Comparative cytotoxicities of selected minor dietary non-nutrients with chemopreventive properties

Inositol Hexaphosphate (IP6) and Colon Cancer: From Concepts and First Experiments to Clinical Application

Multiple human health-beneficial effects have been related to highly phosphorylated inositol hexaphosphate (IP6). This naturally occurring carbohydrate and its parent compound, myo-inositol (Ins), are abundantly present in plants, particularly in certain high-fiber diets, but also in mammalian cells, where they regulate important cellular functions. However, the striking and broad-spectrum anticancer activity of IP6, consistently demonstrated in different experimental models, has been in a spotlight of the scientific community dealing with the nutrition and cancer during the last several decades. First experiments were performed in colon cancer 30 years ago. Since then, it has been shown that IP6 reduces cell proliferation, induces apoptosis and differentiation of malignant cells with reversion to normal phenotype, affecting several critical molecular targets. Enhanced immunity and antioxidant properties also contribute to the tumor cell destruction. Although Ins possesses a modest anticancer potential, the best anticancer results were obtained from the combination of IP6 + Ins. Here we review the first experimental steps in colon cancer, when concepts and hypotheses were put together almost without real knowledge and present clinical studies, that were initiated in colon cancer patients. Available as a dietary supplement, IP6 + Ins has been shown to enhance the anticancer effect of conventional chemotherapy, controls cancer metastases, and improves quality of life in cancer patients. Emerging clinical and still vast amount of experimental data suggest its role either as an adjuvant or as an "alternative" to current chemotherapy for cancer.

Overview of the Role of Vanillin on Redox Status and Cancer Development

Bioactive natural products play critical roles in modern drug development, especially anticancer agents. It has been widely reported that various pharmacological activities of such compounds are related to their antioxidant properties. Vanillin is a natural substance widely found in many plant species and often used in beverages, foods, cosmetics, and pharmaceutical products. Antioxidant and anticancer potential have been described for this compound. Considering the importance of vanillin in the area of human health and food and pharmaceuticals sectors, in this review, we discuss the role of vanillin on redox status and its potential contribution to the prevention and the treatment of cancer.

Factors causing compositional changes in soy protein hydrolysates and effects on cell culture functionality

Soy protein hydrolysates significantly enhance cell growth and recombinant protein production in cell cultures. The extent of this enhancement in cell growth and IgG production is known to vary from batch to batch. This can be due to differences in the abundance of different classes of compounds (e.g., peptide content), the quality of these compounds (e.g., glycated peptides), or the presence of specific compounds (e.g., furosine). These quantitative and qualitative differences between batches of hydrolysates result from variation in the seed composition and seed/meal processing. Although a considerable amount of literature is available that describes these factors, this knowledge has not been combined in an overview yet. The aim of this review is to identify the most dominant factors that affect hydrolysate composition and functionality. Although there is a limited influence of variation in the seed composition, the overview shows that the qualitative changes in hydrolysate composition result in the formation of minor compounds (e.g., Maillard reaction products). In pure systems, these compounds have a profound effect on the cell culture functionality. This suggests that the presence of these compounds in soy protein hydrolysates may affect hydrolysate functionality as well. This influence on the functionality can be of direct or indirect nature. For instance, some minor compounds (e.g., Maillard reaction products) are cytotoxic, whereas other compounds (e.g., phytates) suppress protein hydrolysis during hydrolysate production, resulting in altered peptide composition, and, thus, affect the functionality.

Intestinal lymphangiectasis and lipidosis in rats following subchronic exposure to indole-3-carbinol via oral gavage

