Food and Chemical Toxicology 48 (2010) 937–943

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Food and Chemical Toxicology

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Chlorogenic acid exhibits anti-obesity property and improves lipid metabolismin high-fat diet-induced-obese mice

Ae-Sim Cho a, Seon-Min Jeon b, Myung-Joo Kim c, Jiyoung Yeo d, Kwon-Il Seo e, Myung-Sook Choi b,*,Mi-Kyung Lee e,*

a Department of Nutrition Education, Graduate School of Education, Sunchon National University, Suncheon 540-742, Republic of Koreab Department of Food Science and Nutrition, Kyungpook National University, Daegu 702-701, Republic of Koreac Department of Food Science and Nutrition, Daegu Polytechnic College, Daegu 706-022, Republic of Koread School of Oriental Medicine, Pusan National University, Busan 626-810, Republic of Koreae Department of Food and Nutrition, Sunchon National University, Suncheon 540-742, Republic of Korea

a r t i c l e i n f o a b s t r a c t

Article history:Received 5 September 2009Accepted 5 January 2010

Keywords:Chlorogenic acidCaffeic acidHigh-fat dietLipid metabolismObesity

0278-6915/$ - see front matter � 2010 Elsevier Ltd. Adoi:10.1016/j.fct.2010.01.003

* Corresponding authors. Addresses: Department oKyungpook National University, 1370 Sankyuk-donKorea (M.-S. Choi); Department of Food and Nutrition,413 Jungangno, Suncheon, Jeonnam, 540-742, Repub+82 53 950 6232; fax: +82 53 950 6229 (M.-S. Choi), T61 752 3657 (M.-K. Lee).

E-mail addresses: mschoi@knu.ac.kr (M.-S. Choi),Lee).

This study investigated the efficacy of chlorogenic acid on altering body fat in high-fat diet (37% caloriesfrom fat) induced-obese mice compared to caffeic acid. Caffeic acid or chlorogenic acid was supple-mented with high-fat diet at 0.02% (wt/wt) dose. Both caffeic acid and chlorogenic acid significantly low-ered body weight, visceral fat mass and plasma leptin and insulin levels compared to the high-fat controlgroup. They also lowered triglyceride (in plasma, liver and heart) and cholesterol (in plasma, adipose tis-sue and heart) concentrations. Triglyceride content in adipose tissue was significantly lowered, whereasthe plasma adiponectin level was elevated by chlorogenic acid supplementation compared to the high-fatcontrol group. Body weight was significantly correlated with plasma leptin (r = 0.894, p < 0.01) and insu-lin (r = 0.496, p < 0.01) levels, respectively. Caffeic acid and chlorogenic acid significantly inhibited fattyacid synthase, 3-hydroxy-3-methylglutaryl CoA reductase and acyl-CoA:cholesterol acyltransferase activ-ities, while they increased fatty acid b-oxidation activity and peroxisome proliferator-activated receptorsa expression in the liver compared to the high-fat group. These results suggest that caffeic acid and chlor-ogenic acid improve body weight, lipid metabolism and obesity-related hormones levels in high-fat fedmice. Chlorogenic acid seemed to be more potent for body weight reduction and regulation of lipidmetabolism than caffeic acid.

� 2010 Elsevier Ltd. All rights reserved.

1. Introduction

Phenolic acids are secondary metabolites, which are commonlyfound in plants. Many epidemiological studies have found that theconsumption of foods and drinks with high phenolic content isassociated with the prevention of coronary disease, cancer and soon (Hertog et al., 1995; Scalbert and Williamson, 2000). Amongthese, hydroxycinnamic acids constitute a major class of phenolicacids that are widely available in seeds, fruits and vegetables.The daily intake of hydroxycinnamic acid derivates may easilyreach 0.5–1 g in humans (Radtke et al., 1998; Clifford, 1999). Pre-vious studies revealed that hydroxycinnamic acids (q-coumaric

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f Food Science and Nutrition,g, Buk-gu, Daegu, 702-701,Sunchon National University,lic of Korea (M.-K. Lee). Tel.:el.: +82 61 750 3656; fax: +82

leemk@sunchon.ac.kr (M.-K.

acid, caffeic acid, ferulic acid) and their derivates efficiently im-proved hypercholesterolemia and type 2 diabetes (Kim et al.,2003; Lee et al., 2003; Jung et al., 2006). In particular, caffeic acidis one of the most abundant hydroxycinnamic acids in the humandiet and may occur in esterified form with ether quinic acid or tar-taric acid (Gonthier et al., 2006). Among the quinic acid conjugates,chlorogenic acid (5-O-caffeoylquinic acid, Fig. 1) is predominant inplants, fruits and vegetables such as coffee beans, apples, pears,tomatoes, blueberries, potatoes, peanuts and eggplants (Azumaet al., 2000).

