EFFECTS OF FEEDING OYSTER ON LIPID MeTABOLISM ...oyster-symposium.bangor.ac.uk/abstracts/Session...

EFFECTS OF FEEDING OYSTER ON LIPID METABOLISM IN RATS

Tsubasa Haraguchi and Kazunari Tanaka

Graduate School of Human Health Science,University of Nagasaki

Japan

Tokyo

Nagasaki

Fatty acid compositions (%)

Major components of lyophilized oyster（/100g）

Protein 44.1g1Fat 8.6gTaurine 14.5 mg

14:0 7.716:0 25.116:1 5.518:0 7.418:1 8.418:2 (n-6) 3.118:3 (n-3) 0.820:1 1.720:4 (n-6) 2.620:5 (n-3) 14.022:6 (n-3) 6.2

Fresh oyster meat was separated from the shell, minced and lyophilized.

University of Nagasaki, Siebold

Sterol contentsTotal sterols (mg/g lyophilized oyster) 9.7

Sterol compositions (%)C26-Sterol b2.1Cholesterol 52.1Brassicasterol 16.524-Methylene cholesterol 20.1Sitosterol q6.7

Rats were fed a diet ad libitum for 3 weeks

Schedule

SD rats（♂5 wk old）

6 hour fasting• Serum and liver lipid concentrations • Fecal steroid excretion

(%)・Mineral mixture・Vitamin mixture・t- Butylhydroquinone・Choline bitartrate・0.1% Cholesterol

0 20 40 60 80 100

Soybean oil Cellulose

α-CornstarchCasein カゼインβ-Cornstarch Sucrose

Dietary composition(based on AIN-93G composition)

Oyster 45.4%

Soybean protein 22.1%

The protein content was adjusted to 20% on an isonitrogenous basis. Oyster diet contains0.33% cholesterol, 0.21% phytosterols, 0.66% taurine,1.01% n-3 fatty acids.


Serum and liver lipids in rats fed diet added cholesterolat the leuel of 0.1%

0

20

40

60

80

100

120

(mg/

dL)

Serum cholesterol

05

10152025303540

(mg/

dL)

Serum Triglyceride

0

25

50

75

100

(%)

Serum HDL-/total cholesterol ratio

0.0

2.0

4.0

6.0

8.0

(mg/

g liv

er)

Liver cholesterol

0

5

10

15

20

25

30

35

(mg/

g liv

er)

Liver triglyceride

Con

trol

Con

trol

Con

trol

Con

trol

Con

trol

Oys

ter

Oys

ter

Oys

ter

Oys

ter

Oys

ter

Soyb

ean

Soyb

ean

Soyb

ean

Soyb

ean

Soyb

ean a,b,c：Values bearing letters are

significantly different at p < 0.05.Means ± SE of 6 rats.

a

b

c

a

bb

bb

a

b

bab

a

a


a,b,c：Values bearing letters are significantly different at p < 0.05.

Means ± SE of 6 rats.

Fecal neutral and acidic steroid excretion in rats fed diet containing 0.1% cholesterol


0

10

20

30

40

50

60

（m

g/da

y) AcidicsteroidsNeutralsteroidsa

b

Con

trol

Soyb

ean

c

Oys

ter


Schedule


6 hour fasting

• Serum and liver lipid concentrations • Fecal steroid excretion

(%)・Mineral mixture・Vitamin mixture・t- Butylhydroquinone・Choline bitartrate・Cholesterol

0 20 40 60 80 100



Dietary composition (based on AIN-93G composition)

Defatted oyster 42.6%

Soybean protein 22.1%

The protein content was adjusted to 20% on an isonitrogenous basis.Defatted oyster diet contains 0.33% cholesterol


0

25

50

75

100

125

150

(mg/

dL)

Serum cholesterol

Serum and liver lipids in rats

0

10

20

30

40

50

(%)

SerumHDL-/total cholesterol ratio

0

10

20

30

40

(mg/

dL)

Serum triglyseride

0

2

4

6

8

10

(mg/

g liv

er)

Liver cholesterol

0

10

20

30

40

50

(mg/

g liv

er)

Liver triglyceridel



Con

trol

Def

atte

d oy

ster

Soyb

ean

a

a

ba

bb

a

b

c

a

bb


Con

trol

Def

atte

d oy

ster

Soyb

ean

Con

trol

Def

atte

d oy

ster

Soyb

ean

Con

trol D

efat

ted

oyst

er

Soyb

ean

Con

trol D

efat

ted

oyst

er

Soyb

ean

Fecal neutral and acidic steroid excretion in ratsUniversity of Nagasaki, Siebold

0

10

20

30

40

50

60

70

(mg/

day) Acidic

steroidsNeutralsteroids

b

Con

trol

Soyb

ean

Def

atte

d oy

ster

a

b



9

Oyster meat

boiled at 75℃

+ endoprotease from bacillus subtilis

+ exoprotease from Aspergillus oryzae

Undigested proteins were removed by centrifugation

Oyster extract containing high molecular peptide was obtained

Oyster extract contained・36% protein・0.1% fat・54%carbohydrate・4.1% moisture・3.6% ash

Preparation of oyster extract containing high molecular peptides


Experimental schedule


(%) ・Mineral mixture・Vitamin mixture・t- Butylhydroquinone・Choline bitartrate・Cholesterol

0 20 40 60 80 100



Dietary composition (based on AIN-93G composition)

Casein16.3%

Oyster extract13.9%

The protein content was adjusted to 20% on an isonitrogenous basis.A quarter of the casein was replaced with oyster extract in oyster diet.



