Protective effect of Methylamine Irisolidone, a novel compound, on acute myocardial ischemia in anesthetized dogs

Abstract

Kakkalide, a compound obtained from a traditional Chinese medicine Puerariae flos, has been shown significant anti-ischemia activity in animal experiments recently. However, the solubility of the compound need to be enhanced with hydroxypropyl-β-cyclodextrin, which is a strong controversial solution adjuvant via intravenous administration. Methylamine irisolidone is a structurally modified kakkalide with good solubility in the water. In this study, the effect of this new compound on acute myocardial ischemia in dogs was investigated. The results showed that methylamine irisolidone (80 mg/kg, i.v) could reduce the myocardial infarct areas in dogs with myocardial infarction. The serum lactate dehydrogenase (LDH) activity and MB isoenzyme of creatine kinase (CK-MB) were suppressed by methylamine irisolidone after 240 min of administration. These results suggested that methylamine irisolidone exerts the protective effects on myocardial ischemia injury, which may be due to its function of inhibiting LDH and CK-MB releasing, stabilizing myocardial cell membrane and improving myocardial microcirculation and metabolism.

Full text

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Journal of Food and Drug Analysis, Vol. 17, No. 1, 2009, Pages 11-16
11
藥物食品分析　第十七卷　第一期
Protective Effect of Methylamine Irisolidone, a Novel
Compound, on Acute Myocardial Ischemia in
Anesthetized Dogs
YAN-LING MU1,2, YAN-YING XIE2, FU-WEN WANG2, YING ZHONG2, JIE LI2, ZHI-LI HU2,
YUAN-SHU WANG2 AND XIU-MEI ZHANG1*
1.Department of Pharmacology, School of Medicine, Shandong University, Shandong, P. R. China
2.Department of Pharmacology, Institute of Materia Medica of Shandong Academy of Medical Sciences, Shandong, P. R. China
(Received: Febuary 15, 2008; Accepted: October 7, 2008)
ABSTRACT
Kakkalide, a compound obtained from a traditional Chinese medicine Puerariae flos, has been shown significant anti-ischemia
activity in animal experiments recently. However, the solubility of the compound need to be enhanced with hydroxypropyl-β-
cyclodextrin, which is a strong controversial solution adjuvant via intravenous administration. Methylamine irisolidone is a
structurally modified kakkalide with good solubility in the water. In this study, the effect of this new compound on acute myocardial
ischemia in dogs was investigated. The results showed that methylamine irisolidone (80 mg/kg, i.v) could reduce the myocardial
infarct areas in dogs with myocardial infarction. The serum lactate dehydrogenase (LDH) activity and MB isoenzyme of creatine
kinase (CK-MB) were suppressed by methylamine irisolidone after 240 min of administration. These results suggested that
methylamine irisolidone exerts the protective effects on myocardial ischemia injury, which may be due to its function of inhibiting
LDH and CK-MB releasing, stabilizing myocardial cell membrane and improving myocardial microcirculation and metabolism.
Key words: Methylamine irisolidone, myocardial ischemia, infarct area, myocardial zymogram
INTRODUCTION
Puerariae flos is the dried flower bud of Pueraria lobata
(Wild.) Ohwi, which belongs to the leguminosae family. It is
commonly employed to relieve fever and dysentery, promote
the production of body fluid, and reduce stiffness and pain
of the nape. Previous phytochemistry studies on Puerari-
ae flos reported a number of bioactive isoflavones, such as
kakkalide, kakkalidone, irisolidone and so on. Puerariae
flos is usually used for counteracting symptoms associated
with alcohol drinking, liver injury, and menopause in tradi-
tional medicine clinic(1-5). Yamazaki et al.(6) reported that
intraperitoneally administered kakkalide reduced mortality
and serum alanine aminotransferase (ALT) and aspartate
aminotransferase (AST) activities associated with adminis-
tration of ethanol. Lee et al.(7) and Han et al.(8) reported that
kakkalide is metabolized to irisolidone by human intestinal
microflora to show hepatoprotective activity. However, the
cardiovascular effects of Puerariae flos and its constituents
have not been thoroughly investigated.