Chlorogenic acid inhibits carcinogenesis in the colon, liver, andtongue, and protects against oxidative stress in vivo (Mori et al.,1986; Tanaka et al., 1993; Tsuchiya et al., 1996). Chlorogenic acidhas been claimed to modulate the glucose-6-phosphatase involvedin glucose metabolism (Hemmerle et al., 1997) and to reduce therisk cardiovascular disease by decreasing oxidation of low densitylipoprotein (LDL)-cholesterol and total cholesterol (Nardini et al.,1995). More recently, Hsu et al. (2006) reported that chlorogenicacid inhibited preadipocyte population growth, which may providea proposed mechanism for reducing obesity. Therefore, there is

Table 1Composition of the experimental diets.

Component Normal %(w/w)

HF control %(w/w)

HF-caffeicacid % (w/w)

HF-chlorogenicacid % (w/w)

Casein 20.0 20.0 20.0 20.0Corn starch 50.0 34.0 33.98 33.98Sucrose 15.0 15.0 15.0 15.0Cellulose 5.0 5.0 5.0 5.0Corn oil 5.0 – – –Beef tallow – 21.0 21.0 21.0AIN-mineral mixturea 3.5 3.5 3.5 3.5AIN-vitamin mixtureb 1.0 1.0 1.0 1.0

DL-Methionine 0.3 0.3 0.3 0.3

Choline bitartrate 0.2 0.2 0.2 0.2Caffeic acid – – 0.02 –Chlorogenic acid – – – 0.02

Total (%) 100 100 100 100

kcal/100 g diet 421.5 515.5 510 513.5Calories from fat (%) 11.0 37.0 37.0 37.0

a Mineral mixture according to AIN-76.b Vitamin mixture according to AIN-76.

Fig. 1. Chemical structures of caffeic acid and chlorogenic acid.

938 A.-S. Cho et al. / Food and Chemical Toxicology 48 (2010) 937–943

increasing interest in an anti-obesity effect of chlorogenic acidin vivo. In this study, the anti-obesity potential of chlorogenic acidwas investigated using high-fat diet-induced-obese mice by com-paring it with that of caffeic acid.

2. Methods and materials

2.1. Animals and diets

Thirty-two male ICR mice (4 weeks old) were obtained from Orient Inc. (Seoul,Republic of Korea). The mice were all individually housed in polycarbonate cages at22 ± 2 �C on a 12 h light–dark cycle. All mice were fed pellets of commercial chowfor 1 week after arrival. The mice were randomly divided into four groups (n = 8),and respectively fed a normal diet (5% corn oil, wt/wt), a high-fat diet containing37% calories from fat (21% beef tallow, wt/wt), a high-fat diet plus 0.02% caffeic acid(0.2 g/kg diet, TCI Co., Ltd., Japan) and a high-fat diet plus 0.02% chlorogenic acid(0.2 g/kg diet, TCI Co., Ltd., Japan). The composition of the experimental diet (Ta-ble 1) was based on the AIN-76 semisynthetic diet (American Institute of Nutrition,1977, 1980). The mice had free access to food and water, and their food consump-tion was measured daily while their weight gain was measured weekly.

At the end of the experimental period, the mice were anesthetized with etherafter withholding food for 12 h. Blood samples were taken from the inferior venacava to determine the plasma biomarkers. After collecting the blood, the liver, adi-pose tissue and heart were removed, rinsed with a physiological saline solution andimmediately stored at �70 �C. The white adipose tissues (epididymal and perirenal)were collected and then weighed immediately. All of the mice were treated in strictaccordance with the Sunchon National University guidelines for the care and use oflaboratory animals.

