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Effect of dietary starches on the serum, aorta and hepatic lipid levels in high-fat high cholesterol-fed rats
247
A themsclerosis
Elsevier Publishing
Company,
Amsterdam
- Printed in The Netherlands
EFFECT OF DIETARY STARCHES ON THE SERUM, AORTA AND HEPATIC LIPID LEVELS IN HIGH-FAT HIGH CHOLESTEROL-FED PART
2. NATURE
OF THE
P. VIJAYAGOPXLAN
STARCH
AND
HYPOLIPIDAEMIC
RATS
ACTIVITY
AND P. A. IiURUP*
Department
of Biochemistry,
(Received
March 6th, 1972)
UniversitJj
of
Kerala,
Trivandrum-
1 (India)
SUMMAR‘I
The effect of different aorta gluccse
purified starches on the lipid levels of the serum, liver and
of high fat-cholesterol-fed and
sucrose.
Purified
rats has been studied ragi starch
cholesterol
and phospholipid
comparable
to those of the glucose-fed
lipid levels were jowar rice and wheat. Fasting
(Eleusine
levels in these tissues
and compared coracana)
with that
showed
and the values
of
the lowest
obtained
were
group. The other starches in increasing order of (Sorghum w&are), tapioca, bajra (Pennisetum typhoideum),
blood glucose levels were normal in all the groups, but showed
variation 1 h after oral glucose load. The level was normal in the ragi starch-fed group, the other starches showing higher levels, the maximum being in the rice starch group. The levels of myocardial
lipoprotein
lipase and hepatic
total free NAD-NADP
levels in the different groups were also in agreement with the observed lipid levels. No correlation could be found between the effect on lipid levels and the amylose content of the different starches. Similarly, the amount of N in the different starches also had no relation to their lipid-lowering effect. Ragi and tapioca starch which showed maximum lipid-lowering effect were the least digested with pancreatic a-amylase. The other starches
in order of increasing
digestibility
were bajra,
rice, wheat and jowar.
The ease of acid hydrolysis of the different starches also showed variation, correlation between this and the lipid-lowering effect could be found.
Key words:
but no
Aorta - Cholesterol-fed rat - Lipids - Liver - Serum - Starches
* Reprint requests should be sent to the second author (P.A.K.). Atherosclerosis,
1972,
16: 247-256
248
I’. VIJAYAGOPALAN,P.A.KURUP
INTRODUCTION
Dietary
carbohydrates
are known to influence
both man and experimental taining
cholesterol
cholesterol
starches
been
the level of serum cholesterol
Rats maintained
reported
by several
on a semisynthetic workers
level when fed sucrose, than when fed starchi-3.
are reports However
have
animals.
that
there
starch appears
themselves
In a previous
is more
hypercholesterolaemic
to be very little
information
on the lipid levels of animals
communication
to show higher
about
than
there
sucrose4.
the effect of different
fed high fat-high
from this laboratorys,
serum
On the other hand, in rabbits
in
diet con-
cholesterol
it was reported
that
diets.
rats fed
purified rice starch showed lower lipid levels in serum, liver and aorta than those fed sucrose, but considerably starch
showed
experiments.
much
lower levels
This investigation
other cereals. The nature results
higher than those fed glucose. Animals
are reported
MATERIALSAND
than
those
fed rice starch
has now been extended
fed purified
tapioca
in long term feeding
to starches
prepared
of the starch in each case has also been investigated
from
and the
in this paper.
METHODS
Young male albino rats of average weight 130 g were divided into 8 groups of 10 animals each. Their basal diet consisted of casein-17.0%, carbohydrate-59.6%, hydrogenated salt mixture7
ground -5.3%.
hydrate
portion
purified
rice starch,
(Eleusine
coracana),
7-purified
of the respective group
diet: group
4-purified
wheat
l-glucose, starch,
group 2-sucrose, group
group &purified bajra starch (Pennisetum jowar starch (Sorghum vulgare) and group &purified
The animals Preparation
nut oil-16 %, cholesterol-2 %, vitamin mixture6 -0.1 y0 and The rats were grouped as follows depending on the carbo-
were maintained
of $wiJied
5-purified
group 3ragi starch
typhoideunz),
tapioca
group
starch.
on this diet for 4 months.
starches
The purified starches were prepared by defatting the dehulled, powdered material with petroleum ether (40-60°C) and following a procedure similar to that described for potato starchs. The starch sediment was finally stirred with dilute NaOH solution (pH 9.0-9.5) for 18 h in the cold, washed free of alkali and finally washed with methanol. The material was dried at room temperature in vacua. After 4 months feeding, the rats were fasted for 24 h and killed by a blow on the head. Serum, liver, aorta and heart were removed for various estimations. The aorta was stripped of its adventitial adipose tissue. The liver and aorta were extracted first with ethanol-ether (3:1, v/v) and then with chloroform-methanol (1: 1, v/v). The extract in each case was made up to a known volume and the solvent was evaporated from an aliquot for lipid estimation. Total cholesterol was estimated by the method of CARR-DREKTER~. Free cholesterol was estimated by the SCHOENHEIMER-SPERRY methodlo. Phospholipid was estimated by the method described by Atherosclerosis,
1972, 16: 247-256
249
DIETARY STARCHES AND LIPID LEVELS
ACKERMANN
AND ToRo~~. The lipoprotein
lipase activity
of the heart
was estimated
as described previously, using lipaemic serum as the substrater2. Total NAD and NADP in the liver were estimated by homogenizing the liver in ice-cold 5 y0 trichloroacetic acid (TCA), and extracting aqueous portion was evaporated
the supernatant with ether to remove the TCA. The to dryness in vacua at 0°C and the total NAD and
NADP estimated in an aqueous solution of the residue by spectrophotometryra. Blood glucose was estimated by the method of ASATOOR AND KINGL4, with the modification that a weakly alkaline copper reagent was usedr5. The nitrogen content of the purified starches was estimated Kjeldahl method. The amylose and amylopectin by determining their iodine affinityle. The ease of digestibility
of the purified
content starches
by the micro-
of the starches was estimated by pancreatic
a-amylase
was
determined as follows: The starch in 0.1 M phosphate buffer pH 7.0 containing 0.0067 M NaCl was incubated with pancreatic a-amylase at 37°C. Aliquots were withdrawn at zero time and at intervals
of 30, 60, 120 and 240 min;
reducing
of ASATOOR AND KINGLY, modified
sugar by the method
The rate at which reducing
sugars were liberated
they were analysed
for
as above.
from the different
starches,
when subjected to acid hydrolysis under the same conditions, was also determined. The samples were heated in a boiling water-bath under identical conditions with 1 N HCl. Aliquots were removed at intervals of 15, 30 and 60 min and the amount reducing sugar formed estimated by Hane’s methodIT.
of
RESULTS
(1)
efect
of different
starches
on serum,
liver and aortic lipids
The effect of various purified starches on serum, liver and lipids is given in Table la (the t- and p-values are given in Table lb). The results have been compared with those obtained
with rats fed sucrose
and glucose.
