The Latest Ellagic Acid Research

STUDY ABSTRACT 1

Effect of chemopreventive agents on DNA adduction induced by the potent mammary carcinogen dibenzo[a,l]pyrene in the human breast cells MCF-7.

Taken from: Mutat Res 2001 Sept 1;480-481:97-108
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 oltripraz 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.

STUDY ABSTRACT 2

Tannins, xenobiotic metabolism and cancer chemoprevention in experimental animals.

Taken from: Eur J drug Metab Pharmacokinet 1999 Apr-Jun; 24(2):183-9
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 anti-promoting 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.

STUDY ABSTRACT 3

The effects of dietary ellagic acid on rat hepatic and esophageal mucosal cytochromes P450 and phase II enzymes.

Taken from: Carcinogenesis 1996Apr;17(4):821-8
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 tratment 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 decresed 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-dinotrobenzene (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 2B2 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 demontrate that EA causes a decrease in total hepatic P450 with a significatn effect on hepatic P450 2E1, increases some hepatic phase II enzyme activites ?GST, NAD-(P)H:QR and UDPGT? and decreases hepatic mEH expression. It aslo 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 the 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.

STUDY ABSTRACT 4

p53/p21(WAF1/CIP1) expression and its possible role in G1 arrest and apoptosis in ellagic acid treated cancer cells.

Taken from: Cancer Lett 1999 Mar 1;136(2):215-21
Narayanan BA, Geoffroy O, Willingham MC, Re GG, Nixon DW.
Cancer Prevention Program, Hollings Cancer Center, Medical University of South Carolina, Charleston 29425, USA.
bhagavati@musc.edu

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.

STUDY ABSTRACT 5

Chemoprevention of esophageal tumorigenesis by dietary administration of lyophilized black raspberries.

Taken from: Cancer Res 2001 Aug 15;61(16):6112-9
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.

STUDY ABSTRACT 6

DNA gyrase inhibitory activity of ellagic acid derivatives.

Taken from: Cancer Res 2001 Aug 15;61(16):6112-9
Bioorg Med Chem Lett 1998 Jan 6;8(1):97-100
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.

STUDY ABSTRACT 7

Antioxidant properties of novel preparations--bioflavonoid derivatives and tannins. --- (This is translation. Article written in Russian)

Taken from: Eksp Klin Farmakol 2001 Mar-Apr;64(2):55-9
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.

STUDY ABSTRACT 8

Human immunodeficiency virus type 1 cDNA integration: new aromatic hydroxylated inhibitors and studies of the inhibition mechanism.

Taken from: Antimicrob Agents Chemother 1998 Sep;42(9):2245-53
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.

STUDY ABSTRACT 9

Inhibition of liver fibrosis by ellagic acid.

Taken from: Indian J Physiol Pharmacol 1996 Oct;40(4):363-6
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.

STUDY ABSTRACT 10

The protective action of ellagic acid in experimental myocarditis --- [This is translation. Article written in Russian]

Taken from: Eksp Klin Farmakol 1998 May-Jun;61(3):32-4
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.