Oleuropein-Rich Diet Attenuates Hyperglycemia and Impaired

Jul 13, 2015 - Safa Souilem , Ines Fki , Isao Kobayashi , Nauman Khalid , Marcos A. Neves , Hiroko Isoda , Sami Sayadi , Mitsutoshi Nakajima. Food and...
1 downloads 0 Views 906KB Size
Page 1 of 32

Journal of Agricultural and Food Chemistry

Oleuropein-Rich Diet Attenuates Hyperglycemia and Impaired Glucose Tolerance in Type 2 Diabetes Model Mouse

Kazutoshi Murotomi1∗, Aya Umeno1, Mayu Yasunaga1, Mototada Shichiri2, Noriko Ishida2, Taisuke Koike3, Toshiki Matsuo3, Hiroko Abe1, Yasukazu Yoshida1, Yoshihiro Nakajima1

1

Health Research Institute, National Institute of Advanced Industrial Science and

Technology (AIST), Takamatsu, Kagawa 761-0395, Japan 2

Health Research Institute, National Institute of Advanced Industrial Science and

Technology (AIST), Ikeda, Osaka 563-8577, Japan 3

Eisai Food & Chemical Co., Ltd., Chuo-ku, Tokyo 103-0027, Japan

∗Correspondence: Kazutoshi Murotomi, National Institute of Advanced Industrial Science and Technology (AIST), Takamatsu, Kagawa 761-0395, Japan. TEL/FAX: +81-87-869-4207/+81-87-869-4178, E-mail: [email protected]

Short title: Effects of oleuropein-rich diet on type 2 diabetic phenotypes

1

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

1

Abstract

2

Oleuropein, a phenolic compound found in abundance in olive leaves, has

3

beneficial effects on various diseases. However, it is unknown whether an oleuropein-rich

4

diet is efficacious against type 2 diabetic phenotypes. In this study, we investigated the

5

effects of the oleuropein-containing supplement OPIACE, whose oleuropein content

6

exceeds 35% (w/w), on the diabetic phenotypes in type 2 diabetes model Tsumura Suzuki

7

Obese Diabetes (TSOD) mouse. TSOD mice were fed OPIACE at 4 weeks of age, i.e.,

8

before the TSOD mice exhibited diabetic phenotypes. We revealed that OPIACE attenuated

9

hyperglycemia and impaired glucose tolerance in TSOD mice over the long term (from 10

10

to 24 weeks of age), but had no effect on obesity. Furthermore, we demonstrated that

11

OPIACE mildly reduced oxidative stress in TSOD mice by 26.2%, and attenuated

12

anxiety-like behavioral abnormality in aged TSOD mice. The results suggest that

13

oleuropein suppresses the progression of type 2 diabetes and diabetes-related behavioral

14

abnormality over the long term.

15 16

Key words: type 2 diabetes, oleuropein, hyperglycemia, impaired glucose tolerance,

17

anxiety

18

2

ACS Paragon Plus Environment

Page 2 of 32

Page 3 of 32

Journal of Agricultural and Food Chemistry

19

■ Introduction

20

Type 2 diabetes mellitus is a chronic and common lifestyle disease that is caused

21

by complex interactions between multiple susceptibility genes and environmental factors1.

22

The pathogenesis of type 2 diabetes is characterized by the progressive decline in insulin

23

action (insulin resistance) in peripheral tissues, accompanied by the impairment of insulin

24

secretion by pancreatic β cells to compensate for the insulin resistance, leading to overt

25

hyperglycemia1. Although insulin resistance and the impairment of insulin secretion are

26

caused by complex and multiple mechanisms, oxidative stress is an early risk factor in the

27

pathogenesis of type 2 diabetes2. We have demonstrated that the type 2 diabetes model

28

Tsumura Suzuki Obese Diabetes (TSOD) mouse, a polygenic model of obese type 2

29

diabetes3, is exposed to a constant level of oxidative stress before and after the onset of

30

diabetes4. In addition, insulin resistance and insulin secretory function are exacerbated by

31

oxidative stress5. Thus, it is expected that the intake of antioxidants may be an effective

32

means of preventing type 2 diabetes.

33

Chronic hyperglycemia leads to severe and lethal complications, including

34

atherosclerosis, neuropathy, nephropathy, and retinopathy6. It has been reported that

35

Alzheimer’s disease7, Parkinson’s disease8, depression9, and anxiety disorder10 are also

36

kinds of diabetic complications. The risk of microvascular complications in diabetes

37

patients was reduced by improving long-term glycemic control11. It was shown that

38

cognitive function in type 2 diabetes patients was negatively associated with hemoglobin

39

A1c level12. Thus, the control of blood glucose level is a critical step to prevent the

40

progression of type 2 diabetes and its complications.

41

In traditional medicine, natural products have been used for the treatment of

42

diabetes. It has been reported that various plant components, including triterpenoids13 and

3

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

Page 4 of 32

43

flavonoids14, exert anti-diabetic effects. Polyphenols are also a kind of plant component that

44

is regularly consumed as part of the human diet. Numerous studies have demonstrated that

45

polyphenols have beneficial effects on various diseases because of their antioxidant,

46

anti-inflammatory,

47

Oleuropein (Figure 1), a phenolic compound found in abundance in Olea europaea leaves,

48

has several pharmacological activities, including antioxidant, anti-inflammatory, and

49

antimicrobial activities16. As oleuropein exhibits potent antioxidant activity in vitro17, it is

50

speculated to be the main component responsible for the potentially beneficial effects of

51

olive leaves on various diseases18. In fact, previous studies have indicated that oleuropein

52

ameliorates hepatic steatosis19, cardiovascular diseases20, and neurodegenerative diseases21.

