosmarinic acid (RA) and luteolin-7-glucoside (L-7-G), on DNA protection in Caco-2 and HeLa cells exposed to oxidative agents and on DNA repair in Caco-2 cells. The comet assay was used to measure DNA damage and repair capacity. The final concentration of each sage extract was 50 microg/mL, and concentrations of RA and L-7-G were 50 and 20 microM, respectively. After a short incubation (2 h), L-7-G protected DNA in Caco-2 cells from damage induced by H(2)O(2) (75 microM); also, after a long incubation (24 h), SF, RA, and L-7-G had protective effects in Caco-2 cells. In HeLa cells, SO, SF, and RA protected against damage induced by H(2)O(2) after 24 h of incubation. Assays of DNA repair show that SO, SF, and L-7-G increased the rate of DNA repair (rejoining of strand breaks) in Caco-2 cells treated with H(2)O(2). The incision activity of a Caco-2 cell extract on a DNA substrate containing specific damage (8-oxoGua) was also measured to evaluate effects on base excision repair (BER) activity. Preincubation for 24 h with SO and L-7-G had a BER inductive effect, increasing incision activity in Caco-2 cells. In conclusion, SO, SF, and the isolated compounds (RA and L-7-G) demonstrated chemopreventive activity by protecting cells against oxidative DNA damage and stimulating DNA repair (SO, SF, and L-7-G).

Characterization of low molecular weight chemical fractions of dry bean (Phaseolus vulgaris) for bioactivity using Caenorhabditis elegans longevity and metabolite fingerprinting

Dry bean consumption has been reported to be associated with reduced risk for a number of chronic diseases including cancer. The extent to which these benefits are associated with primary versus secondary plant metabolites is not known. The work reported herein focuses on low molecular weight secondary metabolites and uses longevity extension of wild-type Caenorhabditis elegans nematodes as a surrogate marker for human health benefits. A modified Bligh and Dyer technique was used to extract freeze-dried bean, and the resulting fractions were evaluated for longevity extension and metabolite fingerprinting using ultra performance liquid chromatography-mass spectrometry (UPLC-MS). Dry bean extracts extended adult C. elegans lifespan by as much as 16%. Hydrophilic fractions increased lifespan, whereas the hydrophobic fraction induced longevity reduction. Metabolite fingerprinting revealed distinguishing spectral differences among the four chemical fractions evaluated and demonstrated that within each fraction chemical composition differed significantly based on dry bean genetic heritage.

Alkaloid-rich fraction of Himatanthus lancifolius contains anti-tumor agents against leukemic cells

The effects of the alkaloid-rich fraction of Himatanthus lancifolius (Müll. Arg) Woodson on normal marrow cells and leukemic cell lines were investigated. After 48 h exposure, the proliferation assay showed significant cell growth inhibition for Daudi (0.1-10 µg/mL), K-562 (1-10 µg/mL), and REH cells (10-100 µg/mL), yet was inert for normal marrow cells. A similar inhibition profile was observed in clonogenic assays. This alkaloid-rich fraction, in which uleine is the main compound, showed no signs of toxicity to any cells up to 10 µg/mL. Cell feature analyses after induction of differentiation showed maintenance of the initial phenotype. Flow cytometric expression of Annexin-V and 7-AAD in K-562 and Daudi cells has indicated that the cells were not undergoing apoptosis or necrosis, suggesting cytostatic activity for tumor cells

TLR4 signaling inhibitory pathway induced by green tea polyphenol epigallocatechin-3-gallate through 67-kDa laminin receptor

Epigallocatechin-3-gallate (EGCG), a major active polyphenol of green tea, has been shown to downregulate inflammatory responses in macrophages; however, the underlying mechanism has not been understood. Recently, we identified the 67-kDa laminin receptor (67LR) as a cell-surface EGCG receptor that mediates the anticancer action of EGCG at physiologically relevant concentrations (0.1-1 microM). In this study, we show the molecular basis for the downregulation of TLR4 signal transduction by EGCG at 1 microM in macrophages. Anti-67LR Ab treatment or RNA interference-mediated silencing of 67LR resulted in abrogation of the inhibitory action of EGCG on LPS-induced activation of downstream signaling pathways and target gene expressions. Additionally, we found that EGCG reduced the TLR4 expression through 67LR. Interestingly, EGCG induced a rapid upregulation of Toll-interacting protein (Tollip), a negative regulator of TLR signaling, and this EGCG action was prevented by 67LR silencing or anti-67LR Ab treatment. RNA interference-mediated silencing of Tollip impaired the TLR4 signaling inhibitory activity of EGCG. Taken together, these findings demonstrate that 67LR plays a critical role in mediating anti-inflammatory action of a physiologically relevant EGCG, and Tollip expression could be modulated through 67LR. These results provide a new insight into the understanding of negative regulatory mechanisms for the TLR4 signaling pathway and consequent inflammatory responses that are implicated in the development and progression of many chronic diseases.