To investigate the toxicity and carcinogenic potential of indole-3-carbinol (I3C), the National Toxicology Program has conducted 13-week subchronic studies in Fisher 344 rats and B6C3F1 mice, and chronic 2-year bioassays in Sprague-Dawley rats and B6C3F1 mice. While the chronic study results are not yet available, subchronic study results and short-term special evaluations of interim sacrifices in the 2-year rat bioassay are presented. F344 rats were orally gavaged ≤300 mg I3C/kg body weight 5 days a week for 13 weeks. Rats treated with ≥150 mg/kg demonstrated a dose-related dilation of lymphatics (lymphangiectasis) of the duodenum, jejunum, and mesenteric lymph nodes. Material within dilated lacteals stained positively for Oil Red O and Sudan Black, consistent with lipid. Electron microscopic evaluation confirmed extracellular lipid accumulation within the villar lamina propria, lacteals, and within villar macrophages. Analyses of hepatic and pulmonary CYP1A enzymes demonstrated dose-dependent I3C induction of CYP1A1 and 1A2. B6C3F1 mice orally gavaged ≤250 mg I3C/kg body weight did not demonstrate histopathological changes; however, hepatic CYP induction was similar to that in rats. The histopathologic changes of intestinal lymphangiectasis and lipidosis in this study share similarities with intestinal lymphangiectasia as observed in humans and dogs. However, the resultant clinical spectrum of protein-losing enteropathy was not present.

Final report on the safety assessment of Glycyrrhetinic Acid, Potassium Glycyrrhetinate, Disodium Succinoyl Glycyrrhetinate, Glyceryl Glycyrrhetinate, Glycyrrhetinyl Stearate, Stearyl Glycyrrhetinate, Glycyrrhizic Acid, Ammonium Glycyrrhizate, Dipotassium Glycyrrhizate, Disodium Glycyrrhizate, Trisodium Glycyrrhizate, Methyl Glycyrrhizate, and Potassium Glycyrrhizinate

