- an anticancer agent - it protects the DNA from mutation
- shrinks tumors within 72 hours (if cancer not caused by mutation in p53 or WAF 1/p21 genes)
- an antioxidant
- an anti bacterial and antiviral agent
- helps ulcers (antibacterial properties)
- protects liver and heart
- inhibits enzyme necessary for cholesterol biosynthesis
- reduces blood sugar levels
Free Radic Res 2002 Sep;36(9):1023-31
Anti-angiogenic property of edible berries.
Roy S, Khanna S, Alessio HM, Vider J, Bagchi D, Bagchi M, Sen CK.
Laboratory of Molecular Medicine, Department of Surgery, 512 Heart and Lung Research Institute, Ohio State University Medical Center, 473 W. 12th Avenue, Columbus, OH 43210, USA.
Recent studies show that edible berries may have potent chemopreventive properties. Anti-angiogenic approaches to prevent and treat cancer represent a priority area in investigative tumor biology. Vascular endothelial growth factor (VEGF) plays a crucial role for the vascularization of tumors. The vasculature in adult skin remains normally quiescent. However, skin retains the capacity for brisk initiation of angiogenesis during inflammatory skin diseases such as psoriasis and skin cancers. We sought to test the effects of multiple berry extracts on inducible VEGF expression by human HaCaT keratinocytes. Six berry extracts (wild blueberry, bilberry, cranberry, elderberry, raspberry seed, and strawberry) and a grape seed proanthocyanidin extract (GSPE) were studied. The extracts and uptake of their constituents by HaCaT were studied using a multi-channel HPLC-CoulArray approach. Antioxidant activity of the extracts was determined by ORAC. Cranberry, elderberry and raspberry seed samples were observed to possess comparable ORAC values. The antioxidant capacity of these samples was significantly lower than that of the other samples studied. The ORAC values of strawberry powder and GSPE were higher than cranberry, elderberry or raspberry seed but significantly lower than the other samples studied. Wild bilberry and blueberry extracts possessed the highest ORAC values. Each of the berry samples studied significantly inhibited both H2O2 as well as TNF alpha induced VEGF expression by the human keratinocytes. This effect was not shared by other antioxidants such as alpha-tocopherol or GSPE but was commonly shared by pure flavonoids. Matrigel assay using human dermal microvascular endothelial cells showed that edible berries impair angiogenesis.
Mutat Res 2001 Sep 1;480-481:97-108
Effect of chemopreventive agents on DNA adduction induced by the potent mammary carcinogen dibenzo[a,l]pyrene in the human breast cells MCF-7.
Smith WA, Freeman JW, Gupta RC.
Graduate Center for Toxicology, 354 Health Sciences Research Building, University of Kentucky Medical Center, Lexington, KY 40536-0305, USA.
Over 1500 structurally diverse chemicals have been identified which have potential cancer chemopreventive properties. The efficacy and mechanisms of this growing list of chemoprotective agents may be studied using short-term bioassays that employ relevant end-points of the carcinogenic process. In this study, we have examined the effects of eight potential chemopreventive agents, N-acetylcysteine (NAC), benzylisocyanate (BIC), chlorophyllin, curcumin, 1,2-dithiole-3-thione (D3T), ellagic acid, genistein, and oltipraz, on DNA adduction of the potent mammary carcinogen dibenzo[a,l]pyrene (DBP) using the human breast cell line MCF-7. Bioactivation of DBP by MCF-7 cells resulted in the formation of one predominant (55%) dA-derived and several other dA- or dG-derived DNA adducts. Three test agents, oltipraz, D3T, and chlorophyllin substantially (>65%) inhibited DBP-DNA adduction at the highest dose tested (30 microM). These agents also significantly inhibited DBP adduct levels at a lower dose of 15 microM, while oltipraz was effective even at the lowest dose of 5 microM. Two other agents, genistein and ellagic acid were moderate (45%) DBP-DNA adduct inhibitors at the highest dose tested, while NAC, curcumin, and BIC were ineffective. These studies indicate that the MCF-7 cell line is an applicable model to study the efficacy of cancer chemopreventive agents in a human setting. Moreover, this model may also provide information regarding the effect of the test agents on carcinogen bioactivation and detoxification enzymes.