2.2. Plasma leptin, insulin and adiponectin levels

The plasma leptin (R&D systme, USA), adiponectin (R&D systme, USA) and insu-lin (Shibaygi Co., Ltd., Japan) levels were determined using a quantitative sandwichenzyme immunoassay kit.

2.3. Plasma and tissue lipids

The plasma concentrations of total cholesterol, HDL-cholesterol and triglyceride(Asan Diagnostics, Seoul, Korea) were determined using an enzymatic method. Theplasma free fatty acid (FFA) concentrations were determined using an enzymaticcolorimetric method (Wako Chemicals, Richmond, VA). The hepatic, adipose tissueand heart lipids were extracted using the procedure developed by Folch et al. (1957)and the cholesterol and triglyceride concentrations were analyzed with the sameenzymatic kit as used in the plasma analysis.

2.4. Preparation of samples

The enzyme source fractions in the liver were prepared according to the methoddeveloped by Hulcher and Oleson (1973) with a slight modification. A 20% (w/v)homogenate was prepared in a buffer containing 0.1 M triethanolamine, 0.02 MEDTA and 2 mM dithiothreitol (pH 7.0). This homogenate was centrifuged at 600gfor 10 min to discard any cellular debris. The supernatant was then centrifuged at10,000g for 20 min and then again at 12,000g for 20 min at 4 �C to remove the mito-chondrial pellet. Subsequently, the supernatant was ultracentrifuged twice at100,000g for 60 min at 4 �C to obtain the cytosolic supernatant. The mitochondrialand microsomal pellets were then redissolved in 800 lL of a homogenization buffer,and their protein content was determined by the method of Bradford (Bradford,1976) using bovine serum albumin (BSA) as the standard.

2.5. Hepatic lipid-regulating enzyme activities

The fatty acid synthase (FAS) activity was determined by a spectrophotometricassay. This assay is based on measuring the malonyl-CoA-dependent oxidation ofNADPH according to the methods by Nepokroeff et al. (1975) with a slight modifi-cation. One unit of enzyme activity represented the oxidation of 1 nmol of NADPHper minute at 37 �C. Fatty acid b-oxidation (b-oxidation) activity was measuredspectrophotometrically by monitoring the reduction of NAD to NADH in the pres-ence of palmitoyl-CoA as described by Lazarow (1981) with a slight modification.3-Hydroxy-3-methylglutaryl (HMG)-CoA reductase activity was determined inthe microsome with [14C]-HMG-CoA as the substrate based on a modification ofthe method of Shapiro et al. (1974). The activity was expressed as the synthesizedmevalonate pmol/min/mg protein. Acyl-CoA:cholesterol acyltransferase (ACAT)activity was determined by the rate of incorporation of [14C]-oleoyl CoA into choles-terol ester fractions, as described by Erickson et al. (1980) and modified by Gillieset al. (1986). The activity was expressed as synthesized cholesteryl oleate pmol/min/mg protein.

2.6. Western blot analysis

The liver was homogenized with a buffer containing 50 mM 4-(2-hydroxy-ethyl)piperazine-1-ethanesulfonic acid (Hepes), 150 mM NaCl, 1 mM ethylenedi-aminetetraacetic acid (EDTA), 2 mM ethylene glycol-bis(2-aminoethylether-tetraacetic acid (EGTA), 50 mM NaF, 1% triton-X, 1 mM phenylmethylsulfonyl fluo-ride, 25 lg/mL leupeptin and 2 lg/mL aprotinin. Lysates were centrifuged at 8550gfor 1 h at 4 �C. The supernatant protein content was determined following themethod established by Bradford (1976), using BSA as the standard. Equal amountsof protein (30 lg per lane) were separated by 7% sodium dodecyl sulfate (SDS)–polyacrylamide gel electrophoresis, transferred onto nitrocellulose membranes,blocked BSA and incubated overnight with polyclonal rabbit anti-PPAR a (1:200)(Santa Cruz Biotechnology, Inc., USA). After a washing procedure, the blots wereincubated with horseradish peroxidase-conjugated anti-rabbit secondary antibody(Santa Cruz Biotechnology, Inc., USA) for 1 h at room temperature. The immunore-active bands were visualized with an enhanced chemiluminescence kit according tothe manufacture’s instructions (Santa Cruz Biotechnology, Inc., USA). The blots werestripped by treating them two times for 30 min with 200 mM glycine, 0.1% SDS and1% Tween-20 followed, washed, again incubated overnight at 4 �C with b-actin anti-body (1:1000) (Santa Cruz Biotechnology, Inc., USA) and the remaining proceduresas described above were followed. The b-actin was used for loading standardization.