Glycyrrhetinic Acid and its salts and esters and Glycyrrhizic Acid and its salts and esters are cosmetic ingredients that function as flavoring agents or skin-conditioning agents - miscellaneous or both. These chemicals may be isolated from licorice plants. Glycyrrhetinc Acid is described as at least 98% pure, with 0.6% 24-OH-Glycyrrhetinic Acid, not more than 20 mu g/g of heavy metals and not more than 2 mu g/g of arsenic. Ammonium Glycyrrhizate has been found to be at least 98% pure and Dipotassium Glycyrrhizate has been found to be at least 95% pure. Glycyrrhetinic Acid is used in cosmetics at concentrations of up to 2%; Stearyl Glycyrrhetinate, up to 1%; Glycyrrhizic Acid, up to 0.1%; Ammonium Glycyrrhizate, up to 5%; Dipotassium Glycyrrhizate, up to 1%; and Potassium Glycyrretinate, up to 1%. Although Glycyrrhizic Acid is poorly absorbed by the intestinal tract, it may be hydrolyzed to Glycyrrhetinic Acid by a beta -glucuronidase produced by intestinal bacteria. Glycyrrhetinic Acid and Glycyrrhizic Acid bind to rat and human albumin, but do not absorb well into tissues. Glycyrrhetinic Acid and Glycyrrhizic Acid and metabolites are mostly excreted in the bile, with very little excreted in urine. Dipotassium Glycyrrhizate was undetectable in the receptor chamber when tested for transepidermal permeation through pig skin. Glycyrrhizic Acid increased the dermal penetration of diclofenac sodium in rat skin. Dipotassium Glycyrrhizate increased the intestinal absorption of calcitonin in rats. In humans, Glycyrrhetinic Acid potentiated the effects of hydrocortisone in the skin. Moderate chronic or high acute exposure to Glycyrrhizic Acid, Ammonium Glycyrrhizate, and their metabolites have been demonstrated to cause transient systemic alterations, including increased potassium excretion, sodium and water retention, body weight gain, alkalosis, suppression of the renin-angiotensis-aldosterone system, hypertension, and muscular paralysis; possibly through inhibition of 11beta -hydroxysteroid dehydrogenase-2 (11beta -OHSD2) in the kidney. Glycyrrhetinic Acid and its derivatives block gap junction intracellular communication in a dose-dependent manner in animal and human cells, including epithelial cells, fibroblasts, osteoblasts, hepatocytes, and astrocytes; at high concentrations, it is cytotoxic. Glycyrrhetinic Acid and Glycyrrhizic Acid protect liver tissue from carbon tetrachloride. Glycyrrhizic Acid has been used to treat chronic hepatitis, inhibiting the penetration of the hepatitis A virus into hepatocytes. Glycyrrhetinic Acid and Glycyrrhizic Acid have anti-inflammatory effects in rats and mice. The acute intraperitoneal LD(50) for Glycyrrhetinic Acid in mice was 308 mg/kg and the oral LD(50) was > 610 mg/kg. The oral LD(50) in rats was reported to be 610 mg/kg. Higher LD(50) values were generally reported for salts. Little short-term, subchronic, or chronic toxicity was seen in rats given ammonium, dipotassium, or disodium salts of Glycyrrhizic Acid. Glycyrrhetinic Acid was not irritating to shaved rabbit skin, but was considered slightly irritating in an in vitro test. Glycyrrhetinic Acid inhibited the mutagenic activity of benzo[a]pyrene and inhibited tumor initiation and promotion by other agents in mice. Glycyrrhizic Acid inhibited tumor initiation by another agent, but did not prevent tumor promotion in mice. Glycyrrhizic Acid delayed mortality in mice injected with Erlich ascites tumor cells, but did not reduce the mortality rate. Ammonium Glycyrrhizate was not genotoxic in in vivo and in vitro cytogenetics assays, the dominant lethal assay, an Ames assay, and heritable translocation tests, except for possible increase in dominant lethal mutations in rats given 2000 mg/kg day(-1) in their diet. Disodium Glycyrrhizate was not carcinogenic in mice in a drinking water study at exposure levels up to 12.2 mg/kg day(-1) for 96 weeks. Glycyrrhizate salts produced no reproductive or developmental toxicity in rats, mice, golden hamsters, or Dutch-belted rabbits, except for a dose-dependent increase (at 238.8 and 679.9 mg/kg day(-1)) in sternebral variants in a study using rats. Sedation, hypnosis, hypothermia, and respiratory depression were seen in mice given 1250 mg/kg Glycyrrhetinic Acid intraperitoneally. Rats fed a powdered diet containing up to 4% Ammonium Glycyrrhizate had no treatment related effects in motor function tests, but active avoidance was facilitated at 4%, unaffected at 3%, and depressed at 2%. In a study of 39 healthy volunteers, a no effect level of 2 mg/kg/day was determined for Glycyrrhizic Acid given orally for 8 weeks. Clinical tests in seven normal individuals given oral Ammonium Glycyrrhizate at 6 g/day for 3 days revealed reduced renal and thermal sweat excretion of Na+ and K+, but carbohydrate and protein metabolism were not affected. Glycyrrhetinic Acid at concentrations up to 6% was not a skin irritant or a sensitizer in clinical tests. Neither Glycyrrhizic Acid, Ammonium Glycyrrhizate, nor Dipotassium Glycyrrhizate at 5% were phototoxic agents or photosensitizers. Birth weight and maternal blood pressure were unrelated to the level of consumption of Glycyrrhizic Acid in 1049 Finnish women with infants, but babies whose mother consumed > 500 mg/wk were more likely to be born before 38 weeks. The Cosmetic Ingredient Review (CIR) Expert Panel noted that the ingredients in this safety assessment are not plant extracts, powders, or juices, but rather are specific chemical species that may be isolated from the licorice plant. Because these chemicals may be isolated from plant sources, however, steps should be taken to assure that pesticide and toxic metal residues are below acceptable levels. The Panel advised the industry that total polychlorobiphenyl (PCB)/pesticide contamination should be limited to not more than 40 ppm, with not more than 10 ppm for any specific residue, and that toxic metal levels must not contain more than 3 mg/kg of arsenic (as As), not more than 0.002% heavy metals, and not more than 1 mg/kg of lead (as Pb). Although the Panel noted that Glycyrrhizic Acid is cytotoxic at high doses and ingestion can have physiological effects, there is little acute, short-term, subchronic, or chronic toxicity and it is expected that these ingredients would be poorly absorbed through the skin. These ingredients are not considered to be irritants, sensitizers, phototoxic agents, or photosensitizers at the current maximum concentration of use. Accordingly, the CIR Expert Panel concluded that these ingredients are safe in the current practices of use and concentration. The Panel recognizes that certain ingredients in this group are reportedly used in a given product category, but the concentration of use is not available. For other ingredients in this group, information regarding use concentration for specific product categories is provided, but the number of such products is not known. In still other cases, an ingredient is not in current use, but may be used in the future. Although there are gaps in knowledge about product use, the overall information available on the types of products in which these ingredients are used and at what concentration indicate a pattern of use. Within this overall pattern of use, the Expert Panel considers all ingredients in this group to be safe.

