Experimental evidence for cancer preventive elements in foods

Methyl Group Metabolism in Differentiation, Aging, and Cancer

Methyl group metabolism belongs to a relatively understudied field of research. Its importance lies in the fact that methyl group metabolic pathways are crucial for the successful conversion of dietary nutrients into the basic building blocks to carry out any cellular methylation reaction. Methyl groups play essential roles in numerous cellular functions such as DNA methylation, nucleotide- and protein biosynthesis. Especially, DNA methylation is responsible for organizing the genome into transcriptionally silent and active regions. Ultimately, it is this proper annotation that determines the quality of expression patterns required to ensure and shape the phenotypic integrity and function of a highly specialized cell type. Life is characterized by constantly changing environmental conditions, which are addressed by changes in DNA methylation. This relationship is increasingly coming into focus as it is of fundamental importance for differentiation, aging, and cancer. The stability and permanence of these metabolic processes, fueling the supplementation of methyl groups, seem to be important criteria to prevent deficiencies and erosion of the methylome. Alterations in the metabolic processes can lead to epigenetic and genetic perturbations, causative for diverse disorders, accelerated aging, and various age-related diseases. In recent decades, the intake of methyl group compounds has changed significantly due to, e.g., environmental pollution and food additives. Based on the current knowledge, this review provides a brief overview of the highly interconnected relationship between nutrition, metabolism, changes in epigenetic modifications, cancer, and aging. One goal is to provide an impetus to additionally investigate changes in DNA methylation as a possible consequence of an impaired methyl group metabolism.

Halophilic Carotenoids and Breast Cancer: From Salt Marshes to Biomedicine

Breast cancer is the leading cause of death among women worldwide. Over the years, oxidative stress has been linked to the onset and progression of cancer. In addition to the classical histological classification, breast carcinomas are classified into phenotypes according to hormone receptors (estrogen receptor-RE-/progesterone receptor-PR) and growth factor receptor (human epidermal growth factor receptor-HER2) expression. Luminal tumors (ER/PR-positive/HER2-negative) are present in older patients with a better outcome. However, patients with HER2-positive or triple-negative breast cancer (TNBC) (ER/PR/HER2-negative) subtypes still represent highly aggressive behavior, metastasis, poor prognosis, and drug resistance. Therefore, new alternative therapies have become an urgent clinical need. In recent years, anticancer agents based on natural products have been receiving huge interest. In particular, carotenoids are natural compounds present in fruits and vegetables, but algae, bacteria, and archaea also produce them. The antioxidant properties of carotenoids have been studied during the last years due to their potential in preventing and treating multiple diseases, including cancer. Although the effect of carotenoids on breast cancer during in vitro and in vivo studies is promising, clinical trials are still inconclusive. The haloarchaeal carotenoid bacterioruberin holds great promise to the future of biomedicine due to its particular structure, and antioxidant activity. However, much work remains to be performed to draw firm conclusions. This review summarizes the current knowledge on pre-clinical and clinical analysis on the use of carotenoids as chemopreventive and chemotherapeutic agents in breast cancer, highlighting the most recent results regarding the use of bacterioruberin from haloarchaea.

Epigenetic and miRNAs Dysregulation in Prostate Cancer: The role of Nutraceuticals

The control of cancer onset and progression is recognized to benefit from specific molecular targeting. MiRNAs are increasingly being implicated in prostate cancer, and the evidence suggests they are possible targets for molecular therapy and diagnosis. In cancer cells, growing attention has been dedicated to novel molecular mechanisms linking the epigenetic scenario to miRNA dysregulation. Currently, the rising evidence shows that nutritional and natural agents, the so-called nutraceuticals, could modulate miRNAs expression, and, as a consequence, might influence cellular responses in health or diseases conditions, including cancer. Among dietary components, plant-derived polyphenols are receiving wide interest, either for their anti-aging and anti-oxidant properties, or for their more general "cell-protective" effects. Above all, their role in preventing the occurrence/recurrence of cancer and, in particular, their potentiality in nutritional intervention for modulating the functions of miRNAs and the epigenetic mechanisms, is still under active debate. This review is focused on the more recent highlights of the impact of miRNAs dysregulation on the onset and progression of prostate cancer, their interplay with epigenetic control and their modulation by natural agents.

Curcumin inhibits anchorage-independent growth of HT29 human colon cancer cells by targeting epigenetic restoration of the tumor suppressor gene DLEC1

Colorectal cancer remains the most prevalent malignancy in humans. The impact of epigenetic alterations on the development of this complex disease is now being recognized. The dynamic and reversible nature of epigenetic modifications makes them a promising target in colorectal cancer chemoprevention and treatment. Curcumin (CUR), the major component in Curcuma longa, has been shown as a potent chemopreventive phytochemical that modulates various signaling pathways. Deleted in lung and esophageal cancer 1 (DLEC1) is a tumor suppressor gene with reduced transcriptional activity and promoter hypermethylation in various cancers, including colorectal cancer. In the present study, we aimed to investigate the inhibitory role of DLEC1 in anchorage-independent growth of the human colorectal adenocarcinoma HT29 cells and epigenetic regulation by CUR. Specifically, we found that CUR treatment inhibited colony formation of HT29 cells, whereas stable knockdown of DLEC1 using lentiviral short hairpin RNA vector increased cell proliferation and colony formation. Knockdown of DLEC1 in HT29 cells attenuated the ability of CUR to inhibit anchorage-independent growth. Methylation-specific polymerase chain reaction (MSP), bisulfite genomic sequencing, and methylated DNA immunoprecipitation revealed that CUR decreased CpG methylation of the DLEC1 promoter in HT29 cells after 5 days of treatment, corresponding to increased mRNA expression of DLEC1. Furthermore, CUR decreased the protein expression of DNA methyltransferases and subtypes of histone deacetylases (HDAC4, 5, 6, and 8). Taken together, our results suggest that the inhibitory effect of CUR on anchorage-independent growth of HT29 cells could, at least in part, involve the epigenetic demethylation and up-regulation of DLEC1.

Prophylactic Role of Averrhoa carambola (Star Fruit) Extract against Chemically Induced Hepatocellular Carcinoma in Swiss Albino Mice

Liver cancer remains one of the severe lethal malignancies worldwide and hepatocellular carcinoma (HCC) is the most common form. The current study was designed to evaluate the prophylactic role of the fruit of Averrhoa carambola (star fruit or Kamrak) on diethylnitrosamine- (DENA-) induced (15 mg/kg b.wt.; single i.p. injection) and CCl4-promoted (1.6 g/kg b.wt. in corn oil thrice a week for 24 weeks) liver cancer in Swiss albino mice. Administration of ACE was made orally at a dose of 25 mg/kg b.wt/day for 5 consecutive days and it was withdrawn 48 hrs before the first administration of DENA (preinitiational stage). CCl4 was given after 2 weeks of DENA administration. A cent percent tumor incidence was noted in carcinogen treated animals while ACE administration resulted in a considerable reduction in tumor incidence, tumor yield, and tumor burden. Further, ACE treatment brings out a significant reduction in lipid peroxidation (P < 0.001) along with an elevation in the activities of enzymatic antioxidants (superoxide dismutase, P < 0.001, and catalase, P < 0.001), nonenzymatic antioxidant (reduced glutathione, P < 0.001), and total proteins (P < 0.001) when compared to the carcinogen treated control. These results demonstrate that ACE prevents the DENA/CCl4 induced adverse physical and biochemical alterations during hepatic carcinogenesis in mice. This study suggests the prophylactic role of Averrhoa carambola against hepatocellular carcinoma in mice; therefore, it could be employed for the further screening as a good chemopreventive natural supplement against cancer.