Eur J Drug Metab Pharmacokinet 1999 Apr-Jun;24(2):183-9
Tannins, xenobiotic metabolism and cancer chemoprevention in experimental animals.
Nepka C, Asprodini E, Kouretas D.
Cytopathology Laboratory, Serres, Greece.
Tannins are plant polyphenolic compounds that are contained in large quantities in food and beverages (tea, red wine, nuts, etc.) consumed by humans daily. It has been shown that various tannins exert broad cancer chemoprotective activity in a number of animal models. This review summarizes the recent literature regarding both the mechanisms involved, and the specific organ cancer models used in laboratory animals. An increasing body of evidence demonstrates that tannins act as both anti-initiating and antipromoting agents. In view of the fact that tannins may be of valid medicinal efficacy in human clinical trials, the present review attempts to integrate results from animal studies, and considers their possible application in humans.
Carcinogenesis 1996 Apr;17(4):821-8
The effects of dietary ellagic acid on rat hepatic and esophageal mucosal cytochromes P450 and phase II enzymes.
Ahn D, Putt D, Kresty L, Stoner GD, Fromm D, Hollenberg PF.
Department of Surgery, Wayne State University, Detroit, MI 48201, USA.
Ellagic acid (EA), a naturally occurring plant polyphenol possesses broad chemoprotective properties. Dietary EA has been shown to reduce the incidence of N-2-fluorenylacetamide-induced hepatocarcinogenesis in rats and N-nitrosomethylbenzylamine (NMBA)-induced rat esophageal tumors. In this study changes in the expression and activities of specific rat hepatic and esophageal mucosal cytochromes P450 (P450) and phase II enzymes following dietary EA treatment were investigated. Liver and esophageal mucosal microsomes and cytosol were prepared from three groups of Fisher 344 rats which were fed an AIN-76 diet containing no EA or 0.4 or 4.0 g/kg EA for 23 days. In the liver total P450 content decreased by up to 25% and P450 2E1-catalyzed p-nitrophenol hydroxylation decreased by 15%. No changes were observed in P450 1A1, 2B1 or 3A1/2 expression or activities or cytochrome b5 activity. P450 reductase activity decreased by up to 28%. Microsomal epoxide hydrolase (mEH) expression decreased by up to 85% after EA treatment, but mEH activities did not change. The hepatic phase II enzymes glutathione S-transferase (GST), NAD(P)H:quinone reductase ?NAD-(P)H:QR? and UDP glucuronosyltransferase (UDPGT) activities increased by up to 26, 17 and 75% respectively. Assays for specific forms of GST indicated marked increases in the activities of isozymes 2-2 (190%), 4-4 (150%) and 5-5 (82%). In the rat esophageal mucosa only P450 1A1 could be detected by Western blot analysis and androstendione was the only P450 metabolite of testosterone detectable. However, there were no differences in the expression of P450 1A1, the formation of androstendione or NAD(P)H:QR activities between control and EA-fed rats in the esophagus. Although there was no significant decrease in overall GST activity, as measured with 1-chloro-2,4-dinitrobenzene (CDNB), there was a significant decrease in the activity of the 2-2 isozyme (66% of control). In vitro incubations showed that EA at a concentration of 100 microM inhibited P450 2E1, 1A1 and 2B1 activities by 87, 55 and 18% respectively, but did not affect 3A1/2 activity. Using standard steady-state kinetic analyses, EA was shown to be a potent non-competitive inhibitor of both liver microsomal ethoxyresorufin O-deethylase and p-nitrophenol hydroxylase activities, with apparent Ki values of approximately 55 and 14 microM respectively. In conclusion, these results demonstrate that EA causes a decrease in total hepatic P450 with a significant effect on hepatic P450 2E1, increases some hepatic phase II enzyme activities ?GST, NAD-(P)H:QR and UDPGT? and decreases hepatic mEH expression. It also inhibits the catalytic activity of some P450 isozymes in vitro. Thus the chemoprotective effect of EA against various chemically induced cancers may involve decreases in the rates of metabolism of these carcinogens by phase I enzymes, due to both direct inhibition of catalytic activity and modulation of gene expression, in addition to effects on the expression of phase II enzymes, thereby enhancing the ability of the target tissues to detoxify the reactive intermediates
Cancer Lett 1999 Mar 1;136(2):215-21
p53/p21(WAF1/CIP1) expression and its possible role in G1 arrest and apoptosis in ellagic acid treated cancer cells.