The plenitudinous ground studies on pueraria
radix have been made in our lab and then much more
research concerning the constituents of Puerariae flos
on cardiovascular activity has been progressed on
this ground(9-11). There is large amount of kakkalide
in Puerariae flos and our recent research proved that
kakkalide had significant anti-ischemia activity in the
whole animal experiments. However, the compound need
to be dissolved with help of hydroxypropyl-β-cyclodextrin.
Hydroxypropyl-β-cyclodextrin is a strong controversial
solution adjuvant via intravenous administration. So
kakkalide was modified, the saccharide group hydrolyzed
with 4′, 5, 7 powerful active groups on, and alkalinity
group insertion at 8 position, so that the water-solubility
was boosted. A new compound was obtain, 8-methylene-
methylamine-irisolidone. It could combine a weak acid to
form a water-soluble salt, making the preparation without
any auxiliary solvent. The purity of this new compound is
above 99.9%. The present study was aimed to investigate
the protective effect of the new compound on the acute
myocardial ischemia in anesthetized dogs.
MATERIALS AND METHODS
I. Animals
Twenty four male and female beagle dogs weighed
* Author for correspondence. Tel/Fax: +86-531-88383146;
E-mail: zhangxm@sdu.edu.cn

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Journal of Food and Drug Analysis, Vol. 17, No. 1, 2009
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between 8.0 and 12.0 kg were purchased from the
Shanghai Laboratory Animal Multiplying Field. The
animals were all individually housed in stainless steel
cages in a temperature and light controlled room and fed
with standard laboratory diet for 7 days after arrival. The
dogs were given free access to food and distilled water.
II. Preparation of Puerariae flos Extracts and Methylamine
Irisolidone
Kakkalide was extracted from the Puerariae flos with
ethanol and distilled ethanol, and then was hydrolyzed into
irisolidone. One gram irisolidone, 1 mL formaldehyde, 2
mL methylamine 30 mL ethanol were mixed, incubated
for 4 hours at 70°C, cool down and filtered, and 1.3 g of
methylamine irisolidone was produced.
III. Preperation of Myocardial Infarction Model in Dogs
The Animal and Ethics Review Committee at Shan-
dong University evaluated and approved the protocol
used in this study and the research was adhered to the
“Principle of Laboratory Animal Care” (NIH publica-
tion #85-23, revised in 1985). All the experiments were
performed on healthy beagle dogs which were anes-
thetized with 2.5% continal (1 mL/kg, i.v.). The surgi-
cal procedure was performed as reported(12,13). In brief,
the trachea was incised longitudinally and cannulated.
The chest was opened under ventilation with room air
by left thoracotomy. After the pericardium was opened,
the left anterior descending (LAD) coronary artery was
ligated near its origin by a 6.0 prolene suture according
to Harris’s two-step ligation method and the epicardium
electrocardiogram was recorded.
IV. Treatment
Twenty four dogs were randomly divided into four
groups. The control group consisted of dogs treated with
normal saline. The three treatment groups consisted of
dogs treated with methylamine irisolidone at the doses
of 80 and 40 mg/kg and 100 mg/kg puerarin (as positive
control) i.v, respectively. All dogs were sacrificed after
4 hours administration and hearts were removed and
treated as described below.
V. Measurement of Epicardium Electrocardiogram and
Myocardial Zymogram
XD-2-epicardial lead (Xiyuan Hospital of Beijing
Traditional Chinese Medicine Academy) was stitched
on epicardium and connected with BioPAC multiplying
channel physiological signal collection analytical
system (BioPAC, USA) with waver, and the epicardial
electrogram was recorded. After operation, normal saline
was infused to the supplement body fluid. Thirty minutes
after coronary artery ligation, epicardial electrogram was
recorded to calculate the total-value of 30 leads ST shift
(Σ-ST) and lead numbers of ST shift (N-ST) over 2 mv
as basic value before drug administration. The speed of
intervenous infusion is 40 drop/min and the volume is
10.0 mL/kg. Myocardial ischemia control group received
the isochoric normal saline. In order to calculateΣ-ST,
N-ST and its change ratio, epicardial electrogram was
recorded at 15, 30, 60, 90, 120, 180 and 240 minutes after
drug administration. At the time intervals of 0, 2 and 4
hours after drug administration, myocardial zymograms
including serum lactate dehydrogenase (LDH), creatine
kinase (CK), MB isoenzyme of creatine kinase (CK-MB)
and aspartate aminotransferase (AST) were determined
using KNOEPRO automatic biochemistry analyzer
(Finland Kangyi Instrument Company).
