












































Journal of Enam Medical College
Vol 11 No 2 May 2021

72

Original Article

Antihyperglycemic and Glucose Homeostasis Effect of Ethanol and 
DCM Extract of Gymnema Sylvestre on Type 1 Diabetic Model Rat

Nasreen Chowdhury1, Rokeya Begum2, Liaquat Ali3, Md. Mahbubur Rahman4
Received: 26 January 2021        Accepted: 30 March 2021

doi: https://doi.org/10.3329/jemc.v11i2.65188

1. Professor, Department of Biochemistry, University of Science and Technology Chittagong (USTC) Medical College, 
Chittagong

2.  Professor, Department of Pharmacology, Bangladesh Institute of Research and Rehabilitation in Diabetes, Endocrine 
and Metabolic Disorders (BIRDEM), Shahbagh, Dhaka 

3. Professor, Department of Biochemistry and Cell Biology, Bangladesh Institute of Research and Rehabilitation in 
Diabetes, Endocrine and Metabolic Disorders (BIRDEM), Shahbagh, Dhaka

4. Department of Biochemistry, Jahurul Islam Medical College, Bajitpur, Kishoreganj
Correspondence Nasreen Chowdhury, Email: drnasreenchy@yahoo.com

Abstract

Bacground: Plants have formed  the basis for the treatment of diseases in traditional medicine 
systems for thousands of years and continue to play a major role in the primary health care of 
about 80% of the world inhabitants. Gymnema sylvestre is one of the most studied herbs which 
has been claimed to be active against both type of diabetes mellitus. Objective: The dried powder 
leaves of Gymnema extracted with ethanol and dichloromethane (DCM) and then its effect were 
studied in streptozotocin induced type 1 diabetic model rat at different prandial state. Materials 
and Methods: In the present study both of the extracts (GS EthOH and GS DCM) of Gymnema 
sylvestre produced a significant antihyperglycemic effect in type 1 diabetic model rats when the 
extract was given 30 minutes before glucose load. The effectiveness of the extracts in type 1 
diabetic rats with residual insulin secretion indicates that the hypoglycemic effect of active plant 
compound(s) is probably mediated either by improving insulin secretion from the existing β cells 
or by increasing its sensitivity. Results: The baseline value of fasting serum glucose reflects that 
the degree of damage of β cells by the toxic effect of streptozotocin was gradual. The findings 
at one week show some spontaneous recovery in water control group and better recovery in all 
the treated groups. After two weeks, fasting serum glucose level was improved in all the extract 
treated groups. Conclusion: The data suggest that Gymnema sylvestre leaf extracts improve the 
glycemic status in type 1 diabetic model rat.

Key words: Gymnema sylvestre; Type 1 diabetes; Streptozotocin; Antihyperglycemic 

J Enam Med Col 2021; 11(2): 72−77
Introduction

Plants have formed the basis for the treatment of 
diseases in traditional medicinal systems for thousands 
of years, and continue to play a major role in the primary 
health care of about 80% of the world’s inhabitants.1 
Traditional antidiabetic plants might provide a useful 
source of new oral hypoglycemic compounds for 

development as pharmaceutical entities or as simple 
dietary adjuncts to existing therapies.2 Many of the 
currently available drugs have been derived directly 
or indirectly from plants. However, only a few have, 
till now, been subjected to scientific and systematic 
medicinal studies to assess their efficiency. Various 



May 2021J Enam Med Col Vol 11 No 2

73

plant extracts have been found to be active both in 
type 1 and type 2 which may potentially be the 
pharmacological target of modern antidiabetic drug 
research.

Gymnema sylvestre a plant used in the Ayurvedic 
medicine of India for the treatment of diabetes 
mellitus for over 2000 years by Ayurvedic and Unani 
practitioners.3 It is one of the most studied herbs 
which has been claimed to be active against both 
type of diabetes mellitus.4 The plant belongs to the 
family Asclepiadaceae and grows in open woods in 
India, China, Indonesia, Japan, Malaysia, Sri Lanka, 
Vietnam and South Africa. 

