Hypoglycemic effects of crude polysaccharide from purslane.

Abstract

The effects of crude polysaccharide from Purslane (CPP) on body weight (bw), blood glucose, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-c), triglyceride (TG) and serum insulin levels were studied in diabetes mellitus mice. CPP treatment (200, 400 mg/kg bw) for 28 days resulted in a significant decrease in the concentrations of fasting blood glucose (FBG), TC and TG. Furthermore, CPP significantly increased the concentration of HDL-c, body weight and serum insulin level in the mice. In addition, according to acute toxicity studies and single cell gel electrophoresis analysis, CPP did not produce any physical or behavioral signs of toxicity. More significantly, our data demonstrated CPP exhibited the best effects at the dose of 400 mg/kg bw. The above results suggest that CPP can control blood glucose and modulate the metabolism of glucose and blood lipids in diabetes mellitus mice, so we conclude that CPP should be evaluated as a candidate for future studies on diabetes mellitus.

Full text

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Int. J. Mol. Sci. 2009, 10, 880-888; doi:10.3390/ijms10030880

International Journal of
Molecular Sciences
ISSN 1422-0067
www.mdpi.com/journal/ijms
Article

Hypoglycemic Effects of Crude Polysaccharide from Purslane

Fayong Gong 1,*, Fenglin Li 2, Lili Zhang 2, Jing Li 1, Zhong Zhang 1 and Guangyao Wang 2

1 Department of Food Science, XiChang College, Sichuan Province, 615000, P. R. China
2 Department of Bioengineering, Jilin Agricultural Science and Technology College, Jilin Province,
132101, P.R. China; E-Mail: swgclifenglin@sina.com (F.L.); zhanglili1975@sina.com (L.Z.)

* Author to whom correspondence should be addressed; E-Mail: gongfayong@126.com;
Tel. +86-13989251031; Fax: +86-0834-2580001

Received: 1 February 2009; in revised form: 19 February 2009 / Accepted: 23 February 2009 /
Published: 2 March 2009


Abstract: The effects of crude polysaccharide from Purslane (CPP) on body weight
(bw), blood glucose, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-c),
triglyceride (TG) and serum insulin levels were studied in diabetes mellitus mice. CPP
treatment (200, 400 mg/kg bw) for 28 days resulted in a significant decrease in the
concentrations of fasting blood glucose (FBG), TC and TG. Furthermore, CPP
significantly increased the concentration of HDL-c, body weight and serum insulin level
in the mice. In addition, according to acute toxicity studies and single cell gel
electrophoresis analysis, CPP did not produce any physical or behavioral signs of
toxicity. More significantly, our data demonstrated CPP exhibited the best effects at the
dose of 400 mg/kg bw. The above results suggest that CPP can control blood glucose and
modulate the metabolism of glucose and blood lipids in diabetes mellitus mice, so we
conclude that CPP should be evaluated as a candidate for future studies on
diabetes mellitus.

Keywords: Diabetes; Purslane; polysaccharide; hypoglycemia.


OPEN ACCESS

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1. Introduction

Purslane (Little Hogweed; Chinese name: Ma-Chi-Xian) is a grassy plant with small yellow
flowers and stems sometimes flushed red or purple, which grows widely in different areas of the world
including the north of China [1,2]. The plant contains many biologically active compounds, including
free oxalic acids, alkaloids, omega-3 fatty acids, coumarins, flavonoids, cardiac glycosides, and
anthraquinone glycosides [3,4]. Purslane is considered a type of common weed, but it can be eaten as
a potherb without any side effects. Moreover, Purslane is known in folk medicine in some parts of
China as a hypotensive and antidiabetic [5,6,7]. Though there is no scientific evidence to support the
antidiabetic effects of Purslane, people continue to use it in the treatment of this condition. The
objective of this study was to extract crude polysaccharide(s) from Purslane and assess the
hypoglycemic effects of these constituents with animal tests for the use of this plant in the treatment
of diabetes.

2. Results and Discussion

2.1. Acute toxicity studies

Acute toxicity studies revealed no obvious symptom of toxicity of CPP or any significant changes
in general behavior in mice. There was no lethality or any toxic reactions found at any of the doses
selected through the end of the study period.