As can be seen, the various
dietary starches caused different lipid levels. The animals fed on purified ragi starch showed the lowest cholesterol and phospholipid levels in the serum, liver and aorta, and the values
obtained
were comparable
to those of the glucose-fed
group.
The
other starches in increasing order of resulting lipid levels are jowar, tapioca, bajra, rice and wheat. The latter two showed lipid levels only slightly lower than those of the sucrose-fed
group.
(2) Blood glucose levels Blood glucose levels in the fasting condition and 1 h after a glucose load (4 g/kg body weight orally) were determined in rats maintained on the various starches and compared with those fed glucose and sucrose. The results are given in Table 2a (the t- and p-values are given in Table 2b). The results showed that the fasting blood glucose level was within normal limits in all the groups, but differences were found in the glucose level 1 h after the oral glucose load. The level was normal in the ragi starch-fed Atherosclerosis,
1972,16:247-256
b
Weight
changes:
Ragi Jowar Bajra Rice Tapioca Sucrose Glucose
Group
(2) (3) (4) (5) (6) (7) (8)
2
I II III IV V VI VII VIII
4.1 2.6 + 4.5 ?? f 6.8 * 6.1 & 4.8 + 6.7 i 4.8
*
357.6 92.5 142.25 225.8 348.45 205.2 371.68 92.92
(1) Wheat
z
3
i
PURIFIED
g
Serum
OF DIFFERENT
la
&
Group
EFFECT
TABLE
total cholesterol (mg/lOO ml,
e
k B 2 *.
s Fz
E
~ -
ON
$25 +20 +15 +30 +35 +15 +32 +12
6.2 5.1 6.2 7.1 6.0 7.1 7.0 3.5
i_ 3.5 * 4.0 ??3.0 f 3.5 & 5.0 + 3.0 i 4.0 f 3.0
304 + 148.1 180.0 f 245.0 i 280.0 & 200.0 f 350.0 * 101.0 f
S.E.)
phospholipid
STARCHES
LIPIDS
41.1 f 2.6 15.77 2.3 19.85 & f 3.2 24.85 * 4.1 30.66 f 3.5 24.33 & 3.1 48.16 + 4.1 9.74 f 3.2
total cholesterol
phospholipid
29.9 f 2.1 11.50 1.9 16.25 +?? 2.1 19.32 h 3.2 21.36 f 4.1 17.52 f 2.6 32.98 + 3.9 6.35 & 4.1
50.35 28.54 30.72 37.83 45.29 34.46 60.74 24.22
+ 3.1 3.1 f 2.8 * 4.6 & 3.2 & 3.1 + 3.6 * 2.7
15.97 + 5.16 7.96 fi 10.75 & 13.80 f 8.09 f 17.53 * 2.23 &
1.2 1.0 1.6 1.5 1.7 2.1 2.1 1.4
11.1 3.75 6.05 7.83 9.38 5.74 12.15 1.60
1.1 1.2 & 2.1 f 1.2 f 1.2 f 1.4 & 1.8 & 1.2
f
Aorta
HEPATIC
total free cholesterol cholesterol (mglg of wet tissue, & S.E.)
AND
free cholesterol (mglg of wet tissue. & S.E.)
AORTIC
Liver
SERUM,
26.6 10.75 14.79 22.56 25.0 17.09 27.77 8.36
& 2.3 1.8 * 2.6 & 2.6 + 2.0 += 2.5 f 2.0 * 1.4
phospholipid
E
s
.G?
G
?
lb
and and and and and and
1 2 3 4 5 6
8 8 8 8 8 8
7 7 7 7 7 7 7
132.34 0.24e 23.72 50.52 104.30 52.22
5.68 122.97 89.97 6.82 8.09 63.79 106.80
total cholesterol
a p = 0.001 < 0.002. b p = 0.002 < 0.01. c p = 0.02 < 0.05. d p = 0.05 < 0.1. e p greater than 0.1. In all other cases p is less than
and and and and and and and
1 2 3 4 5 6 8
between
PCRIFIED
Se?%WZ
DIFFERENT
and p-values
OF
t-Values
t-
EFFECT
TABLE ON
0.001.
90.22 24.03 35.11 56.92 81.36 39.13
15.54 73.69 57.43 33.33 23.97 47.62 100.81
fihospholipids
STARCHES
AORTfC
24.12 4.82 7.07 9.21 13.95 11.05
4.58 21.74 17.69 12.74 10.29 14.62 23.43
total cholesterol
Liver
SERUM,
HEPATIC
16.13 3.6Ob 3.63% 7.91 8.20 7.25
2.2oc 15.68 12.77 8.54 6.80 10.45 14.88
free cholesterol
AND
LIPIDS
20.10 3.32b 5.28 8.10 15.96 7.88
6.93 21.47 21.44 12.38 10.16 17.29 25.72
phospholipids
23.69 5.43 8.55 13.11 16.57 7.33
2.036 16.72 11.53 8.27 4.35 10.04 19.13
total cholesterol
Aorta
21.46 3.32b 6.91 15.27 21.61 9.59
1.22e 20.02 12.60 5.06 3.11 10.57 25.21
1.57e 12.35 7.01 6.35 4.07 8.90 15.51 18.63 3.98 5.86 3.668 14.41 7.14
@iospholapids
free cholesterol
252
P. VIJAYAGOPALAN,
TABLE
2a
BLOOD
GLUCOSE
LEVELS
-
FASTING
AND
1
h
AFTER
ORAL
GLUCOSE
LOAD
Blood glucose
Group
(1) (2) (3) (4) (5) (6) (7) (8)
P. A. KURUP
Wheat Ragi Jowar Bajra Rice Tapioca Sucrose Glucose
TABLE
fas&%g (nag/l00 ml)
7 h after glucose load
90.50 82.56 75.86 78.54 93.24 83.8 83.9 74.6
135.35 97.29 120.09 135.58 140.0 115.3 130.5 93.25
* & & & * & f *
3.6 3.4 5.1 4.6 2.5 3.2 3.7 3.52
& + * & f f + +
4.2 4.1 4.0 4.8 4.8 4.01 6.5 4.10
2b
BLOOD
GLUCOSE
LEVELS
-
1
h
AFTER
ORAL
GLUCOSE
LOAD
and p values
t
t-Values between
I h after glucose load
1 2 3 4 5 6 8 8 8 8 8 8 8
1.9& 13.67 4.32 1.98c 3.71& 6.26 15.33 11.54 23.38 21.17 14.83 2.2lb 22.63
and and and and and and and and and and and and and
7 7 7 7 7 7 7 6 5 4 3 2 1
& p = 0.001 < O.OO!!. b p = 0.02 < 0.05. c p = 0.05 < 0.1. In all other cases, p is less than
0.001.