2.7. Statistical analysis

All data are presented as the mean ± S.E. The data were evaluated by a one-wayANOVA SPSS program and by determining the differences between the means usingthe Duncan’s multiple-range test. Correlation analyses utilized the Pearson’s coeffi-cient. Values were considered statistically significant when p < 0.05.

3. Results

3.1. Body weight, food intake, energy intake and visceral fat weight

The final body weight of mice fed the high-fat diet was signifi-cantly higher than that of mice fed the normal diet (Table 2). How-

Table 2Effect of caffeic acid and chlorogenic acid supplementation on body weight, food intake and daily energy intake in high-fat diet-induced-obese mice.*

Initial body weight (g) Final body weight (g) Body weight gain (g) Food intake (g/day) Energy intake (kcal/day)

Normal 28.49 ± 0.38 42.28 ± 0.73a 13.90 ± 0.91ab 7.07 ± 0.30 29.83 ± 1.26a

HF control 28.75 ± 0.42 47.47 ± 2.05b 18.50 ± 1.32c 6.58 ± 0.30 33.90 ± 0.38b

HF-caffeic acid 28.42 ± 0.40 43.53 ± 1.05a 15.45 ± 1.07bc 6.32 ± 0.13 32.24 ± 0.46b

HF-chlorogenic acid 28.53 ± 0.22 40.05 ± 1.26a 11.79 ± 0.97a 6.28 ± 0.08 32.20 ± 0.49b

abc The means in the column not sharing a common letter are significantly different between groups (p < 0.05).* Values are expressed as means ± S.E.

Fig. 2. Effect of caffeic acid and chlorogenic acid supplementation on visceral fatweight in high-fat diet-induced-obese mice. Values are expressed as means ± S.E.abcThe means not sharing a common letter are significantly different betweengroups (p < 0.05).

Table 3Effect of caffeic acid and chlorogenic acid supplementation on plasma leptin, insulinand adiponectin concentrations in high-fat diet-induced-obese mice.*

Leptin(ng/mL)

Insulin(ng/mL)

Adiponectin(ug/mL)

Normal 3.32 ± 0.30a 5.32 ± 0.21a 7.41 ± 0.41ab

HF control 5.58 ± 0.50b 6.93 ± 0.25b 3.92 ± 0.37c

HF-caffeic acid 3.32 ± 0.34a 5.21 ± 0.33a 4.24 ± 0.49c

HF-chlorogenic acid 2.52 ± 0.15a 4.86 ± 0.45a 6.02 ± 0.23b

abcThe means in the column not sharing a common letter are significantly differentbetween groups (p < 0.05).* Values are expressed as means ± S.E.

A.-S. Cho et al. / Food and Chemical Toxicology 48 (2010) 937–943 939

ever, the caffeic acid and its ester chlorogenic acid supplementssignificantly reduced body weight compared to the high-fat controlgroup by 8% and 16%, respectively. Among the high-fat fed groups,body weight gain was significantly lower in the chlorogenic acidgroup compared to the high-fat control or caffeic acid supple-mented group. Caffeic acid and chlorogenic acid did not affect foodintake and daily energy intake in high-fat feeding mice (Table 2).

Obesity with predominant visceral fat is associated with diabe-tes mellitus, dyslipidemia and hypertension. As shown in Fig. 2,visceral fat weight of mice fed high-fat diet for 8 weeks was signif-icantly higher than the normal group. However, the epididymalwhite adipose tissues weight was significantly lower in the caffeicacid and chlorogenic acid groups as compared to the high-fat con-trol group by 22% and 46%, respectively (Fig. 2). In particular, theperirenal adipose tissue weight of the chlorogenic acid was only42% of the high-fat control value (Fig. 2).

3.2. Plasma leptin, insulin and adiponectin levels

A high-energy diet generally increases adipose tissue mass andleptin secretion, which induces leptin resistance, resulting in lipo-toxicity (Torre-Villalvazo et al., 2008). To evaluate the effect ofchlorogenic acid on plasma insulin and adipokine levels, we deter-mined the plasma leptin, insulin and adiponectin concentrationsusing ELISA assay.

