The following article is reprinted here with the kind permission of

Dr. Susan Thorpe-Vargas

 

___________________________

 

Berry Good Health


by
Susan Thorpe-Vargas Ph.D.


 
Multiple studies have discovered that phytonutrients found in raspberries can protect us from cancer and can even shrink some types of cancer tumors.  These substances can also act as an antibacterial and as an antiviral agent.  Does this sound too good to be true?  One particular substance found in this natural “medicine chest”, is a series of compounds called ellagitannins. The highest levels are found in raspberries, but the ellagitannins are also in certain types of grapes, strawberries, blackberries, blueberries and some nuts too.  Recent work (2001), published by Dr. Gary Stoner at Ohio State University, showed that components in the seeds and berry, but particularly ellagitannins, inhibited the initiation and promotion/progression stages of esophageal cancer.  This is an extremely important finding, considering the potential benefits .In addition, edible berries, including raspberries also inhibit angiogenesis. This is a term used to describe the development of blood vessels needed for tumor growth.
 
We do not as yet know all of the functions of the ellagitannins in terms of cancer. A study at Hollings Cancer Center, Medical University of South Carolina has shown one of the ways they work is to "turn on" a normal cellular process called apoptosis.  Apoptosis is "science speak" for something called programmed cell death.  This natural cell death is just one of several ways our body protects us from cancer. As we age, cellular replication mistakes can occur.  Cancer cells somehow become immune to the signals that cause cells to self-destruct, so they become virtually immortal and reproduce indefinitely.
 
The disease with a thousand faces
 
Cancer is not just one disease but is the general name for more than 200 different types of malignancies.  Cancers are classified by the tissue type from which they arise. To illustrate:
·         osteosarcoma-bone cancer
·         melanoma-skin cancer
·         lymphoma-cancer of lymph nodes
·         leukemia – blood cancer
 
Every cellular type has its own form of cancer. The one thing all cancers share in common is uncontrolled growth.  Cancer occurs when cells lose control over critical checkpoints during the process of one cell splitting and becoming two cells.  This control over cellular replication is in the hands of several specific types of genes.
 
Two classes of genes are suspected of being associated with the occurrence of cancer.  A mutation in a tumor suppressor gene is like having faulty brakes in your car.  Just as their name implies, tumor suppressor genes function by making sure there are no mistakes in the genes that are replicated prior to one cell becoming two.  In this "quality control" process, if errors are detected, the cell is instructed not to divide.  Thus, tumor suppressor genes put the brakes on cellular division.  The other class of genes thought to be involved with preventing cancer is called proto-oncogenes. Researchers have found that these genes "code" for proteins involved in mechanisms that regulate the social behavior of cells.  Signals from those cells in the immediate environment induce their neighbors to divide, differentiate and even undergo apoptosis.  So, this type of gene is involved in promoting the normal growth and division of cells and could be likened to your car's accelerator.  A change in the genetic message - a mutation, can turn the proto-oncogene into an oncogene and cause your accelerator to become stuck, thus initiating "runaway" cellular replication.  Nevertheless, there seem to be no pattern to these mutations.  What is so frustrating for both researchers and clinicians alike is that different combinations of mutations are found in different types of cancer and even in cancers of supposedly the same type in different patients. What is most important to remember is that cancer begins as a single abnormal cell that somehow is able to hide from the body’s defense system and begins to multiply out of control.
 
So, what causes most mutations?
 
We live in a polluted environment. For instance, the outgassing from asphalt on a hot summer day produces the deadly carcinogen benzo{a}pyrene, the same chemical found on meat that has been charcoal broiled.  This is just but one example.  Exposure to such chemicals in the environment can cause the mutations in our genetic material that lead to cancer. Even normal metabolic processes like breathing and exercise produce free radicals that can wreak havoc on our cellular DNA.  We can protect ourselves from mutations caused by environmental toxins and free radicals by taking antioxidants.  Guess what?  Ellagitannins are also very good antioxidants and chemoprotective agents.  Researchers at Wayne State University have a theory about how ellagitannins might work. The liver produces enzymes that rid the body of toxins. These enzymes break down or chemically change toxic substances we ingest or inhale so that they can be excreted.  During this detox process, the breakdown products, called metabolites, are frequently more damaging then the original substance. It appears that ellagitannins are able to safeguard the liver from damage caused by these breakdown products. Another theory held by some investigators is that ellagitannins are able to protect our genetic material from certain types of chemical reactions that lead to misreading of damaged DNA.
 