53

In addition, hyperglycemia in type 1 diabetes model animals22 and metabolic abnormalities

54

in high-carbohydrate and high-fat diet rats20 were partially attenuated by feeding

55

oleuropein-rich extracts. However, it is unknown whether an oleuropein-rich diet is

56

efficacious against type 2 diabetic phenotypes, including chronic hyperglycemia and

57

impaired glucose tolerance.

antimicrobial,

anticancer,

and

immunomodulatory

activities15.

58

In the present study, we investigated the effect of the oleuropein-containing

59

supplement OPIACE, an olive leaf extract whose oleuropein content exceeds 35% (w/w),

60

on the diabetic phenotypes in type 2 diabetes model TSOD mice. We found that OPIACE

61

attenuated hyperglycemia and impaired glucose tolerance over the long term, but had no

62

effect on obesity in TSOD mice. Furthermore, we demonstrated that OPIACE mildly

63

reduced oxidative stress in TSOD mice when feeding duration was extended. Interestingly,

64

OPIACE also attenuated anxiety-like behavioral abnormality in aged TSOD mice. Our

65

findings suggest that the oleuropein-rich diet has beneficial effects on the progression of

66

type 2 diabetes and behavioral disorder that is likely related to diabetes.

4

ACS Paragon Plus Environment

Page 5 of 32

Journal of Agricultural and Food Chemistry

67

■ Materials and Methods

68

Chemicals. 13-Hydroxy-9Z,11E-octadecadienoic

69

acid acid

[13-(Z,E)-HODE],

70

9-hydroxy-10E,12Z-octadecadienoic

[9-(Z,E)-HODE],

and

71

13S-Hydroxy-10E,12Z-octadecadienoic-9,10,12,13-d4 acid (13-HODE-d4) were obtained

72

from Cayman Chemical Company (MI, USA). 9-Hydroxy-10E,12E-octadecadienoic acid

73

(9-(E,E)-HODE) and 13-hydroxy-9E,11E-octadecadienoic acid (13-(E,E)-HODE) were

74

purchased from Larodan Fine Chemicals AB (Malmo, Sweden). OPIACE was provided by

75

Eisai Food & Chemical Co., Ltd. (Tokyo, Japan). The nutrient composition in OPIACE

76

was measured by high performance liquid chromatography (HPLC). OPIACE was

77

dissolved in methanol/water (60:40, v/v) and subjected to HPLC analysis. Other materials

78

were of the highest grade commercially available.

79 80

Animals.

81

Male TSOD mice and male TSNO mice (control) were obtained from the Institute

82

for Animal Reproduction (Ibaraki, Japan). The animals were housed individually and had

83

free access to food (CE-2; Clea Japan Inc., Tokyo, Japan) and water. The animal room was

84

maintained at 23 ± 2 °C and 50 ± 10% humidity under a 12 h light (8:00-20:00) and dark

85

(20:00-8:00) cycle. The animals were acclimated to the laboratory environment for at least

86

one week before the experiment. TSOD mice were divided into two weight-matched

87

groups (n=12 each); the control diet group and OPIACE-containing diet group. The

88

OPIACE-containing diet was prepared by mixing the control diet (CE-2) with 0.2% (w/w)

89

OPIACE, and began to feed TSOD mice from 4 weeks of age. The experimental protocols

90

were approved by the Institutional Animal Care and Use Committee of the National 5

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

91

Institute of Advanced Industrial Science and Technology.

92 93

Measurements of body weight, food intake, and biochemical parameters.

94

Body weight, food intake, and non-fasting blood glucose levels were measured

95

once a week. Non-fasting blood glucose level was measured with the same method as that

96

described previously4. For the measurement of plasma triglyceride levels, mice at 5, 8, 11,

97

and 13 weeks of age were sacrificed after fasting for 16 h. Blood was collected from the

98

vena cava and gently mixed with heparin. The obtained plasma samples were stored at -30

99

°C until use. Plasma triglyceride levels were measured with a LabAssay Triglyceride kit

100

(Wako Pure Chemical Industries, Ltd., Osaka, Japan) according to the manufacturer’s

101

instructions. The weight of epididymal white adipose tissue (WAT), a type of visceral fat, in

102

mice was measured at 5, 8, 11, and 13 weeks of age.

103 104

Oral glucose tolerance test (OGTT).

105

After fasting for 16 h, glucose solution at the dose of 1.5 g/kg body weight was

106

administered orally with a gavage needle to mice at 5, 8, 11, 13, 15, and 24 weeks of age.

107

For the measurement of blood glucose level, mice were placed in a mouse restrainer and

108

their tail tips were resected with surgical scissors. Glucose level in effused blood

109

(approximately 1 µL) was measured with a glucose meter (Life Check; EIDIA Co., Ltd.,

110

Tokyo, Japan). Measurement of blood glucose levels in tail was performed at 0

111

(pre-administration), 15, 30, 60, and 120 min after glucose administration. The area under

112

the curve (AUC) after OGTT was calculated using the trapezoidal method.

113 114

Analysis of hydroxyoctadecadienoic acid by liquid chromatography-mass/mass

6

ACS Paragon Plus Environment

Page 6 of 32

Page 7 of 32

Journal of Agricultural and Food Chemistry

115

spectrometry (LC-MS/MS).