The high-fat control diet caused to increase the plasma leptinand insulin levels significantly compared to the normal diet fedmice, while it decreased the plasma adiponectin level. However,both caffeic acid and chlorogenic acid supplemented groups werelower in the plasma letpin and insulin levels compared to thehigh-fat control group (Table 3). In this study, the leptin levelwas positively correlated with the insulin level in plasma(r = 0.594, p < 0.01). Body weight was positively correlated withthe plasma leptin level (r = 0.894, p < 0.01) and the insulin level(r = 0.496, p < 0.01), respectively. Epididymal white adipose tissue

weight was positively correlated with the plasma leptin level(r = 0.791, p < 0.01) and the insulin level (r = 0.462, p < 0.01) afterthe 8-week experimental period (Fig. 3). When compared to thehigh-fat control group, the plasma adiponectin concentration wasonly significantly higher in the chlorogenic acid group (Table 3).

3.3. Lipid contents in plasma, liver, adipose tissue and heart

Supplementation of caffeic acid and chlorogenic acid to a high-fat diet significantly lowered the plasma triglyceride and total cho-lesterol concentrations compared to the high-fat group. Plasmafree fatty acid concentration was significantly lowered by caffeicacid and chlorogenic acid supplementation. In addition, the caffeicacid and chlorogenic acid supplementation significantly increasedHDL-cholesterol to total cholesterol ratio compared to the high-fat control group (Table 4).

Supplementation with caffeic acid and chlorogenic acid signifi-cantly lowered the triglyceride concentrations in the liver andheart compared to the high-fat control group (Fig. 4). Adipose tis-sue triglyceride concentration was only decreased by chlorogenicacid supplementation. The cholesterol concentrations of adiposetissue and heart were significantly lower in the caffeic acid andchlorogenic acid groups compared to the high-fat control group(Fig. 4).

3.4. Activities of hepatic lipid-regulating enzymes

To understand the mechanism involved in the effect of chloro-genic acid on lipid metabolism, hepatic lipid-regulating enzymesactivities such as lipogenesis, fatty acid oxidation and cholesterolsynthesis were investigated.

The hepatic FAS, HMG-CoA reductase and ACAT activities weresignificantly higher in the high-fat control group than in the nor-mal group, whereas the b-oxidation activity was significantly low-er (Table 5). The caffeic acid and chlorogenic acid lowered hepaticFAS, HMG-CoA reductase and ACAT activities compared to thehigh-fat control group, while they elevated fatty acid b-oxidationactivity. Thus, caffeic acid and chlorogenic acid inhibited fatty acidand cholesterol synthesis and stimulated fatty acid oxidation in theliver (Table 5).

Fig. 3. Effect of caffeic acid and chlorogenic acid supplementation on correlation between parameters in high-fat diet-induced-obese mice.

Table 4Effect of caffeic acid and chlorogenic acid supplementation on plasma lipid contents in high-fat diet-induced-obese mice.*

Triglyceride (mmol/L) Free fatty acid (mmol/L) Total cholesterol (mmol/L) HDL-cholesterol (mmol/L) HTRA (%)

Normal 1.65 ± 0.12b 0.40 ± 0.03a 3.23 ± 0.31a 1.76 ± 0.05 52.17 ± 1.72ab

HF control 1.95 ± 0.26c 0.52 ± 0.05b 5.53 ± 0.47b 1.82 ± 0.06 34.73 ± 3.08c

HF-caffeic acid 1.22 ± 0.16ab 0.33 ± 0.01a 4.09 ± 0.28a 1.90 ± 0.17 46.15 ± 1.92b

HF-chlorogenic acid 0.91 ± 0.09a 0.30 ± 0.04a 3.42 ± 0.27a 1.86 ± 0.18 53.73 ± 1.19a

abcThe means in the column not sharing a common letter are significantly different between groups (p < 0.05).* Values are expressed as means ± S.E.

A HTR = HDL-cholesterol/total cholesterol � 100.