Effects of oxysterols on cell viability, inflammatory cytokines, VEGF, and reactive oxygen species production on human retinal cells: cytoprotective effects and prevention of VEGF secretion by resveratrol

BACKGROUND AND AIMS

Oxysterols are assumed to play important roles in age-related macular degeneration, a major cause of blindness. So we characterized the cytotoxic, oxidative, inflammatory, and angiogenic activities of oxysterols (7β-hydroxycholesterol (7β-OH), 7-ketocholesterol (7KC), 25-hydroxycholesterol (25-OH)) in human retinal ARPE-19 cells, and evaluated the protective effects of resveratrol (Rsv: 1 μM), a polyphenol from red wine.

METHODS

ARPE-19 cells were treated with 7β-OH, 7KC, or 25-OH (5-40 μg/mL; 24-48 h) without or with Rsv. Cell viability was determined using trypan blue and the MTT assay. Cell death was characterized by electron microscopy and in situ detection of activated caspases with fluorochrome-labeled inhibitors of caspases. Reactive oxygen species (ROS) production was measured with hydroethidine. ELISA methods and a cytometric bead assay were used to quantify cytokines involved in inflammation (IL-8, IL-1β, IL-6, IL-10, IL-12p70, TNF-α, MCP-1) and VEGF.

RESULTS

7β-OH and 7KC triggered a caspase-independent cell death process associated with the presence of multilamellar cytoplasmic structures evocating phospholipidosis, increased ROS production, and IL-8 secretion. 7β-OH enhanced VEGF secretion. No cytotoxic effects were identified with 25-OH, which highly stimulated ROS production, MCP-1, and VEGF secretion. With oxysterols, no IL-10, TNF-α, and IL-12p70 secretion were detected. 25-OH induced IL-8 secretion through the MEK/ERK½ signaling pathway, and Rsv showed cytoprotective activities and inhibited VEGF secretion.

CONCLUSION

7β-OH, 7KC, and 25-OH have cytotoxic, oxidative, inflammatory, and/or angiogenic activities on ARPE-19 cells. As Rsv has some protective effects against oxysterol-induced cell death and VEGF secretion it could be valuable in ARMD treatment.

Estimation of dietary sources and flavonoid intake in a Spanish adult population (EPIC-Spain)

BACKGROUND

Epidemiologic studies have suggested associations between flavonoid intake and health benefits. Traditional Mediterranean diets consist of a high consumption of plant products rich in flavonoids.

OBJECTIVE

This study estimates dietary flavonoid intake and main food sources in a Mediterranean population (Spanish adults).

DESIGN

The study included 40,683 subjects aged 35 to 64 years from northern and southern regions of Spain who were included in the European Prospective Investigation into Cancer and Nutrition study Spanish cohort. Usual food intake was assessed by personal interviews using a computerized version of a validated diet history method. Expanded US Department of Agriculture databases for the flavonoid, isoflavone, and proanthocyanidin content were used.

RESULTS

The median and mean of total flavonoids were 269.17 and 313.26 mg/day, respectively. The most abundant flavonoid subgroup was proanthocyanidins (60.1%), followed by flavanones (16.9%), flavan-3-ols (10.3%), flavonols (5.9%), anthocyanidins (5.8%), flavones (1.1%), and isoflavones (<0.01%). The main sources of total flavonoid intake were apples (23%), red wine (21%), unspecified fruit (12.8%), and oranges (9.3%).

CONCLUSIONS

These results should be very useful for evaluating the relationships between flavonoid intake and several diseases.

Complementary roles in cancer prevention: protease inhibitor makes the cancer preventive peptide lunasin bioavailable

BACKGROUND

The lower incidence of breast cancer among Asian women compared with Western countries has been partly attributed to soy in the Asian diet, leading to efforts to identify the bioactive components that are responsible. Soy Bowman Birk Inhibitor Concentrate (BBIC) is a known cancer preventive agent now in human clinical trials.