Why does chemotherapy and radiation eventually stop working?
 
It is becoming clear that normal therapeutic cancer treatment works by turning on apoptosis. We used to think that chemotherapy and radiation killed rapidly dividing cells, which is why these procedures were able to shrink tumors. However, at some point these treatments begin to lose their effectiveness. Why is that? Scott Lowe, a research scientist at Cold Spring Harbor Laboratory may have found the answer. Instead of killing these cells, chemotherapy and radiation damage their cellular DNA. This alerts the cellular watchdogs that control the cell cycle that something is wrong and tells the cell to stop dividing or to commit suicide. Therefore, chemotherapy and radiation act somewhat like a "vaccination" that works by helping the body help itself. The evidence for Dr. Lowe's theory is pretty convincing, because when these treatments start to fail, researchers have found that the genes that control apoptosis are no longer functioning.
 
Why don't ellagitannins induce normal cells to commit suicide?
 
As we know, cancer cells become immortal; this means that they are able to replicate themselves after something called the Hayflick limit has been reached. The Hayflick limit is the number of "allowed" cellular replications. Each cell type has its own limit. Human cancer studies show that mutations in the tumor suppressor gene called p53 account for many of the tumors found. One of the functions of this gene is that it normally prevents cells with damaged DNA from proceeding through the cell cycle. The presence of the protein product encoded by p53 turns on the waf-1 gene. The waf-1 gene produces a protein that normally inhibits the activity of several similar cellular proteins called kinases. These proteins are involved in stopping cell cycle progression. A mutation in either the p53 or waf-1 gene can cause the loss of that "emergency brake" function and allow uncontrolled growth. However, only "damaged" cells are induced to commit suicide and so normal cells are not affected.
 
Other Phytochemicals found in raspberries
 
Besides ellagitannins, the short list of other beneficial compounds found in red raspberries includes anthocyanins, salicylic acid, quercitin and catechins.  Some recent work has shown that these anthocyanins are more effective then Vitamin E and equivalent to ibuprofen and naproxen in inhibiting the COX-1 and COX-2 enzymes. Both Cox-1 and Cox-2 are associated with the pain of arthritis and other inflammatory diseases, and Cox-2 inhibition is positively linked to preventing breast cancer. Besides their anticancer properties, anthocyanins provide many other health benefits. Among these are controlling diabetes, improving circulation and aiding the retention of motor skills and preventing the loss of memory due to aging.  Salicylic acid may have the same effects as aspirin in protecting us from cancer and the progression of atherosclerosis. Both quercitin and catechins are flavonals that are known to have antioxidant benefits including cancer prevention, and quercitin may act as an antihistamine also. Besides the anticancer properties of ellagitannins they can protect us against infections.
 
 
An Antibacterial and an Antiviral agent
 
Ellagitannins can act as antibacterial agents and as antiviral agents too, and now we know how.  Think of the genetic material of bacteria as a rubber band that is all twisted up.  In order to replicate, the DNA must untwist itself through a process requiring the enzyme gyrase. Ellagitannins inhibits gyrase activity so replication of the bacterial DNA is restricted. More importantly, bacteria cannot easily become resistant to this type of antibacterial action.  Resistance to antibiotics has become a real concern to the international medical community. A federal government task force noted that antibiotic resistance was “a growing menace to all people” but children, the elderly and those with weakened immune systems are especially at risk.


Besides its antibacterial action, ellagitannins have antiviral activity also. Viruses do not have the ability to replicate themselves. Instead they must "hijack" the host cell and insert their own DNA into the host cell genome. This requires an enzyme called integrase and the ellagitannins inhibit this enzyme also.
 