116

Hydroxyoctadecadienoic acids (HODEs) were measured with a previously

117

described method23. Briefly, mouse plasma sample was mixed with the internal standard,

118

13-HODE-d4, and then butylated hydroxytoluene and triphenylphosphine were added to

119

reduce hydroperoxides in the sample. The reduced sample was saponified by adding KOH

120

in methanol. The mixture was acidified with 10% (v/v) acetic acid in water and extracted

121

with chloroform/ethyl acetate (4:1, v/v). The chloroform/ethyl acetate layer was

122

concentrated and divided equally into two portions, and each portion was evaporated to

123

dryness under nitrogen. One portion of the derivatized sample was reconstituted with

124

methanol/water (70:30, v/v), and subjected to LC-MS/MS analysis of HODEs. The

125

precursor, the product ions, and the collision energies were determined after the

126

optimization of MS/MS conditions as follows: m/z = 295.0 and 194.6–195.6 at 21 eV for

127

13-(E,E)-HODE; m/z = 295.0 and 170.5–171.5 at 24 eV for 9-(E,E)-HODE; m/z = 295.0

128

and 182.6-183.6 at 22 eV for both 10-(Z,E)-HODE and 12-(Z,E)-HODE; and m/z = 299.0

129

and 197.6–198.6 at 15 eV for 13-HODE-d4. Plasma total hydroxyoctadecadienoic acid

130

(tHODE) levels were determined from the total amount of the products of the

131

free-radical-mediated oxidation of the four isomers: 13-(Z,E)-HODE, 13-(E,E)-HODE,

132

9-(Z,E)-HODE, and 9-(E,E)-HODE.

133 134

Open field test.

135

The open field test was performed according to a modified version of the test

136

described previously24. The open field apparatus was constructed by a square box with a

137

black wall (35×35×20 cm). The field was divided two areas: the central and peripheral

138

zones. A central square (15×15 cm) was set in the middle of the open field, and another

7

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

139

square was set in the peripheral area. A mouse was placed in one corner of the field and

140

allowed to explore for 10 min. Locomotor activity (movement distance, line crossing, and

141

movement rate) and anxiety-related parameters (freezing, entry into central area, and

142

latency of entry into central area) were measured with the ANY-maze video tracking

143

system (Brain Science Idea Co., Ltd., Osaka, Japan). The field was cleaned before the start

144

of each session.

145 146

Statistics.

147

The results were expressed as means ± standard error. Outliers were omitted by

148

the Smirnov-Grubbs’ outlier test. Statistical analysis was performed by using analysis of

149

variance (ANOVA) followed by Tukey’s test for multiple comparisons with

150

Ekuseru-Toukei 2012 (Social Survey Research Information Co., Ltd., Tokyo, Japan).

151

Differences with a probability of 5% or less were considered significant.

8

ACS Paragon Plus Environment

Page 8 of 32

Page 9 of 32

Journal of Agricultural and Food Chemistry

152

■ Results

153

Effect of OPIACE on obesity-related parameters in TSOD mouse.

154

We investigated the effect of OPIACE (the nutrient composition indicated in

155

Table 1) on obesity, which is a major risk factor for the development of type 2 diabetes, in

156

TSOD mice. As shown in Figures 2A and B, body weight and food intake of TSOD mice

157

(black circle) were significantly higher than those of control TSNO mice (white circle)

158

throughout the experiments. However, there were no significant differences in body weight

159

and food intake between TSOD and OPIACE-fed TSOD (gray triangle) mice (Figures 2A

160

and B). Whereas plasma triglyceride level and epididymal WAT weight, which are related

161

to obesity, were significantly higher in TSOD mice (black bar) than in TSNO mice (white

162

bar), these parameters were not significantly different between TSOD mice and

163

OPIACE-fed TSOD mice (gray bar) (Figures 2C and D). The results indicate that

164

OPIACE has no effect on obesity in TSOD mice.

165 166

Effect of OPIACE on blood glucose level in TSOD mouse.

167

Next, we investigated the effect of OPIACE on the diabetic phenotypes in TSOD

168

mice. As shown in Figure 3, non-fasting blood glucose levels in TSOD mice (black circle)

169

gradually increased with age, and a significant increase was noted from 6 weeks of age

170

compared with age-matched TSNO mice (white circle). Whereas non-fasting blood glucose

171

levels in OPIACE-fed TSOD mice (gray triangle) were comparable to those in TSOD mice

172

until 9 weeks of age, glucose levels in the OPIACE-fed TSOD mice were significantly

173

lower than those in the TSOD mice up to 24 weeks of age (Figure 3). The results indicate

174

that OPIACE partially attenuates blood glucose elevation in TSOD mice over the long

175

term.

9

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

Page 10 of 32

176 177

Effect of OPIACE on glucose tolerance in TSOD mouse.

178

To evaluate the effect of OPIACE on glucose tolerance, we performed OGTT in

179

TSOD mice at 5, 8, 11, 13, 15, and 24 weeks of age. At 5 weeks of age, there was no

180

obvious abnormality in glucose tolerance of TSOD mice (black circle) compared with

181

age-matched TSNO mice (white circle) (Figure 4). However, glucose levels after glucose

182

loading in TSOD mice increased with age, and a significant increase was noted from 8

183

weeks of age compared with age-matched TSNO mice (Figure 4), indicating that glucose

184

tolerance in TSOD mice was impaired from around 8 weeks of age, consistent with our

185

previous report25. Glucose tolerance in TSOD mice was markedly impaired after 11 weeks

186

of age. On the other hand, the impaired glucose tolerance in TSOD mice at 11 and 24

187

weeks of age was almost completely attenuated by OPIACE (gray triangle). Glucose levels

188

after glucose loading in OPIACE-fed TSOD mice at 13 and 15 weeks of age tended to be

189

lower than those of age-matched TSOD mice, although there were no significant

190

differences between those glucose levels (Figure 4). Those findings indicate that the

191

impaired glucose tolerance in TSOD mice is partially inhibited by OPIACE.