METHODOLOGY/PRINCIPAL FINDINGS

The objectives of this work are to establish the presence and delineate the in vitro activity of lunasin and BBI found in BBIC, and study their bioavailability after oral administration to mice and rats. We report that lunasin and BBI are the two main bioactive ingredients of BBIC based on inhibition of foci formation, lunasin being more efficacious than BBI on an equimolar basis. BBI and soy Kunitz Trypsin Inhibitor protect lunasin from in vitro digestion with pancreatin. Oral administration of (3)H-labeled lunasin with lunasin-enriched soy results in 30% of the peptide reaching target tissues in an intact and bioactive form. In a xenograft model of nude mice transplanted with human breast cancer MDA-MB-231 cells, intraperitoneal injections of lunasin, at 20 mg/kg and 4 mg/kg body weight, decrease tumor incidence by 49% and 33%, respectively, compared with the vehicle-treated group. In contrast, injection with BBI at 20 mg/kg body weight shows no effect on tumor incidence. Tumor generation is significantly reduced with the two doses of lunasin, while BBI is ineffective. Lunasin inhibits cell proliferation and induces cell death in the breast tumor sections.

CONCLUSIONS/SIGNIFICANCE

We conclude that lunasin is actually the bioactive cancer preventive agent in BBIC, and BBI simply protects lunasin from digestion when soybean and other seed foods are eaten by humans.

Protective effect of apricot (Prunus armeniaca L.) on hepatic steatosis and damage induced by carbon tetrachloride in Wistar rats

The present study was planned to investigate the protective effect of 10 % and 20 % apricot-containing feed on carbon tetrachloride (CCl4)-induced hepatic steatosis and damage. Adult male Wistar rats (n 42) were divided into six groups of seven each, as follows: control group; CCl4 group; CCl4+10 % apricot group; CCl4+20 % apricot group; 10 % apricot group; 20 % apricot group. All apricot groups were fed with 10 % or 20 % apricot-containing feed for 5 months. CCl4 injections were applied to the CCl4 groups at the dose of 1 mg/kg for 3 d at the end of 5 months. In the CCl4 group, vacuolated hepatocytes and hepatic necrosis were seen, especially in the centrilobular area. Hepatocytes showed an oedematous cytoplasmic matrix, large lipid globules and degenerated organelles. The area of liver injury was found significantly decreased with apricot feeding. Malondialdehyde and total glutathione levels and catalase, superoxide dismutase and glutathione peroxidase activities were significantly changed in the CCl4 group and indicated increased oxidative stress. Apricot feeding decreased this oxidative stress and ameliorated histological damage. We concluded that apricot feeding had beneficial effects on CCl4-induced liver steatosis and damage probably due to its antioxidant nutrient (beta-carotene and vitamin) contents and high radical-scavenging capacity. Dietary intake of apricot can reduce the risk of liver steatosis and damage caused by free radicals.

Genetic engineering to enhance crop-based phytonutrients (nutraceuticals) to alleviate diet-related diseases

Nutrition studies have provided unambiguous evidence that a number of human health maladies including chronic coronary artery, hypertension, diabetes, osteoporosis, cancer and age- and lifestyle-related diseases are associated with the diet. Several favorable and a few deleterious natural dietary ingredients have been identified that predispose human populations to various genetic and epigenetic based disorders. Media dissemination of this information has greatly raised public awareness of the beneficial effects due to increased consumption of fruit, vegetables and whole grain cereals-foods rich in phytonutrients, protein and fiber. However, the presence of intrinsically low levels of the beneficial phytonutrients in the available genotypes of crop plants is not always at par with the recommended daily allowance (RDA) for different phytonutrients (nutraceuticals). Molecular engineering of crop plants has offered a number of tools to markedly enhance intracellular concentrations of some of the beneficial nutrients, levels that, in some cases, are closer to the RDA threshold. This review brings together literature on various strategies utilized for bioengineering both major and minor crops to increase the levels of desirable phytonutrients while also decreasing the concentrations of deleterious metabolites. Some of these include increases in: protein level in potato; lysine in corn and rice; methionine in alfalfa; carotenoids (beta-carotene, phytoene, lycopene, zeaxanthin and lutein) in rice, potato, canola, tomato; choline in tomato; folates in rice, corn, tomato and lettuce; vitamin C in corn and lettuce; polyphenolics such as flavonol, isoflavone, resveratrol, chlorogenic acid and other flavonoids in tomato; anthocyanin levels in tomato and potato; alpha-tocopherol in soybean, oil seed, lettuce and potato; iron and zinc in transgenic rice. Also, molecular engineering has succeeded in considerably reducing the levels of the offending protein glutelin in rice, offering proof of concept and a new beginning for the development of super-low glutelin cereals for celiac disease patients.