Citizen: Heal Thyself.  (With apologies to Mr. Hippocrates)
 
People are turning to alternative forms of medical treatment and prevention. Not only is the medical delivery system failing but, our costs for health services are rising at an astronomical rate. What this means for the medical consumer is that we need to be more responsible for our own health. We need to look at prevention instead of always looking to health care providers to "fix" what exposure to a toxic environment and/or years of unhealthy lifestyle practices have wrought. The quality of medical care is uneven at best. Too often, our insurance providers do not cover necessary tests and procedures, especially those of a preventative nature. However, we can become involved in our own health care. A diet rich in fresh fruits and vegetables is a good start towards preventing disease. Unfortunately, current tests show that our soil is severely lacking in many minerals or electrolytes and other components that are essential for proper nutrition. It is necessary to sometimes take supplements as it may not be physically or economically possible to eat enough food to get the proper nutrition. In addition, the cost of fresh fruits and vegetables can be prohibitive. For instance, unless you grow your own raspberries, the cost of the American Cancer Institute’s recommended daily bowl of the whole berries could run as high as $300 a month. Not only that, but research has shown that the ellagitannin content is much higher in the seeds then in the fruit. In addition, the powdered seed may be much more bioavailable then the whole fruit, especially so for the short carnivorous gut of the cat or dog. It seems that our pets are particularly at risk for cancer because they interact so closely with the environment (unless of course you lick your paws after crossing the street). Cancer is epidemic in dogs and pandemic in cats.
 So nutraceutical supplements appear to be the answer. Raspberry seeds contain many more times the ellagic acid than the fruit at one-tenth the cost. It’s your choice, whatever form you may decide to use- the take home message is: “Eat your ellagitannins!”
 

 

Some Ellagic acid citations

Antibiotic action 

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. 

 

Adv Exp Med Biol. 1995;390:59-69. 

A comparison of active site binding of 4-quinolones and novel flavone gyrase inhibitors to DNA gyrase.

 

Hilliard JJ, Krause HM, Bernstein JI, Fernandez JA, Nguyen V, Ohemeng KA, Barrett JF.

R. W. Johnson Pharmaceutical Research Institute, Raritan, NJ, USA.

 

The activity of 4-quinolone antibacterials at the enzyme target level is based on the well known and reported observations that 4-quinolone antibacterials target the Gyr A subunit of the DNA gyrase holoenzyme, inhibiting supercoiling while facilitating the "cleavable complex". Such inhibition can be observed by running the in vitro DNA gyrase supercoiling inhibition assay or the "cleavable complex" DNA gyrase assay. Although potency of the gyrase inhibitor is dependent on many factors including permeability and pharmacokinetics, the inherent potency of a gyrase inhibitor lies in its activity against the target enzyme. We have examined the binding activity of novel flavones [Bioorganic & Med. Chem. Letters 3:225-230, 1993] to Escherichia coli DNA gyrase and have found differences in binding consistent with inhibition of DNA gyrase supercoiling and ability to facilitate the cleavable complex, but of different rank order. [3H]norfloxacin was used in vitro competition studies with test compounds, pBR322 and E. coli DNA gyrase. Binding affinity results indicate the rank order of greatest to weakest binding (ability to compete with [3H]norfloxacin) of test compounds: Levofloxacin = ciprofloxacin > ofloxacin > norfloxacin > flavone compounds (including ellagic acid, quercetin, and compounds 5a through 5n [Bioorganic & Med. Chem. Letters 3:225-230, 1993]). Such differences in binding ability of the 4-quinolones and flavones to the ternary complex of DNA.DNA gyrase.drug, as compared to the catalytic inhibition and "cleavable complex" data, suggests a more complex binding of flavones than the previously hypothesized models for 4-quinolone binding.

 

Antiviral action

 

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.

 

Chemoprotective ( Cancer, IBD, etc.)

 

Biochem Pharmacol. 2003 Sep 15;66(6):907-15.  

 

Intestinal epithelial cell accumulation of the cancer preventive polyphenol ellagic acid--extensive binding to protein and DNA.

 

Whitley AC, Stoner GD, Darby MV, Walle T.