group, as in the case of the glucose-fed the maximum (3)
group. The other starches
Myocardial
li$oprotein
The lipoprotein
lipase and total hepatic NAD-NADP
lipase levels of the heart
levels in the animals fed different starches are given in Table 3b). The lipoprotein group;
animals
starch-fed
fed tapioca
animals
1972,
and the total
NAD-NADP
lipase level is highest in the ragi starch-fed
and jowar starch
show slightly
showed much lower levels, approaching
16: 247-256
levels hepatic
are given in Table 3a (the t- and p-values
sucrose group. The total hepatic NAD-NADP Atherosclerosis,
caused higher levels,
being in the rice starch group.
lower levels. The other the values found in the
level was lowest in the ragi and tapioca
DIETARY
‘I-ABLE
253
STARCHES AND LIPID LEVELS
3a NAD-NADP
MYOCARDIAI. LIPOPROTEINLIPASE AND TOTAL HEPATIC
Group
(1) (2) (3) (4) \; (5) (6) (7) (8)
\f’hcat Ragi Jowar Baira _ Rice Tapioca sucrose Glucose
TABLE
Lipoprotein lipase levels in the heart (/lmle of glyxwl liberated/g sf tissue)
Total he$atic IVA DNA DP levels i+z the liver
0.71 0.89 0.81 0.76 0.70 0.81 0.50 0.99
381.4 245.0 324.0 352.0 383.0 250.0 410.0 230.0
* & i & * & + *
LEVELS
(/%lS)
0.12 0.16 0.16 0.18 0.17 0.18 0.22 0.15
& i i & i & & +
5.2 6.1 6.4 5.6 4.8 6.7 8.6 7.5
3b
MYOCARDIAL
LIPOPROTEIN
LIPASE
AND
TOTAL
HEPATIC
N41)+-NADP+
LEVELS
t- and p-values between
t-Values
Lifioprotezn lipase
NA D+-NA DP+
1 2 3 4 5 6
and and and and and and
7 7 7 7 7 7
2.66~ 4.53 3.60~ 2.89& 2.276 3.44”
8.99 4.95 25.37 17.85 8.68 46.38
8 8 8 8 8 8 8
and and and and and and and
7 6 5 4 3 2 1
5.83 2.43d 4.03 3.11* 2.61e 1.45e 4.59
49.86 6.29 5.43 41.22 30.13 4.90 52.39
a p m= 0.001 < 0.002. b p = 0.002 < 0.01. c p == 0.01 < 0.02. d p := 0.02 < 0.05. e p = greater than 0.1. In all other cases p is less than
starch-fed
0.001.
groups, the other starches
showing values approaching
that of the sucrose-
fed group. (4)
Amylose
content and N yO of the di$erent
The amylose determined
content
of the different
starches purified starches
to find out whether these characteristics
and the N content
can be correlated
lowering effect. The results are given in Table 4. As can be seen, no correlation found between amylose content
were
with the lipidwas
and the effect of the starch on lipid levels. Ragi starch Atherosclerosis,
1972,
16: 247-256
254
P. VIJAYAGOPALAN,
TABLE
4
AMYLOSE
CONTENT
Starch 1) 2) 3) 4) 5) 6)
P. A. KUKUP
Wheat Ragi Jowar Bajra Rice Tapioca
N ok
AND
OF THE
DIFFERENT
STARCHES
N ( %) * S.E.
Amylose
0.75 0.80 0.35 0.50 1.0 0.15
26.67 12.82 6.15 20.92 14.36 16.67
* * i 5 + *
0.12 0.14 0.06 0.11 0.15 0.01
+ k & f f i
(%)
& S.E.
1.02 1.6 1.4 2.3 1.8 2.2
which shows maximum lipid-lowering effect, contains 12.820/O amylose; but jowar starch which causes higher lipid levels than ragi starch contains only 6.15”. The maximum
amylose
content
is seen in wheat starch,
but it results in high lipid levels.
All alkali-soluble protein has been removed from the starches by alkali digestion during preparation of the starches. Therefore, the N content might be due to either residual alkali-resistant protein in the starch or the presence of other containing substances either as part of the starch or present as extraneous (5)
Digestibility
of the different
The digestibility
starches
of the different
with pancreatic
starches
a-amylase
with pancreatic
Table 5. As can be seen, the digestibility
of the different
is the least digestible
tapioca
among the starches;
ty. The other starches,
in order of increasing
nitrogenmaterial.