Cancer chemoprevention by carotenoids

Carotenoids are natural fat-soluble pigments that provide bright coloration to plants and animals. Dietary intake of carotenoids is inversely associated with the risk of a variety of cancers in different tissues. Preclinical studies have shown that some carotenoids have potent antitumor effects both in vitro and in vivo, suggesting potential preventive and/or therapeutic roles for the compounds. Since chemoprevention is one of the most important strategies in the control of cancer development, molecular mechanism-based cancer chemoprevention using carotenoids seems to be an attractive approach. Various carotenoids, such as β-carotene, a-carotene, lycopene, lutein, zeaxanthin, β-cryptoxanthin, fucoxanthin, canthaxanthin and astaxanthin, have been proven to have anti-carcinogenic activity in several tissues, although high doses of β-carotene failed to exhibit chemopreventive activity in clinical trials. In this review, cancer prevention using carotenoids are reviewed and the possible mechanisms of action are described.

Epigenetic changes induced by curcumin and other natural compounds

Epigenetic regulation, which includes changes in DNA methylation, histone modifications, and alteration in microRNA (miRNA) expression without any change in the DNA sequence, constitutes an important mechanism by which dietary components can selectively activate or inactivate gene expression. Curcumin (diferuloylmethane), a component of the golden spice Curcuma longa, commonly known as turmeric, has recently been determined to induce epigenetic changes. This review summarizes current knowledge about the effect of curcumin on the regulation of histone deacetylases, histone acetyltransferases, DNA methyltransferase I, and miRNAs. How these changes lead to modulation of gene expression is also discussed. We also discuss other nutraceuticals which exhibit similar properties. The development of curcumin for clinical use as a regulator of epigenetic changes, however, needs further investigation to determine novel and effective chemopreventive strategies, either alone or in combination with other anticancer agents, for improving cancer treatment.

Structural analysis of DNA interaction with retinol and retinoic acid

Dietary constituents of fresh fruits and vegetables may play a relevant role in DNA adduct formation by inhibiting enzymatic activities. Studies have shown the important role of antioxidant vitamins A, C, and E in the protection against cancer and cardiovascular diseases. The antioxidant activity of vitamin A and beta-carotene may consist of scavenging oxygen radicals and preventing DNA damage. This study was designed to examine the interaction of calf-thymus DNA with retinol and retinoic acid in aqueous solution at physiological conditions using a constant DNA concentration and various retinoid contents. Fourier transform infrared (FTIR), circular dichroism (CD), and fluorescence spectroscopic methods were used to determine retinoid binding mode, the binding constant, and the effects of retinol and retinoic acid complexation on DNA conformation and aggregation. Structural analysis showed that retinol and retinoic acid bind DNA via G-C and A-T base pairs and the backbone phosphate groups with overall binding constants of Kret = 3.0 (±0.50) × 103 (mol·L–1)–1 and Kretac = 1.0 (±0.20) × 104 (mol·L–1)–1. The number of bound retinoids per DNA were 0.84 for retinol and 1.3 for retinoic acid. Hydrophobic interactions were also observed at high retinol and retinoic acid contents. At a high retinoid concentration, major DNA aggregation occurred, while DNA remained in the B-family structure.

Modulation of the effect of prenatal PAH exposure on PAH-DNA adducts in cord blood by plasma antioxidants

The fetus is more susceptible than the adult to the effects of certain carcinogens, such as polycyclic aromatic hydrocarbons (PAH). Nutritional factors, including antioxidants, have been shown to have a protective effect on carcinogen-DNA adducts and cancer risk in adults. We investigated whether the effect of prenatal airborne PAH exposure, measured by personal air monitoring during pregnancy, on the level of PAH-DNA adducts in a baby's cord blood is modified by the concentration of micronutrients in maternal and cord blood. The micronutrients examined were: retinol (vitamin A), alpha-tocopherol and gamma-tocopherol (vitamin E), and carotenoids. With the use of multiple linear regression, we found a significant interaction between prenatal PAH exposure and cord blood concentration of alpha-tocopherol and carotenoids in predicting the concentration of PAH adducts in cord blood. The association between PAH exposure and PAH adducts was much stronger among those with low alpha-tocopherol (beta = 0.15; P = 0.001) and among those with low carotenoids (beta = 0.16; P < 0.001) compared with babies with high levels of these micronutrients (among those with high alpha-tocopherol: beta = 0.05; P = 0.165; among those with high carotenoids: beta = 0.06; P = 0.111). These results suggest a protective effect of micronutrients on the DNA damage and potential cancer risk associated with prenatal PAH exposure.

Potent modulation of P-glycoprotein activity by naturally occurring phenylbutenoids from Zingiber cassumunar

Five phenylbutenoid derivatives from the rhizomes of Zingiber cassumunar Roxb. (Zingiberaceae) were evaluated for their P-glycoprotein (P-gp) inhibitory effects in a P-gp over-expressing multidrug resistant (MDR) human breast cancer cell line, MCF-7/ADR. As a result, a phenylbutenoid dimer, (+/-)-trans-3-(3,4-dimethoxyphenyl)-4-[(E)-3,4-dimethoxystyryl]cyclohex-1-ene (1), exhibited highly potent P-gp inhibitory activity, decreasing the IC(50) value of daunomycin (DNM) to 4.31 +/- 0.40 microm in the cells (DNM IC(50) = 37.1 +/- 0.59 microm). The positive control, verapamil decreased the IC(50) value of DNM to 6.94 +/- 0.40 microm. Three phenylbutenoid monomers, 2-4 from this plant, also resulted in a significant decrease in the IC(50) values of DNM compared with the control. In particular, compound 1 markedly enhanced [(3)H]-DNM accumulation and significantly reduced [(3)H]-DNM efflux compared with the control, and this effect was more potent than that of verapamil, a well-known P-gp inhibitor. These results suggest that compound 1 of Z. cassumunar can be developed as a potent chemo-sensitizing agent that reverses P-gp-mediated MDR in human cancer chemotherapy.