 

Department of Cellular and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, 173 Ashley Avenue, PO Box 250505, Charleston, SC 29425, USA.

 

Ellagic acid (EA), a polyphenol present in many berries, has been demonstrated to be preventive of esophageal cancer in animals both at the initiation and promotion stages. To be able to extrapolate these findings to humans we have studied the transcellular absorption and epithelial cell accumulation of [14C]EA in the human intestinal Caco-2 cells. The apical (mucosal) to basolateral (serosal) transcellular transport of 10 microM [14C]EA was minimal with a P(app) of only 0.13 x 10(-6)cm/s, which is less than for the paracellular transport marker mannitol. In spite of observations of basolateral to apical efflux, Caco-2 cell uptake studies showed high accumulation of EA in the cells (1054+/-136 pmol/mg protein), indicating facile absorptive transport across the apical membrane. Surprisingly, as much as 93% of the cellular EA was irreversibly bound to macromolecules (982+/-151 pmol/mg protein). To confirm the irreversible nature of the binding to protein, Caco-2 cells treated with 10 microM [14C]EA were subjected to SDS-PAGE analysis. This resulted in radiolabeled protein bands trapped in the stacking gel, consistent with [14C]EA-crosslinked proteins. Treatment of Caco-2 cells with 10 microM [14C]EA also revealed irreversible binding of EA to cellular DNA as much as five times higher than for protein (5020+/-773 pmol/mg DNA). Whereas the irreversible binding to protein required oxidation of EA by reactive oxygen species, this did not seem to be the case with the DNA binding. The avid irreversible binding to cellular DNA and protein may be the reason for its highly limited transcellular absorption. Thus, EA appears to accumulate selectively in the epithelial cells of the aerodigestive tract, where its cancer preventive actions may be displayed.

 

J Nutr. 2003 Aug;133(8):2669-74.   

 

Low concentrations of quercetin and ellagic acid synergistically influence proliferation, cytotoxicity and apoptosis in MOLT-4 human leukemia cells.

Mertens-Talcott SU, Talcott ST, Percival SS.

 

Food Science and Human Nutrition Department, University of Florida, Gainesville, FL 32611, USA.

 

Little information is available regarding possible synergistic or antagonistic biochemical interactions among polyphenols contained in fruits and vegetables. Identifying potential interactions among these compounds may help to define the efficiency of polyphenol-containing foods in cancer prevention as related to structure-function activity of the compounds. The objective of this study was to investigate interactions between quercetin and ellagic acid, two polyphenolics that are present predominantly in small fruits, on cell death and proliferation-related variables in the MOLT-4 human leukemia cell line. Assays were performed to determine cell cycle kinetics, proliferation, apoptotic DNA-fragmentation and caspase-3-activity after 12, 24 and 48 h. Ellagic acid significantly potentiated the effects of quercetin (at 5 and 10 micro mol/L each) in the reduction of proliferation and viability and the induction of apoptosis. Significant alterations in cell cycle kinetics were also observed. The synergy was confirmed by an isobolographic analysis of the cell proliferation data. The interaction of ellagic acid and quercetin demonstrated an enhanced anticarcinogenic potential of polyphenol combinations, which was not based solely on the additive effect of individual compounds, but rather on synergistic biochemical interactions.

 

 Microbios 1998;93(375):115-27

 

Inhibitory actions of ellagic acid on growth and arylamine N-acetyltransferase activity in strains of Helicobacter pylori from peptic ulcer patients.

 

Chung JG.

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]

 

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. abei@ys7.u-shizuoka-ken.ac.jp

 

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 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. bhagavat@earthlink.net

 

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

 

Experimental evidence for cancer preventive elements in foods.

Wargovich MJ.

 

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.

 

FEBS Lett. 2003 Jun 5;544(1-3):252-7. 

 

Anti-angiogenic property of edible berry in a model of hemangioma.

Atalay M, Gordillo G, Roy S, Rovin B, Bagchi D, Bagchi M, Sen CK.

 

Laboratory of Molecular Medicine, Department of Surgery, 512 Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Medical Center, 473 W. 12th Avenue, Columbus 43210, USA.