192 193

Effect of OPIACE on oxidative stress in TSOD mouse.

194

It is known that oxidative stress induces insulin resistance that in turn leads to the

195

progression of type 2 diabetes5. To investigate the effect of OPIACE on oxidative stress in

196

vivo, we examined plasma levels of tHODE, which has been used as a biomarker for the

197

evaluation of oxidative stress23, in TSNO and TSOD mice. tHODE were determined from

198

the total amount of the four isomers: 13-(Z,E)-HODE, 13-(E,E)-HODE, 9-(Z,E)-HODE,

199

and

9-(E,E)-HODE,

which

were

measured

with

LC-MS/MS

10

ACS Paragon Plus Environment

as

reported

Page 11 of 32

Journal of Agricultural and Food Chemistry

200

previously23(Figure 5A; also see Materials and Methods). As shown in Figure 5B, plasma

201

tHODE levels in TSOD mice (black bar) were significantly higher than those in TSNO

202

mice (white bar), consistent with our previous report4, and the levels were maintained

203

during the measurements. Plasma tHODE levels in OPIACE-fed TSOD mice (gray bar)

204

tended to decrease with feeding duration, and significantly decreased at 13 weeks of age

205

compared with those in TSOD mice. The results indicate that OPIACE mildly attenuates

206

oxidative stress in TSOD mice by long-term feeding.

207 208

Effect of OPIACE on locomotor activity and anxiety-like behavior in TSOD mice.

209

It has been reported that locomotor activity is reduced in type 2 diabetes model

210

animals, including db/db mouse24, Akita mouse26, and high-fat fed rat27. The behavioral

211

abnormality is more clearly observed in older animals with diabetes than younger

212

animals24,27. In addition, repeated hyperglycemia was found to reduce locomotor activity

213

in an open field test28, which is used to assess general locomotor activity and as an initial

214

screen for anxiety-related behavior in rodents29. To investigate the long-term effects of

215

OPIACE on the behavioral traits of TSOD mice, we performed an open field test in TSOD

216

mice at 36 weeks of age. We found that the differences in body weight and food intake

217

between TSNO and TSOD mice remained unchanged at 36 weeks of age (body weights of

218

TSNO and TSOD mice were 37.8 ± 0.88 and 64.6 ± 1.24 g, respectively; food intake in

219

TSNO and TSOD mice was 3.42 ± 0.13 and 4.64 ± 0.18 g/day, respectively), and that

220

there were no significant differences in non-fasting blood glucose level and glucose

221

tolerance between TSNO and TSOD mice (non-fasting blood glucose levels in TSNO and

222

TSOD mice were 120 ± 0.85 and 136 ± 9.45 mg/dL, respectively; OGTT AUCs in TSNO

223

and TSOD mice were 2.53 ± 0.09 and 3.08 ± 0.71 arbitrary units, respectively) (Table 2),

11

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

224

as observed in other diabetic model ob/ob mice of a similar age30. Movement distance

225

(Figure 6B), line crossing (Figure 6C), and movement rate (Figure 6D) were

226

significantly decreased in TSOD mice (black bar) compared with TSNO mice (white bar),

227

indicating that TSOD mice have low locomotor activity. OPIACE-fed TSOD mice (gray

228

bar) tended to attenuate the decreases in locomotor activity compared with TSOD mice

229

(Figure 6B-D), although there were no significant differences in the results. TSOD mice

230

showed increased freezing (Figure 6E), decreased frequency of entry into the central

231

square (Figure 6F), and longer latency of entry into the central square (Figure 6G)

232

compared with TSNO mice, indicating that TSOD mice have anxiety-like phenotypes.

233

Interestingly, the anxiety-like phenotypes in free-fed TSOD mice were significantly

234

attenuated by the feeding of OPIACE (Figure 6E and G). Thus, long-term feeding of

235

OPIACE has a preventive effect on the anxiety-like symptoms in type 2 diabetes model

236

mouse.

12

ACS Paragon Plus Environment

Page 12 of 32

Page 13 of 32

Journal of Agricultural and Food Chemistry

237

■ Discussion

238

Our results indicated that OPIACE attenuated chronic hyperglycemia (Figure 3)

239

and impaired glucose tolerance (Figure 4) in TSOD mice. Those effects are likely to be due

240

to oleuropein because it is the major component in OPIACE (Table 1). It has been

241

demonstrated that an oleuropein-containing diet improved insulin sensitivity in middle-aged

242

overweight men31, and decreased homeostasis model assessment as an index of insulin

243

resistance (HOMA-IR) in high-fat diet fed mice32. In addition, plasma insulin levels were

244

unchanged between TSOD mice and OPIACE-fed TSOD mice from 5 to 13 weeks of age

245

(unpublished data). These findings suggest that the improvement effects of OPIACE on

246

blood glucose level are due to not the acceleration of insulin secretion but the improvement

247

of insulin resistance.

248

As oleuropein has potent antioxidative activity in vitro17, we expected that the

249

preventive effects of an oleuropein-rich diet on blood glucose elevation in TSOD mice

250

would be partly due to the antioxidative capacity of oleuropein. However, OPIACE did not

251

clearly reduce plasma tHODE levels in TSOD mice even at 11 weeks of age, which is the

252

age when OPIACE exerted a preventive effect on the diabetic phenotypes (Figure 5B).