Gymnema sylvestre possesses tremendous importance 
as a medicinal plant. The hot water extract of 
Gymnema sylvestre leaves is usually taken orally for 
the treatment of diabetes.5,6 Hypoglycemic effects of 
water and methanol extracts of Gymnema sylvestre 
leaves have been reported in diabetic rats and 
humans.7,8 A pure compound conduritol also isolated 
from methanol extract.9 It has been claimed that, 
oral administration of water soluble acidic fraction 
of ethanol extract normalized blood sugar level in 
Streptozotocin treated rat by secretion of endogenous 
insulin, possibly due to regeneration of beta cell.10 The 
present work was undertaken to study the glucose-
lowering effects of the ethanol extract and DCM 
extracts in streptozotocin-induced types 1 diabetic rat 
at different prandial states.

Materials and Methods

Collection & identification of Gymnema sylvestre 
leaves

Dried Gymnema sylvestre leaves (5 kg) were 
purchased from a local herbal medicinal shop of old 
Dhaka town. Botanical identification was performed 
and the accession no is 30381 by National Herbarium, 
Bangladesh. The leaves were cleaned, separated 
from petiole and stems and dried in an oven at 40 0C. 
Finally they were grounded to powder and stored in a 
well-stopper plastic container. 

Extraction and fractionation procedure

Gymnema sylvestre leaves powders were extracted 
with 80% ethanol in the extraction tank for about 

4 days at room temperature by changing ethanol 
every alternate day. The extracts were filtered and 
evaporated by rotary evaporator and finally freeze-
dried to obtain a 210 g extract. The dry samples were 
stored in reagent bottles at 4oC in a freezer.

The ethanol extract (100 g) was partitioned between 
Dichloromethane and water. DCM part was separated 
and evaporated to dryness to get DCM soluble 
material, which was kept, separately for chemical 
analysis. The residual aqueous part was condensed by 
rotary evaporator and finally freeze-dried (60 g).

Animal preparation

Adult male Long-Evans rats weighing 180−220 gm 
were used throughout the study. The animals were 
bred at BIRDEM (Bangladesh) and maintained on 
12 hour light-dark cycle, fed on a standard laboratory 
pellet diet and with water supplied ad libitum. Animal 
described as fasted were deprived of food for at least 
12 hr but allowed free access to drinking water. 

Induction of Type 1 diabetes in rats

Type 1 diabetes was induced by intraperitoneal 
injection of streptozotocin (stz, 65 mg/kg body weight) 
dissolved in citrate buffer (pH 4.5) immediately before 
use to 3 month old, healthy adult rats fasted for 18 
hours. The blood glucose level was checked on the 
5th day after injection of STZ. Animals having high 
blood glucose levels (>20 mM) were considered as 
type 1 diabetic. 

 Administration of extracts and glucose loading

Rats were kept fasted for 12 h before use. Solutions or 
suspensions of plant extracts (1.25 g/kg body weight 
in 10 ml of water) were administered orally by gastric 
intubations. For postprandial condition the extracts 
were fed 30 minutes before glucose (2.5 g/kg body 
weight in 10 ml of water) load following the standard 
procedure developed in BIRDEM laboratory. The 
corresponding negative control rats were fed orally 
with deionized water (10 mL) and positive control 
rats were given injection Insulin (Actrapid HM-40 U: 
1mL).