VI. Measurement of Ischemia and Infarct Area
Both ischemia and infarct areas were measured
in five horizontal sections between the point of ligation
and the apex. The non-ischemia and ischemia or non-
infarction and infarction areas were demarcated after
incubation with black ink from auricula sinistra region
and stained with 0.5% nitroblue tetrazolium （N-BT） in
phosphate buffered solution (pH 7.4) at 37°C for 15 min.
With the digital imaging program from Meta Imaging
Series 6.0, the sizes of ischemia and infarct myocardium
were calculated and infarct size was reported as a
percentage of ischemia area.
VII. Statistical Analysis
Data are expressed as mean ± SD. Statistical signifi-
cance among the groups was assessed by ANOVA followed
by Dunnett’s test. A level of P < 0.05 was considered
statistically significant.
RESULTS
I. Effect of Methylamine Irisolidone on Myocardial
Ischemia Degree (∑-ST) in Acute Myocardial Ischemia
Dogs
After 240 minutes of administration, methylamine
irisolidone (80 mg/kg) can lessen the degree of myocardial
ischemia obviously. In contrast with myocardial ischemia
control group, the difference is significant (P < 0.05). Puer-
arin obviously mitigated the degree of myocardial ischemia
of acute myocardial infarction in anesthetized dogs, too
(P < 0.05). There is no manifest significance in low dose
of methylamine irisolidone group (40 mg/kg). Results are
shown in Table 1.
II. Effect of Methylamine Irisolidone on the Range of
Myocardial Ischemia (N-ST) in Acute Myocardial Ischemia
Dogs

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13
After 240 minutes of administration, methylamine
irisolidone (80 mg/kg) can manifestly reduce the range of
myocardial ischemia (N-ST) in contrast with the myocar-
dial ischemia control group (P < 0.05). With puerarin
injection, the range of myocardial ischemia N-ST was
reduced obviously (P < 0.05). There is no manifest signifi-
cance in 40 mg/kg methylamine irisolidone group. Results
are shown in Table 2.
III. Effect of Methylamine Irisolidone on the Infarct Area in
Acute Myocardial Ischemia Dogs
Myocardial infarct area displayed by the N-BT
staining is roughly similar to the results measured by
the epicardial electrogram. Methylamine irisolidone (80
mg/kg) exhibited obvious effects of lessening injury in
myocardial ischemia, and the infarct area is conspicuously
decreased as compared with the ischemia control group
(P < 0.05). The effect of puerarin is comparable with that
of methylamine irisolidone (80 mg/kg), but not with that
of low dose methylamine irisolidone group. Results are
shown in Table 3.