Subchronic exposure to ellagic acid impairs cytotoxic T-cell function and suppresses humoral immunity in mice

Ellagic acid (EA) is present in a variety of foods such as grapes, strawberries, raspberries, and nuts. It is a dietary plant phenol that has been shown to inhibit oxidative stress and chemical carcinogenesis. Although several studies have examined the protective mechanisms of dietary EA including the induction of detoxifying enzymes, regulation of cell cycle, chelation of nickel, and prevention of DNA methylation, none have addressed the role of EA in immunological surveillance. This study investigates the status of immune function in B6C3F1 mice exposed continuously to EA in drinking water at 0.5, 1.0, or 2.0 mg/kg/day for 28 days. Although this range of exposure is above the estimated human daily intake (approximately 940 microg/day for 70 kg person or 13.4 microg/kg/day), these levels would not be unreasonable if EA were used as a dietary supplement or as a chemotherapeutic agent. Previous reports have demonstrated the anticarcinogenic effects of EA at levels 10- to 250-fold greater than those applied in this study. Immunological parameters assessed included natural killer (NK) cell activity, cytotoxic T lymphocyte (CTL) activity, IgM antibody plaque forming cell (PFC) response, thymus, spleen, kidney, and liver mass, and total cellularity for the thymus and spleen. Subchronic exposure to EA for 28 days in drinking water caused significant suppression of specific IgM antibody responses in the 2.0 mg/kg EA treatment group and suppressed cytotoxic T-cell function in the 0.5 and 1.0 mg/kg EA treatment groups. All other immunological parameters were within normal ranges. Kidney and liver mass were not altered after treatment with EA. The results from this study indicate that EA suppressed both IgM antibody responses and CTLs. These observations suggest important implications on human health should EA be prescribed as a chemotherapeutic agent or a preventative dietary supplement for cancer.

Psychosocial predictors of fruit and vegetable consumption in adults a review of the literature

BACKGROUND

Adequate fruit and vegetable intake has been found to promote health and reduce the risk of several cancers and chronic diseases. Understanding the psychological determinants of fruit and vegetable intake is needed to design effective intervention programs.

METHODS

Papers published in English from 1994 to 2006 that described the relationship between psychosocial predictors and fruit and vegetable intake in adults were reviewed. Studies and their constructs were independently rated based on the direction of significant effects, quality of execution, design suitability, and frequency. Methodology from the Guide to Community Preventive Services was used to systematically review and synthesize findings.

RESULTS

Twenty-five psychosocial constructs spanning 35 studies were reviewed (14 prospective and 21 cross-sectional/descriptive studies). Strong evidence was found for self-efficacy, social support, and knowledge as predictors of adult fruit and vegetable intake. Weaker evidence was found for variables including barriers, intentions, attitudes/beliefs, stages of change, and autonomous motivation.

CONCLUSIONS

The findings underscore the need to design future behavioral interventions that use strong experimental designs with efficacious constructs and to conduct formal mediation analyses to determine the strength of these potential predictors of fruit and vegetable intake.

Antioxidant biofactor, a processed grain food, inhibits iron nitrilotriacetate–induced renal tumorigenesis, hyperproliferative response, and oxidative damage

We have evaluated the effect of dietary antioxidant, antioxidant biofactor (a processed grain food), on iron nitrilotriacetate–induced renal tumorigenesis, hyperproliferative response, and oxidative damage. In tumorigenesis studies, iron nitrilotriacetate alone treatment resulted in a development of 75% renal cell tumor incidence, whereas, in the group of animals fed with antioxidant biofactor diet and treated with iron nitrilotriacetate, only 43% of renal cell tumor incidence was observed. In oxidative damage studies, the decrease in the level of renal glutathione and antioxidant enzymes induced by iron nitrilotriacetate was significantly reversed by antioxidant biofactor diet pretreatment in a dose-dependent manner (18–71% recovery, P < 0.05). Antioxidant biofactor diet pretreatment also resulted in a dose-dependent inhibition (35–49% inhibition, P < 0.05) of iron nitrilotriacetate–induced lipid peroxidation as measured by thiobarbituric acid reactive substances formation in renal tissues. Similarly, in hyperproliferation studies, antioxidant biofactor diet pretreatment showed a strong inhibition of iron nitrilotriacetate–induced renal ornithine decarboxylase activity (18–54% inhibition, P < 0.05). In addition, antioxidant biofactor fed diet pretreatment also protected the kidney tissues against observed histopathological alterations. From this data, it can be concluded that antioxidant biofactor diet can abrogate the toxic and tumor promoting effects of iron nitrilotriacetate and can serve as a potent chemopreventive agent to suppress oxidant–induced tissue injury and tumorigenesis.

CURCUMIN: THE INDIAN SOLID GOLD

Turmeric, derived from the plant Curcuma longa, is a gold-colored spice commonly used in the Indian subcontinent, not only for health care but also for the preservation of food and as a yellow dye for textiles. Curcumin, which gives the yellow color to turmeric, was first isolated almost two centuries ago, and its structure as diferuloylmethane was determined in 1910. Since the time of Ayurveda (1900 Bc) numerous therapeutic activities have been assigned to turmeric for a wide variety of diseases and conditions, including those of the skin, pulmonary, and gastrointestinal systems, aches, pains, wounds, sprains, and liver disorders. Extensive research within the last half century has proven that most of these activities, once associated with turmeric, are due to curcumin. Curcumin has been shown to exhibit antioxidant, anti-inflammatory, antiviral, antibacterial, antifungal, and anticancer activities and thus has a potential against various malignant diseases, diabetes, allergies, arthritis, Alzheimer's disease, and other chronic illnesses. These effects are mediated through the regulation of various transcription factors, growth factors, inflammatory cytokines, protein kinases, and other enzymes. Curcumin exhibits activities similar to recently discovered tumor necrosis factor blockers (e.g., HUMIRA, REMICADE, and ENBREL), a vascular endothelial cell growth factor blocker (e.g., AVASTIN), human epidermal growth factor receptor blockers (e.g., ERBITUX, ERLOTINIB, and GEFTINIB), and a HER2 blocker (e.g., HERCEPTIN). Considering the recent scientific bandwagon that multitargeted therapy is better than monotargeted therapy for most diseases, curcumin can be considered an ideal "Spice for Life".