Experiment on glucose homeostasis 

For chronic study, type 1 diabetic rats were fed plant 



May 2021J Enam Med Col Vol 11 No 2

74

extracts (1.25 g/kg bw) by a metallic tube once daily 
for 14 days. Control rats were administered water (10 
ml/kg bw). The extract treated rats were divided into 
3 subgroups depending on the administration of the 
extracts. GS-0 group received extracts immediately 
after injection of streptozotocin. The GS-3 group and 
GS-5 group were fed with the extracts after 3 days 
and 5 days of giving streptozotocin injection. All 
the groups remained under similar environmental 
conditions, and were provided with enough food and 
water throughout the experiment. Body weight of 
each rat was recorded every 7th day. Blood samples 
were collected at the beginning of the experiment 
from the tail tips under mild ether anaesthesia and 
at the end directly from heart/abdominal aorta under 
pentobarbital anaesthesia. Serum was separated by 
centrifugation for the analysis of glucose and insulin. 
Serum was preserved immediately at –70 0C and 
stored until analyzed.

Blood collection from the experimental rats and 
biochemical analysis 

Blood samples were collected by cutting tail tip 
under mild ether anesthesia at 0 min, 60 min and 105 
min. After collecting blood at 0 min, extracts, water 
and insulin were given to rats; the experiment was 
followed by glucose load 30 min after feeding extracts. 
The glucose level was measured immediately by the 

glucose-oxidase method using ACCUTREND GC 
blood glucose analyzer from Boehringer Mannheim 
GmbH (Germany).

Statistical analysis 

Results are expressed as mean ± SD or median (range) 
as appropriate. Between groups, comparison of data 
was done by using One-way ANOVA with Post hoc 
Bonferroni test. The level of significance was set at 
0.05. Data were managed using the computer software 
Statistical Package for Social Sciences (SPSS) for 
Windows, Version 10.0.

Results

Acute effect of G sylvestre on serum glucose level

Ethanol extract of G sylvestrae (GS-EthOH) was fed 
30 min before oral glucose load. Statistical analysis 
indicated that oral administration of the ethanol extract 
of G sylvestrae (GS-EthOH) significantly opposed the 
rise of serum glucose at 60 min (p=0.033) compared 
to water control (WC) but it did not bring significant 
effect on the group, which was fed DCM extract (GS-
DCM) in compared to WC at 60 min (p=0.06). At 105 
min, serum glucose level of the WC and GS-EthOH 
groups was comparable. Compared to WC, GS-DCM 
extract significantly opposed the rise of serum glucose 
at 105 min (p=0.01) (Table I).  

Table I: Effect of 80% ethanol extract and aqueous part of DCM extract of on serum glucose level of Type 1 
diabetic model rats when the extract was fed 30 minutes before glucose load 

Groups Min 0 (mmol/L) Min 60 (mmol/L) Min 105 (mmol/L)
WC (n=10) 22.2 ± 4.2 31.3 ± 3.0 28.4 ± 4.3
IC (n = 12) 16.2 ± 3.9 3.9 ±  0.37 7.5 ± 1.7
GSeth (n=11) 18.8 ± 5.1 23.1 ± 3.2 24.4 ± 3.3
GSdcm (n=9) 20.3 ± 2.7 26.0 ± 3.4 21.7 ± 4.8

Bonferroni p values
WC vs IC 0.198 <0.001 <0.001
WC vs GSeth 0.375 0.033 0.684
WC vs GSdcm 2.871 0.06 0.010
IC vs GSeth 1.809 <0.001 <0.001
IC vs GSdcm 0.045 <0.001 <0.001
GSeth vs GSdcm 0.168 0.726 1.206

Results are expressed as Mean ± SD; WC, Water Control; IC, Insulin Control; GS, Gymnema sylvestre; eth, Ethanol; dcm 
Dichloromethane. One way ANOVA with post hoc Bonferroni test was performed as the test of significance.