starches
a-amylase
is given in
varies. Ragi starch
starch shows similar low digestibili-
digestibility,
are bajra,
rice, wheat and
jowar. (6)
Ease
of hydrolysis
of the stavches
by acid
The ease of hydrolysis of the different starches when subjected to hydrolysis by 1 N HCl in a boiling water-bath is given in Table 6. Rice, ragi and jowar starch seem to be hydrolysed to approximately hydrolysed to a slightly lesser extent,
the same extent. Bajra and wheat while tapioca starch shows maximum
starch are hydrolysis
under these conditions. TABLE
5
DIGESTIBILITY
Starch
OF THE
DIFFERENT
Reducing in
STARCHES
Rice Ragi Wheat Bajra Jowar Tapioca
Atherosclerosis,
6.87 + 0.65 9.81 2.29 11.49 2.92
k 1.65 * 0.78 & 1.25 &- 0.80
1972, 16: 247-256
PANCREATIC
sugar liberated expressed
30 min (1) (2) (3) (4) (5) (6)
WITH
60 min 13.3 3.04 13.61 4.59 13.61 5.12
* & & i_ & +
a-AMYLASE
as g i. S.E. of glucose per 700 g of starch 4h
2h 1.01 0.26 2.1 1.01 1.60 1.8
14.7 4.0 15.16 7.35 15.61 5.97
* i + & + f
1.20 0.65 2.0 2.3 2.1 2.01
14.7 4.19 15.16 7.35 17.0 5.97
+ * f f f f
1.35 1.01 1.68 1.8 1.9 2.3
255
DIETARY STARCHES AND LIPID LEVELS TABLE EASE
OF
6 HYDROLYSIS
OF
DIFFERENT
Reducing
Starches
STARCHES
BY
sugar expressed
as g 5 S.E. o_f glucose 30
15 min
(1) Rice (2) Ragi (3) Tapioca (4) Bajra (5) Jowar (6) Wheat
40.46 44.15 46.75 38.25 40.46 38.25
+ * & 5 f +
ACID
2.5
min
60.35
2.1 2.8 2.60 1.98 3.1
liberated
63.75 70.55 46.75 64.05 50.15
per 1OOg
of starch
in
60 min
* 2.3
i * f + i
63.75 68.85
3.8 1.9 2.50 2.1 2.8
80.75 53.60 66.30 56.95
& 3.0 + 3.2
+ + & +
2.0 2.46 3.2 3.25
DISCUSSION All the dietary
starches
there were considerable had the maximum fat-high
studied resulted in lower lipid levels than sucrose, but
differences
lipid-lowering
cholesterol
diet. The levels of cholesterol
were close to those observed
in the glucose-fed
starch also showed considerable of ragi starch. starches;
in the action of the different starches.
Ragi starch
effect on serum, liver and aorta in rats fed a high
hypolipidaemic
Rice and wheat starch
and phospholipid animals.
Jowar
in these tissues
starch
and tapioca
effect, but much less than in the case
caused least effect on lipid levels among the
the lipid levels being close to those observed in the sucrose-fed
animals. The
fasting blocd glucose levels in the animals in the various groups lay within the normal range, but higher levels were observed
1 h after an oral glucose load in the rice, wheat,
bajra and starch groups, similar to those in the sucrose-fed
group. Jowar and tapioca
starch showed lower levels, while the group fed ragi starch had the same normal
level
found in the glucose-fed
from
this laboratory cholesterol
group. It has been reported in another
that carbohydrate
dietIs.
metabolism
is deranged in rats fed a high fat-high
The insulin levels are lower and blood glucose levels, 1 h after an
oral glucose load, are higher than in animals
fed a normal
glucose
with their
produced
by dietary
levels. Myocardial
lipoprotein
in rats fed a high fat-high levels are considerably the
hepatic
communication
starches
diet. Changes
different
cholesterol
dietIs,
while the total hepatic
The results with myocardial
levels
now
obtained
with
the
in blood
effects
levels have been reported to be considerably
elevatedso.
NAD-NADP
accord
NAD-NADP
lipoprotein different
on lipid decreased lipase and
starches
also
accord with their effect on lipid levels. It appears that the action of the different to the amylose-amylopectin in jowar
starch
(6.15%),
content
while it was highest
varied, ranging from 0.15% Since all alkali-extractable either
to an alkali-resistent
starches
of the starch.
on lipid levels is not related
The amylose
in wheat starch.
content
was lowest
The N content
also
in the case of tapioca to l.Oo/ in the case of rice starch. protein protein
had been removed,
this residual N may be due
residue or to the presence
of amino sugars or
amino acid residues in the starch, Differences
in the digestibility
with pancreatic
a-amylase
were observed in the
Atherosclerosis,
1972,
16: 247-256
256
P. VIJAYAGOPALAN,
different
starches.
ragi and tapioca
starch
with a-amylase
reducing
sugar was liberated
were least hydrolysed.
seems to be somewhat
Ragi and tapioca, lowering
Maximum
which were least digested was observed
It is possible that the lipid-lowering to the presence substance
of a hypolipidaemic
or an unusual
acetylated
while
of the various
starches action.
starches
had the maximum
lipid-
showed lower lipid-lowering
with ease of acid hydrolysis. effects of ragi, jowar and tapioca
principle.
sugar configuration
amino sugars, or uranic
from jowar starch
with their lipid-lowering
by a-amylase,
effect, while the other more digestible
effects. But no such pattern
Digestibility
correlated
P. A. KURUP
This principle
may be due
may be an extraneous
in a starch molecule,
such as sulphated
acid. These aspects are being further
or
investigated
in detail. REFERENCES 1
2
3
4
5
6
7
8
9
10
11
12
13
14
15 13
17
13
19
20
STAUB, R. W. AND J. R. THIESSEN, Dietary carbohydrate and Serum cholesterol in rats, Federation Proc., 1967, 26: 490. PORTMAN, 0. W., E. Y. LOWRY AND D. BRUNO, Effect of dietary carbohydrate on experimentally induced hypercholesteremia and hyperbetalipoproteinemia in rats, Proc. Sot. Exp. Biol. Med., 1956, 91: 321. BAILEY, E., C. B. TAYLOR AND W. BARTLEY, Effect of dietary carbohydrate on hepatic lipo1968, 217: 471. genesis in the rat, Nature, KRITCHEVSKY, D., P. SALLATA AND S. A. TEPPER, Experimental atherosclerosis in rabbits fed cholesterol free diets, J. Atheroscler. Res., 19@3, 8: 697. VIJAYAGOPALAN, P. AND P. A. KURUP, Effect of dietary starches on the serum. aorta and hepatic lipid levels in cholesterol fed rats, Atherosclerosis, 1970, 11: 257. HAWK, P. B., B. L. OSER AND W. H. SUMMERSON Practical Physiological Chemistry, McGraw Hill, New York, N.Y., 1954, p. 1373. HAWK, P. B., B. L. OSER AND W. H. SUMMERSON, Practical Physiological Chemistry, McGraw Hill, New York, 1965, p. 1377. SCHOCH, T. M., Preparation of starch and starch fractions. In: S. P. COLOWICK AND N. 0. KAPLAN (Eds.), Methods in Enzymology, Vol. 3, Academic Press, New York, N.Y., 1957, p. 299. ACKERMANN, P. G. AND G. TORO, Blood lipids-total cholesterol. In: S. FRANKEL AND S. REITMAN (Eds.), Gradwohl’s Clinical Laboratory Methods and Diagnosis, Mosby, St. Louis, 1963, p. 251. ACKERMANN, P. G. AND G. TORO, Blood lipids, total and free cholesterol. In: S. FRANKEL AND S. REITMAN (Eds.), Gradwohl’s Clinical Laboratory Methods and Diagnosis, Mosby, St. Louis, MO., 1963, p.