Chemo-preventive effect of Star anise in N-nitrosodiethylamine initiated and phenobarbital promoted hepato-carcinogenesis

The generation of free radicals is a cause of many pathological conditions like diabetes mellitus, cancer, stroke, etc. Free radicals cause damage to cellular DNA and initiate carcinogenesis. Free radicals also bring about proliferation of cells via cell signaling. An inverse relationship between the consumption of vegetable diets and the risk of cancer has been established. In the present study, Star anise (Illicium verum), which is a commonly used condiment in Indian cuisine, was assessed for its anti-carcinogenic potential in N-nitrosodiethylamine (NDEA) initiated and phenobarbital (PB) promoted hepato-carcinogenesis. Rats were randomly selected for eight experimental groups. The carcinogenesis was induced by injecting the rats, with a single dose of NDEA (200mg/kg body weight) intraperitoneally as initiator, followed by promotion with PB (0.05%) in drinking water for 14 consecutive weeks. The treatment with NDEA increased liver weight, while Star anise (Star) treatment reduced the liver weight of rats. The treatment with Star throughout for 20 weeks or during the promotion stage (6-20 weeks) significantly reduced the nodule incidence and nodule multiplicity in the rats, while the treatment with Star at the initiation phase (first 4 weeks) only could not reduce these parameters. The treatment with Star for 20 consecutive weeks significantly reduced the nodule size and nodule volume. The treatment with Star throughout as well as at the promotion stage lowered the lipid peroxidation (LPO) in liver and erythrocytes, while the LPO was not lowered, when Star was administered during initiation stage only. The treatment with Star restored the liver and erythrocyte super-oxide dismutase (SOD) activities to normal in the carcinogenesis-induced rats. The liver catalase (CAT) activity increased in all the treated groups. The erythrocyte CAT activity increased in the rats treated with Star during initiation and promotion stage only. The liver glutathione (GSH) level increased significantly in the groups treated with Star. The erythrocyte GSH level was lowered in the rats treated with NDEA and PB, however, Star treatment helped in increasing the erythrocyte GSH level to some extent. The liver and erythrocyte glutathione-S-transferase (GST) activity increased in all the groups treated with NDEA and PB. The treatment with Star decreased GST level significantly. These results indicate that the treatment with Star reduces the tumor burden, lowers oxidative stress and increases the level of phase II enzymes, which may contribute to its anti-carcinogenic potential.

Inhibition of P-glycoprotein by natural products in human breast cancer cells

Multidrug resistance (MDR) is one of the most significant obstacles in cancer chemotherapy. One of the mechanisms involved in the development of MDR is the over-expression of P-glycoprotein (P-gp). It is widely known that natural compounds found in vegetables, fruits, plant-derived beverages and herbal dietary supplements not only have anticancer properties, but may also modulate P-gp activity. Therefore, the purpose of this investigation was to examine the effects of naturally occurring products on P-gp function in human breast cancer cell lines, MCF-7 (sensitive) and MCF-7/ADR (resistant). The accumulation of daunomycin (DNM), a P-gp substrate, was greater in the sensitive cells compared to the resistant cells, while the efflux of DNM was higher in the resistant cells compared to the sensitive cells over a period of 2 h. The IC50 value of DNM in the resistant cells was about 22 times higher than that in the sensitive cells, indicating an over-expression of P-gp in the resistant cells, MCF-7/ADR. All of the compounds tested, with the exception of fisetin, significantly decreased the IC50 value of DNM. Biochanin A showed the greatest increase in [3H]-DNM accumulation, increasing by 454.3 +/- 19.5% in the resistant cells, whereas verapamil, the positive control, increased the accumulation by 229.4 +/- 17.6%. Also, the accumulation of [3H]-DNM was increased substantially by quercetin and silymarin while it was reduced by fisetin. Moreover, biochanin A, silymarin, and naringenin significantly decreased DNM efflux from MCF-7/ADR cells compared with the control. These results suggest that some flavonoids such as biochanin A and silymarin may reverse MDR by inhibiting the P-gp function.

Potential protein markers for nutritional health effects on colorectal cancer in the mouse as revealed by proteomics analysis

It is suggested that colorectal cancer might be prevented by changes in diet, and vegetable consumption has been demonstrated to have a protective effect. Until now, little is known about the effects of vegetable consumption at the proteome level. Therefore, the effect of increased vegetable intake on the protein expression in the colonic mucosa of healthy mice was studied. Aim was to identify the proteins that are differentially expressed by increased vegetable consumption and to discriminate their possible role in the protection against colorectal cancer. Mice were fed four different vegetable diets, which was followed by analysis of total cellular protein from colonic mucosal cells by a combination of 2-DE and MS. We found 30 proteins that were differentially expressed in one or more diets as compared to the control diet. Six could be identified by MALDI-TOF MS: myosin regulatory light chain 2, carbonic anhydrase I, high-mobility group protein 1, pancreatitis-associated protein 3, glyceraldehyde-3-phosphate dehydrogenase and ATP synthase oligomycin sensitivity conferral protein. Alterations in the levels of these proteins agree with a role in the protection against colon cancer. We conclude that these proteins are suitable markers for the health effect of food on cancer. The observed altered protein levels therefore provide support for the protective effects of vegetables against colorectal cancer.

Dietary intakes of fruit, vegetables, and fiber, and risk of colorectal cancer in a prospective cohort of women (United States)

OBJECTIVE

Although animal studies suggest an inverse association between consumption of plant foods and risk of colorectal cancer, many observational data have failed to support such an association. We prospectively examined the association between dietary intakes of fruit, vegetables, and fiber and colorectal cancer risk in a large female cohort from the Women's Health Study.

METHODS

Among 39,876 healthy women aged >/=45 years at baseline, 36,976 with baseline self-reported information on dietary intakes and other risk factors for colorectal cancer were included in the analyses. During an average follow-up of 10 years, 223 women were diagnosed with colorectal cancer. Intakes of fruit, vegetables, and fiber were assessed by a baseline food-frequency questionnaire. The analyses were carried out using the Cox proportional hazards regression and all tests were two-sided.

RESULTS

Intakes of fruit, vegetables, and the specific subgroups were not found to be associated with colorectal cancer risk. Multivariate relative risks (RRs) comparing the highest with lowest quintile were 0.79 (95% CI=0.49-1.27,p for trend =0.30) for fruit intake, and 0.88 (95% CI=0.56-1.38,p for trend=0.30) for vegetables intake. Similarly, intake of total fiber was not associated with colorectal cancer risk; the RR for the highest relative to lowest quintile was 0.75 (95% CI=0.48-1.17,p for trend=0.12). However, higher intake of legume fiber was associated with a lower risk of colorectal cancer; the RR for the highest versus slowest quintile was 0.60 (95% CI=0.40-0.91,p for trend=0.02).

CONCLUSIONS

Our data offer little support for associations between intakes of fruit, vegetables, and fiber, and colorectal cancer risk. However, our data suggest that legume fiber and/or other related sources may reduce risk of colorectal cancer.

Phase I/II enzyme gene polymorphisms and esophageal cancer risk: A meta-analysis of the literature

AIM: Phase I/II enzymes metabolize environmental carcin-ogens and several functional polymorphisms have been reported in their encoding genes. Although their significance with regard to esophageal carcinogenicity has been examined epidemiologically, it remains controversial. The present systematic review of the literature was performed to clarify associations.

METHODS: Eligible studies were case-control or cohort studies published until September 2004 that were written in any language. From PubMed and a manual review of refe-rence lists in relevant review articles, we obtained 16 studies related to the CYP1A1 Ile-Val substitution in exon 7, CYP1A1 MspI polymorphisms, CYP2E1 RsaI polymorphisms, GSTM1 null type, GSTT1 null type and GSTP1 Ile104Val. All were of case-control design. Summary statistics were odds ratios (ORs) comparing heterozygous-, homozygous-non-wild type or these two in combination with the homozygous wild type, or the null type with the non-null type for GSTM1 and GSTT1. A random effect model was used to estimate the summary ORs. A meta-regression analysis was applied to explore sources of heterogeneity.