 

Hemangiomas represent a powerful model to study in vivo angiogenesis. Monocyte chemotactic protein 1 (MCP-1) is known to be responsible for recruiting macrophages to sites of infection or inflammation and facilitate angiogenesis. Recently we have demonstrated that edible berry extracts potently suppress inducible vascular endothelial growth factor expression and in vitro angiogenesis. Comparative analysis of several berry extracts led to the observation that wild blueberry and a berry mix were most effective. Our goal was to follow up on our findings with wild blueberry and the berry mix (OptiBerry). The present work rests on our current finding that these two berry powders significantly inhibit inducible MCP-1 expression in endothelioma cells. Therefore, we sought to examine the effects of wild blueberry and berry mix in an in vivo model of experimental angiogenesis. Reporter studies showed that the berry powders significantly inhibited basal MCP-1 transcription and inducible nuclear factor kappaB transcription. Endothelioma cells pre-treated with berry powders showed diminished ability to form hemangioma. Histological analysis demonstrated markedly decreased infiltration of macrophages in hemangioma of treated mice compared to placebo-treated controls. The current results provide the first in vivo evidence substantiating the anti-angiogenic property of edible berries.

 

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.

 

 Carcinogenesis. 2003 Oct;24(10):1651-6. Epub 2003 Jul 17. 

 

Induction of rat hepatic and intestinal UDP-glucuronosyltransferases by naturally occurring dietary anticarcinogens.

van der Logt EM, Roelofs HM, Nagengast FM, Peters WH.

 

Department of Gastroenterology, University Medical Centre St Radboud, PO Box 9101, 6500 HB Nijmegen, The Netherlands.

 

Gastrointestinal tumours are among the most common malignancies in Western society, the majority of which are associated with dietary and lifestyle factors. Many dietary or lifestyle factors have been identified which may have toxic or carcinogenic properties. However, several dietary compounds also able to reduce gastrointestinal cancer rates in both humans and animals have been characterized. Though the exact mechanism leading to the anticarcinogenic action of these compounds is not fully known, it has been demonstrated that this chemopreventive capacity may be due to elevation of the glutathione S-transferase detoxification enzymes. Here we have investigated the effect of several anticarcinogens on the gastrointestinal UDP-glucuronosyltransferase (UGT) enzymes. Diets of male Wistar rats were supplemented with ellagic acid, ferulic acid, Brussels sprouts, quercetin, alpha-angelicalactone, tannic acid, coumarin, fumaric acid, curcumin and flavone, separately, and combinations of alpha-angelicalactone and flavone. Hepatic and intestinal (proximal, mid and distal small intestine and colon) UGT enzyme activities were quantified using 4-nitrophenol and 4-methylumbelliferone as substrates. All anticarcinogens tested increased UGT enzyme activity with both substrates, at one at least of the five different sites investigated. alpha-Angelicalactone, coumarin and curcumin showed enhanced UGT enzyme activities at all five sites. Both small and large intestinal UGT enzyme activities were increased by quercetin, alpha-angelicalactone, coumarin, curcumin and flavone. Except for tannic acid, all agents induced hepatic UGT enzyme activity. Furthermore, dietary administration of alpha-angelicalactone and flavone, given individually or in combination, enhanced the UGT detoxification system in the liver and, to a lesser extent, in intestine. In conclusion, induction of gastrointestinal UGT enzyme activities after consumption of dietary anticarcinogens may contribute to a better detoxification of potentially carcinogenic compounds and subsequently to the prevention of gastrointestinal cancer.

 

J Nutr. 2002 Dec;132(12):3819S-3823S.

 

Antioxidant regulation of protein kinase C in cancer prevention.

Gopalakrishna R, Gundimeda U.