May 2021J Enam Med Col Vol 11 No 2

75

0

5

10

15

20

25

30

35

0 60 105

Time (min)

S
 g

lu
c
o
se

 (
m

m
o
l/

L
)

WC

IC

GS DCM

GS EthOH

Fig 1. Effect of Gymnema sylvestre (GS) ethanol (EthOH) and DCM extracts on serum glucose level when fed 30 min 
after glucose load. DCM, Dichlormethane; WC, water control; IC, insulin control 

Table II: Effect on fasting serum glucose of the study rats after 14 days 

Groups
S Glucose 
Baseline 
(mmol/L)

S Glucose 
1 wk 

(mmol/L)

S Glucose 
2 wk 

(mmol/L)

t/p value
Baseline vs 

1 wk
Baseline vs 

2 wks
1 wk vs  
2 wks

WC (n = 17) 22.2 ± 4.1 15.5 ± 4.9 17.6  ± 5.1 3.36/0.02 0.33/0.75 1.58/0.13
GS-0  (n=9) 8.5 ± 3.1 14.1 ± 4.7 11.0 ± 4.3 1.35/0.35 1.02/0.25 0.25/0.80
GS-3 (n=7) 16.7 ± 6.4 6.4 ± 1.4 8.4 ± 4.1 2.10/0.17 2.81/0.04 1.95/0.10

GS-5 (n=10) 20.9 ± 3.5 11.4 ± 6.7 10.4 ± 5.6 1.77/0.15 1.33/0.27 0.04/0.96

Bonferroni p values
WC vs GS-0 0.003 1.506 0.012
WC vs GS-3 0.055 0.003 0.006
WC vs GS-5 0.483 0.348 0.033
GS-0 vs GS-3 0.032 0.003 0.567
GS-0 vs GS-5 0.012 0.972 2.364
GS-3 vs GS-5 0.124 0.144 1.212

Results are expressed as Mean + SD; WC, Water control; GS, Gymnema sylvestre; GS-0, Extract feeding started on 0 
day of STZ injection; GS-3, Extract feeding started on 3 day of STZ injection; GS-5, Extract feeding started on 5 day of 
STZ injection; Between group comparison was done using One way ANOVA with post hoc Bonferroni test.  Within group 
comparison was done using paired t test.



May 2021J Enam Med Col Vol 11 No 2

76

Chronic effect of G sylvestre on glucose 
homeostasis

Results of fasting serum glucose (FSG) level of the 
study rats at baseline (before onset of feeding), at 1 
week and at 2 week after feeding is shown in Table II. 

At baseline, the mean fasting serum glucose (FSG) 
(mmol/L) of the GS-O group was significantly lower 
than the WC group (p=0.003). The level of FSG 
(mmol/L) at baseline of the GS-3 & GS-5 group was 
lower than the WC group but was not statistically 
significant. 

At 1 week, the value of FSG (mmol/L) level of the 
GS-3 group was significantly lower than the WC 
group (p=0.003). The mean FSG (mmol/L) at 1 week 
of the group GS-3 was significantly lower than the 
GS-0 group (p=0.003). Compared to WC, the level of 
FSG at 1 week of the GS-0 and GS-5 groups were not 
significantly different.

At 2 week, the level of fasting serum glucose level 
of the group GS-0, GS-3 and GS-5 were significantly 
lower (p=0.012, p=0.006 and p=0.033 respectively) 
compared to WC. 

Discussion

Diabetes is a serious disorder that has a significant 
impact on health and life expectancy of the patient. 
The cost of treating this disease already put a heavy 
burden on the health care system. Among the non-
communicable diseases diabetes now considered as an 
emerging epidemic in Bangladesh.11 People living with 
diabetes are especially facing an increasing demand 
for long term continuous care of health service and 
burden of health care cost. Currently available drug 
regimens for management of diabetes have certain 
drawback. There is need for safer and more effective 
antidiabetic drugs. The present study was undertaken 
to assess hypoglycemic properties and to investigate 
the underlying mechanism of action of G sylvetre leaf 
extracts in type 1 diabetic model rats.