RESULTS: Individuals with the Ile-Val substitution in CYP1A1 exon 7 had increased esophageal cancer risk, with ORs (95%CI) compared with Ile/Ile of 1.37 (1.09-1.71), 2.52 (1.62-3.91) and 1.44 (1.17-1.78) for Ile-Val, Val/Val genotype and the combined group. No significant association was found between esophageal cancer risk and the other genetic parameters.

CONCLUSION: A significant association exists between the CYP1A1 Ile-Val polymorphism and risk of esophageal cancer. Polymorphisms that increase the internal exposure to activated carcinogens may increase the risk of esophageal cancer.

Results of the Healthy Body Healthy Spirit Trial

Healthy Body Healthy Spirit was a multicomponent intervention to increase fruit and vegetable (F & V) consumption and physical activity (PA) delivered through Black churches. Sixteen churches were randomly assigned to 3 intervention conditions. At baseline, 1,056 individuals were recruited across the 16 churches, of which 906 (86%) were assessed at 1-year follow-up. Group 1 received standard educational materials, Group 2 received culturally targeted self-help nutrition and PA materials, and Group 3 received the same intervention as did Group 2 as well as 4 telephone counseling calls based on motivational interviewing (MI) delivered over the course of 1 year. At 1-year follow-up, Groups 2 and 3 showed significant changes in both F & V intake and PA. Changes were somewhat larger for F & V. For F & V, but not PA, there was a clear additive effect for the MI intervention.

The influence of dietary flaxseed and other grains, fruits and vegetables on the frequency of spontaneous chromosomal damage in mice

Spontaneous genetic damage, whether mutations or chromosomal aberrations, undoubtedly arise from a variety of sources including replication errors, oxidative damage, background radiation, and chemical exposure. Given the numerous correlations between diet and cancer, it seemed possible that diet could influence the spontaneous rate of DNA damage and its genetic consequences. Since diets high in vegetables, fruits, and grains are associated with lower rates of cancer, we supplemented the diets of mice and measured the frequency of micronuclei in the peripheral blood. Micronuclei arise from broken chromosomes or chromosome loss in the erythroblast. They are first seen in the short reticulocyte stage of the red blood cell but persist for the entire 30-day lifespan of the cell in mice. C57Bl mice were placed on a defined diet (AIN-93G) supplemented to 20% final dry weight with grains or freeze-dried fruits or vegetables. The micronucleus frequency was measured in a pre-exposure blood sample and every 2 weeks thereafter for 6 weeks. This was possible in spite of the low spontaneous frequency of 1/1000-2/1000 cells by the use of a novel flow cytometric method, which permitted the analysis of both the mature red blood cells and reticulocytes. Of the foods tested, flaxseed proved to be the most protective by reducing the incidence of micronuclei in both the reticulocyte and normochromatic erythrocyte cell populations by 30 and 11%, respectively. The results show that at least one class of spontaneous genetic damage can be modified by diet and suggests that short-term experiments with small numbers of animals can be used to identify dietary anticarcinogens that may influence human cancer rates.

Effect of dietary supplementation on the frequency of spontaneous lacZ mutations in the developing colon

Epidemiological studies have demonstrated that dietary modifications can reduce the incidence of cancer. Specifically, diets high in vegetables and fruits are associated with lower rates of cancer at many sites. Somatic mutations have a critical role in carcinogenesis suggesting the use of in vivo mutation assays as an alternative approach to studying the relationship between diet and cancer. Since the rate of accumulation of spontaneous mutations is highest during growth and development early in life, we tested whether certain foods as dietary supplements could reduce the rate of mutation during this period using lacZ transgenic mice. Pregnant female mice were placed on a control diet or a diet supplemented to 20% final dry weight with broccoli, cabbage, carrots, flaxseed, green peas, green peppers, oranges or strawberries for the entire duration of their pregnancy and lactation. Mutation frequencies were subsequently measured at the lacZ transgene in colonic epithelial cells of the offspring at 3 weeks of age. A small number of measurements were also made on siblings at 8 weeks of age. While the control AIN-96G diet on its own resulted in lower mutant frequencies than had been observed in earlier experiments with lab chow, no significant reduction in mutant frequencies was detected for any of the foods tested as compared to the AIN-93G diet alone. Significantly more mutations were found at 3 weeks of age in mice fed diets supplemented with broccoli or oranges, but the result with oranges may be the result of jackpot mutations.

Effects of commonly consumed fruit juices and carbohydrates on redox status and anticancer biomarkers in female rats

Administration of apple juice, black currant juice, or a 1:1 combination of the two juices significantly decreased the level of the lipid peroxidation biomarker malondialdehyde in plasma of female rats, whereas the protein oxidation biomarker 2-amino-adipic semialdehyde, was significantly increased following administration of orange juice, black currant juice, or the 1:1 combination of apple and black currant juice. A significant increase in 2-amino-adipic semialdehyde was also observed in control rats given sucrose, fructose, and glucose in the drinking water at concentrations approximating the average carbohydrate levels in the employed fruit juices. None of the fruit juices were found to affect the activities of antioxidant enzymes in red blood cells or hepatic glutathione S-transferase. Hepatic quinone reductase activity, on the other hand, was significantly increased by grapefruit juice, apple juice, and black currant juice. The total daily intake of a selected subset of flavonoid aglycones ranged from 0.2 to 4.3 mg, and quercetin was found to be a minor constituent of all the juices investigated. In a parallel study, rats were fed quercetin at doses ranging from 0.001 to 10 g/kg of diet. However, no effects were observed on hepatic glutathione S-transferase or quinone reductase activities, plasma redox status, or the activity of red blood cell antioxidant enzymes. Overall, the results of the present study suggest that commonly consumed fruit juices can alter lipid and protein oxidation biomarkers in the blood as well as hepatic quinone reductase activity, and that quercetin may not be the major active principle. The observation that natural carbohydrates are capable of mediating oxidative stress in vivo warrants further studies due to the central role refined and unrefined carbohydrates play in human nutrition.

