Antihyperglycemic Activity of Strychnos potatorum
Seed and Leaf Methanolic Extracts in Alloxan- Induced Diabetic Rats
T
Pandu Raju1*, KJR Shastri2
, C Srinivas Reddy1 and VM
Reddy1
1Department of Pharmacognosy, Vaagdevi College of Pharmacy, Hanumakonda,
Warangal, Andhra Pradesh, India.
2Department of Ayurvedic, Ananthalaxmi Ayurvedic Government Medical College, Warangal, Andhra
Pradesh, India.
ABSTRACT
The pharmacognostic and phytochemical
examinations of different solvents extracts of seeds and leaves of Strychnos potatorum
were conducted and their antidiabetic activity was evaluated.The administration of methanolic
extracts of seeds and leaves of Strychnos potatorum by oral route at doses; 200 and 400 mg/kg b.w. at every 3 hour interval reduced blood
glucose levels by24.23%, 25.67%, 16.47% and 17.88%, respectively in alloxan-induced diabetic rats.
KEYWORDS: Strychnos potatorum; Alloxan;
antihyperglycemic activity; Loganiaceae; MESP (methanolic
extract of seed
Powder);
MELP (methanolic extract of leaf powder).
1. INTRODUCTION
Diabetes mellitus is a
chronic disease characterized by high blood glucose levels due to absolute of
relative deficiency of circulating insulin levels. Diabetes is known to be
hereditary metabolic disease since ancient times; however the existing methods
of treatment for this disease are not completely satisfactory which led to
search for herbal folk medicines.
Strychnos potatorum belonging to the
family Loganiaceae
used in the treatment of urinary infections, skin diseases, eye troubles,
inflammation, and gonorrhoea. The traditional healers
used its seeds in diabetes treatment1, 2. Since the antidiabetic activity of this plant has not been
scientifically evaluated, the present study was undertaken to investigate the
effect of methanolic extracts of seeds and leaves of Strychnos potatorum on
blood sugar levels in normal and hyperglycemic rats.
2.
EXPERIMENTAL:
2.1. Plant Material:
The leaves and seeds of Strychnos
potatorum Linn.
(Loganiaceae) were collected in November and December
2006 from Pakhal and Etturnagarum,
Warangal (A.P), India. The plant parts are identified by Dr. Raju S. Vastavya, Taxanomist, Dept of Botany, Kakatiya
University, Warangal, India and authenticated by
comparing with the voucher specimen.
2.2. Extraction:
The leaves were dried,
crushed, powdered and macerated with methanol for 2 days to afford a greenish
brown semisolid mass (MELP; yield: 6.76% w/w on dried wt). Shade dried and
powdered seeds were soxhlet extracted with methanol
to afford a brown semisolid mass (MESP; yield: 3.72% w/w on dried wt).
2.3. Preliminary phytochemical studies:3-6
Preliminary
qualitative phytochemical analysis of MELP and MESP
indicated the presence of steroids, alkaloids, tannins and reducing sugars
(Carbohydrates).
Table 1: Effect of the methanolic
extracts of seed and leaf of Strychnos potatorum (MESP & MELP) on blood glucose levels in
normal and diabetic rats.
|
Materials |
Dose |
Glucose
level (mg/dL) |
|||
|
Normal rats (Glucose loaded model) |
Diabetic rats |
||||
|
T0 |
T3 |
T0 |
T3 |
||
|
Control (Normal saline) |
-- |
56.47+1.38 |
58.12+1.46 |
207.11+0.99 |
300.92+2.15 |
|
Glibenclamide |
5 mg/kg |
54.71+1.75 |
45.31+1.21 |
230.64+1.48 |
166.51+1.66** |
|
MESP |
200 mg/kg |
39.67+1.17 |
40.16+1.02 |
235.37+1.27 |
178.32+1.22* |
|
MESP |
400 mg/kg |
37.74+1.97 |
39.07+2.68 |
241.68+0.95 |
179.63+1.55** |
|
MELP |
200 mg/kg |
32.71+1.60 |
34.77+0.97 |
215.43+1.16 |
179.94+0.90* |
|
MELP |
400 mg/kg |
35.18+2.87 |
37.05+1.30 |
210.47+1.89 |
172.82+1.49* |
Values are mean +
SD, N = 6. T0 = basal glucose level; T3 = glucose after 3rd
hour of treatment, *P<0.01, **P<0.0001 (Students
Newman-Keul’s method).