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3.5. Expression of hepatic PPAR a

PPAR a is one of nuclear transcription factors that act as lipidsensors and regulate lipid metabolism (Willson and Wahli,1997). Liver is the major target tissue of PPAR a, and its keygenes include the enzymes involved in the b-oxidation of fattyacid (Chen et al., 2008). Therefore, we examined the hepaticPPAR a expression by Western blotting. In comparison withthe high-fat control group, supplementation of caffeic acid andchlorogenic acid stimulated the expression of PPAR a in the liver(Fig. 5).

4. Discussion

The role of chlorogenic acid in a diet-induced obesity model hasnot yet been fully established. Therefore, the effect of chlorogenicacid has been investigated on body weight, body fat distributionand lipid metabolism in high-fat diet-induced-obese mice by com-paring it with caffeic acid, which is an unesterified structure ofchlorogenic acid.

This study demonstrated that caffeic acid and its ester, chloro-genic acid, significantly reduced body weight, by approximately8% and 16%, respectively, and epididymal adipose tissue weight,

Fig. 4. Effect of caffeic acid and chlorogenic acid supplementation on lipid contents of liver (A and B), epididymal adipose tissue (C and D) and heart (E and F) in high-fat diet-induced-obese mice. Values are expressed as means ± S.E. abcThe means not sharing a common letter are significantly different between groups (p < 0.05).

Table 5Effect of caffeic acid and chlorogenic acid supplementation on hepatic lipid-regulating enzyme activities in high-fat diet-induced-obese mice.*

Fatty acid synthaseA (nmol/min/mgprotein)

Fatty acid b-oxidation (nmol/min/mgprotein)

HMG-CoA reductase (pmol/min/mgprotein)

ACAT (pmol/min/mgprotein)

Normal 2.09 ± 0.17a 7.06 ± 0.49a 220.64 ± 20.89a 169.34 ± 8.91a

HF control 3.62 ± 0.08b 3.41 ± 0.54c 462.57 ± 19.33c 250.60 ± 10.58c

HF-caffeic acid 2.01 ± 0.26a 5.43 ± 0.65b 352.43 ± 23.30b 210.87 ± 16.39b

HF-chlorogenicacid

1.57 ± 0.11a 7.24 ± 0.47a 348.05 ± 20.21b 207.40 ± 6.70b

abcThe means in the column not sharing a common letter are significantly different between groups (p < 0.05).* Values are expressed as means ± S.E.

A FAS, fatty acid synthase; b-oxidation, free fatty acid b-oxidation; HMG-CoA reductase, 3-hydroxy-3-methylglutaryl CoA reductase; ACAT, acyl-coenzyme A:cholesterolacyltransferase.

A.-S. Cho et al. / Food and Chemical Toxicology 48 (2010) 937–943 941

by approximately 22% and 46%, respectively, compared to the high-fat control group without changing daily food or energy intake. Un-der a normal diet feeding condition, the oral administration ofchlorogenic acid (30 and 60 mg/kg/day) for 14 days reduced thehepatic triglyceride content but the amount of visceral fat was un-changed (Shimoda et al., 2006). However, in this study, chlorogenicacid significantly lowered the body weight gain and perirenal adi-pose weight compared to the high-fat control group and caffeicacid group. Thus, chlorogenic acid suppressed body weight gain

and lowered visceral fat mass more efficiently than caffeic acid inhigh-fat diet fed mice.

Visceral adipose tissue releases a large amount of free fattyacids (FFA) and hormones/cytokines in the portal vein that canbe delivered to the liver and interact with hepatocytes and variousimmune cells (Lafontan and Girard, 2008). It was also observedthat both the body weight and epididymal adipose weight werepositively correlated with plasma leptin and insulin levels, respec-tively. The plasma leptin and insulin levels were significantly

Fig. 5. Effect of caffeic acid and chlorogenic acid supplementation on the expressionof PPAR a in high-fat diet-induced-obese mice.

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higher in the high-fat group than in the normal diet group; how-ever, these hormone levels were significantly lowered by caffeicacid and chlorogenic acid supplementation. These results showeda significant positive correlation between leptin and insulin levelsin the plasma (r = 0.594, p < 0.01).