Protection against cancer by dietary IP6 and inositol

Inositol hexaphosphate (IP(6)) is a naturally occurring polyphosphorylated carbohydrate, abundantly present in many plant sources and in certain high-fiber diets, such as cereals and legumes. In addition to being found in plants, IP(6) is contained in almost all mammalian cells, although in much smaller amounts, where it is important in regulating vital cellular functions such as signal transduction, cell proliferation, and differentiation. For a long time IP(6) has been recognized as a natural antioxidant. Recently IP(6) has received much attention for its role in cancer prevention and control of experimental tumor growth, progression, and metastasis. In addition, IP(6) possesses other significant benefits for human health, such as the ability to enhance immune system, prevent pathological calcification and kidney stone formation, lower elevated serum cholesterol, and reduce pathological platelet activity. In this review we show the efficacy and discuss some of the molecular mechanisms that govern the action of this dietary agent. Exogenously administered IP(6) is rapidly taken up into cells and dephosphorylated to lower inositol phosphates, which further affect signal transduction pathways resulting in cell cycle arrest. A striking anticancer action of IP(6) was demonstrated in different experimental models. In addition to reducing cell proliferation, IP(6) also induces differentiation of malignant cells. Enhanced immunity and antioxidant properties also contribute to tumor cell destruction. Preliminary studies in humans show that IP(6) and inositol, the precursor molecule of IP(6), appear to enhance the anticancer effect of conventional chemotherapy, control cancer metastases, and improve quality of life. Because it is abundantly present in regular diet, efficiently absorbed from the gastrointestinal tract, and safe, IP(6) + inositol holds great promise in our strategies for cancer prevention and therapy. There is clearly enough evidence to justify the initiation of full-scale clinical trials in humans.

Inositol hexaphosphate (IP6): a novel treatment for pancreatic cancer

BACKGROUND

Inositol hexaphosphate (IP6) is a naturally occurring polyphosphorylated carbohydrate found in food sources high in fiber content. IP6 has been reported to have significant inhibitory effects against a variety of primary tumors including breast and colon. The effects of IP6 have not been evaluated in pancreatic cancer. We hypothesized that IP6 would significantly inhibit cell growth and increase the apoptotic rate of pancreatic cancer in vitro.

MATERIALS AND METHODS

Two pancreatic cancer cell lines (MIAPACA and PANC1) were cultured using standard techniques and treated with IP6 at doses of 0.5, 1.0, and 5.0 mm. Cell viability was measured by MTT at 24 and 72 h. Apoptosis was evaluated by Annexin V-FITC and results calculated using FACS analysis. Statistical analysis was performed by ANOVA.

RESULTS

Significant reductions (P < 0.01) in cellular proliferation were observed with all IP6 concentrations tested in both cell lines and at both time points. Reductions in cell proliferation ranged from 37.1 to 91.5%. IP6 increased early and late apoptotic activity (P < 0.01).

CONCLUSIONS

Treatment of pancreatic cancer with the common dietary polyphosphorylated carbohydrate IP6 significantly decreased cellular growth and increased apoptosis. Our findings suggest that IP6 has the potential to become an effective adjunct for pancreatic cancer treatment. Further in vivo and human studies are needed to evaluate safety and clinical utility of this agent in patients with pancreatic cancer.