In the present study both of the extracts (GS EthOH 
and GS DCM) of G sylvetre produced a significant 
antihyperglycemic effect in type 1 diabetic model rats 
when the extract was given 30 minutes before glucose 
load. The effectiveness of the extracts in type 1 diabetic 

rats with residual insulin secretion indicates that the 
hypoglycemic effect of active plant compound(s) 
is probably mediated either by improving insulin 
secretion from the existing β cells or by increasing 
its sensitivity. The antihyperglycemic properties of G 
sylvetre was supported by the results of others.7,8,12,13

In the chronic study, the baseline values of fasting 
serum glucose (at 0, 3 and 5 days of giving 
streptozotocin) reflects that the degree of damage of β 
cells by the toxic effect of streptozotocin was gradual. 
The findings at one week show some spontaneous 
recovery in water control group and better recovery 
in all the treated groups. After 2 weeks, fasting 
serum glucose in the water control group deteriorated 
whereas it was improved in all the extract treated 
groups.

The data suggest that Gymnema sylvestre leaf extracts 
improve the glycemic status in type 1 diabetic model 
rat.

Acknowledgement

Financial support from the Asian Network of Research 
on Antidiabetic Plants (ANRAP), Bangladesh is 
gratefully acknowledged. We thank Dr. Mahbuba 
Akhter for the identification of plant materials.

References

1. Farnsworth NRO, Akerele AS, Bingel DD, Guo Z.  
Medicinal plants in therapy. Bul World Health Org 
1985; 63: 965−981.

2. Bailey CJ, Day C. Traditional plant medicines as 
treatment for diabetes. Diabetes care 1989; 12(8): 
553−564.

3. Warren RP, Warren RM, Weninger MG, Inhibition of 
the sweet taste by Gymnema sylvestre. Nature 1969; 
223: 94−95.

4. Kirtikar KR and Basu BD (reprinted 1987) Indian 
medicinal plant 3, International Book Distributors, 
India : 1625−1627.

5. Jain SR, Sharma SN. Gymnema sylvestre leaves for 
treatment of diabetes mellitus. Plant Med 1967; 15: 
439−442.

6. Gupta SS. Effect of hot water extract of Gymnema 



May 2021J Enam Med Col Vol 11 No 2

77

Shanmugasundaram KR, Rajendran VM. Possible 
regeneration of islets of langerhans in streptozotocin 
diabetic rats given Gymnema sylvestre leaf extracts. J 
Ethnopharmacol 1990; 30: 265−279.

11. ICDDRB Documents, Annual Report: 2008, 
Discovery: Diabetes the emerging epidemic in 
Bangladesh. Available at: http://centre.icddrb.org/pub/
publication.jsp?classificationID=46&pubID=10327

12. Baskaran K, Ahmath BK, Shanmugasundaram KR, 
Shanmugasundaram ER. Antidiabetic effect of a 
leaf extract from Gymnema sylvestre in non insulin 
dependent diabetes mellitus. J Ethnopharmacol 1990; 
30: 295−300.

13. Persaud SJ, Al-Majed H, Rahman A, Jones PM. 
Gymnema sylvestre stimulates insulin release 
in vitro by increased membrane permeability. J 
Ethnopharmacol 1999; 163: 207−212.

sylvestre leaves on diabetic subjects. Indian J  Med 
Sci 1963; 17: 501−505.

7. Rokeya B, Nahar N, Ali L, Hassan Z, Nur-e-Alam M, 
Chowdhury NS et al. Effects of five medicinal plants 
on blood glucose levels of nondiabetic and diabetic 
model rats. Diabetes Res 1999; 34: 219−228.

8. Shanmugasundaram ERB, Rajeshwari G, Baskaran K, 
Rajeshkumar BR, Shanmugasundaram KR, Ahmath 
BK. Use of Gymnema sylvestre leaf extract in the 
control of blood glucose in insulin dependent diabetes 
mellitus. J Ethnopharmacol 1990; 30: 281−294.

9. Nahar N, Rokeya B, Ali L, Hassan Z, Nur-e-Alam M, 
Chowdhury NS et al. Effects of three medicinal plants 
on blood glucose levels of nondiabetic and diabetic 
model rats. Diabetes Res 2000; 35: 41−49.

10. Shanmugasundaram ERB, Gopinath KL, 