 

Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles 90089, USA. rgopalak@usc.edu

 

Besides scavenging free radicals, antioxidants inhibit signaling enzymes such as protein kinase C (PKC) that play a crucial role in tumor promotion. By having different oxidation susceptible regions, PKC can respond to both oxidant tumor promoters and cancer-preventive antioxidants to elicit opposite cellular responses. Oxidant tumor promoters activate PKC by reacting with zinc-thiolates present within the regulatory domain. In contrast, the oxidized forms of some cancer-preventive agents, such as polyphenolics (ellagic acid, 4-hydroxytamoxifen and curcumin) and selenocompounds, can inactivate PKC by oxidizing the vicinal thiols present within the catalytic domain. This brings an efficient counteractive mechanism to block the signal transduction induced by tumor promoters at the first step itself. Because prostate cancer prevention clinical trials in large human population are under way, we have focused more on understanding the cancer-preventive mechanism of selenium. Methylselenol, the postulated cancer-preventive metabolite, has no direct effect on PKC activity. However, methylseleninic acid, locally generated by the reaction of membrane methylselenol with PKC-bound tumor-promoting fatty acid hydroperoxides, selectively inactivates PKC. This mechanism clarifies how the volatile methylselenol that is present in a low concentration induces the inactivation of PKC selectively in the promoting precancer cells. Selenoprotein thioredoxin reductase reverses selenium-induced inactivation of PKC, suggesting that selenoproteins may serve as a safeguard against the toxicity induced by selenometabolites. Moreover, this also explains how a resistance to selenium develops in advanced malignant cells. The redox-mediated inactivation of PKC may, at least in part, be responsible for the antioxidant-induced inhibition of tumor promotion and cell growth, as well as for the induction of cell death.

 

Life Sci. 2002 Mar 1;70(15):1821-39. 

 

Interactive gene expression pattern in prostate cancer cells exposed to phenolic antioxidants.

Narayanan BA, Narayanan NK, Stoner GD, Bullock BP.

 

Microarray Systems Laboratory, American Health Foundation, Valhalla, NY 10595, USA. bhagavat@mindspring.com

 

Dietary phenolic compounds are known to elicite vital cellular responses such as cell cycle arrest, apoptosis and differentiation by activating a cascade of molecular events. As there is an increasing interest to improve the efficacy of these compounds for use as potential chemopreventive agents, we wanted to understand the impact of phenolic compounds on target genes in prostate cancer. In this study we used human cDNA microarrays with 2400 clones consisting of 17 prosite motifs to characterize alterations in gene expression pattern in response to the phenolic antioxidants ellagic acid (EA) and resveratrol (RE). Over a 48-hr exposure of androgen - sensitive LNCaP cells to EA and RE, a total of 593 and 555 genes respectively, showed more than a two fold difference in expression. A distinct set of genes in both EA-and RE-treated cells may represent the signature profile of phenolic antioxidant-induced gene expression in LNCaP cells. Although extensive similarity was found between effects of EA - and RE - responsive genes in prostate cancer cells, out of 246 genes with overlapping responses, 25 genes showed an opposite effect. Quantitative RT-PCR was used to verify and validate the differential expression of selected genes identified from cDNA microarrays. In-depth analysis of the data from this study provided insight into the alterations in the p53 - responsive genes, p300, Apaf-1, NF-kBp50 and p65 and PPAR families of genes, suggesting the activation of multiple signaling pathways that leads to growth inhibition of LNCaP cells. This is a first study to look for changes in a large number of human genes in response to dietary compounds.

 

 Urol Res. 2001 Dec;29(6):371-6.

 

 Ellagic [correction of ellagica] acid inhibits arylamine N-acetyltransferase activity and DNA adduct formation in human bladder tumor cell lines (T24 and TSGH 8301).

Lin SS, Hung CF, Tyan YS, Yang CC, Hsia TC, Yang MD, Chung JG.

 

Department of Radiological Technology, Chungtai Institute of Health Sciences and Technology, Taichung, Taiwan, Republic of China.