A transcriptomic computational analysis of mastic oil-treated Lewis lung carcinomas reveals molecular mechanisms targeting tumor cell growth and survival

Background

Mastic oil from Pistacia lentiscus variation chia, a blend of bioactive terpenes with recognized medicinal properties, has been recently shown to exert anti-tumor growth activity through inhibition of cancer cell proliferation, survival, angiogenesis and inflammatory response. However, no studies have addressed its mechanisms of action at genome-wide gene expression level.

Methods

To investigate molecular mechanisms triggered by mastic oil, Lewis Lung Carcinoma cells were treated with mastic oil or DMSO and RNA was collected at five distinct time points (3-48 h). Microarray expression profiling was performed using Illumina mouse-6 v1 beadchips, followed by computational analysis. For a number of selected genes, RT-PCR validation was performed in LLC cells as well as in three human cancer cell lines of different origin (A549, HCT116, K562). PTEN specific inhibition by a bisperovanadium compound was applied to validate its contribution to mastic oil-mediated anti-tumor growth effects.

Results

In this work we demonstrated that exposure of Lewis lung carcinomas to mastic oil caused a time-dependent alteration in the expression of 925 genes. GO analysis associated expression profiles with several biological processes and functions. Among them, modifications on cell cycle/proliferation, survival and NF-κB cascade in conjunction with concomitant regulation of genes encoding for PTEN, E2F7, HMOX1 (up-regulation) and NOD1 (down-regulation) indicated some important mechanistic links underlying the anti-proliferative, pro-apoptotic and anti-inflammatory effects of mastic oil. The expression profiles of Hmox1, Pten and E2f7 genes were similarly altered by mastic oil in the majority of test cancer cell lines. Inhibition of PTEN partially reversed mastic oil effects on tumor cell growth, indicating a multi-target mechanism of action. Finally, k-means clustering, organized the significant gene list in eight clusters demonstrating a similar expression profile. Promoter analysis in a representative cluster revealed shared putative cis-elements suggesting a common regulatory transcription mechanism.

Conclusions

Present results provide novel evidence on the molecular basis of tumor growth inhibition mediated by mastic oil and set a rational basis for application of genomics and bioinformatic methodologies in the screening of natural compounds with potential cancer chemopreventive activities.

Antioxidant mechanisms of Quercetin and Myricetin in the gas phase and in solution--a comparison and validation of semi-empirical methods

Flavonoids have long been recognized for their general health-promoting properties, of which their antioxidant activity may play an important role. In this work we have studied the properties of two flavonols, quercetin and myricetin, using semi-empirical methods in order to validate the application of the recent Parametric Model 6 and to understand the fundamental difference between the two molecules. Their geometries have been optimized and important molecular properties have been calculated. The energetic of the possible antioxidant mechanisms have also been analyzed. The two studied flavonols do not differ significantly in their molecular properties, but the antioxidant mechanisms by which they may act in solution can be rather different. Moreover, we also show that the Parametric Model 6 can produce reliable information for this type of compounds.

Synergistic anti-inflammatory effects of low doses of curcumin in combination with polyunsaturated fatty acids: docosahexaenoic acid or eicosapentaenoic acid

Inflammatory response plays an important role not only in the normal physiology but also in the pathology such as cancers. As chronic inflammations are associated with malignancies, it is important to prevent inflammation-mediated neoplastic formation, promotion and/or progression. One possible intervention will be using cancer chemopreventive agents such as curcumin (CUR), a potent anti-inflammatory and anti-oxidative stress compound. Polyunsaturated fatty acids (PUFA) such as docosahexaenoic acid (DHA) or eicosapentaenoic acid (EPA) are potent anti-inflammatory agents by decreasing the production of inflammatory eicosanoids, cytokines, and reactive oxygen species (ROS). The present study aims at examining whether CUR with DHA or EPA would have synergistic anti-inflammatory effects in RAW 264.7 cells. Non-toxic concentrations of single and combination of the compounds were investigated at 6, 12 and 24h. The nitric oxide (NO) suppression effects were most prominent at 24h. All the combinations of CUR and DHA or EPA with lower concentrations of CUR 5 microM and 25 microM of DHA or EPA were found to have synergistic effects in suppressing LPS-stimulated NO and endogenous NO levels. Importantly, very low doses of CUR 2.5 microM and DHA or EPA of 0.78 microM could synergistically suppress the LPS-induced prostaglandin E(2) (PGE(2)). The combinations were also found to suppress iNOS, COX-2, 5-lipoxygenase (5-LOX) and cPLA(2) but induce HO-1. Taken together, the present study clearly shows the synergistic anti-inflammatory as well as anti-oxidative stress effects of CUR and PUFA.

