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Journal of Ethnopharmacology 107 (2006) 291–296

Inhibitory effects of Euterpe oleracea Mart. on nitric oxideproduction and iNOS expression

Maria Eline Matheus a, Sidnei Bessa de Oliveira Fernandes b, Cristiane Silva Silveira b,Veronica Pinto Rodrigues b, Fabio de Sousa Menezes b, Patricia Dias Fernandes a,∗

a Departamento de Farmacologia Basica e Clınica, ICB, Caixa Postal: 68016, Universidade Federal do Rio de Janeiro, 21944-970 Rio de Janeiro, Brazilb Departamento de Produtos Naturais e Alimentos, Faculdade de Farmacia, Universidade Federal do Rio de Janeiro, Brazil

Received 9 August 2005; received in revised form 24 February 2006; accepted 15 March 2006Available online 22 March 2006

bstract

The palm Euterpe oleracea is a plant of great economic value in Brazil. Although the heart of palm extracted from its trunk is considered aelicacy the world over, its fruits are popular only among Brazilians. In some poor regions of Brazil, there are reports on the popular use of itsuice in the treatment of several disorders, mainly those of oxidative onset as cardiovascular ones. Because of its wide utilization; because therere very few scientific studies of this species, and to discover if its use in folk medicine for problems related with oxidation is in fact justifiable,e decided, in this study, to evaluate the effects of Euterpe oleracea flowers, fruits and spikes fractions on: nitric oxide (NO) production, NO

cavenger capacity, and on the expression of inducible nitric oxide synthase enzyme, as well. Results showed that the fractions obtained from fruitsere the most potent in inhibiting NO production, followed by those from flowers and spikes. Only in high doses, did some fractions reduce celliability. Reduction on NO production was not due to NO scavenger activity. These results were accompanied by inhibition of iNOS expression.

he more pronounced effect was observed in the fractions in which the concentration of cyanidin-3-O-glucoside and cyanidin-3-O-rhamnosideere higher. To sum up, our results indicate that fractions from Euterpe oleracea inhibits NO production by reducing the levels of inducible nitricxide synthase expression.

2006 Elsevier Ireland Ltd. All rights reserved.

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eywords: Nitric oxide; inducible nitric oxide synthase; Euterpe oleracea

. Introduction

Nitric oxide is a water-soluble gas involved in physiolog-cal and pathological conditions such as vasodilation, hostefense, tumor cell death and apoptosis (Walter, 1989; Rapoportnd Murad, 1993; Zhao et al., 2000; Monteiro et al., 2004).he action of the enzyme nitric oxide synthase (NOS) in themino acid l-arginine leads to the production of nitric oxide

NO). Physiological conditions involve endothelial or neuronalOS (eNOS or nNOS, respectively) (Bredt and Snyder, 1992;chmidt and Walter, 1994). In pathological conditions, over-

Abbreviations: FlT, ethanolic extracts of flowers; FrT, fruits; SpT, spikes;lE, ethyl acetate fraction of flowers; FrE, fruits; SpE, spikes; FlB, butanolicraction of flowers; FrB, fruits; SpB, spikes∗ Corresponding author. Tel.: +55 21 2562 64 42/55 11 81111623;

ax: +55 21 2562 64 42/55 11 30917744.E-mail address: patfern@farmaco.ufrj.br (P.D. Fernandes).

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378-8741/$ – see front matter © 2006 Elsevier Ireland Ltd. All rights reserved.oi:10.1016/j.jep.2006.03.010

roduction of NO occurs after the induction and expression ofhe inducible nitric oxide synthase (iNOS) in response to agentsuch as interleukin 1�, tumor necrosis factor-�, interferon-�IFN-�) lipopolisaccharide (LPS) in different cells, includingacrophages, endothelial cells and hepatocytes (Moncada andiggs, 1993). The use of agents that inhibit activity and/or induc-

ion of iNOS may be a useful tool with therapeutic focus in manynflammatory processes.