During the development of leptin resistance, there is an in-creased release of FFA from adipose tissue to other tissues, mainlyto the liver (Torre-Villalvazo et al., 2008). As a result, hepatic ester-ification of FFA to triglycerides leads to the formation of fatty liverthat is accelerated by an increased lipogenesis as a consequence ofhyperinsulinemia and decreased FFA oxidation (Torre-Villalvazoet al., 2008). In this study, it was confirmed that high-fat feedingfor 8 weeks to mice induced a (Mathieu et al., 2008) decrease offatty acid oxidation in the liver. Several studies have pointed outthat the most common form of insulin resistance is associated withan increased accumulation visceral fat (Slawik and Vidal-Puig,2006). Prevention of hyperinsulinemia may ameliorate metabolicabnormalities that occur in the liver as a consequence of obesity(Torre-Villalvazo et al., 2008). In particular, visceral fat depot wasassociated with metabolic abnormalities contributing to the devel-opment of cardiovascular disease (Mathieu et al., 2008). The lipo-toxic theory states that the accumulation of lipid in target organssuch as skeletal muscle, kidney, pancreas and heart, may contrib-ute to the development of obesity-related disorders (Slawik and Vi-dal-Puig, 2006). Recently, it has been reported that chlorogenicacid (5 mg/kg body weight, intravenously) improved glucose toler-ance and decreased plasma and hepatic lipids without changingtriglyceride concentration in the adipose tissue of (fa/fa) Zuckerrats, which is an animal model for obese type 2 diabetes (de Sotilloand Hadley, 2002). However, in this study, caffeic acid and chloro-genic acid significantly lowered the plasma FFA, triglyceride andtotal cholesterol concentrations as well as lipid contents of tissuessuch as liver, epididymal adipose tissue and heart.

This study showed that caffeic acid and chlorogenic acid in-creased the expression of PPAR a with a simultaneous increase infatty acid b-oxidation in the liver compared to the high-fat controlgroup. In particular, chlorogenic acid normalized the activity of he-patic fatty acid b-oxidation in diet-induced-obese mice to similarto values of a normal diet fed group. In some preclinical studies,more potent and selective PPAR a agonists have been shown toprevent the development of diabetes/insulin resistance in rodentmodels of diabetes by reducing adiposity, improving peripheralinsulin action, and exerting beneficial effects on pancreatic b-cells(Guerre-Millo et al., 2000; Kim et al., 2003; Bergeron et al., 2006).Previous research suggested that adiponectin increased fatty acidcombustion and energy consumption via PPAR a activation at leastin part, which led to decreased triglyceride content in the liver andskeletal muscle and thus coordinately increased in vivo insulin sen-sitivity (Kadowaki and Yamauchi, 2005). Plasma adiponectin levelhas been reported to be significantly reduced in obese/diabeticmice and humans (Yamauchi et al., 2001; Arita et al., 1999) and

to be decreased in patients with cardiovascular disease (Kumadaet al., 2003), hypertension (Ouchi et al., 2003), or metabolic syn-drome (Trujillo and Scherer, 2005). Although both chlorogenic acidand caffeic acid improved adiponectin to leptin ratio in diet-in-duced-obese mice, only chlorogenic acid significantly elevatedplasma adiponectin concentration compared to the high-fat con-trol group and caffeic acid group. Moreover, chlorogenic acidseems to be a more potential stimulator of hepatic fatty acid b-oxi-dation than caffeic acid. Furthermore, we showed that caffeic acidand chlorogenic acid also efficiently inhibited fatty acid and cho-lesterol biosynthesis as evidenced by suppressing the activities offatty acid synthase, HMG-CoA reductase and ACAT in the liver.

In conclusion, chlorogenic acid and caffeic acid exhibited a po-tential anti-obesity effect in high-fat diet-induced mice, whichmay be mediated by altering plasma adipokine level and body fatdistribution and down-regulating fatty acid and cholesterol bio-synthesis, whereas up-regulating fatty acid oxidation and PPAR aexpression in the liver. Chlorogenic acid seemed to be more potentand efficacious anti-obesity agent in diet-induced-obese mice thancaffeic acid. Although, more studies are needed to support thispromising mechanism, this research might provide implication inhuman anti-obesity effect.

Conflict of Interest

The authors declare that there are no conflicts of interest.

Acknowledgement

This work was supported by the Science Research Center (SRC)program of Korea Science and Engineering Foundation (KOSEF, No.2009-0063409).

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