Cancer inhibition by inositol hexaphosphate (IP6) and inositol: from laboratory to clinic

Inositol hexaphosphate (IP6) is a naturally occurring polyphosphorylated carbohydrate that is present in substantial amounts in almost all plant and mammalian cells. It was recently recognized to possess multiple biological functions. A striking anticancer effect of IP6 was demonstrated in different experimental models. Inositol is also a natural constituent possessing moderate anticancer activity. The most consistent and best anticancer results were obtained from the combination of IP6 plus inositol. In addition to reducing cell proliferation, IP6 increases differentiation of malignant cells, often resulting in a reversion to normal phenotype. Exogenously administered IP6 is rapidly taken into the cells and dephosphorylated to lower-phosphate inositol phosphates, which further interfere with signal transduction pathways and cell cycle arrest. Enhanced immunity and antioxidant properties can also contribute to tumor cell destruction. However, the molecular mechanisms underlying this anticancer action are not fully understood. Because it is abundantly present in regular diet, efficiently absorbed from the gastrointestinal tract, and safe, IP6 holds great promise in our strategies for the prevention and treatment of cancer. IP6 plus inositol enhances the anticancer effect of conventional chemotherapy, controls cancer metastases, and improves the quality of life, as shown in a pilot clinical trial. The data strongly argue for the use of IP6 plus inositol in our strategies for cancer prevention and treatment. However, the effectiveness and safety of IP6 plus inositol at therapeutic doses needs to be determined in phase I and phase II clinical trials in humans.

Anti‐cancer function of phytic acid

Summary Inositol hexaphosphate (InsP6 a.k.a. phytic acid or IP6) is ubiquitous. In the plant kingdom it is particularly abundant in cereals and legumes; in much smaller amounts IP6 and its lower phosphorylated forms (IP1−5) are contained in most mammalian cells, where they are important in regulating vital cellular functions. Both in vivo and in vitro experiments have demonstrated striking anticancer (preventive as well as therapeutic) effects of IP6. Inositol also is anti‐carcinogenic, albeit to a lesser extent; it acts synergistically IP6 in inhibiting cancer. In addition to reduction in cell proliferation, IP6 increases differentiation of malignant cells often resulting in reversion to the normal phenotype. IP6 is quickly absorbed from the rat stomach and upper intestine and distributed as inositol and IP1. In vitro, it is instantaneously taken up by malignant cells undergoing variable dephosphorylation to inositol and IP1−5, pointing towards their role in mediating the action of IP6. In humans, IP6 has recently been detected in urine, plasma and other biological fluids; the levels fluctuating with ingestion or deprivation of IP6 or IP6‐rich diet. As IP6 is high in high‐fibre diets, these also may explain, at least in part, the epidemiological observation showing the association of ingesting high‐fibre diets with a lower incidence of certain cancers. Along with safety, the reproducible efficacy of IP6 and inositol in the prevention of cancer in laboratory animals warrant their inclusion in our strategies for cancer prevention and perhaps therapy in humans. Aside from the anticancer action, IP6 and inositol also have numerous other health benefits. All these facts of normal physiological presence of IP6 in our body the level of which fluctuates with intake, association of an IP6‐rich diet with low incidence of several diseases and vice versa, and finally reversal of some of these conditions, at least in part, by IP6 supplementation strongly argue in favour of its inclusion as an essential nutrient or perhaps a vitamin.

Development of a multi-organ rat model for evaluating chemopreventive agents: efficacy of indole-3-carbinol

Indole-3-carbinol (I-3-C) is among the most widely and popularly known antiestrogens. Due to its putative chemopreventive action, I-3-C is being marketed to the general public in health food establishments. Although it has been demonstrated to prevent cancer in animal bioassays, I-3-C also acts as a promoter in the liver and colon. Because of this potential dual biological activity, it is important to investigate both the inhibitory and promotional activities of I-3-C in multi-organ tumorigenesis animal models. 7,12-Dimethylbenz[a]anthracene, aflatoxin B1 and azoxymethane were used to initiate mammary, liver and colon carcinogenesis, respectively in female Sprague-Dawley rats. The rats were fed continuously on a diet containing I-3-C for 25 weeks after initiation. I-3-C treatment was begun one week after the last carcinogen treatment had been administered. I-3-C treatment resulted in a delay in latency of mammary tumor formation, but did not alter tumor incidence or multiplicity among survivors. In the colon, the protocol produced a 40% decrease in aberrant colon crypt foci. However, in the liver, it strongly-induced GST-P foci in carcinogen-treated (a four-fold increase in volume percent foci) and in the vehicle controls (a 69-fold increase). These data support previous findings in other rodent and fish tumor models that I-3-C both inhibits and promotes carcinogenesis. The results of this study clearly demonstrate that I-3-C is not an appropriate chemoprotective agent for human use, in spite of its effects in the breast and colon in this rat animal model.