‘251: ACKERMANN, P. G. AND G. TORO, Blood lipids phospholipids. In: S. FRANKEL AND S. REITMAN (Eds.), Gradeerohl’s Clinical Laboratory Methods and Diagnosis, Mosby, St. Louis, MO., 1963, p. 258. AUGUSTI. K. T. AND P. A. KURUP. Effect of tolbutamide on the lipolvtic response of adipose _ tissue to adrenaline and ACTH, Indian J. Biochem., 1968, 5: 76. _ _ CIOTTI, M. M. AND N. 0. KAPLAN, Procedure for determining pyridine nucleotides. In: S. P. COLOWICK AND N. 0. KAPLAN (Eds.), Methods in EnzymoZog,y, Vol. 3, Academic Press, New York, N.Y.. 1957, p. 890. ASATOOR, A. AND E. J. KING, Simplified calorimetric blood sugar method, Biochem. J., 1954, 56: xliv. SOMOGYI, M., Note on sugar determination, J. Biol. Chem., 1952, 195: 19. SCHOCH, T. J., Determination of iodine affinity. In: S. P. COLOWICK AND N. 0. KAPLAN (Eds.), Methods in Enzymology, Vol. 3, Academic Press, New York, N.Y., 1957, p. 13. HAWK, P. B., B. L. OSER AND W. H. SUMMERSON, Practical Physiological Chemistry, 13th ed., McGraw Hill, New York, N.Y., 1954, p. 923. SEETHANATHAN, P. AND P. A. KURUP, Carbohydrate metabolism in the liver and muscle in rats fed a hvnercholesterolaemic diet. Atherosclerosis. 1970. 11: 463-472. SEETH~~ATHAN, P., P. VIJAYAG~PALAN, K. T. AU~U~TI AND P. A. KURUP, Myocardial lipoDrotein lipase in rats fed a hvpercholesterolaemic diet, Atherosclerosis, 1970, 11: 333. SEETHAN~THAN, P., P. VIJA;~GOPALAN, K. T. AUGUSTI AND P. A. KURUP, Changes in hepatic free NAD and NADP levels in rats fed a hypercholesterolaemic diet, Atherosclerosis, 1970, 11: 339.
Atherosclerosis,
1972, 16: 247-256
A themsclerosis
Elsevier Publishing
Company,
Amsterdam
- Printed in The Netherlands
EFFECT OF DIETARY STARCHES ON THE SERUM, AORTA AND HEPATIC LIPID LEVELS IN HIGH-FAT HIGH CHOLESTEROL-FED PART
2. NATURE
OF THE
P. VIJAYAGOPXLAN
STARCH
AND
HYPOLIPIDAEMIC
RATS
ACTIVITY
AND P. A. IiURUP*
Department
of Biochemistry,
(Received
March 6th, 1972)
UniversitJj
of
Kerala,
Trivandrum-
1 (India)
SUMMAR‘I
The effect of different aorta gluccse
purified starches on the lipid levels of the serum, liver and
of high fat-cholesterol-fed and
sucrose.
Purified
rats has been studied ragi starch
cholesterol
and phospholipid
comparable
to those of the glucose-fed
lipid levels were jowar rice and wheat. Fasting
(Eleusine
levels in these tissues
and compared coracana)
with that
showed
and the values
of
the lowest
obtained
were
group. The other starches in increasing order of (Sorghum w&are), tapioca, bajra (Pennisetum typhoideum),
blood glucose levels were normal in all the groups, but showed
variation 1 h after oral glucose load. The level was normal in the ragi starch-fed group, the other starches showing higher levels, the maximum being in the rice starch group. The levels of myocardial
lipoprotein
lipase and hepatic
total free NAD-NADP
levels in the different groups were also in agreement with the observed lipid levels. No correlation could be found between the effect on lipid levels and the amylose content of the different starches. Similarly, the amount of N in the different starches also had no relation to their lipid-lowering effect. Ragi and tapioca starch which showed maximum lipid-lowering effect were the least digested with pancreatic a-amylase. The other starches
in order of increasing
digestibility
were bajra,
rice, wheat and jowar.
The ease of acid hydrolysis of the different starches also showed variation, correlation between this and the lipid-lowering effect could be found.
Key words:
but no
Aorta - Cholesterol-fed rat - Lipids - Liver - Serum - Starches
* Reprint requests should be sent to the second author (P.A.K.). Atherosclerosis,
1972,
16: 247-256
248
I’. VIJAYAGOPALAN,P.A.KURUP
INTRODUCTION
Dietary
carbohydrates
are known to influence
both man and experimental taining
cholesterol
cholesterol
starches
been
the level of serum cholesterol
Rats maintained
reported
by several
on a semisynthetic workers
level when fed sucrose, than when fed starchi-3.
are reports However
have
animals.
that
there
starch appears
themselves
In a previous
is more
hypercholesterolaemic
to be very little
information
on the lipid levels of animals
communication
to show higher
about
than
there
sucrose4.
the effect of different
fed high fat-high
from this laboratorys,
serum
On the other hand, in rabbits
in
diet con-
cholesterol
it was reported
that
diets.
rats fed
purified rice starch showed lower lipid levels in serum, liver and aorta than those fed sucrose, but considerably starch
showed
experiments.
much
lower levels
This investigation
other cereals. The nature results
higher than those fed glucose. Animals
are reported
MATERIALSAND
than
those
fed rice starch
has now been extended
fed purified
tapioca
in long term feeding
to starches
prepared
of the starch in each case has also been investigated
from
and the
in this paper.
METHODS
Young male albino rats of average weight 130 g were divided into 8 groups of 10 animals each. Their basal diet consisted of casein-17.0%, carbohydrate-59.6%, hydrogenated salt mixture7
ground -5.3%.
hydrate
portion
purified
rice starch,
(Eleusine
coracana),
7-purified
of the respective group
diet: group
4-purified
wheat
l-glucose, starch,
group 2-sucrose, group
group &purified bajra starch (Pennisetum jowar starch (Sorghum vulgare) and group &purified
The animals Preparation
nut oil-16 %, cholesterol-2 %, vitamin mixture6 -0.1 y0 and The rats were grouped as follows depending on the carbo-
were maintained
of $wiJied
5-purified
group 3ragi starch
typhoideunz),
tapioca
group
starch.
on this diet for 4 months.
