Comparative effects of curcumin and its analog on alcohol and PUFA induced alterations in circulatory lipid profiles

8/8/2019 Comparative effects of curcumin and its analog on alcohol and PUFA induced alterations in circulatory lipid profiles

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ficiency of curcumin in inhibiting the increase in lipid profilesunder the influence of the known hyperlipidemic agents alco-hol and PUFAs and compared these results with the effects of the o-hydroxy-substituted analog of curcumin (CA) (Fig. 1B),whose anti-hyperlipidemic role is not well established.

MATERIALS AND METHODS

Animals

Male albino Wistar rats, weighing 140160 g, bred inCentral Animal House, Rajah Muthiah Medical College,Tamil Nadu, India, and fed on pellet diet (Agro Corp. Pri-vate Ltd., Bangalore, India), were used for the study, andwater was given ad libitum. The standard pellet diet com-prised 21% protein, 5% lipids, 4% crude fibre, 8% ash, 1%calcium, 0.6% phosphorus, 3.4% glucose, 2% vitamin, and55% nitrogen-free extract (carbohydrates). It provides me-tabolizable energy of 3,600 kcal.

The animals were housed in plastic cages under controlledconditions of 12-hour light/dark cycle, 50% humidity, and30 2C. The animals used in the present study were main-tained in accordance with the guidelines of the NationalInstitute of Nutrition, Indian Council of Medical Research,Hyderabad, India and approved by the Animal Ethical Com-mittee, Annamalai University.

Materials

Absolute ethanol was obtained from Hayman Ltd.

(Witham, UK). To obtain PUFAs, sunflower oil was sub- jected to heating at 180C for 30 minutes, twice. 2 Curcuminwas obtained from Central Drug House Private Ltd. (Mum-bai, India). CA was synthesized by the method described byDinesh Babu and Rajasekaran. 13

Experimental design

The animals were divided into 12 groups of six rats each:Group 1 (Control), control rats; Group 2 (Alcohol), rats

given 20% ethanol (7.9 g/kg of body weight) 14 orally, us-ing an intragastric tube; Group 3 ( PUFA), rats given ahigh-fat diet (15% sunflower oil) mixed with the diet;Group 4 (Alcohol PUFA), rats given 20% ethanol15% sunflower oil; Group 5 (Alcohol C), rats givencurcumin (80 mg/kg of body weight) dissolved in 20%ethanol; Group 6 (Alcohol CA), rats given CA (80 mg/kgof body weight) dissolved in 20% ethanol; Group 7 ( P-UFA C), rats given 15% sunflower oil curcumin (80mg/kg of body weight) dissolved in distilled water; Group8 ( PUFA CA), rats given 15% sunflower oil CA(80 mg/kg of body weight) dissolved in distilled water;Group 9 (Alcohol PUFA C), rats given curcumin (80mg/kg body weight) dissolved in 20% ethanol 15% sun-flower oil; Group 10 (Alcohol PUFA CA), rats givenCA (80 mg/kg of body weight) dissolved in 20% ethanol15% sunflower oil; Group 11 (Curcumin), rats given cur-cumin (80 mg/kg of body weight) dissolved in distilled wa-ter orally using an intragastric tube; and Group 12 (CA), ratsgiven CA (80 mg/kg of body weight) dissolved in distilledwater orally using an intragastric tube.

Rats were maintained on an isocaloric diet using glucosesolution (total calories per day, 508 kcal/kg of body weight).At the end of the experimental period of 45 days, the ratswere sacrificed, the blood was collected in heparinizedtubes, and plasma was separated for various biochemical es-timations.