Secreted enzymatic activities of wild-type and pilD-deficient Legionella pneumophila

Legionella pneumophila, the agent of Legionnaires' disease, is an intracellular pathogen of protozoa and macrophages. Previously, we had determined that the Legionella pilD gene is involved in type IV pilus biogenesis, type II protein secretion, intracellular infection, and virulence. Since the loss of pili and a protease do not account for the infection defect exhibited by a pilD-deficient strain, we sought to define other secreted proteins absent in the mutant. Based upon the release of p-nitrophenol (pNP) from p-nitrophenyl phosphate, acid phosphatase activity was detected in wild-type but not in pilD mutant supernatants. Mutant supernatants also did not release either pNP from p-nitrophenyl caprylate and palmitate or free fatty acid from 1-monopalmitoylglycerol, suggesting that they lack a lipase-like activity. However, since wild-type samples failed to release free fatty acids from 1,2-dipalmitoylglycerol or to cleave a triglyceride derivative, this secreted activity should be viewed as an esterase-monoacylglycerol lipase. The mutant supernatants were defective for both release of free fatty acids from phosphatidylcholine and degradation of RNA, indicating that PilD-negative bacteria lack a secreted phospholipase A (PLA) and nuclease. Finally, wild-type but not mutant supernatants liberated pNP from p-nitrophenylphosphorylcholine (pNPPC). Characterization of a new set of mutants defective for pNPPC-hydrolysis indicated that this wild-type activity is due to a novel enzyme, as opposed to a PLC or another known enzyme. Some, but not all, of these mutants were greatly impaired for intracellular infection, suggesting that a second regulator or processor of the pNPPC hydrolase is critical for L. pneumophila virulence.

Effects of vegetables-fruit extracts and indole-3-carbinol on stearic acid-modulated intercellular communication and cytochrome P450-IA activity

Modulatory effects were investigated of extracts of a vegetables-fruit mixture and indole-3-carbinol (I3C) on stearic acid-modulated gap junctional intercellular communication (GJIC) and cytochrome P450-IA activity (EROD). In V79 cells, pure water and hexane extracts of a vegetables-fruit mixture and 25 μg/ml I3C significantly protected against decreased GJIC caused by 10 μM stearic acid. Furthermore, pure, 10× and 100× diluted vegetables-fruit extracts significantly maintained their capacity to induce EROD activity in Caco-2 cells, but only when these extracts were added to the cells in media already containing 500 μM stearic acid for 48 h. Stearic acid itself did not induce EROD activity. I3C (10, 25, and 50 μg/ml) clearly induced EROD activity in Caco-2 cells, irrespective of the order at which I3C and stearic acid were added to the cells. In conclusion, the present in vitro study showed that vegetables-fruit extracts and I3C modulate effects of stearic acid on intercellular communication and cytochrome P450-IA activity.