IV. Effect of Methylamine Irisolidone on Myocardial Zymo-
gram in Acute Myocardial Ischemia Dogs
Under ischemia and hypoxia conditions, the physi-
ological function and biochemical metabolism of cardiac
muscle will change accordingly. Serum LDH levels and
CK and CK-MB activity increased significantly, which
may also reflect the extent of myocardial ischemia. After
2 hours of methylamine irisolidone (80 mg/kg) administra-
tion, methylamine irisolidone obviously decreased blood
serum LDH and CK-MB activity. There is no statistic
Table 1. Effect of methylamine irisolidone on the myocardial ischemia degree (∑-ST change ratio %）
Time (min)
Group
ABCD
0————
152.78 ± 8.04-5.68 ± 4.86-7.76 ± 13.653.15 ± 6.46
30 4.67 ± 13.75-5.59 ± 8.43 4.52 ± 27.42 7.07 ± 11.96
6011.52 ± 17.90 -5.74 ± 13.571.15 ± 31.56 6.19 ± 17.05
90 9.59 ± 17.87-5.65 ± 18.31 -2.20 ± 24.69 3.38 ± 19.13
1209.06 ± 17.55 -15.04 ± 17.46 -8.97 ± 19.79-1.64 ± 23.42
1809.98 ± 26.91 -27.23 ± 24.32-27.60 ± 17.28-15.99 ± 20.87
240 4.97 ± 24.66-40.06 ± 20.77* -26.61 ± 12.64-30.75 ± 16.36*
Note : data are expressed by mean ± SD, same as the follows.
* P < 0.05 for compared with ischemia control group analyzed by one way ANOVA followed by Dunnett’s test.
A: ischemia control group received vehicle, i.v
B: ischemia group received methylamine irisolidone 80 mg/kg, i.v
C: ischemia group received methylamine irisolidone 40 mg/kg, i.v
D: ischemia group received puerarin 100 mg/kg, i.v
Table 2. Effect of methylamine irisolidone on the range of myocardial ischemia (N-ST change ratio %)
Time (min)
Group
ABCD
0――――
15-5.54 ± 15.29-4.44 ± 4.82- 4.09 ± 12.60-2.50 ± 5.59
30-9.00 ± 15.05-2.11 ± 2.88- 2.41 ± 24.43-2.38 ± 3.67
603.30 ± 5.22-5.05 ± 6.87- 1.14 ± 24.06-4.64 ± 3.27
90 2.02 ± 11.905.44 ± 6.81- 0.21 ± 29.85 -2.98 ± 4.69
120 0.17 ± 12.220.77 ± 5.70-11.12 ± 14.81 -6.95 ± 5.01
18015.94 ± 22.46 -5.26 ± 12.69-14.09 ± 16.02 -7.16 ± 7.35
24022.67 ± 33.36 -12.60 ± 6.66*-4.72 ± 6.14 -13.31 ± 9.80*

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Journal of Food and Drug Analysis, Vol. 17, No. 1, 2009
14
difference for CK and AST, though with declining tenden-
cy. Results are shown in Table 4.
DISCUSSION
Methylamine irisolidone is a new structurally
modified compound， which has the main structure of
flavonoid. Flavonoids are widely distributed in food
and drinks and act as antioxidants and iron chelators(14).
Lines of evidence indicated that flavonoid intake
correlates inversely with coronary heart disease risk.
Consumption of flavonoid-rich foods and beverages is
thought to reduce the risk of cardiovascular diseases(15).
Puerarin, as one of flavonoid, has been used to treat
patients with coronary artery diseases(16). The action
mechanism of puerarin may be due to coronary artery
dilatation, lower oxygen consumption of myocardium,
microcirculation improvement, and serum nitric oxide
level elevation of rat with myocardial infarction(17).
Zhang et al. found that puerarin induced angiogenesis in
myocardium of rat with myocardial infarction(18).