Narayanan BA, Geoffroy O, Willingham MC, Re GG, Nixon DW.
Cancer Prevention Program, Hollings Cancer Center, Medical University of South Carolina, Charleston 29425, USA. [email protected]
Ellagic acid is a phenolic compound present in fruits and nuts including raspberries, strawberries and walnuts. It is known to inhibit certain carcinogen-induced cancers and may have other chemopreventive properties. The effects of ellagic acid on cell cycle events and apoptosis were studied in cervical carcinoma (CaSki) cells. We found that ellagic acid at a concentration of 10(-5) M induced G arrest within 48 h, inhibited overall cell growth and induced apoptosis in CaSki cells after 72 h of treatment. Activation of the cdk inhibitory protein p21 by ellagic acid suggests a role for ellagic acid in cell cycle regulation of cancer cells.
Cancer Res 2001 Aug 15;61(16):6112-9
Chemoprevention of esophageal tumorigenesis by dietary administration of lyophilized black raspberries.
Kresty LA, Morse MA, Morgan C, Carlton PS, Lu J, Gupta A, Blackwood M, Stoner GD.
Division of Environmental Health Sciences, School of Public Health, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio 43210, USA.
Fruit and vegetable consumption has consistently been associated with decreased risk of a number of aerodigestive tract cancers, including esophageal cancer. We have taken a "food-based" chemopreventive approach to evaluate the inhibitory potential of lyophilized black raspberries (LBRs) against N-nitrosomethylbenzylamine (NMBA)-induced esophageal tumorigenesis in the F344 rat, during initiation and postinitiation phases of carcinogenesis. Anti-initiation studies included a 30-week tumorigenicity bioassay, quantification of DNA adducts, and NMBA metabolism study. Feeding 5 and 10% LBRs, for 2 weeks prior to NMBA treatment (0.25 mg/kg, weekly for 15 weeks) and throughout a 30-week bioassay, significantly reduced tumor multiplicity (39 and 49%, respectively). In a short-term bioassay, 5 and 10% LBRs inhibited formation of the promutagenic adduct O(6)-methylguanine (O(6)-meGua) by 73 and 80%, respectively, after a single dose of NMBA at 0.25 mg/kg. Feeding 5% LBRs also significantly inhibited adduct formation (64%) after NMBA administration at 0.50 mg/kg. The postinitiation inhibitory potential of berries was evaluated in a second bioassay with sacrifices at 15, 25, and 35 weeks. Administration of LBRs began after NMBA treatment (0.25 mg/kg, three times per week for 5 weeks). LBRs inhibited tumor progression as evidenced by significant reductions in the formation of preneoplastic esophageal lesions, decreased tumor incidence and multiplicity, and reduced cellular proliferation. At 25 weeks, both 5 and 10% LBRs significantly reduced tumor incidence (54 and 46%, respectively), tumor multiplicity (62 and 43%, respectively), proliferation rates, and preneoplastic lesion development. Yet, at 35 weeks, only 5% LBRs significantly reduced tumor incidence and multiplicity, proliferation indices and preneoplastic lesion formation. In conclusion, dietary administration of LBRs inhibited events associated with both the initiation and promotion/progression stages of carcinogenesis, which is promising considering the limited number of chemopreventives with this potential.
Cancer Res 2001 Aug 15;61(16):6112-9
Bioorg Med Chem Lett 1998 Jan 6;8(1):97-100
DNA gyrase inhibitory activity of ellagic acid derivatives.
