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.
University of Nagasaki, Siebold
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
University of Nagasaki, Siebold
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
University of Nagasaki, Siebold
0
10
20
30
40
50
60
(m
g/da
y) AcidicsteroidsNeutralsteroidsa
b
Con
trol
Soyb
ean
c
Oys
ter
Rats were fed a diet ad libitum for 2 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・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)
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
University of Nagasaki, Siebold
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
a,b,c:Values bearing letters are significantly different at p < 0.05.
Means ± SE of 6 rats.
Con
trol
Def
atte
d oy
ster
Soyb
ean
a
a
ba
bb
a
b
c
a
bb
University of Nagasaki, Siebold
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
a,b,c:Values bearing letters are significantly different at p < 0.05.
Means ± SE of 6 rats.
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
University of Nagasaki, Siebold
Experimental schedule
University of Nagasaki, Siebold
(%) ・Mineral mixture・Vitamin mixture・t- Butylhydroquinone・Choline bitartrate・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)
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.
Rats were fed a diet ad libitum for 2 weeks
SD rats(♂5 wk old)
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
University of Nagasaki, Siebold
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
University of Nagasaki, Siebold
*:Significant difference from the control group at p < 0.05.
Means ± SE of 6 rats.
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
University of Nagasaki, Siebold
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
University of Nagasaki, Siebold
(%)・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)
Rats were fed a diet ad libitum for 4 weeks
• 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.
University of Nagasaki, Siebold
Thank you for your attention!
You are welcomed to visit to Naga
I am welcomed you to visit to Nagasaki.
Thank you for your attention!