Euterpe oleracea Mart. (Arecaceae), popularly known inrazil as “acaı”, is an economically important plant found

hroughout the country. Although the heart of palm extractedrom its trunk is considered a delicacy the world over, its fruits consumed only in Brazil. There are several non-publishedeports (popular relates) indicating the positive effect of the

edicinal use of acaı juice, especially among people in the poor-

st regions of Brazil (mainly the North and the Northeast), as aeterrent in cases of fever, pain and the flu (Menezes, personalommunication). Because its pharmacological properties and

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ioactive constituents have not yet been fully characterized, andlso because of the significance of its juice in folk medicine,study of its pharmacological effects is overdue. Moreover,great variety of acaı products are now being produced and

ommercialized as possessing anti-ageing properties and antiox-dant activity (Menezes et al., 2005). They are also being usedopically for the management of inflammatory skin conditionsssociated with acne, for example. However, there is no scien-ific study that proves its antioxidant, anti-ageing qualities, orven its anti-inflammatory activity. Therefore, as the plant isidely used in folk medicine by the North and Northeast people

n Brazil and is also, in parts and or extracts (fractions), the basisf several products commercially available in pharmacies andrugstores (even with no governmental official permission), weecided to start this study.

In this paper, we show that some fractions obtained fromifferent parts of Euterpe oleracea inhibited NO production byAW 264.7 cells stimulated with LPS and IFN-�, and also that

ome fractions developed inhibitory activity on NO productiony inhibiting iNOS enzyme expression.

. Materials and methods

.1. Reagents

Lipopolysaccharide (from Salmonella thyphimurium), NG-onomethyl-l-arginine (l-NMMA), 3-(4,5-dimethylthiazol-2-

l)-2,5-diphenyl tetrazolium bromide (MTT), RPMI 1640edium, fetal calf serum, 96-well microplates were purchased

rom Sigma. Rutin was purchased from Merk. Nitrocelluloseembranes (250 nm) were from Bio Rad, anti-mouse iNOS anti-

ody was purchased from Sigma, anti-mouse IgG antibody con-ugated to horseradish peroxidase and enhanced chemilumines-ence (ECL) kit were purchased from Amersham. Cyanidin-3--glucoside and cyanidin-3-O-rhamnoside were acquired fromxtrasynthese (Lyon, France).

.2. Preparations of Euterpe oleracea fractions

The plant material, separated in flowers, fruits and spikes,as collected in the district of Imperatriz, Maranhao, Brazil,

n February 2000. A herbarium sample (Voucher number 179)as been deposited at the Atipo Ceabra Herbarium, Universi-ade Federal do Maranhao, Brazil. Crude ethanolic extracts wereeparately obtained from the different parts by static macerationith ethanol 70◦ (150 g/5 l; 600 g/20 l; 300 g/10 l, respectively)

or 72 h each 2.5 l of ethanol. The ethanolic extracts obtainedrom fruits, flowers and spikes were, then, dried under reducedressure and, after total dryness and suspension in water, theyere submitted to a liquid–liquid extraction procedure with ethyl

cetate, followed by n-butanol so as to obtain fractions withifferent polarities (ethyl acetate first and butanol after). Eachraction received the following code: Total ethanolic extracts

rom Flowers (FlT), Fruits (FrT), Spikes (SpT); Ethyl acetateraction from Flowers (FlE), Fruits (FrE), Spikes (SpE), andutanolic fraction from Flowers (FlB), Fruits (FrB) and Spikes

SpB).nn

armacology 107 (2006) 291–296

.3. Chemical analysis of Euterpe oleracea fractions

A Lachrom HPLC system (Merck, Rio de Janeiro, RJ, Brazil)quipped with a model D7000 interface, an L-7100 pump, an-7450A diode array detector (DAD) and an L-7612 solventegasser was used for the analysis of the polar fractions. For thethyl acetate and butanol fractions and also for the crude ethano-ic extract, the analysis was made using a HPLC/DAD systemith a Lachrom RP-18 Column (250 mm × 4.5 mm, 4.5 �m par-

icle) eluted with a binary high pressure gradient at a flowate of 1 ml min−1; solvent A, H2O:HCOOH, 9/1; solvent B

2O:HCOOH:CH3CN, 4/1/5. After an initial hold of 1 min, theercentage of solvent B was increased linearly from 12 to 30%or 25 min; then, to 100% for an additional 9 min. The columnas then reconditioned with the initial mobile phase for about0 min. The absorbance detection was on 518 nm (Mandello etl., 2000). In order to calculate the standard error of the mean inhe chromatographic analysis of anthocyanins aiming to achievehe concentration of each one there were made three injectionsor each plant part extract.