starches
The purified starches were prepared by defatting the dehulled, powdered material with petroleum ether (40-60°C) and following a procedure similar to that described for potato starchs. The starch sediment was finally stirred with dilute NaOH solution (pH 9.0-9.5) for 18 h in the cold, washed free of alkali and finally washed with methanol. The material was dried at room temperature in vacua. After 4 months feeding, the rats were fasted for 24 h and killed by a blow on the head. Serum, liver, aorta and heart were removed for various estimations. The aorta was stripped of its adventitial adipose tissue. The liver and aorta were extracted first with ethanol-ether (3:1, v/v) and then with chloroform-methanol (1: 1, v/v). The extract in each case was made up to a known volume and the solvent was evaporated from an aliquot for lipid estimation. Total cholesterol was estimated by the method of CARR-DREKTER~. Free cholesterol was estimated by the SCHOENHEIMER-SPERRY methodlo. Phospholipid was estimated by the method described by Atherosclerosis,
1972, 16: 247-256
249
DIETARY STARCHES AND LIPID LEVELS
ACKERMANN
AND ToRo~~. The lipoprotein
lipase activity
of the heart
was estimated
as described previously, using lipaemic serum as the substrater2. Total NAD and NADP in the liver were estimated by homogenizing the liver in ice-cold 5 y0 trichloroacetic acid (TCA), and extracting aqueous portion was evaporated
the supernatant with ether to remove the TCA. The to dryness in vacua at 0°C and the total NAD and
NADP estimated in an aqueous solution of the residue by spectrophotometryra. Blood glucose was estimated by the method of ASATOOR AND KINGL4, with the modification that a weakly alkaline copper reagent was usedr5. The nitrogen content of the purified starches was estimated Kjeldahl method. The amylose and amylopectin by determining their iodine affinityle. The ease of digestibility
of the purified
content starches
by the micro-
of the starches was estimated by pancreatic
a-amylase
was
determined as follows: The starch in 0.1 M phosphate buffer pH 7.0 containing 0.0067 M NaCl was incubated with pancreatic a-amylase at 37°C. Aliquots were withdrawn at zero time and at intervals
of 30, 60, 120 and 240 min;
reducing
of ASATOOR AND KINGLY, modified
sugar by the method
The rate at which reducing
sugars were liberated
they were analysed
for
as above.
from the different
starches,
when subjected to acid hydrolysis under the same conditions, was also determined. The samples were heated in a boiling water-bath under identical conditions with 1 N HCl. Aliquots were removed at intervals of 15, 30 and 60 min and the amount reducing sugar formed estimated by Hane’s methodIT.
of
RESULTS
(1)
efect
of different
starches
on serum,
liver and aortic lipids
The effect of various purified starches on serum, liver and lipids is given in Table la (the t- and p-values are given in Table lb). The results have been compared with those obtained
with rats fed sucrose
and glucose.
As can be seen, the various
dietary starches caused different lipid levels. The animals fed on purified ragi starch showed the lowest cholesterol and phospholipid levels in the serum, liver and aorta, and the values
obtained
were comparable
to those of the glucose-fed
group.
The
other starches in increasing order of resulting lipid levels are jowar, tapioca, bajra, rice and wheat. The latter two showed lipid levels only slightly lower than those of the sucrose-fed
group.
(2) Blood glucose levels Blood glucose levels in the fasting condition and 1 h after a glucose load (4 g/kg body weight orally) were determined in rats maintained on the various starches and compared with those fed glucose and sucrose. The results are given in Table 2a (the t- and p-values are given in Table 2b). The results showed that the fasting blood glucose level was within normal limits in all the groups, but differences were found in the glucose level 1 h after the oral glucose load. The level was normal in the ragi starch-fed Atherosclerosis,
1972,16:247-256
b
Weight
changes:
Ragi Jowar Bajra Rice Tapioca Sucrose Glucose
Group
(2) (3) (4) (5) (6) (7) (8)
2
I II III IV V VI VII VIII
4.1 2.6 + 4.5 ?? f 6.8 * 6.1 & 4.8 + 6.7 i 4.8
*
357.6 92.5 142.25 225.8 348.45 205.2 371.68 92.92
(1) Wheat
z
3
i
PURIFIED
g
Serum
OF DIFFERENT
la
&
Group
EFFECT
TABLE
total cholesterol (mg/lOO ml,
e
k B 2 *.
s Fz
E
~ -
ON
$25 +20 +15 +30 +35 +15 +32 +12
6.2 5.1 6.2 7.1 6.0 7.1 7.0 3.5
i_ 3.5 * 4.0 ??3.0 f 3.5 & 5.0 + 3.0 i 4.0 f 3.0
304 + 148.1 180.0 f 245.0 i 280.0 & 200.0 f 350.0 * 101.0 f
S.E.)
phospholipid
STARCHES
LIPIDS
41.1 f 2.6 15.77 2.3 19.85 & f 3.2 24.85 * 4.1 30.66 f 3.5 24.33 & 3.1 48.16 + 4.1 9.74 f 3.2
total cholesterol
phospholipid
29.9 f 2.1 11.50 1.9 16.25 +?? 2.1 19.32 h 3.2 21.36 f 4.1 17.52 f 2.6 32.98 + 3.9 6.35 & 4.1
50.35 28.54 30.72 37.83 45.29 34.46 60.74 24.22
+ 3.1 3.1 f 2.8 * 4.6 & 3.2 & 3.1 + 3.6 * 2.7
15.97 + 5.16 7.96 fi 10.75 & 13.80 f 8.09 f 17.53 * 2.23 &
1.2 1.0 1.6 1.5 1.7 2.1 2.1 1.4
11.1 3.75 6.05 7.83 9.38 5.74 12.15 1.60
1.1 1.2 & 2.1 f 1.2 f 1.2 f 1.4 & 1.8 & 1.2
f
Aorta
HEPATIC
total free cholesterol cholesterol (mglg of wet tissue, & S.E.)
AND
free cholesterol (mglg of wet tissue. & S.E.)
AORTIC
Liver
SERUM,
26.6 10.75 14.79 22.56 25.0 17.09 27.77 8.36
& 2.3 1.8 * 2.6 & 2.6 + 2.0 += 2.5 f 2.0 * 1.4
phospholipid
E
s
.G?
G
?
lb
and and and and and and
1 2 3 4 5 6
8 8 8 8 8 8
7 7 7 7 7 7 7
132.34 0.24e 23.72 50.52 104.30 52.22
5.68 122.97 89.97 6.82 8.09 63.79 106.80
total cholesterol
a p = 0.001 < 0.002. b p = 0.002 < 0.01. c p = 0.02 < 0.05. d p = 0.05 < 0.1. e p greater than 0.1. In all other cases p is less than
and and and and and and and
1 2 3 4 5 6 8
between
PCRIFIED
Se?%WZ
DIFFERENT
and p-values
OF
t-Values
t-
EFFECT
TABLE ON
0.001.