Biochemical parameters

The lipids were extracted from plasma by the method of Folch et al .15 Anti-hyperlipidemic action of curcumin andCA was assessed by analyzing the levels of cholesterol bythe method of Zlatkis et al. ,16 triglycerides (TGs) by the

method of Foster and Dunn,18

phospholipids (PLs) by the

ANTI-HYPERLIPIDEMIC ROLE OF CURCUMIN AND ITS ANALOG 257

A

B

FIG. 1. Structures of ( A) curcumin and ( B) the curcumin analogused in this study.

m g / d l

Grou ps

250

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1 2 3 4 5 6 7 8 9 10 11 12

ahkl

0

bcicbij

d

egj

fghgefj

hafkl

ibc

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kahl lahk

FIG. 2. Levels of cholesterol in plasma. Values are mean SD fromsix rats in each group: 1, Normal; 2, Alcohol; 3, PUFA; 4, Alco-hol PUFA; 5, Alcohol Curcumin; 6, Alcohol CA; 7, P-UFA Curcumin; 8, PUFA CA; 9, Alcohol PUFA Cur-cumin; 10, Alcohol PUFA CA; 11, Curcumin; 12, CA. Groupsnot sharing a common superscript letter differ significantly at P .05.


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method of Zilversmith and Davis, 18 and free fatty acids(FFAs) by the method of Falholt et al .19

Statistical analysis

Statistical analysis was done by analysis of variance fol-lowed by Duncans Multiple Range Test using SPSS(Chicago, IL) package version 9.0. Values were consideredstatistically significant when P .05.

RESULTS

The levels of cholesterol (Fig. 2), TGs (Fig. 3), PLs (Fig.

4), and FFAs (Fig. 5) were increased significantly in alco-

hol-, PUFA-, and alcohol PUFA-treated groups andwere decreased significantly on treatment with curcumin andCA. The decrease was more significant in CA-treated groupscompared with curcumin-treated groups.

DISCUSSION

The liver is the major organ in which most of the chem-icals and drugs undergo metabolism. Alcohol is known toalter lipid metabolism in the liver and thus elevate lipid lev-els in circulation.

Marked alterations in lipid metabolism have been re-

ported in chronic ethanol feeding.20

The main pathway of alcohol degradation, the alcohol dehydrogenase pathway,leads to increased NADH synthesis. This striking redoxchange inhibits tricarboxylic acid cycle activity, fatty acidoxidation, and lipoprotein export and increases fatty acid up-take, 21 thus predisposing to fatty liver.

Ethanol treatment to rats is known to cause centrilobularnecrosis in the liver leading to the accumulation of fat. An-tonenkov et al. 22 have reported that chronic ethanol ingestionresults in hypercholesterolemia and hypertriglyceridemia andincreased concentration of lipids in liver. These increased lev-els of lipids leak out of liver into the circulation.

The increased cholesterol may be due to increased activ-ity of -hydroxy-3-methyl-3-glutaryl CoA reductase, whichis the rate-limiting step in cholesterol biosynthesis, 23 byethanol. Reports have shown that a diet rich in PUFAs stim-ulates the production of chylomicrons by the intestine. 24

Moreover, higher plasma cholesterol levels have been ob-served in oil-fed groups, 25 and so in alcohol-, PUFA-,and alcohol PUFA-treated groups, cholesterol levels arehigher.

Fielding et al. 26 have found an increased plasma TG con-centrations after acute ethanol ingestion. The increased

258 RUKKUMANI ET AL.

m g / d l

Gro ups

250

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50

1 2 3 4 5 6 7 8 9 10 11 12

akl

0

bcicbi

d

ejfhj

gefj

hfj

ibc

jefh

kal lak

FIG. 3. Levels of TGs in plasma. Values are mean SD from sixrats in each group: 1, Normal; 2, Alcohol; 3, PUFA; 4, Alcohol

PUFA; 5, Alcohol Curcumin; 6, Alcohol CA; 7, PUFACurcumin; 8, PUFA CA; 9, Alcohol PUFA Curcumin; 10,Alcohol PUFA CA; 11, Curcumin; 12, CA. Groups not shar-ing a common superscript letter differ significantly at P .05.

m g / d l

Grou ps

300

250

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50

1 2 3 4 5 6 7 8 9 10 11 12

akl

0

bci cbi

d

egjfg

gefj

h

ibc

jeg

kal lak

m g / d l

Gro ups

200

150

100

50

1 2 3 4 5 6 7 8 9 10 11 12

akl

0

bcicbi

d

egj

fghgefj

hf

ibc

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kal lak

FIG. 4. Levels of PLs in plasma. Values are mean SD from sixrats in each group: 1, Normal; 2, Alcohol; 3, PUFA; 4, Alcohol