.4. Cell culture

RAW 264.7 mouse monocyte-macrophages (ATCC TIB-71)ere grown in plastic bottles in a RPMI 1640 medium sup-lemented with 10% fetal bovine serum, penicillin (100 U/ml),treptomycin (100 �g/ml), glutamine (2 mM) and HEPES15 mM) (from now named RPMI) in a humidified atmosphereontaining 5% CO2 and 95% air at 37 ◦C. When cultures formedconfluent, monolayer cells were scrapped, centrifuged and put

o adhere in 96 or 12 wells plate with RPMI at a density of× 106 cell/ml in final volumes of 250 �l or 2 ml, respectively

Raschke et al., 1978).

.5. Cell viability assay

The mitochondrial-dependent reduction of 3-(4,5-imethylthizaol-2yl)-2,5-diphenyltetrazolium bromide (MTT)o formazan was used to measure cell respiration as an indicatorf cell viability (Denizot and Lang, 1986). Briefly, after 24 hncubation of RAW 264.7 adherent cells with or withoutractions (1–300 �g/ml), supernatants were changed by 100 �lf RPMI containing 500 �g/ml MTT and cells incubated forh at 37 ◦C in a 5% CO2 atmosphere. After the medium werespirated, 100 �l of DMSO was added to the cells to dissolvehe formazan. The absorbance from each group was measuredn a Dynatech microplate reader at 570 nm. The control groupsonsisted of cells with medium and was considered as 100% ofiable cells. Results are expressed as percentage of viable cellshen compared with control groups.

.6. Nitric oxide-trapping capacity of Euterpe oleracearactions

To test the capacity of Euterpe oleracea fractions in trappingitric oxide, we used a cell-free system. SNAP (s-nitroso-acetyl dl-penicillamine) was used, as, when in solution,

hnopharmacology 107 (2006) 291–296 293

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Table 1Amount of the anthocyanins contents in the Euterpe oleracea fractions

Samples Cyanidin-3-O-glucosideamount (%)

Cyanidin-3-O-rhamnosideamount (%)

ST 12.0 ± 0.4 5.0 ± 0.2FlT 31.0 ± 0.2 11.0 ± 0.3FrT 42.0 ± 0.4 15.0 ± 0.6SB 7.0 ± 0.4 3.0 ± 0.1FlB 14.0 ± 0.7 8.0 ± 0.1FrB 30.0 ± 0.6 10.0 ± 0.4SE 9.0 ± 0.4 3.0 ± 0.1FlE 18.0 ± 0.1 6.0 ± 0.7FrE 25.0 ± 0.5 9.0 ± 0.1

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t liberates to the medium nitric oxide that transforms toitrite (Field et al., 1978). The addition of a NO scavengero the SNAP solution results in a decay in the supernatantitrite accumulation. Using this protocol, each fraction (inoses of 100 �g/ml) was incubated with 1 mM of SNAP.ositive groups were composed by rutin (at 1 mM). Cyanidin--O-glucoside and cyanidin-3-O-rhamnoside were used at00 �M. After 6 h of incubation, an aliquot of supernatant wasemoved to quantify the nitrite accumulated by Griess reactionGreen et al., 1982). Results are expressed as �M of nitritealculated in comparison with the sodium nitrite standardurve.

.7. Quantification of nitric oxide production

To evaluate NO production, nitrite concentration in the super-atants of RAW 264.7 adherent cells was measured using theriess reaction (Green et al., 1982). Briefly, cells were acti-ated with LPS (100 ng/ml) plus IFN-� (10 U/ml). After 24 h ofncubation with fractions (1–300 �g/ml), 100 �l of the super-atant was collected and mixed with equal volume of Griesseagent (1% sulphanilamide, 0.1% naphthylethylene diamineihydrochloride, 10% H3PO4) for 10 min at room temperature.he absorbance was measured at 540 nm using a Dynatechicroplate reader, and the nitrite concentration was calculated

sing a standard curve of sodium nitrite.