Weinder-Wells MA, Altom J, Fernandez J, Fraga-Spano SA, Hilliard J, Ohemeng K, Barrett JF.
R.W. Johnson Pharmaceutical Research Institute, Raritan, NJ 08869, USA.
Ellagic acid was found to inhibit E. coli DNA gyrase supercoiling with approximately the same potency as nalidixic acid. Tricyclic analogs of ellagic acid, which vary in the number and position of the hydroxy groups as well as their replacement with halogens, have been synthesized. The biological activity of these analogs is discussed
Eksp Klin Farmakol 2001 Mar-Apr;64(2):55-9
[Antioxidant properties of novel preparations-bioflavonoid derivatives and tannins.]
[Article in Russian]
Iakovleva LV, Gerasimova OA, Karbusheva IV, Ivakhnenko AK, Buniatian ND, Sakharova TS.
Central Research Laboratory, Ukrainian Pharmaceutical Academy, ul. Pushkinskaya 53, Kharkov, 310002 Ukraine.
New medicinal plant preparations of polyphenol nature, representing the derivatives of bioflavonoids (piflamin) and ellagotannins (altan and ellagic acid) were experimentally studied. The drugs exhibited antioxidant properties, which were manifested by inhibition of a pathological lipid peroxidation, restoration of the functional activity of the antioxidant system components, and stabilization of the hepatocyte membranes.
Antimicrob Agents Chemother 1998 Sep;42(9):2245-53
Human immunodeficiency virus type 1 cDNA integration: new aromatic hydroxylated inhibitors and studies of the inhibition mechanism.
Farnet CM, Wang B, Hansen M, Lipford JR, Zalkow L, Robinson WE Jr, Siegel J, Bushman F.
Salk Institute for Biological Studies, La Jolla, California, USA.
Integration of the human immunodeficiency virus type 1 (HIV-1) cDNA is a required step for viral replication. Integrase, the virus-encoded enzyme important for integration, has not yet been exploited as a target for clinically useful inhibitors. Here we report on the identification of new polyhydroxylated aromatic inhibitors of integrase including ellagic acid, purpurogallin, 4,8, 12-trioxatricornan, and hypericin, the last of which is known to inhibit viral replication. These compounds and others were characterized in assays with subviral preintegration complexes (PICs) isolated from HIV-1-infected cells. Hypericin was found to inhibit PIC assays, while the other compounds tested were inactive. Counterscreening of these and other integrase inhibitors against additional DNA-modifying enzymes revealed that none of the polyhydroxylated aromatic compounds are active against enzymes that do not require metals (methylases, a pox virus topoisomerase). However, all were cross-reactive with metal-requiring enzymes (restriction enzymes, a reverse transcriptase), implicating metal atoms in the inhibitory mechanism. In mechanistic studies, we localized binding of some inhibitors to the catalytic domain of integrase by assaying competition of binding by labeled nucleotides. These findings help elucidate the mechanism of action of the polyhydroxylated aromatic inhibitors and provide practical guidance for further inhibitor development.
Inhibitory actions of ellagic acid on growth and arylamine N-acetyltransferase activity in strains of Helicobacter pylori from peptic ulcer patients.
Department of Medicine, China Medical College, Taiwan, Republic of China.
Arylamine N-acetyltransferase (NAT) activity in Helicobacter pylori was inhibited by ellagic acid, a possible chemopreventive drug. The NAT activity was determined using an acetyl CoA recycling assay and high pressure liquid chromatography. Inhibition of growth studies using H. pylori demonstrated that ellagic acid elicited a dose-dependent bactericidal effect in H. pylori cultures, i.e. the greater the concentration of ellagic acid, the greater the inhibition of growth of H. pylori. The IC50 value was 1 mM for inhibition of growth of H. pylori. Cytosols or suspensions of H. pylori with and without selected concentrations of ellagic acid co-treatment showed different percentages of 2-aminofluorene and p-aminobenzoic acid acetylation. The data indicated that there was decreased NAT activity associated with increased ellagic acid in H. pylori cytosols and intact cells. For the cytosol and intact bacteria examinations, the apparent values of K(m) and Vmax decreased after co-treatment with 1 mM ellagic acid. This report is the first demonstration of ellagic acid inhibition of arylamine NAT activity and ellagic acid inhibition of growth in the bacterium H. pylori.