Palm oil alleviates 12-O-tetradecanoyl-phorbol-13-acetate-induced tumor promotion response in murine skin

Palm oil is a rich source of vitamin E, carotenoids, tocotrienols and tocopherols which are natural antioxidants and act as scavengers of oxygen free radicals. 12-O-Tetradecanoyl-phorbol-13-acetate (TPA) is a known oxidant that promotes tumorigenesis in mouse skin through the elaboration of oxidative stress. In this study we therefore assessed the anti-tumor promoting potential of palm oil against TPA-mediated skin tumorigenesis in 7,12-dimethylbenz[a]anthracene-initiated Swiss albino mice. Topical application of palm oil 1 h prior to application of TPA resulted in a significant protection against skin tumor promotion. The animals pre-treated with palm oil showed a decrease in both tumor incidence and tumor yield as compared to the TPA (alone)-treated group. Palm oil application also reduced the development of malignant tumors. Since TPA-induced epidermal ornithine decarboxylase (ODC) activity and [(3)H]thymidine incorporation are conventionally used markers of skin tumor promotion, we also assessed the effect of pre-application of palm oil on these parameters, and it was observed that the application of palm oil prior to the application of TPA alleviated both these TPA-induced markers of tumor promotion. The effect of pre-application of palm oil on TPA-mediated depletion in the non-enzymatic and enzymatic molecules was also assessed and it was observed that palm oil application prior to TPA application resulted in the recovery of TPA-mediated depletion in the levels of these molecules viz. glutathione, glutathione peroxidase, glutathione reductase, glutathione-S-transferase and catalase. Similarly, palm oil also exhibited a protective effect against Fe(2+)-ascorbate-induced lipid peroxidation in the epidermal microsomes. The results of the present study thus suggest that palm oil possesses anti-skin tumor promoting effects, and that the mechanism of such effects may involve the inhibition of tumor promoter-induced epidermal ODC activity, [(3)H]thymidine incorporation and cutaneous oxidative stress.

Antimutagenic properties of bell and black peppers

The wing Somatic Mutation And Recombination Test (SMART) in Drosophila melanogaster was used to study the modulating action of bell pepper (Capsicum annuum) and black pepper (Piper nigrum) in combination with the alkylating agent methyl methanesulfonate (MMS) and the promutagen agent ethyl carbamate (EC). Larvae trans-heterozygous for the third chromosome recessive markers multiple wing hairs (mwh) and flare-3 [flr(3)] were fed genotoxins alone or in combination with each of the two spices. Genetic changes induced in somatic cells of the wing's imaginal discs lead to the formation of mutant clones on the wing blade. Our results showed that bell pepper was effective in reducing the mutational events induced by EC and MMS and black pepper was only effective against EC. Pretreatment of 2-day-old larvae with the spices for 24 h followed by a treatment with EC and MMS was only effective in reducing mutations induced by EC. Suppression of metabolic activation or interaction with the active groups of mutagens could be mechanisms by which the spices exert their antimutagenic action.

Beta-catenin-mediated transactivation and cell-cell adhesion pathways are important in curcumin (diferuylmethane)-induced growth arrest and apoptosis in colon cancer cells

The development of nontoxic natural agents with chemopreventive activity against colon cancer is the focus of investigation in many laboratories. Curcumin (feruylmethane), a natural plant product, possesses such chemopreventive activity, but the mechanisms by which it prevents cancer growth are not well understood. In the present study, we examined the mechanisms by which curcumin treatment affects the growth of colon cancer cells in vitro. Results showed that curcumin treatment causes p53- and p21-independent G(2)/M phase arrest and apoptosis in HCT-116(p53(+/+)), HCT-116(p53(-/-)) and HCT-116(p21(-/-)) cell lines. We further investigated the association of the beta-catenin-mediated c-Myc expression and the cell-cell adhesion pathways in curcumin-induced G(2)/M arrest and apoptosis in HCT-116 cells. Results described a caspase-3-mediated cleavage of beta-catenin, decreased transactivation of beta-catenin/Tcf-Lef, decreased promoter DNA binding activity of the beta-catenin/Tcf-Lef complex, and decreased levels of c-Myc protein. These activities were linked with decreased Cdc2/cyclin B1 kinase activity, a function of the G(2)/M phase arrest. The decreased transactivation of beta-catenin in curcumin-treated HCT-116 cells was unpreventable by caspase-3 inhibitor Z-DEVD-fmk, even though the curcumin-induced cleavage of beta-catenin was blocked in Z-DEVD-fmk pretreated cells. The curcumin treatment also induced caspase-3-mediated degradation of cell-cell adhesion proteins beta-catenin, E-cadherin and APC, which were linked with apoptosis, and this degradation was prevented with the caspase-3 inhibitor. Our results suggest that curcumin treatment impairs both Wnt signaling and cell-cell adhesion pathways, resulting in G(2)/M phase arrest and apoptosis in HCT-116 cells.

Dual role of organosulfur compounds in foods: a review

Organosulfur compounds present in natural food are generally considered as beneficial for health because of their antioxidant and anticarcinogenic properties. This has led to their excessive and long-term consumption. However, there is also evidence that these compounds demonstrate toxicity and adverse health effects suggesting their potential dual biological roles. Thus, they can act as double-edged biological swords.

Herbals, cancer prevention and health

The use of herbs for medical benefit has played an important role in nearly every culture on earth. Herbal medicine was practiced by ancient cultures in Asia, Africa, Europe and the Americas. The recent popularity in use of herbals can be tied to the belief that herbs can provide some benefit over and above allopathic medicine and allow users to feel that they have some control in their choice of medications. The widespread use of herbs, either directly or as dietary supplements, has raised many scientific questions. Are herbal preparations safe? Do herbs interact with pharmaceutical medications to enhance or reduce their efficacy? The first interaction can be shown by the effects of St. John's Wort, a mild herbal antidepressant, and many commonly used medicines. St. John's Wort can induce the CYP3A family of activation enzymes through which approximately 50% of drugs are metabolized. This poses some risk of inadvertently reducing the half-life of such drugs as indinavir, cyclosporin and cyclophosphamide. On the other hand, herbal products may act in a pathway similar to pharmaceuticals yet without side effects. Natural anti-inflammatory compounds abound in the herbal world and are found in green tea, the spices turmeric and rosemary, feverfew and others. Because the use of nonsteroidal anti-inflammatory drugs (NSAID) is associated with a reduced risk for several cancers, it is at least plausible that natural NSAID should be explored for possible use as cancer preventives.

Effect of herbal teas on hepatic drug metabolizing enzymes in rats

We have investigated the effect of herbal teas (peppermint, chamomile and dandelion) on the activity of hepatic phase I and phase II metabolizing enzymes using rat liver microsomes. Female Wistar rats were divided into six groups (n = 5 each). Three groups had free access to a tea solution (2%) while the control group had water. Two groups received either green tea extract (0.1%) or aqueous caffeine solution (0.0625%). After four weeks of pretreatment, different cytochrome P450 (CYP) isoforms and phase II enzyme activities were determined by incubation of liver microsomes or cytosol with appropriate substrates. Activity of CYP1A2 in the liver microsomes of rats receiving dandelion, peppermint or chamomile tea was significantly decreased (P < 0.05) to 15%, 24% and 39% of the control value, respectively. CYP1A2 activity was significantly increased by pretreatment with caffeine solution. No alterations were observed in the activities of CYP2D and CYP3A in any group of the pretreated rats. Activity of CYP2E in rats receiving dandelion or peppermint tea was significantly lower than in the control group, 48% and 60% of the control, respectively. There was a dramatic increase (244% of control) in the activity of phase II detoxifying enzyme UDP-glucuronosyl transferase in the dandelion tea-pretreated group. There was no change in the activity of glutathione-S-transferase. The results suggested that, like green and black teas, certain herbal teas can cause modulation of phase I and phase II drug metabolizing enzymes.