2.4. Animals:
Wistar rats of either sex,
weighing 180-240 gm purchased from NIN, Hyderabad were used. They were housed
in standard environmental conditions of temperature, humidity and light and
provided with standard rodent food and water ad libitum.
2.5. Hyperglycemic effect on normal
and diabetic rats
2.5.1. Normal rats:
The Wistar rats
were divided into six groups of six animals each. Group I served as control and
received normal saline (5 ml/kg), orally. Group II served as positive control
and received glibenclamide (5 mg/kg) I.P. Group II
and Group IV received MELP, orally at a dose of 200 mg/kg and 400 mg/kg,
respectively. Group V and Group VI received MESP, orally at a dose of 200 mg/kg
and 400 mg/kg, respectively.
2.5.2. Diabetic rats:
The experimental diabetes was induced in
overnight fasted rats by a single intraperitoneal (I.P) administration of 120 mg/kg alloxan monohydrate. The animals with fasting blood glucose
levels between 200-400 mg/dL at 72 hrs were divided
into six groups of six animals each. Group I served as diabetic control and
received normal saline (5 ml/kg), orally. Group II served as positive control
and received glibenclamide (5 mg/kg), I.P.7, 8, 9 Groups III and IV
received MELP, orally at a dose of 200 mg/kg and 400 mg/kg, respectively. Whereas Groups V and VI received MESP, orally at a dose of 200
mg/kg and 400 mg/kg, respectively.
2.5.3. Collection and processing of blood for
estimation of blood sugar levels:
Blood was collected by orbital sinus puncture
of alloxan induced diabetic and normal rats in heparinized Eppendorff’s tubes (1
ml) under anesthesia (Ether).Blood samples were collected at 0, 1, 3, and
5hrs.After collection of blood samples, plasma was separated by centrifuging at
6000 rpm for 15 min. the estimation was done in vitro by enzymatic colorimetric method to know the glucose
levels in plasma (GOD – POD method)13.
2.6. Statistical analysis:
Statistically, the values were analyzed with
the analysis of variance (one way ANOVA) with Newman-Keul’s
method to determine the significance of difference within the experimental
groups. P-values of 0.05 or less were taken as significant.
3. RESULTS
AND DISCUSSION:
Alloxan has several effects
on b-cells of the pancreas and it is likely that
a combination of these effects result in the destruction of b-cells.
Alloxan has been shown to produce hyperglycemia due
to selective necrotic action on the b-cells of pancreas
leading to insulin deficiency10, 11. Insulin deficiency leads to
various metabolic aberrations, increased blood glucose level, decreased protein
content, increased cholesterol and triglyceride levels, increased alkaline phosphatase and transaminases
levels. Notably, restoration of normal levels of blood sugar by the methanolic extracts of seed and leaf was possible only in
moderate alloxan diabetic rats, which seemed to
retain partial beta cells activity. Ineffectiveness in severe diabetes may be
due to complete destruction of beta cells by alloxan.
As expected in alloxan treated rats, there was
significant increase in blood glucose levels. Oral treatment with MESP (200 and
400 mg/kg) and MELP (200 and 400 mg/kg) reduced the elevated blood glucose
levels respectively. The reduction was significant and dose-dependent (Table
1). On the contrary, no change in blood glucose levels was observed with both
the extracts in normal animals, ruling out its hypoglycemic activity.
It could be noted that the plant extracts
containing phytochemicals like alkaloids,
steroids, tannins, and carbohydrates exhibit antihyperglycemic
activity (reduce the elevated blood glucose levels). Thus the antihyperglycemic effect of the methanolic
extracts of seeds and leaves of Strychnos potatorum could possibly be related to its chemical
constituents. Oliver B.J 198012 listed glycosides, alkaloids, flavonoids, carbohydrates, tannins, and steroidal compounds
as active ingredients for hypoglycemic activity from plants. Hence, the
presence of reported constituents in the extracts of present study may be
responsible for the hypoglycemic activity observed.
In conclusion, the results of this study
confirm the antihyperglycemic activity of the methanolic extracts of seeds and leaves of Strychnos potatorum.
Further investigations are under way to isolate the principal constituents from
these extracts to under take the mechanism based anti
diabetic studies.
Authors wish to acknowledge Viswambhara Educational Society and the management,
Warangal, and Dr. A. V. Jithan, Principal, Vaagdevi College of Pharmacy, Warangal (A.P) for the
infrastructural facilities and moral support.
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Received on 26.12.2009
Accepted on 24.03.2010
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Research Journal of Pharmacognosy and Phytochemistry. 2(2): March -April 2010, 152-154