90.22 24.03 35.11 56.92 81.36 39.13
15.54 73.69 57.43 33.33 23.97 47.62 100.81
fihospholipids
STARCHES
AORTfC
24.12 4.82 7.07 9.21 13.95 11.05
4.58 21.74 17.69 12.74 10.29 14.62 23.43
total cholesterol
Liver
SERUM,
HEPATIC
16.13 3.6Ob 3.63% 7.91 8.20 7.25
2.2oc 15.68 12.77 8.54 6.80 10.45 14.88
free cholesterol
AND
LIPIDS
20.10 3.32b 5.28 8.10 15.96 7.88
6.93 21.47 21.44 12.38 10.16 17.29 25.72
phospholipids
23.69 5.43 8.55 13.11 16.57 7.33
2.036 16.72 11.53 8.27 4.35 10.04 19.13
total cholesterol
Aorta
21.46 3.32b 6.91 15.27 21.61 9.59
1.22e 20.02 12.60 5.06 3.11 10.57 25.21
1.57e 12.35 7.01 6.35 4.07 8.90 15.51 18.63 3.98 5.86 3.668 14.41 7.14
@iospholapids
free cholesterol
252
P. VIJAYAGOPALAN,
TABLE
2a
BLOOD
GLUCOSE
LEVELS
-
FASTING
AND
1
h
AFTER
ORAL
GLUCOSE
LOAD
Blood glucose
Group
(1) (2) (3) (4) (5) (6) (7) (8)
P. A. KURUP
Wheat Ragi Jowar Bajra Rice Tapioca Sucrose Glucose
TABLE
fas&%g (nag/l00 ml)
7 h after glucose load
90.50 82.56 75.86 78.54 93.24 83.8 83.9 74.6
135.35 97.29 120.09 135.58 140.0 115.3 130.5 93.25
* & & & * & f *
3.6 3.4 5.1 4.6 2.5 3.2 3.7 3.52
& + * & f f + +
4.2 4.1 4.0 4.8 4.8 4.01 6.5 4.10
2b
BLOOD
GLUCOSE
LEVELS
-
1
h
AFTER
ORAL
GLUCOSE
LOAD
and p values
t
t-Values between
I h after glucose load
1 2 3 4 5 6 8 8 8 8 8 8 8
1.9& 13.67 4.32 1.98c 3.71& 6.26 15.33 11.54 23.38 21.17 14.83 2.2lb 22.63
and and and and and and and and and and and and and
7 7 7 7 7 7 7 6 5 4 3 2 1
& p = 0.001 < O.OO!!. b p = 0.02 < 0.05. c p = 0.05 < 0.1. In all other cases, p is less than
0.001.
group, as in the case of the glucose-fed the maximum (3)
group. The other starches
Myocardial
li$oprotein
The lipoprotein
lipase and total hepatic NAD-NADP
lipase levels of the heart
levels in the animals fed different starches are given in Table 3b). The lipoprotein group;
animals
starch-fed
fed tapioca
animals
1972,
and the total
NAD-NADP
lipase level is highest in the ragi starch-fed
and jowar starch
show slightly
showed much lower levels, approaching
16: 247-256
levels hepatic
are given in Table 3a (the t- and p-values
sucrose group. The total hepatic NAD-NADP Atherosclerosis,
caused higher levels,
being in the rice starch group.
lower levels. The other the values found in the
level was lowest in the ragi and tapioca
DIETARY
‘I-ABLE
253
STARCHES AND LIPID LEVELS
3a NAD-NADP
MYOCARDIAI. LIPOPROTEINLIPASE AND TOTAL HEPATIC
Group
(1) (2) (3) (4) \; (5) (6) (7) (8)
\f’hcat Ragi Jowar Baira _ Rice Tapioca sucrose Glucose
TABLE
Lipoprotein lipase levels in the heart (/lmle of glyxwl liberated/g sf tissue)
Total he$atic IVA DNA DP levels i+z the liver
0.71 0.89 0.81 0.76 0.70 0.81 0.50 0.99
381.4 245.0 324.0 352.0 383.0 250.0 410.0 230.0
* & i & * & + *
LEVELS
(/%lS)
0.12 0.16 0.16 0.18 0.17 0.18 0.22 0.15
& i i & i & & +
5.2 6.1 6.4 5.6 4.8 6.7 8.6 7.5
3b
MYOCARDIAL
LIPOPROTEIN
LIPASE
AND
TOTAL
HEPATIC
N41)+-NADP+
LEVELS
t- and p-values between
t-Values
Lifioprotezn lipase
NA D+-NA DP+
1 2 3 4 5 6
and and and and and and
7 7 7 7 7 7
2.66~ 4.53 3.60~ 2.89& 2.276 3.44”
8.99 4.95 25.37 17.85 8.68 46.38
8 8 8 8 8 8 8
and and and and and and and
7 6 5 4 3 2 1
5.83 2.43d 4.03 3.11* 2.61e 1.45e 4.59
49.86 6.29 5.43 41.22 30.13 4.90 52.39
a p m= 0.001 < 0.002. b p = 0.002 < 0.01. c p == 0.01 < 0.02. d p := 0.02 < 0.05. e p = greater than 0.1. In all other cases p is less than
starch-fed
0.001.
groups, the other starches
showing values approaching
that of the sucrose-
fed group. (4)
Amylose
content and N yO of the di$erent
The amylose determined
content
of the different
starches purified starches
to find out whether these characteristics
and the N content
can be correlated
lowering effect. The results are given in Table 4. As can be seen, no correlation found between amylose content
were
with the lipidwas
and the effect of the starch on lipid levels. Ragi starch Atherosclerosis,
1972,
16: 247-256
254
P. VIJAYAGOPALAN,
TABLE
4
AMYLOSE
CONTENT
Starch 1) 2) 3) 4) 5) 6)
P. A. KUKUP
Wheat Ragi Jowar Bajra Rice Tapioca
N ok
AND
OF THE
DIFFERENT
STARCHES
N ( %) * S.E.
Amylose
0.75 0.80 0.35 0.50 1.0 0.15
26.67 12.82 6.15 20.92 14.36 16.67
* * i 5 + *
0.12 0.14 0.06 0.11 0.15 0.01
+ k & f f i
(%)
& S.E.