253

Furthermore, OPIACE had no effect on obesity in TSOD mice (Figure 2). It was reported

254

that potent antioxidants resveratrol33 and epigallocatechin-334 suppressed high-fat diet

255

induced obesity and hyperglycemia. In addition, in a previous DNA microarray analysis,

256

oleuropein was found to have beneficial effects on non-alcoholic fatty liver disease by

257

exerting multiple effects, including anti-lipogenesis, anti-inflammation, and anti-insulin

258

resistance35, and the multiple effects of oleuropein are likely to contribute to the

259

improvement of the diabetic phenotypes. Therefore, our results suggest that an

260

oleuropein-rich diet exerts not only a mild antioxidant effect but also other effects for the

13

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

261

attenuation of the increased glucose levels in TSOD mice. A recent meta-analysis indicated that diabetes is associated with the increased

262 263

possibility of having anxiety disorders36. In fact, our results indicated that TSOD mice

264

exhibited anxiety-like behavior (Figure 6) consistent with other diabetic models, including

265

ob/ob mouse37, Akita mouse26, and high-fat fed mouse38. Some reports suggest that the

266

central nervous system disorder is a kind of diabetic complication9. It is easily presumed

267

that the comorbidity of diabetes and anxiety disorder may lead to a lower quality of life

268

than the morbidity of those diseases separately39. In addition, it was recently suggested that

269

the treatment of anxiety disorder may exacerbate the symptoms of diabetes, as selective

270

serotonin reuptake inhibitor, which is used for the treatment of mood and anxiety disorders,

271

promotes insulin resistance and insulin secretion in Min6 cells40. Thus, as shown in Figure

272

6, our results suggested that OPIACE may be a valuable supplement for reducing

273

diabetes-related anxiety, although the mechanism for attenuating the anxiety-like behavior

274

in TSOD mice is unknown. Blood glucose levels in TSOD mice and OPIACE-fed TSOD

275

mice at 36 weeks of age were not significantly increased compared with those in TSNO

276

mice, probably because food intake in TSOD mice tended to decrease with age (Table 2).

277

The improvement of blood glucose levels in TSOD mice over the long term might

278

contribute to the anti-anxiety effect of OPIACE.

279

In conclusion, we demonstrated that OPIACE attenuated chronic hyperglycemia

280

and impaired glucose tolerance in TSOD mice over the long term. Furthermore, OPIACE

281

attenuated the anxiety-like behavior in aged TSOD mice. Our results suggest that an

282

oleuropein-rich diet has the potential to inhibit the progression of type 2 diabetes and

283

diabetes-related behavioral disorder.

14

ACS Paragon Plus Environment

Page 14 of 32

Page 15 of 32

Journal of Agricultural and Food Chemistry

284

■ Author information

285

Funding This work was supported by a Grant-in-Aid for Young Scientist (B) (Grant

286 287

Number 25860183) from the Japan Society for the Promotion of Science (JSPS), and by a

288

donation from Eisai Food and Chemical Co., Ltd.

289 290

Notes The authors declare no competing financial interest.

291 292 293

■ Acknowledgements

294

We thank Y. Fujita of AIST for technical assistance; Y. Senba of JAC Co., Ltd. for

295

supporting animal care; and Dr. W. Suzuki of Tsumura Co., Ltd., and Dr. K. Ohwada of

296

AIST for valuable suggestions and discussion.

297 298

■ Associated content

299

Supporting information This information is available free of charge via the Internet at http://pubs.acs.org.

300 301 302 303

■ Abbreviations used

304

OPIACE, olive leaf extract with more than 35% (w/w) oleuropein content; TSOD,

305

Tsumura Suzuki Obese Diabetes; TSNO, Tsumura Suzuki Non Obesity; WAT, white

306

adipose tissue; OGTT, oral glucose tolerance test; AUC, area under the curve; HPLC, high

307

performance liquid chromatography; HODE, hydroxyoctadecadienoic acid; LC-MS/MS,

15

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

308

liquid chromatography-mass/mass spectrometry; ANOVA, analysis of variance.

16

ACS Paragon Plus Environment

Page 16 of 32

Page 17 of 32

Journal of Agricultural and Food Chemistry

309

References

310

1.

311

2. Matsuzawa-Nagata, N.; Takamura, T.; Ando, H.; Nakamura, S.; Kurita, S.; Misu, H.; Ota, T.; Yokoyama, M.; Honda, M.; Miyamoto, K.; Kaneko, S., Increased oxidative stress precedes the onset of high-fat diet-induced insulin resistance and obesity. Metabolism 2008, 57, 1071-1077.

312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335

Lin, Y.; Sun, Z., Current views on type 2 diabetes. J. Endocrinol. 2010, 204, 1-11.