Under ischemia and hypoxia conditions, the
physiological function and biochemical metabolism of
cardiac muscle will change accordingly. ST segment
deviation from the baseline and the elevation degree
are closely related to myocardial blood flow and oxygen
tension depression under acute myocardial ischemia
conditions(19). ST elevation represented the degree of
myocardial ischemia infarction scope and the extent
of myocardial necrosis(20). Harris’s two-step ligation
of anterior descending coronary artery is an effective
method to evaluate the pharmacologic effects of drug on
myocardial ischemia. Results of this study showed that
methylamine irisolidone (80 mg/kg) can significantly
reduce the total deviation value of ST-segment of epicardial
electrogram in coronary artery ligation anesthetized dogs,
which suggests that methylamine irisolidone has apparent
Table 4. Effect of methylamine irisolidone on myocardial zymogram in acute myocardial ischemia dogs （n = 6）
Group Index (U/L) 0h 2h4h
ACK-MB 24.40 ± 11.28138.20 ± 23.18 190.40 ± 37.34
CK 122.00 ± 75.41 669.80 ± 224.541025.20 ± 300.65
AST 45.20 ± 20.32 80.40 ± 26.31111.80 ± 47.81
LDH 40.40 ± 22.01 88.80 ± 15.32 105.40 ± 18.96
BCK-MB 26.80 ± 11.61 82.40 ± 34.32* 97.00 ± 34.63**
CK 202.60 ± 151.53 510.40 ± 261.11 659.40 ± 287.58
AST 43.00 ± 10.65 52.60 ± 16.88 57.00 ± 20.55
LDH 40.20 ± 18.83 53.00 ± 21.76* 60.60 ± 21.81*
C CK-MB 25.15 ± 10.25112.23 ± 21.02 130.23 ± 45.25*
CK 189.56 ± 166.34 600.25 ± 146.65 725.23 ± 167.35
AST 44.25 ± 15.23 65.23 ± 20.32 60.23 ± 26.31
LDH 40.15 ± 16.23 70.26 ± 12.48 75.23 ± 22.58
D CK-MB 45.00 ± 15.02 101.40 ± 22.17 100.23 ± 23.94**
CK 240.80 ± 105.48 724.80 ± 185.12 1253.60 ± 474.61
AST46.00 ± 6.89 82.20 ± 24.18 104.60 ± 16.65
LDH 34.40 ± 14.08 55.20 ± 21.48* 70.00 ± 13.56*
Table 3. Effect of methylamine irisolidone on the infarct size in acute myocardial ischemia dogs （n = 6）
GroupIschemia area /Left ventricle area (%)Infarct area /Left ventricle area (%)Infarct area / Ischemia area (%)
A13.56 ± 7.60 9.47 ± 5.2671.51 ± 7.19
B12.02 ± 3.79 6.83 ± 1.6757.90 ± 8.70*
C13.34 ± 4.61 8.42 ± 2.48 63.12 ± 7.59
D13.57 ± 5.27 7.46 ± 3.8353.35 ± 15.91*

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Journal of Food and Drug Analysis, Vol. 17, No. 1, 2009
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protective effect on acute myocardial ischemia dogs.
Biochemical analysis showed that methylamine irisolidone
significantly reduces the serum CK-MB activity, and
improves acute myocardial ischemia and myocardial
infarction in coronary occlusion dogs. Administration
of methylamine irisolidone can significantly reduce the
extent of myocardial ischemia (∑-ST, N-ST), as measured
by the epicardial electrogram mapping. Serum LDH
levels, CK and CK-MB activity increased significantly,
which may also reflect the extent of myocardial ischemia.
After 2 hours of methylamine irisolidone (80 mg/kg)
administration, methylamine
decreased the blood serum LDH and CK-MB activity. The
action mechanisms may be owing to that methylamine
irisolidone could increase myocardial blood flow, promote
the establishment of collateral circulation, increase
myocardial oxygen supply, improve myocardial hypoxia
tolerance, dilate peripheral vessels, reduce the cardiac pre-
and afterload, and reduce myocardial oxygen consumption,
thereby improving the imbalance state of oxygen /
aerobic in myocardial ischemia, stabilizing myocardial
membrane, reducing the enzyme leakage ratio and
improving myocardial microcirculation and metabolism.
The morphologic results showed that the infarct size was
reduced by puerarin injection, which is comparable with
that of methylamine irisolidone. The results mentioned
above show that methylamine-irisolidone has protective
effect on ligation anterior descending coronary artery
induced acute myocardial ischemia in anesthetized dogs
and may be developed into an effective new drug to treat
cardiovascular diseases.
irisolidone obviously
ACKNOWLEDGEMENTS
This work was financially supported by the National
Nature and Science Foundation of China, No: 30701022
and the National Nature and Science Foundation of
Shandong Province, No: Y2007C156. All work was
finished in the key laboratory for modern medicine and
technology of Shandong province.
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