 

The fact that vitamin C (ascorbic acid) exhibits a protective effect in certain types of cancer is well documented. Our previous studies demonstrated that human bladder tumor cell line (T24) has N-acetyltransferase (NAT) activity in cytosols and intact cells. The present studies examined the inhibition of arylamine NAT activity and carcinogen (2-aminofluorene)-DNA adduct formation by ellagic acid (EA) in human bladder tumor cell lines (T24 and TSGH 8301). Two assay systems were performed, one with cellular cytosols (9,000 g supernatant), the other with intact bladder tumor cell suspensions. NAT activity and 2-aminofluorene-DNA adduct formation in T24 and TSGH 8301 cells was inhibited by EA in a dose-dependent manner in both systems, i.e.. the greater the concentration of EA in the reaction the greater the inhibition of NAT activity (dose- and time-course dependent effects). The data also indicated that EA decreased the apparent Km and Vmax of NAT enzymes from T24 and TSGH 8301 cells in cytosols. NAT activity and 2-aminofluorene-DNA adducts in T24 is higher than in TSGH 8301. This report is the first to demonstrate that EA affects human bladder tumor cell NAT activity.

 

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. bhagavat@earthlink.net

 

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. 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. 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.

 

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. bhagavat@earthlink.net

 

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

 

Experimental evidence for cancer preventive elements in foods.

Wargovich MJ.

 

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.

 

 

 

Antioxidant function

 

Anticancer Res. 2001 Nov-Dec;21(6A):3903-8. Strong antioxidant activity of ellagic acid in mammalian cells in vitro revealed by the comet assay.

 

Festa F, Aglitti T, Duranti G, Ricordy R, Perticone P, Cozzi R.

 

Dipartimento di Biologia, Universita degli Studi Roma TRE, Italy.

 

Oxidative stress due to oxygen and various radical species is associated with the induction of DNA single- and double-strand breaks and is considered to be a first step in several human degenerative diseases, cancer and ageing. Naturally occurring antioxidants are being extensively analysed for their ability to protect DNA against such injury. We studied three naturally occuring compounds, Ascorbic Acid, Melatonin and Ellagic acid, for their ability to modulate DNA damage produced by two strong radical oxygen inducers (H2O2 and Bleomycin) in cultured CHO cells. The alkaline Comet assay was used to measure DNA damage and a cytofluorimetric analysis was performed to reveal the intracellular oxidative species. The data showed a marked reduction of H2O2- and Bleomycin-induced DNA damage exerted by Ellagic Acid. On the contrary Ascorbic acid and Melatonin appeared to induce a slight increase in DNA damage per se. In combined treatments, they caused a slight reduction of H2O2-induced damage, but they did not efficiently modulate the Bleomycin-induced one. The Dichlorofluorescein diacetate (DCFH-DA) cytofluorimetric test confirmed the strong scavenging action exerted by Ellagic Acid.

 

J Environ Pathol Toxicol Oncol. 2004;23(3):215-26.

Prevention and repair of DNA damage by selected phytochemicals as measured by single cell gel electrophoresis.

 

Chakraborty S, Roy M, Bhattacharya RK.

 

Department of Environmental Carcinogenesis and Toxicology, Chittaranjan National Cancer Institute, Kolkata, India.

 

We assessed the ability of some natural products--namely, curcumin, resveratrol, indole-3-carbinol, and ellagic acid--to modify the DNA damaging ability of the alkylating carcinogen N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in cultured Chinese hamster lung fibroblast cells (CH V-79). MNNG produced DNA single strand breaks in a dose- and time-dependent manner, as observed by increase in the tail moments of the comet, when the cells were subjected to alkaline single cell gel electrophoresis. When the cells were treated in the presence of each of the natural compounds, the DNA damage caused by MNNG was considerably reduced. This effect was found to be dose related. Preincubation of cells with each of these compounds individually afforded significant protection to DNA against damage caused by subsequent treatment with MNNG, indicating a true chemopreventive role of these substances. The most remarkable aspect of the present study was that all four compounds helped in the recovery of DNA damage by accelerating DNA repair efficiency in the damaged cells. This was further substantiated by the observation on unscheduled DNA synthesis. Our results suggest that these agents are chemopreventive by virtue of their ability to protect DNA as well as to induce DNA repair.

 

 

Biochem Pharmacol. 2003 Sep 15;66(6):907-15.  

Intestinal epithelial cell accumulation of the cancer preventive polyphenol ellagic acid--extensive binding to protein and DNA.