1.02 1.6 1.4 2.3 1.8 2.2
which shows maximum lipid-lowering effect, contains 12.820/O amylose; but jowar starch which causes higher lipid levels than ragi starch contains only 6.15”. The maximum
amylose
content
is seen in wheat starch,
but it results in high lipid levels.
All alkali-soluble protein has been removed from the starches by alkali digestion during preparation of the starches. Therefore, the N content might be due to either residual alkali-resistant protein in the starch or the presence of other containing substances either as part of the starch or present as extraneous (5)
Digestibility
of the different
The digestibility
starches
of the different
with pancreatic
starches
a-amylase
with pancreatic
Table 5. As can be seen, the digestibility
of the different
is the least digestible
tapioca
among the starches;
ty. The other starches,
in order of increasing
nitrogenmaterial.
starches
a-amylase
is given in
varies. Ragi starch
starch shows similar low digestibili-
digestibility,
are bajra,
rice, wheat and
jowar. (6)
Ease
of hydrolysis
of the stavches
by acid
The ease of hydrolysis of the different starches when subjected to hydrolysis by 1 N HCl in a boiling water-bath is given in Table 6. Rice, ragi and jowar starch seem to be hydrolysed to approximately hydrolysed to a slightly lesser extent,
the same extent. Bajra and wheat while tapioca starch shows maximum
starch are hydrolysis
under these conditions. TABLE
5
DIGESTIBILITY
Starch
OF THE
DIFFERENT
Reducing in
STARCHES
Rice Ragi Wheat Bajra Jowar Tapioca
Atherosclerosis,
6.87 + 0.65 9.81 2.29 11.49 2.92
k 1.65 * 0.78 & 1.25 &- 0.80
1972, 16: 247-256
PANCREATIC
sugar liberated expressed
30 min (1) (2) (3) (4) (5) (6)
WITH
60 min 13.3 3.04 13.61 4.59 13.61 5.12
* & & i_ & +
a-AMYLASE
as g i. S.E. of glucose per 700 g of starch 4h
2h 1.01 0.26 2.1 1.01 1.60 1.8
14.7 4.0 15.16 7.35 15.61 5.97
* i + & + f
1.20 0.65 2.0 2.3 2.1 2.01
14.7 4.19 15.16 7.35 17.0 5.97
+ * f f f f
1.35 1.01 1.68 1.8 1.9 2.3
255
DIETARY STARCHES AND LIPID LEVELS TABLE EASE
OF
6 HYDROLYSIS
OF
DIFFERENT
Reducing
Starches
STARCHES
BY
sugar expressed
as g 5 S.E. o_f glucose 30
15 min
(1) Rice (2) Ragi (3) Tapioca (4) Bajra (5) Jowar (6) Wheat
40.46 44.15 46.75 38.25 40.46 38.25
+ * & 5 f +
ACID
2.5
min
60.35
2.1 2.8 2.60 1.98 3.1
liberated
63.75 70.55 46.75 64.05 50.15
per 1OOg
of starch
in
60 min
* 2.3
i * f + i
63.75 68.85
3.8 1.9 2.50 2.1 2.8
80.75 53.60 66.30 56.95
& 3.0 + 3.2
+ + & +
2.0 2.46 3.2 3.25
DISCUSSION All the dietary
starches
there were considerable had the maximum fat-high
studied resulted in lower lipid levels than sucrose, but
differences
lipid-lowering
cholesterol
diet. The levels of cholesterol
were close to those observed
in the glucose-fed
starch also showed considerable of ragi starch. starches;
in the action of the different starches.
Ragi starch
effect on serum, liver and aorta in rats fed a high
hypolipidaemic
Rice and wheat starch
and phospholipid animals.
Jowar
in these tissues
starch
and tapioca
effect, but much less than in the case
caused least effect on lipid levels among the
the lipid levels being close to those observed in the sucrose-fed
animals. The
fasting blocd glucose levels in the animals in the various groups lay within the normal range, but higher levels were observed
1 h after an oral glucose load in the rice, wheat,
bajra and starch groups, similar to those in the sucrose-fed
group. Jowar and tapioca
starch showed lower levels, while the group fed ragi starch had the same normal
level
found in the glucose-fed
from
this laboratory cholesterol
group. It has been reported in another
that carbohydrate
dietIs.
metabolism
is deranged in rats fed a high fat-high
The insulin levels are lower and blood glucose levels, 1 h after an
oral glucose load, are higher than in animals
fed a normal
glucose
with their
produced
by dietary
levels. Myocardial
lipoprotein
in rats fed a high fat-high levels are considerably the
hepatic
communication
starches
diet. Changes
different
cholesterol
dietIs,
while the total hepatic
The results with myocardial
levels
now
obtained
with
the
in blood
effects
levels have been reported to be considerably
elevatedso.
NAD-NADP
accord
NAD-NADP
lipoprotein different
on lipid decreased lipase and
starches
also
accord with their effect on lipid levels. It appears that the action of the different to the amylose-amylopectin in jowar
starch
(6.15%),
content
while it was highest
varied, ranging from 0.15% Since all alkali-extractable either
to an alkali-resistent
starches
of the starch.
on lipid levels is not related
The amylose
in wheat starch.
content
was lowest
The N content
also
in the case of tapioca to l.Oo/ in the case of rice starch. protein protein
had been removed,
this residual N may be due
residue or to the presence
of amino sugars or
amino acid residues in the starch, Differences
in the digestibility
with pancreatic
a-amylase
were observed in the
Atherosclerosis,
1972,
16: 247-256
256
P. VIJAYAGOPALAN,
different
starches.
ragi and tapioca
starch
with a-amylase
reducing
sugar was liberated
were least hydrolysed.
seems to be somewhat
Ragi and tapioca, lowering
Maximum
which were least digested was observed
It is possible that the lipid-lowering to the presence substance
of a hypolipidaemic
or an unusual
acetylated
while
of the various
starches action.
starches
had the maximum
lipid-
showed lower lipid-lowering
with ease of acid hydrolysis. effects of ragi, jowar and tapioca
principle.
sugar configuration
amino sugars, or uranic
from jowar starch
with their lipid-lowering
by a-amylase,
effect, while the other more digestible
effects. But no such pattern
Digestibility
correlated
P. A. KURUP
This principle
may be due
may be an extraneous
in a starch molecule,
such as sulphated
acid. These aspects are being further
or
investigated
in detail. REFERENCES 1
2
3
4
5
6
7
8
9
10
11
12
13
14
15 13
17
13
19
20
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1972, 16: 247-256