3. Suzuki, W.; Iizuka, S.; Tabuchi, M.; Funo, S.; Yanagisawa, T.; Kimura, M.; Sato, T.; Endo, T.; Kawamura, H., A new mouse model of spontaneous diabetes derived from ddY strain. Exp. Anim. 1999, 48, 181-189. 4. Murotomi, K.; Umeno, A.; Yasunaga, M.; Shichiri, M.; Ishida, N.; Abe, H.; Yoshida, Y.; Nakajima, Y., Type 2 diabetes model TSOD mouse is exposed to oxidative stress at young age. J. Clin. Biochem. Nutr. 2014, 55, 216-220. 5. Evans, J. L.; Goldfine, I. D.; Maddux, B. A.; Grodsky, G. M., Are oxidative stress-activated signaling pathways mediators of insulin resistance and beta-cell dysfunction? Diabetes 2003, 52, 1-8. 6. Krentz, A. J.; Clough, G.; Byrne, C. D., Interactions between microvascular and macrovascular disease in diabetes: pathophysiology and therapeutic implications. Diabetes Obes. Metab. 2007, 9, 781-791. 7. De Felice, F. G.; Ferreira, S. T., Inflammation, defective insulin signaling, and mitochondrial dysfunction as common molecular denominators connecting type 2 diabetes to Alzheimer disease. Diabetes 2014, 63, 2262-2272. 8. Santiago, J. A.; Potashkin, J. A., System-based approaches to decode the molecular links in Parkinson's disease and diabetes. Neurobiol. Dis. 2014, 72PA, 84-91. 9 Siddiqui, S., Depression in type 2 diabetes mellitus--a brief review. Diabetes Metab. Syndr. 2014, 8, 62-65. 10. Collins, M. M.; Corcoran, P.; Perry, I. J., Anxiety and depression symptoms in patients with diabetes. Diabet. Med. 2009, 26, 153-161.

17

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364

11. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. The Diabetes Control and Complications Trial Research Group. N. Engl. J. Med. 1993, 329, 977-986. 12. Geijselaers, S. L.; Sep, S. J.; Stehouwer, C. D.; Biessels, G. J., Glucose regulation, cognition, and brain MRI in type 2 diabetes: a systematic review. Lancet Diabetes Endocrinol. 2015, 3, 75-89. 13. Wu, S. B.; Yue, G. G.; To, M. H.; Keller. A. C.; Lau, C. B.; Kennelly, E. J., Transport in Caco-2 cell monolayers of antidiabetic cucurbitane triterpenoids from Momordica charantia fruits. Planta Med. 2014, 80, 907-911. 14. Bhathena, S. J,; Velasquez, M. T., Beneficial role of dietary phytoestrogens in obesity and diabetes. Am. J. Clin. Nutr. 2002, 76, 1191-1201. 15. Servili, M.; Sordini, B.; Esposto, S.; Urbani, S.; Veneziani,G.; Maio, I. D.; Selvaggini R,; Taticchi, A., Biological Activities of Phenolic Compounds of Extra Virgin Olive Oil. Antioxidants 2014, 3, 1-23. 16 Omar, S. H., Oleuropein in olive and its pharmacological effects. Sci. Pharm. 2010, 78, 133-154. 17. Lee, O. H.; Lee, B. Y.; Lee, J.; Lee, H. B.; Son, J. Y.; Park, C. S.; Shetty, K.; Kim, Y. C., Assessment of phenolics-enriched extract and fractions of olive leaves and their antioxidant activities. Bioresour. Technol. 2009, 100, 6107-6113. 18. El, S. N.; Karakaya, S., Olive tree (Olea europaea) leaves: potential beneficial effects on human health. Nutr. Rev. 2009, 67, 632-638. 19. Park, S.; Choi, Y.; Um, S. J.; Yoon, S. K.; Park, T., Oleuropein attenuates hepatic steatosis induced by high-fat diet in mice. J. Hepatol. 2011, 54, 984-993. 20. Poudyal, H.; Campbell, F.; Brown, L., Olive leaf extract attenuates cardiac, hepatic, and metabolic changes in high carbohydrate-, high fat-fed rats. J. Nutr. 2010, 140, 946-953. 21. Grossi, C.; Rigacci, S.; Ambrosini, S.; Dami, T. E.; Luccarini, I.; Traini, C.; Failli, P.; Berti, A.; Casamenti, F.; Stefani, M., The polyphenol oleuropein aglycone protects TgCRND8 mice against Ass plaque pathology. PLoS One 2013, 8, e71702. 18

ACS Paragon Plus Environment

Page 18 of 32

Page 19 of 32

Journal of Agricultural and Food Chemistry

365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394

22. Jemai, H.; El Feki, A.; Sayadi, S., Antidiabetic and antioxidant effects of hydroxytyrosol and oleuropein from olive leaves in alloxan-diabetic rats. J. Agric. Food Chem. 2009, 57, 8798-8804. 23. Yoshida, Y.; Kodai, S.; Takemura, S.; Minamiyama, Y.; Niki, E., Simultaneous measurement of F2-isoprostane, hydroxyoctadecadienoic acid, hydroxyeicosatetraenoic acid, and hydroxycholesterols from physiological samples. Anal. Biochem. 2008, 379, 105-115. 24. Sharma, A. N.; Elased, K. M.; Garrett, T. L.; Lucot, J. B., Neurobehavioral deficits in db/db diabetic mice. Physiol. Behav. 2010, 101, 381-388. 25. Murotomi, K.; Umeno, A.; Yasunaga, M.; Shichiri, M.; Ishida, N.; Abe, H.; Yoshida, Y.; Nakajima, Y., Switching from singlet-oxygen-mediated oxidation to free-radical-mediated oxidation in the pathogenesis of type 2 diabetes in model mouse. Free Radic. Res. 2014, in press. 26. Maher, P.; Dargusch, R.; Ehren, J. L.; Okada, S.; Sharma, K.; Schubert, D., Fisetin lowers methylglyoxal dependent protein glycation and limits the complications of diabetes. PLoS One 2011, 6, e21226. 27. Erdos, B.; Kirichenko, N.; Whidden, M.; Basgut, B.; Woods, M.; Cudykier, I.; Tawil, R.; Scarpace, P. J.; Tumer, N., Effect of age on high-fat diet-induced hypertension. Am. J. Physiol. Heart Circ. Physiol. 2011, 301, H164-172. 28. Moghadami M.; Moghimi, A.; Ahangar, E.; Jalal, R.; Rassouli, M. B.; Shahri, N. M., Effects of infantile repeated hyperglycemia on behavioral alterations in adult male and female rats. Basic. Clin. Neurosci. 2012, 3, 60-67. 29 Prut, L.; Belzung, C., The open field as a paradigm to measure the effects of drugs on anxiety-like behaviors: a review. Eur. J. Pharmacol. 2003, 463, 3-33. 30 Genuth, S. M.; Przybylski, R. J.; Rosenberg, D. M., Insulin resistance in genetically obese, hyperglycemic mice. Endocrinology 1971, 88, 1230-1238. 31. de Bock, M.; Derraik, J. G.; Brennan, C. M.; Biggs, J. B.; Morgan, P. E.; Hodgkinson, S. C.; Hofman, P. L.; Cutfield, W. S., Olive (Olea europaea L.) leaf polyphenols improve insulin sensitivity in middle-aged overweight men: a randomized, placebo-controlled, crossover trial. PLoS One 2013, 8, e57622. 19