 

Whitley AC, Stoner GD, Darby MV, Walle T.

 

Department of Cellular and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, 173 Ashley Avenue, PO Box 250505, Charleston, SC 29425, USA.

 

Ellagic acid (EA), a polyphenol present in many berries, has been demonstrated to be preventive of esophageal cancer in animals both at the initiation and promotion stages. To be able to extrapolate these findings to humans we have studied the transcellular absorption and epithelial cell accumulation of [14C]EA in the human intestinal Caco-2 cells. The apical (mucosal) to basolateral (serosal) transcellular transport of 10 microM [14C]EA was minimal with a P(app) of only 0.13 x 10(-6)cm/s, which is less than for the paracellular transport marker mannitol. In spite of observations of basolateral to apical efflux, Caco-2 cell uptake studies showed high accumulation of EA in the cells (1054+/-136 pmol/mg protein), indicating facile absorptive transport across the apical membrane. Surprisingly, as much as 93% of the cellular EA was irreversibly bound to macromolecules (982+/-151 pmol/mg protein). To confirm the irreversible nature of the binding to protein, Caco-2 cells treated with 10 microM [14C]EA were subjected to SDS-PAGE analysis. This resulted in radiolabeled protein bands trapped in the stacking gel, consistent with [14C]EA-crosslinked proteins. Treatment of Caco-2 cells with 10 microM [14C]EA also revealed irreversible binding of EA to cellular DNA as much as five times higher than for protein (5020+/-773 pmol/mg DNA). Whereas the irreversible binding to protein required oxidation of EA by reactive oxygen species, this did not seem to be the case with the DNA binding. The avid irreversible binding to cellular DNA and protein may be the reason for its highly limited transcellular absorption. Thus, EA appears to accumulate selectively in the epithelial cells of the aerodigestive tract, where its cancer preventive actions may be displayed.

 

Cell Prolif. 2003 Dec;36(6):307-19.

 

Stages of activation of hepatic stellate cells: effects of ellagic acid, an inhibiter of liver fibrosis, on their differentiation in culture.

 

Buniatian GH.

 

Max-Planck-Institut fur Zellbiologie, Ladenburg, Germany. buniatian@web.de

 

To further explore that hepatic stellate cell (HSC) activation results in physiological protection against environmental insult, the profile of differentiation of HSC has been examined upon treatment with ellagic acid (EA), a plant-derived antioxidant that shows multiple protective effects during liver disease. Sparse rat liver cell cultures were grown in media containing EA (3, 6, 30 and 100 microg/ml) and, as controls, without EA, and inspected until day 7 in culture. The cells were double-labelled with antibodies against glial fibrillary acidic protein (GFAP) and smooth muscle alpha-actin (SMAA), marker proteins of quiescent and activated HSC, respectively. In EA-free culture conditions, the quiescent (SMAA-/GFAP+) HSC transiently acquired a semi-activated (SMAA+/GFAP+), phenotype and were further transformed into activated (SMAA+/GFAP-), pleomorphic HSC. Up to a concentration of 30 microg/ml, EA induced an early synthesis of SMAA in all HSC and inhibited their morphologic differentiation and individual growth throughout the culture period. At a concentration of 6 microg/ml, EA supported the semi-activated (SMAA+/GFAP+) phenotype of HSC throughout the culture period, whereas treatment with high EA concentrations (30 microg/ml) resulted in an early loss of GFAP expression. In conclusion: (i) the uniform response of HSC to EA by mild activation adds functional significance to cellular features preceding the transformation of HSC to myofibroblasts; (ii) the high sensitivity of HSC to EA treatment suggests their involvement in any mechanisms of protection by this antioxidant; (iii) the maintenance of HSC morphology might be one of the factors playing a role in the prevention or slowing down of liver fibrosis; (iv) because the effects of EA are concentration- and time-dependent, an arbitrary usage of this antioxidant is a matter of potential concern; (v) the various patterns of HSC activation observed might correspond to distinct activities of these cells, which, in turn, might lead to different outcomes of liver fibrosis.

 

ã Copyright 1995 Helen L. McKinnon All Rights Reserved

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