FIG. 5. Levels of FFAs in plasma. Values are mean SD from sixrats in each group: 1, Normal; 2, Alcohol; 3, PUFA; 4, Alcohol



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NADH/NAD ratio during alcohol intake enhances the con-centration of -glycerophosphate, which favors hepatic TGaccumulation by trapping fatty acids. In vitro , alcohol hasbeen shown to exert a direct effect on myocardial lipid me-tabolism, causing an increase in fatty acid esterification anda decrease in oxidation, thus accumulating TGs. The in-creased TG levels after PUFA ingestion may be due to theincreased availability of FFAs for esterification. Since theavailability of FFAs is greater in the Alcohol PUFA-treated group, the TG levels are also comparatively higher.

PLs are the vital components of biomembranes. They arethe primary targets of peroxidation and can be altered byethanol. 27 The increased levels of PLs may be due to the in-creased availability of FFAs. Since PUFAs are componentsof PLs, the increased PUFA intake may increase the levelsof PLs.

The FFA levels are enhanced in the alcohol-fed group,which may be attributed to increased formation of acetate,which in turn forms FFAs. The increased NADH/NAD ra-tio also favors fatty acid synthesis. Increased FFAs in the

PUFA- and alcohol PUFA-treated groups may be due

to the increased membrane lipid breakdown. The increaseddietary PUFAs may also eventually increase the FFA levels.

Treatment with curcumin effectively reduced the lipidlevels. The hypocholesterolemic effect of curcumin is dueto the increased high-density lipoprotein formation, whichtransports the excess cholesterol from extrahepatic tissuesto liver where it is catabolized. 28 Curcumin also decreasesthe absorption of cholesterol. 29 Reports suggest that cur-cumin increases activity of 7 -hydroxylase, the main en-zyme in the conversion of cholesterol to bile acid, and thusfacilitates biliary cholesterol excretion. 30 The exact mecha-nism by which it lowers levels of other lipids is not known.However, studies have shown that spices play a vital role in

lipid metabolism, because of their active principles. Thespices are known to affect bile acid excretion and therebyinfluence lipid levels. 31 The decreased levels of PLs andTGs may also be due to the decreased FFA synthesis by cur-cumin, which may suppress the enzymes involved in FFAsynthesis. 31

The levels of lipids were significantly decreased in CA-treated groups compared with curcumin-treated groups.Since CA resembles mostly the parent structure curcumin,it may also have an impact on lipid excretion. We proposethat this CA may effectively increase the excretion of lipidsvia bile and thus exert a control over lipids. Moreover, theantioxidant-sparing action of CA might also have con-tributed to its anti-hyperlipidemic action. Among the manyclasses of compounds, phenolics have been recognized aspowerful countermeasures against lipid peroxidation. 32 Nor-mally phenolic compounds act by scavenging free radicalsand quenching the lipid peroxidative side chain. It has beenproposed that hydroxy and hydroperoxy radicals initiate Habstraction from a free phenolic substrate to form phenoxyradical, which can rearrange to the quinone methide radicalintermediate, 33 which is excreted via bile. Thus CA, beinga phenolic compound, might have inhibited lipid peroxida-

tion and hence membrane damage and prevented the releaseof FFAs. The decrease in FFAs, which are the substrates forother lipids, may reflect on the levels of lipids. Thus CA ef-fectively prevents the increase in the levels of lipids duringcombined ingestion of alcohol and PUFAs.

The increased efficacy of this novel curcuminoid may beattributed to the presence of the hydroxyl group at the or-tho position. The o-hydroxyl group, because of its positionalisomerism, easily donates an electron to the free radicals andeffectively neutralizes them. This property makes CA anovel compound for treating hyperlipidemia.

Thus both curcumin and CA effectively modulate the lipidmetabolism and prevent the accumulation of lipids in liverand hyperlipidemia. Thus because of their property of elic-iting a significant effect on lipid profiles, curcumin and CAmay become promising candidates for the treatment of hy-perlipidemia.

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Comparative effects of curcumin and its analog on alcohol and PUFA induced alterations in circulatory lipid profiles