Functional food science and defence against reactive oxidative species

This paper assesses critically the science base that underpins the argument that oxidative damage is a significant causative factor in the development of human diseases and that antioxidants are capable of preventing or ameliorating these disease processes. The assessment has been carried out under a number of headings, and some recommendations for future research are made based on the present day knowledge base. The knowledge database (1) Consideration of the basic science that underlies understanding of the role of free radicals in causing cellular pathologies, and the role of antioxidants in preventing this, shows that an imbalance of reactive oxygen species and antioxidant defence systems may lead to chemical modifications of biologically relevant macromolecules. This imbalance provides a logical pathobiochemical mechanism for the initiation and development of several disease states. Experimental data obtained in vivo provide evidence that antioxidants function in systems that scavenge reactive oxygen species and that these are relevant to what occurs in vivo. The relevance in vivo of these observations depends inter alia on knowledge of the uptake and distribution of the antioxidant within the human body, and on what tissue levels of the antioxidant may be expected in relation to dietary levels. (2) There is some way to go until validated precise methods are available for measuring biomarkers of oxidative damage in human subjects in vivo under minimally invasive conditions. With respect to oxidative damage in DNa, HPLC and GC-mass spectrophotometry methods have both merits and limitations. Lipid oxidation products in plasma are best measured as isoprostanes or as lipid hydroperoxides using specific HPLC techniques. Development of isoprostane measurement will advance specificity and precision. The measurement of oxidative damage to proteins has some potential but such methods have not been effectively exploited. (3) Epidemiological studies support the hypothesis that the major antioxidant nutrients vitamin E and vitamin C, and beta-carotene (which may or may not be acting as an antioxidant in vivo), may play a beneficial role in prevention of several chronic disorders. More research is needed on the impact of other non-nutrient compounds, such as other carotenoids and flavonoids, on human health. In general, human intervention studies using hard end-points are the gold standard. Trials are restricted mainly to the major antioxidants and do not allow firm conclusions because of inconsistent findings, an insufficient number of studies and the use of varying doses. There is evidence that large doses of beta-carotene may be deleterious to the health of certain subgroups of the population such as heavy habitual smokers. (4) With respect to the safety of administration of supplementary vitamins, vitamin C is safe at levels of supplementation up to 600 mg/d, and higher levels, up to 2000 mg/d, are without risk. Vitamin E has a very low human toxicity and an intake of 1000 mg/d is without risk; 3200 mg/d has been shown to be without any consistent risk. Large intakes of beta-carotene must be viewed with caution because they have been shown to confer detriment to a population at high risk of lung cancer when administered after many years of high risk (smoking) behaviour. Until further work clarifies the situation in heavy smokers with respect to taking supplements, larger doses should be avoided by such individuals. There is little reliable information about the human toxicology of flavonoids and related non-nutrient antioxidant constituents of the diet. (5) The food industry has long experience in the control of oxidative damage in foods and this experience can be used to advantage for the protection of food antioxidants which are beneficial. Some of these, such as vitamins C and E and beta-carotene, are well known, and strategies for their protection in foods are already exploited by food technologies. (ABSTRACT TRUNCATED)

Inhibition of thymocyte apoptosis by berberine

To find anti-apoptotic substances in plant resources, a microassay method for estimating DNA fragmentation was established using fluorochrome 3,5-diaminobenzoic acid dihydrochloride. Examination was made of various herbal medicines for inhibitory effects on glucocorticoid-induced apoptosis in thymocytes. Several Kampo medicines, e.g. Oren-gedoku-to and San'o-shashin-to, were found to inhibit dexamethasone-induced apoptosis in murine thymocytes. Some of these medicines contain Coptidis rhizoma (CR) as the major constituent, and the CR extract showed the most potent inhibitory activity on thymocyte apoptosis of more than 200 species of herbal extracts. The inhibition of apoptosis by CR extract was confirmed by the trypan blue exclusion test, lactate dehydrogenase release measurement, and morphological evaluation by electron microscopy. The benzodioxolo-benzoquinolizine alkaloid, berberine, and five berberine-type alkaloids, isolated from CR extract, had an inhibitory effect, whereas no effect was noted for the aporphin-type alkaloid magnoflorine. The inhibitory action of berberine was also demonstrated on etoposide- and camptothecin-induced apoptosis.

IP6: a novel anti-cancer agent

Inositol hexaphosphate (InsP6 or IP6) is ubiquitous. At 10 microM to 1 mM concentrations, IP6 and its lower phosphorylated forms (IP(1-5)) as well as inositol (Ins) are contained in most mammalian cells, wherein they are important in regulating vital cellular functions such as signal transduction, cell proliferation and differentiation. A striking anti-cancer action of IP6 has been demonstrated both in vivo and in vitro, which is based on the hypotheses that exogenously administered IP6 may be internalized, dephosphorylated to IP(1-5), and inhibit cell growth. There is additional evidence that Ins alone may further enhance the anti-cancer effect of IP6. Besides decreasing cellular proliferation, IP6 also causes differentiation of malignant cells often resulting in a reversion to normal phenotype. These data strongly point towards the involvement of signal transduction pathways, cell cycle regulatory genes, differentiation genes, oncogenes and perhaps, tumor suppressor genes in bringing about the observed anti-neoplastic action of IP6.