Indian J Physiol Pharmacol 1996 Oct;40(4):363-6
Inhibition of liver fibrosis by ellagic acid.
Thresiamma KC, Kuttan R.
Amala Cancer Research Centre, Amala Nagar, Trichur, Kerala.
Chronic administration of carbon tetrachloride in liquid paraffin (1.7) ip; 0.15 ml, (20 doses) has been found to produce severe hepatotoxicity, as seen from the elevated levels of serum and liver glutamate-pyruvate transaminase, alkaline phosphatase and lipid peroxides. The chronic administration of carbon tetrachloride was also found to produce liver fibrosis as seen from pathological analysis as well as elevated liver-hydroxy proline. Oral administration of ellagic acid was found to significantly reduce the elevated levels of enzymes, lipid peroxide and liver hydroxy proline in these animals and rectified liver pathology. These results indicate that ellagic acid administration orally can circumvent the carbon tetrachloride toxicity and subsequent fibrosis
Eksp Klin Farmakol 1998 May-Jun;61(3):32-4
[The protective action of ellagic acid in experimental myocarditis]
[Article in Russian]
Iakovleva LV, Ivakhnenko AK, Buniatian ND.
Central Research Laboratory, Ukranian Pharmaceutical Academy, Kharkov, Ukraine.
The article presents the material on the study of the cardioprotective effect of ellagic acid on a model of neoepinephrine myocarditis in rats. In doses of 0.5-1 mg/kg ellagic acid causes a marked antioxidant effect. Restores the disturbed myocardial functions. The reference-agent vitamin E (50 mg/kg) yields to ellagic acid as a cardioprotector. The effect of 0.5 mg/kg of ellagic acid was more stable than that of a 1 mg/kg dose. The cardioprotective activity of the drugs under study was determined according to the POL parameters in a myocardial homogenate and blood serum and according to the EEG parameters and the degree of cardiomyocyte cytolysis.
J Nat Prod 2001 Aug;64(8):1010-4
Ellagitannins and hexahydroxydiphenoyl esters as inhibitors of vertebrate squalene epoxidase.
Abe I, Kashiwagi Y, Noguchi H, Tanaka T, Ikeshiro Y, Kashiwada Y.
School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan. [email protected]
Ellagitannins isolated from various plant sources as well as newly synthesized n-alkyl (C(1)-C(18)) esters of hexahydroxydiphenyl (HHDP) dicarboxylic acid were evaluated as enzyme inhibitors of recombinant rat squalene epoxidase, a rate-limiting enzyme of cholesterol biosynthesis. Among the ellagitannins tested, pedunculagin (IC(50) = 2.0 microM) and eugeniin (IC(50) = 1.6 microM), both containing (S)-HHDP ester group(s), showed remarkable inhibition, which was more potent than those of previously reported substrate analogue inhibitors. Furthermore, ellagic acid (IC(50) = 2.0 microM), a bislactone formed by hydrolytic release of a HHDP group from ellagitannins, was also a good inhibitor of the enzyme. On the other hand, the synthetic HHDP esters with C(6) (IC(50) = 0.93 microM) and C(8) alkyl side chains (IC(50) = 0.83 microM) showed potent enzyme inhibition at the submicromolar concentration range, while esters with shorter chain lengths (C(1)-C(4)) and a C(18) ester exhibited moderate inhibition (IC(50) = 8-47 microM).
Planta Med 2001 Dec;67(9):825-32
Antileishmanial activity of hydrolyzable tannins and their modulatory effects on nitric oxide and tumour necrosis factor-alpha release in macrophages in vitro.
Kolodziej H, Kayser O, Kiderlen AF, Ito H, Hatano T, Yoshida T, Foo LY.