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422

32. Kim, S. W.; Hur, W.; Li, T. Z.; Lee, Y. K.; Choi, J. E.; Hong, S. W.; Lyoo, K. S.; You, C. R.; Jung, E. S.; Jung, C. K.; Park, T.; Um, S. J.; Yoon, S. K., Oleuropein prevents the progression of steatohepatitis to hepatic fibrosis induced by a high-fat diet in mice. Exp. Mol. Med. 2014, 46, e92. 33. Kim, S.; Jin, Y.; Choi, Y.; Park, T., Resveratrol exerts anti-obesity effects via mechanisms involving down-regulation of adipogenic and inflammatory processes in mice. Biochem. Pharmacol. 2011, 81, 1343-1351. 34. Bose, M.; Lambert, J. D.; Ju, J.; Reuhl, K. R.; Shapses, S. A.; Yang, C. S., The major green tea polyphenol, (-)-epigallocatechin-3-gallate, inhibits obesity, metabolic syndrome, and fatty liver disease in high-fat-fed mice. J. Nutr. 2008, 138, 1677-1683. 35. Kim, Y.; Choi, Y.; Park, T., Hepatoprotective effect of oleuropein in mice: mechanisms uncovered by gene expression profiling. Biotechnol. J. 2010, 5, 950-960. 36. Smith, K. J.; Beland, M.; Clyde, M.; Gariepy, G.; Page, V.; Badawi, G.; Rabasa-Lhoret, R.; Schmitz, N., Association of diabetes with anxiety: a systematic review and meta-analysis. J. Psychosom. Res. 2013, 74, 89-99. 37. Asakawa, A.; Inui, A.; Inui, T.; Katsuura, G.; Fujino, M. A.; Kasuga, M., Leptin treatment ameliorates anxiety in ob/ob obese mice. J. Diabetes Complications 2003, 17, 105-107. 38. Kaczmarczyk, M. M.; Machaj, A. S.; Chiu, G. S.; Lawson, M. A.; Gainey, S. J.; York, J. M.; Meling, D. D.; Martin, S. A.; Kwakwa, K. A.; Newman, A. F.; Woods, J. A.; Kelley, K. W.; Wang, Y.; Miller, M. J.; Freund, G. G., Methylphenidate prevents high-fat diet (HFD)-induced learning/memory impairment in juvenile mice. Psychoneuroendocrinology 2013, 38, 1553-1564. 39. Santos, M. A.; Ceretta, L. B.; Reus, G. Z.; Abelaira, H. M.; Jornada, L. K.; Schwalm, M. T.; Neotti, M. V.; Tomazzi, C. D.; Gulbis, K. G.; Ceretta, R. A.; Quevedo, J., Anxiety disorders are associated with quality of life impairment in patients with insulin-dependent type 2 diabetes: a case-control study. Rev. Bras. Psiquiatr. 2014, 36, 298-304.

20

ACS Paragon Plus Environment

Page 20 of 32

Page 21 of 32

Journal of Agricultural and Food Chemistry

423 424 425

40. Isaac, R.; Boura-Halfon, S.; Gurevitch, D.; Shainskaya, A.; Levkovitz, Y.; Zick, Y., Selective serotonin reuptake inhibitors (SSRIs) inhibit insulin secretion and action in pancreatic beta cells. J. Biol. Chem. 2013, 288, 5682-5693.

21

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

426

Figure captions

427

Figure 1. Chemical structure of oleuropein

428 429

Figure 2. Effects of OPIACE on obesity-related parameters

430

Time course of changes in body weight (A), food intake (B), plasma triglyceride

431

level (C), and epididymal WAT weight (D) in TSNO (white circle), TSOD (black circle),

432

and 0.2% (w/w) OPIACE-fed TSOD (gray triangle) mice. Results are expressed as means ±

433

standard error (n = 6-12). Statistical analyses were carried out using ANOVA (Tukey’s

434

post-hoc test). *Significant difference from age-matched TSNO mice (p < 0.05).

435 436

Figure 3. Effect of OPIACE on blood glucose level

437

Time course of changes in non-fasting blood glucose level in TSNO (white circle),

438

TSOD (black circle), and 0.2% (w/w) OPIACE-fed TSOD (gray triangle) mice. Results are

439

expressed as means ± standard error (n = 11-12). Statistical analyses were carried out using

440

ANOVA (Tukey’s post-hoc test). *Significant difference from age-matched TSNO mice (p

441

< 0.05). #Significant difference from age-matched TSOD mice (p < 0.05).