Abyssinones and related flavonoids as potential steroidogenesis modulators

Abyssinones and related flavonoids were screened against 3 enzymes (3betaHSD, 17betaHSD and Aromatase) of steroidogenesis pathway. The virtual screening experiment shows high affinity for flavonones than their respective chalcones. A 4' -OH blocked prenylated flavonone 2b (2-(2', 2'-dimethyl chroman-6'-yl)-7-hydroxy chroman-4-one) had consistent binding affinity to all the three enzymes used in this study showing higher binding affinity to aromatase. A good correlation was observed between cytotoxic data (MCF-7, breast cancer cell line) and docking results indicating flavonone as a better steroidogenesis modulator in hormone dependent cancer.

A novel liquid multi-phytonutrient supplement demonstrates DNA-protective effects

This study explored the DNA protective (anti-mutagenic) effects of an oral, liquid, multi-phytonutrient dietary supplement containing a proprietary blend of fruits, vegetables and aloe vera concentrated components in addition to a proprietary catechin complex from green tea (VIBE Cardiac & Life, Eniva Nutraceuticals, Anoka, MN; herein described as "VIBE"). This study tested the hypothesis that VIBE would reduce DNA damage in skin cells exposed to UVR. Human epidermal cells, from the cell line A431NS, were treated with 0% (control), 0.125%, 0.5%, 1% and 2% VIBE, and then exposed to 240 J/m(2) UVR. The amount of DNA damage was assessed using the COMET assay. At each concentration tested, a significantly smaller amount of DNA damage was measured by the COMET assay for the VIBE treated cells compared to the control cells exposed to UVR without VIBE. The dose response curves showed a maximal response at 0.5% VIBE with a threefold reduction in COMET tail density compared to the control samples without VIBE (p < 0.001). Additional research is warranted in human clinical trials to further explore the results of this study which demonstrated the DNA protective and anti-mutagenic effects of VIBE for human skin cells exposed to UVR-induced DNA damage.

Serum nutrients and habitual dietary intake in colectomized FAP patients in Norway

BACKGROUND

Patients with familial adenomatous polyposis (FAP) are colectomized in young age in order to avoid development of colorectal cancer. Because colectomy radically changes gastrointestinal physiology, and food avoidance may be present, colectomized patients may be at risk for nutritional deficiency.

AIM OF THE STUDY

to evaluate: (1) serum biochemical levels as compared to reference; (2) dietary intake as compared to the recommendations.

METHODS

Blood samples, interviews and food frequency questionnaire were collected from 38 colectomized FAP patients with duodenal adenomas (mean age 40 years, range: 24-70). They were recruited from the Norwegian database on FAP.

RESULTS

Serum albumin was significantly higher (P < or = 0.0001), and Mg (P = 0.02), ferritin (P < or = 0.001), and cholesterol (P = 0.03) significantly lower, than reference levels. Compared to recommendations, a low intake was seen for folate and fiber (<50%), iron, thiamin, riboflavin (< 25%), and omega-3 fatty acids (8%). Sugar intake exceeded the recommendation, mainly due to a high intake of soft drinks. Food avoidance was reported by 53%.

CONCLUSIONS

We would suggest that the nutrient intake among FAP patients should at least meet the recommendations for healthy subjects. Their risk of metachronous cancers should also cause special attention to dietary factors that may prevent nutritional deficiency and carcinogenesis.

Electrospray ionization tandem mass spectrometry fragmentation of protonated flavone and flavonol aglycones: a re-examination

Flavonoids are important phytochemicals which have been intensively studied in the last decades in view of their antioxidant activity, which is of particular importance in the case of flavones and flavonols, that differ in a single 3-OH group. Mass spectrometry has been used to elucidate the structures of many types of flavonoids and their metabolites. The work we present here is focused on the electrospray ionization tandem mass spectrometry (ESI-MS/MS) analysis of flavone and flavonols aglycones. Their fragmentation mechanisms in the positive ion mode are described and compared with previously reported mechanisms. We analyzed flavonoid derivatives produced by reaction of the flavonoids with chemically synthesized hypohalous acids (HOCl, HOBr and HOI) and peroxynitrite, reactive species involved in the inflammatory response. All the proposed pathways have been analyzed using computational chemistry methods in order to seek for possible variations and establish the most plausible ones. We observed that the losses of one and two CO molecules can be useful in terms of antioxidant activity prediction. Losses of one and two C(2)H(2)O groups are also informative in terms of structure and activity predictions. The retro-Diels-Alder fragmentations, and subsequent neutral losses, were reviewed and, according to our calculations, the most plausible structures for the product ions were established. These fingerprints will be of great value for differentiating flavonoids from other compounds in complex biological mixtures and for a thorough structural identification of flavonoid aglycones and their in vivo metabolites.