Institut fur Pharmazie, Pharmazeutische Biologie, Freie Universitat Berlin, Berlin, Germany. [email protected]
A series of 27 hydrolyzable tannins and related compounds was tested for antiparasitic effects against both extracellular promastigote and intracellular amastigote Leishmania donovani organisms. In parallel, the compounds were evaluated for their immunomodulatory effects on macrophage functions, including release of nitric oxide (NO), tumour necrosis factor-alpha (TNF-alpha) and interferon (IFN)-like properties using several functional assays. Of the series of polyphenols tested, only gallic acid (54 microM NO) and its methyl ester (32 microM NO) induced murine macrophage-like RAW 264.7 cells to release NO in appreciable amounts (IFN-gamma/LPS 119 microM NO). The in vitro TNF-inducing potential of the polyphenols examined increased in the order of oligomeric ellagitannins (EC(50) > 25 microg/ml) < monomeric ellagitannins, gallotannins (EC(50) 8.5 to > 25 microg/ml) < C-glucosidic ellagitannins, dehydroellagitannins (EC(50) 0.6 - 2.8 microg/ml) at the host cell subtoxic concentration of 50 microg/ml. Furthermore, promastigotes of Leishmania donovani were assayed in the presence of these polyphenols and the results showed that none of the compounds was significantly toxic (EC(50) > 25 microg/ml) to the extracellular forms. In contrast, all polyphenols showed pronounced antileishmanial activities (EC(50) < 0.4 - 12.5 versus 7.9 microg/ml for Pentostam) against intracellular amastigotes of L. donovani residing within RAW cells. Noteworthy, most compounds exhibited low cytotoxicity against the murine host cells (EC(50) >25 microg/ml). Furthermore, some ellagitannins and the majority of dehydroellagitannins induced potent interferon-like activities as reflected by inhibition of the cytopathic effect of encephalomyocarditis virus on fibroblast L929 cells. This is the first report on hydrolyzable tannins as a new class of natural products with leishmanicidal activity including their potential for inducing the release of NO, TNF and IFN-like activity in macrophage-like RAW cells.
Antioxid Redox Signal 2001 Dec;3(6):995-1008
Chemical studies of proanthocyanidins and hydrolyzable tannins.
Bors W, Foo LY, Hertkorn N, Michel C, Stettmaier K.
Institut fur Strahlenbiologie, GSF Forschungszentrum fur Umwelt und Gesundheit, Neuherberg, Germany. [email protected]
We investigated a number of natural polyphenols representing flavan-3-ols, gallotannins, and ellagitannins with regard to their antioxidant potential. For this purpose we used pulse radiolysis to determine scavenging rate constants with hydroxyl radicals and decay rates of the respective aroxyl radicals and EPR spectroscopy to identify the radicals after in situ oxidation. Using NMR spectroscopy, we could confirm phenolic coupling reactions of epigallocatechin gallate and pentagalloyl glucose after radical-induced oxidation.
Planta Med 2002 Feb;68(2):173-5
Ellagitannins from Lagerstroemia speciosa as Activators of Glucose Transport in Fat Cells.
Hayashi T, Maruyama H, Kasai R, Hattori K, Takasuga S, Hazeki O, Yamasaki K, Tanaka T.
Institute of Pharmaceutical Sciences, Faculty of Medicine, Hiroshima University, Hiroshima, Japan.
Abstract.Glucose transport enhancers were searched for in Lagerstroemia speciosa, a Philippine local herbal medicine used for diabetes mellitus. Bioassay-guided fractionation of the aqueous acetone extract of the leaves afforded three active ellagitannins, lagerstroemin, flosin B and reginin A, identified by NMR and optical rotation. These compounds increased glucose uptake of rat adipocytes, and could be responsible for lowering the blood glucose level.
Nutr 2001 Nov;131(11):2837-42
Walnut polyphenolics inhibit in vitro human plasma and LDL oxidation.
Anderson KJ, Teuber SS, Gobeille A, Cremin P, Waterhouse AL, Steinberg FM.