.8. Detection of inducible nitric oxide synthase (iNOS)nzyme expression

After the activation of RAW 264.7 adherent cells withPS/IFN-� and addition of fractions of Euterpe oleracea, cul-

ures were incubated for 6 h. At the end of the incubationeriod, the cells were washed in cold PBS and lysated in a coldysis buffer (10% NP40, 150 mM NaCl, 10 mM Tris HCl pH.6, 2 mM PMSF, 5 �M Leupeptin). Cell debris were removedy centrifugation (12,000 × g, 4 ◦C, 10 min). After the proteinoncentration for each aliquot were determined by the BCAethod (BCATM Protein Assay Kit, Pierce), suspensions were

oiled in an application buffer (100 mM DTT, 0.1% Bromophe-ol Blue). For SDS-PAGE, aliquots of 25 �g of protein fromach sample were subjected to electrophoresis in 10% poly-crylamide gel. After electrophoresis, the proteins were elec-rophoretically transferred into nitrocellulose membrane. Mem-ranes were blocked with 5% nonfat dried milk in Tris bufferedaline-Tween (TBS-T, 10 mM Tris–HCl, 150 mM NaCl, 0.1%ween 20) at room temperature for 2 h. After washing in TBS-Trimary antibody solution, mouse monoclonal IgG was appliedvernight at 4 ◦C against iNOS at dilution of 1:2000. Mem-ranes were washed in TBS-T and secondary antibody solution;nti-mouse IgG antibody conjugated to horseradish peroxidaset a dilution of 1:10,000 was, then, applied for 1 h at roomemperature. The blots were washed twice in TBS-T, incubated

n enhanced chemiluminescence reagent (ECL) and exposed tohotographic film (Kodak, Brazil). Images were collected andands intensity were calculated using DigDoc100 (Alpha EaseC software) program.

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esults are expressed as mean ± S.E.M. (n − 3) of percentage of cyanidin-3-O-lucoside or cyanidin-3-O-rhamnoside.

.9. Statistical analysis

The results are presented as the mean ± S.E.M. (n = 6). Sta-istical significance between groups was performed by the appli-ation of analyses of variance ANOVA followed by Bonferroni’sest. p Values less than 0.05 (p < 0.05) were used as the signifi-ant level.

. Results

.1. Chemical analysis of Euterpe oleracea

Cyanidin-3-O-glucoside (C3G, retention time = 11.6 min)nd cyanidin-3-O-rhamnoside (C3R, retention time = 12.3 min)ere identified in all tested samples. The most prominent con-

entrations of both compounds were observed on the totalthanolic extracts from fruits (FrT) with 42 and 15%, respec-ively. When a composition of each fraction was made, it wasbserved that the fruit fractions were again those with greateroncentration of C3G and C3R. The concentration of each com-ound in each fraction is shown in Table 1.

.2. Effects of fractions from Euterpe oleracea on NOroduction and cell viability

The stable metabolite of NO nitrite, was accumulated andeasured in the supernatant medium after 24 h of incuba-

ion with LPS/IFN-�. Nitrite concentration in the controlroup (without stimulation) was 1.9 ± 0.6 �M, and when cellsere activated with LPS/IFN-�, nitrite concentration was9.5 ± 1.4 �M (mean ± S.E.M., six experiments in triplicate).he inhibitor of iNOS, l-NMMA (300 �M) potently blockedO production and reduced values to 3.1 ± 0.9 �M. Each frac-

ion was tested in cell viability (by MTT method) and NO pro-uction assays. Cell viability with all fractions varied between5 and 100% to doses of 300 �g/ml. Even when doses were asigher as 500/�g ml reduction on cell viability did not overcome

2%. When fractions were evaluated on NO production, com-arison between them showed that flowers and fruits were theost effective in inhibiting NO been FrT the most potent with

n IC50 of 0.9 �g/ml. The comparison between ethyl acetate

294 M.E. Matheus et al. / Journal of Ethnoph

Table 2Inhibitory effects from Euterpe oleracea or pure anthocyanins on nitric oxideproduction and cytotoxicity on LPS/IFN-stimulated RAW 264.7 cells, and NOscavenger activity from SNAP

Compound IC50

NO production Cytotoxicity NO scavenger

FlT 1.2 �g/ml >500 �g/ml >500 �g/ml

FlE 8.3 �g/ml >500 �g/ml >500 �g/ml

FlB 8.5 �g/ml >500 �g/ml >500 �g/ml

FrT 0.9 �g/ml >500 �g/ml >500 �g/ml

FrE 11.2 �g/ml >500 �g/ml 73 �g/ml

FrB 1.3 �g/ml >500 �g/ml 47.3 �g/ml

ST 270 �g/ml >500 �g/ml >500 �g/ml

SE 30.2 �g/ml >400 �g/ml >500 �g/ml

SB 34.5 �g/ml >400 �g/ml >500 �g/ml

C3G 39.7 �M >400 �M 150 �M

C3R 59.3 �M >400 �M 169 �M

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nd the butanolic fractions from the different parts of the planthowed that those from fruits were the most potent in reducingO production, followed by the flower fractions. Spikes frac-