2.2. Effect of CPP on body weight in mice

Alloxan-induced diabetic mice exhibited loss of body weight [8,9]. Before embarking on the
experiments, all the groups had no significant difference in body weight (P >0.05) (Table 1).
Table 1. Effect of CPP on body weight (g) in mice.
Group
Number
of
animals
8
8
8
8
8
Days after dosing
0d 7d 14d 21d 28d
NC
DC
18.99±0.60
19.14±0.75
19.15±1.14
19.49±0.74
19.08±1.07
23.45±0.57
20.65±0.74*
20.97±1.44*
21.50±1.29*
22.62±1.52#
25.39±0.57
22.40±1.06*
22.93±1.53*
23.51±0.95*#
24.97±0.98#
27.56±0.57
23.40±0.99*
25.47±1.07*#
26.01±0.65*#
26.91±0.99#
30.22±0.85
24.41±1.51*
26.90±0.96*#
27.62±1.13*#
29.18±1.05#
DLCPP
DHCPP
DGLI
n=8; (mean±S.D., g); * P < 0.05 as compared with normal control group (NC).# P < 0.05 as compared
with diabetic control group (DC). DLCPP = diabetic mice+ low dose CPP; DHCPP = diabetic mice +
high dose CPP; DGLI = diabetic mice + glibencamide.

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A significant (P < 0.05) decrease in body weight was detected in the DC, DLCPP and DHCPP
groups as compared to the normal control group from 7 days after alloxan injection. However, the
body weights in the DHCPP group were significantly (P < 0.05) and dose-dependently increased as
compared to those of the diabetic control from 14 days after administration. In the DGLI group, a
significant (P < 0.05) increase in body weight as compared to the DC group was also detected from 7
days after administration. The results are shown in Table 1.The present study showed that the body
weight was significantly decreased in the diabetic control group as compared to the normal control
group within 28 days. However, the treatment with CPP for 28 days improved the body weight loss.

2.3. Effect of CPP on fasting blood glucose levels in mice

Effective control of the blood glucose level is a key step in preventing or reversing diabetic
complications and improving the quality of life in both Type 1 and Type 2 diabetic patients [10,11].
The alloxan-induced diabetic mice exhibited hyperglycemia. In the diabetic groups, a significant (P<
0.05) increase in FBG was detected, as compared to the normal control group, but these abnormal
increases in blood glucose levels significantly (P < 0.05) and dose-dependently decreased in the CPP -
administered groups as compared to the diabetic control group from 7 days after administration. On the
28th day, blood glucose levels in the DLCPP and DHCPP groups had decreased by 36.0% and 62.9%,
respectively. In the DGLI group, the decrease was also significant (P < 0.05) from 7 days after
administration. The NC and DC groups did not show any significant variation on the blood glucose
level throughout the experimental period (p > 0.05). The results are shown in Table 2.

Table 2. Effect of CPP on blood glucose Level (mmol/L ) in mice.
Groups
Number
of
animals
8
8
8
8
8
Days after dosing (day)
0 7 14 21 28
NC
DC
5.15±0. 0.17
15.36±0.39*
15.25±0.30*
15.39±0.28*
15.29±0.29*
5.14±0.17
15.33±0.26*
12.67±0.24*#
11.92±0.26*#
9.06±0.14*#
5.10±0.13
15.33±0.35*
11.29±0.28*#
10.48±0.30*#
7.24±0.21*#
5.04±0.08
15.15±0.15*
10.56±0.32*#
9.47±0.29*#
6.47±0.24*#
5.16±0.10
15.23±0.29*
9.76±0.29*#
8.33±0.17*#
5.68±0.33*#
DLCPP
DHCPP
DGLI
n=8; (mean±S.D., g); * P < 0.05 as compared with normal control group.;# P < 0.05 as compared with
diabetic control group.

The present study showed that alloxan-induced diabetic mice presented obvious hyperglycemic
symptoms, but CPP produces a significant antihyperglycemic effect when administered orally to
alloxan-diabetic mice. The dosage of 400mg/kg is more effective than that of 200 mg/kg.