Department of Internal Medicine, Division of Rheumatology, Allergy and Clinical Immunology, School of Medicine, University of California, Davis, CA, USA.
Recent epidemiologic studies have associated nut consumption with a reduced incidence of cardiovascular mortality. However, little is known about the contribution of nut polyphenols to antioxidant and cardiovascular protection. In this investigation, polyphenol-rich extracts from English walnuts (Juglans regia) were studied and compared with ellagic acid for their ability to inhibit in vitro plasma and LDL oxidation, as well as their effects on LDL alpha-tocopherol during oxidative stress. In addition, the Trolox equivalent antioxidant activity (TEAC) was determined and liquid chromatography electrospray detection mass spectrometry (LC-ELSD/MS) analyses of the walnut extracts were performed. 2,2'-Azobis'(2-amidino propane) hydrochloride (AAPH)-induced LDL oxidation was significantly inhibited by 87 and 38% with the highest concentration (1.0 micromol/L) of ellagic acid and walnut extract, respectively. In addition, copper-mediated LDL oxidation was inhibited by 14 and 84% in the presence of ellagic acid and walnut extract, respectively, with a modest, significant LDL alpha-tocopherol sparing effect observed. Plasma thiobarbituric acid reacting substance (TBARS) formation was significantly inhibited by walnut extracts and ellagic acid in a dose-dependent manner, and the extracts exhibited a TEAC value greater than that of alpha-tocopherol. LC-ELSD/MS analysis of the walnut extracts identified ellagic acid monomers, polymeric ellagitannins and other phenolics, principally nonflavonoid compounds. These results demonstrate that walnut polyphenolics are effective inhibitors of in vitro plasma and LDL oxidation. The polyphenolic content of walnuts should be considered when evaluating their antiatherogenic potential.
Anticancer Res 2001 Jan-Feb;21(1A):359-64
IGF-II down regulation associated cell cycle arrest in colon cancer cells exposed to phenolic antioxidant ellagic acid.
Narayanan BA, Re GG.
American Health Foundation, 1, Dana Road Valhalla, NY 10595, USA. [email protected]
Altered cell and tissue differentiation is characteristic of premalignant lesions long before they become invasive and metastatic. One approach to controlling preneoplastic lesions is to block their expansion with non-toxic agents that suppress cell proliferation and induce apoptosis. Here, we show that ellagic acid, a natural, dietary phenolic antioxidant when given at 10(-5) M for 48 hours to colon cancer cells (SW 480), induced down regulation of insulin like growth factor IGF-II, activated p21(waf1/Cip1), mediated a cumulative effect on G1/S transition phase and caused apoptotic cell death. SW480 colon cancer cells expressed significant mRNA levels for the mitogenic insulin like growth factor (IGF-II). Collectively, these observations suggest that growth inhibition by ellagic acid is mediated by signaling pathways that mediate DNA damage, triggers p53, which in turn activates p21 and at the same time alters the growth factor expression, resulting in the down regulation of IGF-II.
Cancer Lett 1997 Mar 19;114(1-2):11-7 Related Articles, Books, LinkOut
Experimental evidence for cancer preventive elements in foods.
Department of Gastrointestinal Medical Oncology and Digestive Diseases, The University of Texas M.D. Anderson Cancer Center, Houston, USA.
The last decade has witnessed an incredible advance in our understanding of how fruits and vegetables work to prevent cancer. Epidemiological studies have suggested that a diet rich in fruits and vegetables is associated with reduced risk for a number of common cancers. Food chemists and natural product scientists have identified hundreds of 'phytochemicals' that are being evaluated for the prevention of cancer. Food components can modify carcinogenesis in one of five different ways. They may: (1) modify carcinogen activation by inhibiting Phase 1 enzymes; (2) modify how carcinogens are detoxified through Phase 2 pathways; (3) scavenge DNA reactive agents; (4) suppress the abnormal proliferation of early, preneoplastic lesions; and (5) inhibit certain properties of the cancer cell.