ions presented the weakest inhibitory effect. In order to testhe effects of C3G and C3R, we incubated 100 �M from eachne with RAW 264.7 cells activated with LPS/IFN-�. At dosef 400 �M neither C3G nor C3R reduced cell viability morehan 42%. Calculation of IC50 in NO production to both antho-yanins indicated values of 39.7 and 59.3 �M to C3G and C3R,espectively (Table 2).

.3. Effects of fractions from Euterpe oleracea on NOcavenger

Previous observations in our laboratorial studies have indi-ated some antioxidant activity for many Euterpe oleracea frac-ions from different parts of the palm, including the ability tocavenge the superoxide free radical (Arruda et al., 2004). Inrder to investigate if inhibitory effects of fractions on NO pro-uction was due to NO sequestration, a “cell-free” system wassed with s-nitroso n-acetyl dl-penicillamine (SNAP) as a NOonor in the presence or absence of fractions. As a control for theree radical scavenger substance, rutin was used. The addition ofmM rutin to the SNAP solution reduced, after 6 h of incubation,

he nitrite accumulated in the supernatant in 26.9%. Incuba-

ion of crescent doses of Euterpe oleracea fractions with 1 mMNAP lead to a reduction on the nitrite accumulated, but only in

he ethyl acetate fruit fractions (FrE) with IC50 of 73 �g/ml. Allther fractions tested did not reduce the levels of NO produced by

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armacology 107 (2006) 291–296

NAP when compared to NO donor alone. When C3G and C3Rere tested it was observed that both significantly reduce theitrite accumulated in the supernatant and IC50 values obtainedas 150 and 169 �M, respectively (Table 2).

.4. Effects of Euterpe oleracea fractions on induction ofNOS protein

iNOS was detected, at 130 kDa, after 6 h of incubation ofAW 264.7 activated cells with LPS/IFN-� in the presence orbsence of the fractions (100 �g/ml) by 10% SDS-PAGE west-rn blotting analysis. The most potent fractions in inhibiting thenduction of iNOS were those from flowers reducing enzymexpression in 50%. When fruits fractions were studied on iNOSxpression it could be observed that only total ethanolic extractFrT) was able to significantly reduce the enzyme expressionhile none of spikes fractions were able to significantly reduce

NOS enzyme expression (Fig. 1A). Incubation of C3G or C3Rith activated cells resulted in 50 and 30% reduction on iNOSrotein (Fig. 1B).

. Discussion

Popular medicine is common practice in countries in whichhe occurrence of a diversified vegetation promotes the medici-al use of plants. In Brazil, the fruits of “acaı” (Euterpe oleracea)re very popular (juice and fruit) among the native populationf the North and Northeast Brazil. There are also several non-ublished reports on the popular use of its juice in the treatmentf several disorders among poor communities. However, thesendications are subjective and lack pharmacological confirma-ion. Recently, a group described the indication of “acaı” juices clinical oral contrast agent for magnetic resonance imagingignals of the gastrointestinal tract (Cordova-Fraga et al., 2004).ur group had demonstrated other effects of Euterpe oleracea

uch as antinociceptive and anti-inflammatory (Marinho et al.,003; Matheus et al., 2003). As part of our continuous interestn Brazilian native plants and our intention of confirming theharmacological use of “acaı” in the treatment of inflammatoryrocesses in folk medicine, we studied its effects on NO pro-uction and cell viability. Our results demonstrate that extractsrom parts of Euterpe oleracea inhibited LPS/IFN-� induced NOroduction by RAW 264.7 macrophage cell line. Some fractionslso inhibited the expression of inducible nitric oxide synthaseiNOS) without affecting cell viability.