6 hour fasting

• Serum and liver lipid concentrations • Fecal steroid excretion

0

40

80

120

160m

g/dL

Con

trol

0

20

40

60

80

100

120

mg/

g liv

er

Con

trol

Serum triglyceride Liver triglyceride

0

50

100

150

200

mg/

dL

Con

trol

0

20

40

60

mg/

g liv

er

Con

trol

Serum cholesterol Liver cholesterolH

-pep

H-p

ep

*

*

H-p

ep

Serum and liver lipids in rats fed diets added oyster extractcontaining high molecular peptides

*：Significant difference from the control group at p < 0.05.Means ± SE of 6 rats.

H-p

ep


0

5.0

10.0

15.0

nmon

/min

/mg

prot

ein

Con

trol

Fatty acid synthase

*

20.0

0

100

200

Con

trol

300

*

nmon

/min

/mg

prot

ein

0

10

20

30

40

Con

trol

Malic enzyme

Oys

ter

pep

0

5.0

10.0

15.0

nmon

/min

/mg

prot

ein

Con

trol

20.0

0

2.0

4.0

6.0

Con

trol

Carnitine palmitoyltransferase

Glucose 6-phosphatedehydrogenase

Phosphatidic acidphosphohydrolase

nmon

/min

/mg

prot

ein

nmon

/min

/mg

prot

ein


*：Significant difference from the control group at p < 0.05.


H-p

ep

H-p

epH

-pep

H-p

ep

Preparation of oyster extract containing low molecular peptides

Enzyme-A Extract

Oyster peptide AOyster

Oyster peptide B

Enzyme-B Extract

Oyster

Oyster peptide B-1

Treatment of dextrin

Commercial product

Experimental materials


Composition of oyster peptide B-1* (%)

Total

Oyster peptide B 88.4-89.4Dextrin 9.6Citric acid 1-2

100* B-1, treated B with dextrin

Dietary compositionbased on AIN-76 (15% high-fat diet)

0 10 20 30 (%)

Casein16.3%Casein16.3%

A13.5%B11.5%

Oyster peptide A diet

Oyster peptide B diet


(%)・Mineral mix ・Vitamin mix ・Choline bitartarte・DL-Methionine

0 20 40 60 80 100

Sucroseβ-Cornstarch

Corn oil Cellulose

Casein21.7% Lard

10 30 50 70 90

Casein16.3%

B-112.5% Oyster peptide B-1* diet * B-1, treated B with dextrin

Schedule

6 hour fastingSD rats（♂5 wk old）


• Serum and liver lipid concentrations

The protein content was adjusted to 5% on an isonitrogenous basis.A quarter of the casein was replaced with oyster extract in oyster diet.

University of Nagasaki, SieboldSerum lipid and glucose levels

Mean±SE (n=7-8)ab, Different letters, p<0.05

mg/

dL

Cholesterol

0

20

40

60

80

100

120

Con

trol

A B B-1

Oyster peptides

Phospholipid

0

50

100

150

200

250

mg/

dL

Con

trol

A B B-1

Oyster peptides

mg/

dL

Triglyceride

Oyster peptides0

100

200

300

400C

ontr

ol

A B B-1

a a

abb

Triglyceride

mg/

g liv

er

0

10

20

30

40

50

60

Con

trol

A

bab

a

b

B B-1

Oyster peptides

Liver lipid levelsm

g/g

liver

Cholesterol

0

1

2

3

4C

ontr

ol

A B B-1

Oyster peptides

Phospholipid

0

4

8

12

16

mg/

g liv

er

Con

trol

A B B-1

Oyster peptides

・ Oyster has cholesterol- and triglyceride-lowering activities.・ High molecular oyster peptides decrease cholesterol and

triglyceride levels.・ Low molecular oyster peptides reduce triglyceride

concentration.・ Low molecular oyster peptides containing dextrin have the

same effect to intact low oyster peptide.

Results

Oyster has lipid-lowering activities, and oyster itself and oyster peptides are promising materials contributing to human health.


Thank you for your attention!

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I am welcomed you to visit to Nagasaki.

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EFFECTS OF FEEDING OYSTER ON LIPID MeTABOLISM ...oyster-symposium.bangor.ac.uk/abstracts/Session...

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