Effect of contingent hunger state on development of appetite for a novel fruit snack

Eating more fruit can reduce risk of cancer and cardiovascular disease. Understanding barriers to this behaviour is critical for strategies to encourage it. We addressed the question whether the level of hunger at which fruit is eaten would influence the development of appetite for fruit. Half the participants were asked to eat a pair of novel fruit snacks (dried fruit bar; 50 kcal each) exclusively when hungry (at least 3 hours since last eating), and half to eat them exclusively when full (20-30 minutes after a meal), twice a day for one week. Rated appetite for the bars, and ad-libitum intake, were measured when hungry and full, on 2 days prior to, and 2 days after this week. Compliance was assessed from dietary diaries. Thirty participants (22 women, 8 men) completed the study satisfactorily. For the group eating the fruit bars only when hungry (hungry-trained), intake increased after the week, but only when full at the time of testing. Other measures of appetite for this group were unaffected, with the exception of a reduced desire to eat the bars when tested hungry. Ranked preference for the trained flavour increased exclusively among hungry-trained subjects, but only for those who had reported their preferred snack food to be fruit. No change in any measure was found for the group eating the fruit bars exclusively when full. The results suggest the hungry-trained group learnt that the bars lacked strong satiation, thus allowing greater intake when full (learnt desatiation). For the same reason, however, the prospect of eating the bars when mildly hungry lost its appeal. Eating fruit between meals may not encourage snacking on fruit, unless hunger is absent at the time of consumption.

Diet and cancer prevention

Research from several sources provides strong evidence that vegetables, fruits, and whole grains, dietary fibre, certain micronutrients, some fatty acids and physical activity protect against some cancers. In contrast, other factors, such as obesity, alcohol, some fatty acids and food preparation methods may increase risks. Unravelling the multitude of plausible mechanisms for the effects of dietary factors on cancer risk will likely necessitate that nutrition research moves beyond traditional epidemiological and metabolic studies. Nutritional sciences must build on recent advances in molecular biology and genetics to move the discipline from being largely 'observational' to focusing on 'cause and effect'. Such basic research is fundamental to cancer prevention strategies that incorporate effective dietary interventions for target populations.

Therapeutic potential of dietary phase 2 enzyme inducers in ameliorating diseases that have an underlying inflammatory component

Many diseases associated with ageing have an underlying oxidative stress and accompanying inflammatory component, for example, Alzheimer's disease or atherosclerosis. Reviewed in this manuscript are: the role of oxidative stress in activating the transcription factor nuclear factor kappa B (NFκB), the role of NFκB in activating pro-inflammatory gene transcription, strong oxidants produced by cells, anti-oxidant defense systems, the central role of phase 2 enzymes in the anti-oxidant defense, dietary phase 2 enzyme inducers and evidence that dietary phase 2 enzymes decrease oxidative stress. It is likely that a diet containing phase 2 enzyme inducers may ameliorate or even prevent diseases that have a prominent inflammatory component to them. Research should be directed into the potential therapeutic effects of dietary phase 2 enzyme inducers in ameliorating diseases with an underlying oxidative stress and inflammatory component to them.Key words: Alzheimer's disease, atherosclerosis, diet, glutathione, inflammation, stroke.

Validation of three food frequency questionnaires and 24-hour recalls with serum carotenoid levels in a sample of African-American adults

The validity of self-reported fruit and vegetable intake in minority populations has not been adequately established. In this study, the authors examined the association of three food frequency questionnaires (FFQs) and 24-hour dietary recalls with serum carotenoid levels. Approximately 1,000 African-American adults recruited from 15 churches in Atlanta, Georgia (1997-1998) completed three fruit and vegetable FFQs: a seven-item instrument assessing intake during the past month; a two-item measure assessing usual intake; and a 36-item measure adapted from the Health Habits and History Questionnaire. A total of 414 participants received a 24-hour recall by telephone, and 105 of them received two additional recalls. Serum levels of lycopene, lutein, cryptoxanthin, alpha-carotene, and beta-carotene were assessed in 813 participants and used as the validity criterion. The correlations of fruit and vegetable servings with specific and total serum carotenoid levels were generally higher for the 36-item FFQ than for the two-item and seven-item instruments. The strongest correlation of fruit and vegetable servings with total carotenoid levels was observed for the three recalls (r = 0.42), with the 36-item FFQ and the single 24-hour recall yielding comparable correlations (r = 0.35 and r = 0.37, respectively). The validity of the 36-item fruit and vegetable FFQ was generally as strong as the validity of both 1 and 3 days of recalls. Given the lower cost and time needed for administration relative to recalls, it appears that the 36-item FFQ has merit for evaluating fruit and vegetable health interventions.

Mutagenicidade e antimutagenicidade dos principais corantes para alimentos

Muitos compostos presentes nos alimentos, tanto naturalmente, como adicionados ou produzidos durante o processamento, já foram testados quanto à mutagenicidade ou antimutagenicidade em diferentes sistemas experimentais. O grande número de corantes para alimentos, naturais ou sintéticos, tem levado os pesquisadores a avaliar a mutagenicidade e/ou antimutagenicidade desses compostos. Alguns corantes sintéticos apresentaram potencial mutagênico e seu uso foi proibido em alguns países. Muitos corantes naturais testados apresentaram potencial antimutagênico em pelo menos um sistema-teste, entretanto, isto não quer dizer que os corantes naturais são inócuos. O corante natural curcumina, por exemplo, apresentou potencial antimutagênico nos testes in vivo e foi mutagênico nos testes in vitro. Este paradoxo ressalta a importância de uma avaliação criteriosa e ampla na avaliação da possível atividade mutagênica e/ou antimutagênica dos corantes.

Diet, metabolic polymorphisms and dna adducts: the EPIC-Italy cross-sectional study

DNA adducts in peripheral leukocytes are considered a reliable indicator of internal dose exposure to genotoxic agents and, possibly, of cancer risk. We investigated their association with diet and other individual characteristics in healthy adults. The prospective study EPIC-Italy, a section of a larger European project, enrolled 47,749 men and women, aged 35-64 years, in 5 centres: all provided individual information about dietary and life-style habits and a blood sample. In a cross-sectional study, approximately 100 volunteers were randomly selected from each of the three main geographical study areas (Northern, Central and Southern Italy). DNA adducts and four polymorphic metabolic genotypes were determined in peripheral leukocytes by using (32)P-postlabelling technique and PCR methods. Among 309 subjects (153 men), 72.8% had detectable levels of DNA adducts (mean: 8.1 +/- 0.6 per 10(9) nucleotides). Strong negative associations emerged with the reported frequency of consumption of fresh fruit and vegetables, olive oil, and the intake of antioxidants. DNA adducts were higher in subjects with GSTT1 null genotype (p = 0.05). Significant differences between study centres emerged in multivariate analyses (mean levels: 11.0, 10.0, 7.2, 6.5 and 5.2 for Florence, Naples, Turin, Varese and Ragusa, respectively). A possible opposite seasonal variation was found according to latitude: adduct levels tended to be lower in winter in Florence and the southern centres, and during summer in the two northern centres. Frequent consumption of fresh fruit and vegetables is associated with reduced levels of DNA adducts, possibly contributing to the role of diet in modulating cancer risk.