Chemical study using the polar fractions (butanolic and ethylcetate) of Euterpe oleracea has lead to the identification ofnthocyanins. This class of compound has a very importantntioxidant activity (Awika et al., 2004; Del Pozo-Insfran etl., 2004; Garcia-Alonso et al., 2004; Williams and Grayer,004). Antioxidant substances with important activity have alsoeen described in other plants (Dreikorn, 2002; Mahady, 2002;anerjee et al., 2003). In our study, no fraction developed NO

cavenger activity, the exception being the ethyl acetate and-butanolic fractions from fruits (FrE and FrB) which showedome activity. Even when C3G and C3R were added to the SNAPolution, no drastic reductions were observed in the nitrite levels

M.E. Matheus et al. / Journal of Ethnopharmacology 107 (2006) 291–296 295

Fig. 1. Effect of Euterpe oleracea fractions on iNOS expression. RAW 264.7 cells activated or not with LPS/IFN were incubated with Euterpe oleracea fractions( . Resa N-�;c mpare

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100 �g/ml). iNOS protein was quantified as described in the method sectionre: M, macrophage without activation; LI, macrophages activated with LPS/IFyanidin-3-O-ganglioside; C3R, cyanidin-3-O-rhamnoside. *p < 0.005 when co

een IC50 of 150 and 169 �M. The antioxidant effect observedo anthocyanins is related to superoxide scavenger capacity andlso to the scavenger ability observed in the evaluation by DPPH2,2-diphenyl-1-picrylhidrazyl) method (Menezes et al., 2005),nd seems to have no correlation with effects on NO. Menezes etl. (2005) described how the less polar fractions from fruits haveompounds from steroidal skeleton together with great amountf fatty acids, and the more polar ones contain, in addition tother flavonoids, glucosyl flavonoids, mainly cyanidin deriva-ives. This observation could explain the scavenger activity ofhe FrE and FrB fractions, since some radical formed from glu-osyl flavonoid could be trapping the NO produced.

iNOS is the enzyme responsible by NO production inacrophages cell lines and several other cells after activationith LPS and/or cytokines (Moncada and Higgs, 1993). Recent

tudies have demonstrated that various extracts or fractions fromlants inhibited selectively the induction and/or activity of iNOSMatsuda et al., 2002, 2003). One of the problems in using plantxtracts and fractions is the possible cytotoxicity resulting fromhe residues of the solvents used in the preparation or from other

oxic substances present in the fractions. For this reason, weecided to test all fractions in cell viability assay. Significanteduction on cell viability (lesser than 80% of viable cells) wasbserved only with high dose (500 �g/ml) in almost all fractions.

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ults are expressed as X ± S.E.M. (n = 6) of iNOS arbitrary units. Codes usedT, total ethanolic extract; E, ethyl acetate fraction; B, butanolic fraction; C3G,d with LI group (ANOVA followed by Mann–Whitney test).

his reduction might explain the effect on NO inhibition whenhis dose was used. However, the reduction on NO productionnduced by others doses cannot be explained by reduction on celliability since this parameter is higher than 90% in all groups.n such cases the explanation may be found in the direct effectf fraction on NO cell production.

Aiming to elucidate the mechanism by which the fractionseduced NO production we investigated iNOS enzyme expres-ion. The flower fractions were those which presented significantnhibitory effect on iNOS expression. With the single exceptionf total fruit extract (FrT), none of the others reduced the lev-ls of the enzyme. Comparing results from fruits, flowers andpikes fractions on NO production by LPS/IFN-� activated cells,e may conclude that the fruit fractions demonstrate the mostronounced effect.

These reductions on iNOS levels correlate directly with thenhibition on NO produced by LPS/IFN-� activated cells thus,xplaining the mechanism by which flower fractions reducedO production on cells. However, the absence of inhibition on

NOS expression in fruits and spikes fractions indicate these

ffects may be due to alterations on enzyme activity and not onheir synthesis. Similar results were also observed with C3Gnd C3R. Both reduced the levels of nitrite accumulated onulture supernatant and iNOS expression enzyme, suggesting

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hat the reduction on the NO produced is paralleled by enzymexpression. It is interesting to note that apart anthocyanins con-entration used were higher than the amount of them on eachraction, the effects observed were not proportional. Taking intoccount that the fractions developed inhibitory effect greaterhan pure anthocyanins, we must remember that Euterpe oler-cea fractions have other substances which conjoined may benhancing the final effect.

In conclusion, Euterpe oleracea showed potent inhibitoryffects on NO production by activated macrophage cell lineAW 264.7. The mechanism of inhibition seems to be due to a

eduction on iNOS expression (in flower fractions) and on iNOSctivity (fruit and spike fractions).

cknowledgments

FSM received grants from FAPERJ and FUJB and fellowshiprom CNPq.

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