442 443

Figure 4. Effect of OPIACE on glucose tolerance

444

Time course of changes in glucose tolerance in TSNO (white circle), TSOD (black

445

circle), and 0.2% (w/w) OPIACE-fed TSOD (gray triangle) mice at 5, 8, 11, 13, 15, and 24

446

weeks of age. Results are expressed as means ± standard error (n = 11-12). Statistical

447

analyses were carried out using ANOVA (Tukey’s post-hoc test). *Significant difference

448

from age-matched TSNO mice (p < 0.05). # Significant difference from age-matched

449

TSOD mice (p < 0.05).

450 22

ACS Paragon Plus Environment

Page 22 of 32

Page 23 of 32

Journal of Agricultural and Food Chemistry

451

Figure 5. Effects of OPIACE on plasma levels of lipid oxidation products

452

(A) Typical chromatograms obtained from LC-MS/MS of mouse plasma samples

453

measured in this study, (B) Time course of changes in the plasma levels of lipid oxidation

454

products in TSNO (white bar), TSOD (black bar) and 0.2% (w/w) OPIACE-fed TSOD

455

(gray bar) mice. Values in age-matched TSNO mice are set to 1. Results are expressed as

456

means ± standard error (n = 4-6). Statistical analyses were carried out using ANOVA

457

(Tukey’s post-hoc test). *Significant difference from age-matched TSNO mice (p < 0.05).

458

#Significant difference from age-matched TSOD mice (p < 0.05).

459 460

Figure 6. Effect of OPIACE on locomotor activity and anxiety-like behavior

461

(A) Representative trajectories of TSNO, TSOD, and 0.2% (w/w) OPIACE-fed

462

TSOD mice in the open field test. Movement distance (B), line crossing (C), movement rate

463

(D), freezing (E), entry into central square (F), and latency of entry into central square (G)

464

were measured for 10 min. Results are expressed as means ± standard error (n=6 each).

465

Statistical analyses were carried out using ANOVA (Tukey’s post-hoc test).

23

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

Table1. Nutrient composition of OPIACE Nutrient composition

(%)

Oleuropein

35

Phenolic compounds

7

Saccharides

54

Ignition residue

2

Moisture

2

Phenolic compounds consist of 0.08% caffeic acid, 0.06% vanillic acid, 0.04% vanillin, 0.26% rutin, 1.89% luteolin-7-glucoside, 1.04% apigenin-7-glucoside, and 3.8% oleuroside.

24

ACS Paragon Plus Environment

Page 24 of 32

Page 25 of 32

Journal of Agricultural and Food Chemistry

Table2. Body weight, food intake, non-fasting blood glucose level, and OGTT AUC in TSNO, TSOD, and OPIACE-fed TSOD mice at 36 weeks of age TSNO

TSOD

Body weight (g)

37.8 ± 0.88

64.6 ± 1.24

Food intake (g/day)

3.42 ± 0.13

4.64 ± 0.18

5.19 ± 0.20

120 ± 0.85

136 ± 9.45

152 ± 32.5

2.53 ± 0.09

3.08 ± 0.71

2.69 ± 0.42

Non-fasting blood glucose (mg/dL) OGTT AUC (× ×104, arbitrary unit)

TSOD+OPIACE ∗ ∗



65.2 ± 0.68



Results are expressed as means ± standard error (n = 6 each). Statistical analyses were carried out using ANOVA (Tukey’s post-hoc test). ∗Significant difference from age-matched TSNO mice (p < 0.05).

25

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

Page 26 of 32

Figure 1

466

O

O

O

OH

OCH3

OH

O O

O OH

OH

OH

HO

26

ACS Paragon Plus Environment

Page 27 of 32

Journal of Agricultural and Food Chemistry

Figure 2

27

ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

Page 28 of 32

Figure 3

Non-fasting blood glucose 400

TSNO



TSOD

(mg/dL)

∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗





∗ ∗

200





TSOD+OPIACE

300



∗ ∗

# # #



∗#

# #

#

# #

#

100

0

4

6

8

10 12 14 16 18 20 22 24 Age (week)

28

ACS Paragon Plus Environment

Page 29 of 32

Journal of Agricultural and Food Chemistry

Figure 4

5 weeks of age

600

TSNO

500

500

TSOD

400

TSOD+OPIACE

300



100

Blood glucose (mg/dL)

0 15 30

60

120

11 weeks of age

500

∗ ∗

400

#

500 400

∗ ∗

60

∗ ∗

∗ ∗

#

∗ ∗

200

#



120

13 weeks of age

400 300

100

0 15 30

60

120

15 weeks of age

∗ ∗



200

0

0 15 30

100

60

500



400



∗ #

300 200

#

100 0 15 30

60

120

120

24 weeks of age

600

∗ ∗

300

0

0 15 30

500

#

200

600

0

600

300

0



200 100

600

100



400 300

200

0

8 weeks of age

600

0

0 15 30

Time after glucose loading (min)

29

ACS Paragon Plus Environment

60

120

Journal of Agricultural and Food Chemistry

Figure 5

30

ACS Paragon Plus Environment

Page 30 of 32

Page 31 of 32

Journal of Agricultural and Food Chemistry

Figure 6

TSNO

(B)

TSOD

(C)

Distance

Line crossing

20

200

15

150

Frequency

(m)

p<