Growth factor-dependent induction of p21(CIP1) by the green tea polyphenol, epigallocatechin gallate

Tea polyphenols inhibit tumorigenesis and cell proliferation in rodent models, but their effects on cell signaling and cell cycle control pathways are undefined. Here, we show that the major polyphenol in green tea, epigallocatechin gallate (EGCG), inhibits S phase entry in epidermal growth factor (EGF) - stimulated MCF10A breast epithelial cells when provided in G0 or mid G1, but not when provided after the late G1 restriction point. EGCG induced p21(CIP1/WAF1/SDI1), inhibited cyclin D1-associated pRB kinase activity, and impaired pRB phosphorylation. The ability of EGCG to induce p21 depended upon the addition of EGF, indicating that EGCG synergizes with growth factor-dependent signals to induce p21 and impair cell cycle progression.

The effects of ellagic acid on arylamine N-acetyltransferase activity in the bacterium Pseudomonas aeruginosa

Arylamine N-acetyltransferase (NAT) activity in Pseudomonas aeruginosa was inhibited by ellagic acid (EA), a naturally occurring dietary plant phenol. By measuring the acetylation of 2-aminofluorene (2-AF), the NAT activity was determined. In P. aeruginosa ATCC 27853, a NAT activity of 1.37 +/- 0.25 nmol/min/10(10) CFU for intact cell and a NAT activity of 5.92 +/- 0.20 nmol/min/mg protein for cytosolic preparation were measured. EA (ranging from 1 to 0.125 mM) showed a dose-dependent inhibition of NAT activities in the analysis of both intact cell and cytosolic preparations. Enzymatic kinetics were determined and found that EA was a potent non-competitive inhibitor of NAT activity in P. aeruginosa ATCC 27853. EA inhibition of NAT activities in P. aeruginosa ATCC 27853 was time-dependent for at least 4 hrs. These data strongly indicated that EA could suppress NAT activity in P. aeruginosa.

Modulation of phase II enzymes by organosulfur compounds from allium vegetables in rat tissues

The naturally occurring organosulfur compounds (OSCs) diallyl sulfide (DAS), diallyl disulfide (DADS), dipropyl sulfide (DPS), and dipropyl disulfide (DPDS) were studied with respect to their effects on hepatic, intestinal, renal, and pulmonary phase II drug metabolizing enzymes, i.e., glutathione S-transferase (GST), microsomal epoxide hydrolase (mEH), quinone reductase (QR), and UDP-glucuronosyltransferase (UGT). OSCs were administered po to male SPF Wistar rats. In addition to assays of total enzyme activity, the ability of OSCs to modify the levels of mEH and rGSTA1/A2, A3/A5, M1, M2, and P1 was assessed by Western blotting. Remarkably, DADS significantly increased all Phase II enzyme activities, except the pulmonary mEH. It was noteworthy that only DADS induced QR activity. DAS, DPS, and DPDS induced mEH, GST, and UGT activities in the liver. Interestingly, DAS, DPS, and DPDS significantly decreased renal GST activity. In the same manner, DAS, DPS, and DPDS decreased rGSTA1/A2 and A3/A5 levels in the kidney. Conversely, all OSCs were able to induce GST of alpha and mu classes in the liver. In the intestine, DADS and DAS increased rGSTA1/A2, M2, and P1, while rGSTA3/A5 and M2 were only increased by DADS. In addition, DADS induced rGSTP1 dramatically in the four tissues analyzed. DADS also increased the mEH levels in the liver, intestine, and kidney, while DAS and DPS moderately induced mEH level in the liver. This study brings additional insights into the effects of OSCs on Phase II enzymes and suggests that DADS could be a promising chemopreventive agent considering its pleiotropic capacity of induction.

Scientific and regulatory aspects of nutraceutical products in the United States

Within the past decade, the so-called health food industry has experienced a tremendous growth such that these products are commonplace in most community pharmacies within the United States. These products have since been defined, by those in the industry, as nutraceuticals. Passage of the Nutrition Labeling and Education Act of 1990 and the Dietary Supplement Health and Education Act of 1994 has had a significant impact on the information available to the consumers to enable them to make educated decisions when "self-medicating" with this class of products. This paper is an attempt to summarize the current state of scientific and regulatory issues that are relevant to nutraceutical products.

The effect of vitamin E acetate on ultraviolet-induced mouse skin carcinogenesis

Despite the benefits of sunscreens, ultraviolet (UV) exposure can still lead to skin cancer. In this study we investigated the effect of topical application of the antioxidant vitamin E acetate (VEA) on the inhibition of UV-induced carcinogenesis. Hairless SKH-1 mice received 5.2 mg of VEA 30 min before (VEA/UV) or after (UV/ VEA) a single minimal erythemic dose of UV light. Vehicle-control animals received acetone 30 min before UV exposure (Ace/UV). After 24 h, cyclobutane dimer repair was twofold and 1.5-fold greater in the UVNEA and VEA/UV groups, respectively. Expression of p53 protein in the UV/VEA group was maximum at 12 h after UV exposure, whereas in the Ace/UV- and VEA/UV-treated mice, maximum p53 immunostaining was statistically higher at 15 h (P = 0.03). DNA synthesis as determined by 5-bromo-2'-deoxyuridine incorporation was twofold higher after 15 h in all groups but was not statistically different among treatment groups. Protein levels of cyclin D1 and p21 were increased in both VEA groups by 6 h. In addition, VEA treatments delayed tumor formation and yield for the first 20 wk, although this difference was lost by 30 wk. The telomerase activity of carcinomas from the UV/VEA-treated mice was statistically lower than that of the Ace/UV-treated mice (P = 0.05). This study showed that although VEA may mitigate some of the initial events associated with UV irradiation such as DNA damage and p53 expression, it has limited potential in preventing UV-induced proliferation and tumor formation.

Protective effects of cruciferous seed meals and hulls against colon cancer in mice

Protective effects of diets containing cruciferous seed meals or hulls against chemically-induced colon tumors were examined in male CF1 mice. When commercial crambe meal, autolyzed crambe meal, crambe hulls, high glucosinolate rapeseed meal, or canola meal were fed as 12% of the diets of mice injected with 1,2-dimethylhydrazine, 25-80% of the animals developed colon tumors. Animals fed a soybean meal control diet had a 100% tumor rate. Data suggest that cruciferous seed meals may contain a number of compounds that can exert protective effects against tumor formation and growth.