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2.4. Effect of CPP on blood lipids levels in mice

Diabetes mellitus is usually complicated with hyperlipoproteinemia. The present results showed
that the TC and TG levels were significantly elevated in the diabetic control group as compared to the
normal control group (P < 0.05), and serum HDL-c level, a friendly lipoprotein, was decreased in
diabetic control group as compared to the normal control group (P < 0.05). After supplementation with
CPP and glibenclamide, the alteration in lipid metabolism was partially attenuated as evidenced by
decreased serum TG and TC levels and by increased HDL-c concentration in diabetic mice. The
response was better in the DHCPP group compared to the DLCPP group which is comparable to that
of the DGLI group. The results are shown in Table 3.

Table 3. Effect of CPP on blood lipids (mmol/L ) in mice.
Groups
Number of
animals
8
8
8
8
8
TG TC HDL-c
NC
DC
1.64±0.02
2.05±0.04*
1.86±0.02*#
1.77±0.02*#
1.72±0.01*#
2.70±0.02
3.34±0.04*
3.16±0.02*#
3.12±0.02*#
3.03±0.05*#
1.64±0.01
0.77±0.02*
0.84±0.02*#
1.11±0.03*#
1.39±0.02*#
DLCPP
DHCPP
DGLI
n=8; (mean±S.D., g);*P<0.05 as compared with normal control group (NC);
#P<0.05 as compared with diabetic control group.

The serum TC and TG were decreased significantly in diabetic mice after CPP supplementation.
These effects may be due to low activity of cholesterol biosynthesis enzymes or low level of lipolysis
which are under the control of insulin [12].

2.5. Effect of CPP on blood serum insulin levels in mice

Serum insulin levels of the normal control group were higher than those of the diabetic control
group, which indicated that alloxan damaged the pancreas islet cells. After 28 days of the CPP
supplementation to the mice, there was a significant elevation in serum insulin level as compared to
the diabetic control group ( p < 0.05), which implied that treatment with CPP improved the insulin
secretion on diabetic mice. In the DHCPP group, the insulin level was higher than that of the DLCPP
group. The results implied that CPP improved the function of islet cells and stimulated the insulin
secretion. The results are shown in Figure 1.
Alloxan could damage pancreatic β cells, resulting in a decrease in endogenous insulin secretion,
which decreased utilization of glucose by the tissues consequently. In this study, we have observed
that CPP increased the concentration of serum insulin in alloxan-induced diabetic mice. The possible
mechanism of action of CPP could be correlated with promoting insulin secretion by closure of K+-
ATP channels, membrane depolarization and stimulation of Ca2+ influx, an initial key step in insulin
secretion[13]. Additional studies are needed to address this hypothesis.

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Figure 1. Effect of CPP on serum insulin level in mice.
0
1
2
3
4
5
6
7
8
9
10
11
12
*
Serum insulin level (uU/ml)
NC DC DLCPP DHCPP

*
*

*P<0.05 as compared with diabetic control group.

3. Experimental Section

3.1. Plant materials

Purslane was collected in Sichuan Province in July and the material was identified by Mr. Wang
Guang-Yao, a botanist from the Jilin Agriculture Science and Technology College. A voucher
specimen has been deposited in the herbarium of the Jilin Agriculture Science and Technology
College. Fresh and intact Purslane dried in the shade was chosen as experimental material.

3.2. Drugs and reagents

Alloxan was purchased from Sigma Co. (USA). Glucose Analyzer and strips were purchased from
Roche Diagnostic Co. (USA). Reagents for total cholesterol (TC), triglyceride (TG), high-density
lipoprotein cholesterol (HDL-c) were obtained from Beijing Chengxinde Biochemistry Reagent
Company (Beijing, P.R. China). Reagents for serum insulin was purchased from Adlitteram Diagnostic
Laboratories Co. (USA).

3.3. Preparation of crude polysaccharide from Purslane (CPP)

The shade dried Purslane was crushed in an electrical grinder and then powdered, 1,000 g of this
powder was immersed in tenfold dH2O and boiled at 100 °C for 9 h [14-16], and then the water extract
was collected. The process was repeated, and the extracts were combined and concentrated on a
vacuum rotary evaporator at 60 °C. The concentrated solution was precipitated by addition of four
times its volume of volume 80% ethanol and the precipitate was washed in turn with 100 % ethanol,
100 % ether and acetone. Crude polysaccharide from Purslane (CPP) was obtained by vacuum drying