Effect of Punica granatum Linn. (Peel) on Blood Glucose Level in Normal and Alloxan- Induced Diabetic Rats

 

Rupesh Gautam¹* and S.C. Sharma²

¹Department of Pharmacology, Jaipur College of Pharmacy, Jaipur.

²Department of Pharmacology, B. N. College of Pharmacy, Udaipur (Raj)

*Corresponding author: rgautam3906@yahoo.co.in

ABSTRACT:

The hydro alcoholic peel extract of Punica granatum Linn. var. arakta was investigated for its effect on blood glucose level in normal and alloxan induced diabetic rats. The effect was studied at two dose levels, 50 and 100 mg/kg body weight. The activity was compared with the standard drug glibenclamide (2 mg/kg, orally). The plant extract significantly lowered blood glucose level in both normal (P<o.o5) and diabetic (P<o.o1)  rats.

 

 

INTRODUCTION:

Punica granatum Linn ( Punicaceae) is a shrub or small tree  considered to be a native of Iran and Afghanistan. It is also found growing wild in the warm valleys and outer hills of the Himalayas between 900 m. and 1,800 m., and is cultivated throughout India¹. The plant is used in folklore medicine for the treatment of various diseases such as ulcer, hepatic damage, snakebite, etc. The unripe fruit is a good appetizer and tonic, useful in vomiting, but causes biliousness. The ripe fruit is a tonic, astringent to bowels, aphrodisiac and is reputed to cures biliousness, fever, heart disease, sore throat, stomatitis, etc. The rind of the fruit is anasthematic and useful in diarrhoea, dysentery and ulcer² .

 

Various parts of this plant have been reported to possess different  biological activities such as antioxidant^3,4, antibacterial^5,6, antifertility ⁷.

 

The antidiabetic activity of different parts like flower^8,9 and seed¹⁰ have already been reported. The present study is aimed to evaluate blood glucose lowering effect of peel extract.

 

MATERIALS AND METHODS:

Drug collection and Extraction-The peel of Punica granatum Linn. (variety arakta) was procured from the local market of Udaipur. A specimen was identified and authenticated at the Department of Horticulture, Rajasthan College of Agriculture, Udaipur (Raj.).

 

For extraction, the drug was soaked in solvent (50% alcohol) for 48 hrs with occasional shaking. After 48 hrs the extract was filtered using muslin cloth. The solvent was distilled to obtain the extract. The yield of the extract was found to be 44.24 % w/w.

 

Pharmacological studies:

Animals: - All studies were approved by the Institutional Animal Ethics Committee, B. N. College of Pharmacy, Udaipur (Rajasthan). Healthy albino wistar rats weighing 150-180 g were maintained on standard rodent fed and water ad libitum. Animals were closely observed for any infection and those showing signs of infection were excluded from the study and replaced. The animals were randomly distributed into groups of 6 each for study.

 

Experimental method:

Study Protocol: For the study of peel extract on blood glucose level-

Normal rats, were divided into three groups (6 each).Group I (normal control) animals were administered vehicle and other two groups II and III (experimental control ) were administered peel extract in dose of 50 and 100 mg/kg, orally.

 

Similarly, In Diabetic rats, were divided into four groups (6 each).Group I (diabetic control) were administered vehicle, group II (positive control) were administered standard drug (glibenclamide, 2 mg/kg, orally, Nicholas Piramal Ltd., Pithampur), group III and IV (diabetic experimental) were administered peel extract in dose of 50 and 100 mg/kg, orally.

 

 

Table 1: Effect of Peel extract on blood glucose level

Group	Treatment	Day 1st	Day 4th	Day 7th	Day 10th
I.	Normal control	88.67±15.18	119.0±13.37	135.0±27.97	126.0±19.93
II	Experimental control (peel, 50mg/kg)	113.0±27.21	101.7±16.50	66.17±4.97*	99.67±17.67
III	Experimental control (peel, 100mg/kg)	85.33±7.61	94.80±11.74	114.4±28.52	64.20±8.26*

Values are represented in mean ± SEM, * P<0.05, **P<0.01 were

considered statistically significant when compared to normal control group

 

Table 2: Antihyperglycemic activity of peel extract

Group	Treatment	Day 1st	Day 4th	Day  10th
I	Diabetic control	285.8±44.65	302.2±48.95	305.5± 44.62
II	Positive control	229.2±84.85	222.3±62.78	172.2± 46.38
III	Diabetic experimental (peel, 50mg/kg)	298.0±72.81	243.5±62.47	122.0±60.04*
IV	Diabetic experimental (peel, 100mg/kg)	265.8±53.71	243.5±74.83	88.67±19.98**

Values are represented in mean ± SEM, * P<0.05, **P<0.01 were

considered statistically significant when compared to normal control group

 

Induction of Diabetes: Animals of diabetic groups were weighed and their fasting blood glucose levels were determined before inducing diabetes. Animals showing very low or high glucose levels were replaced. The animals were injected with a single dose of Alloxan monohydrate (80 mg/kg) (S.D-Fine Chemicals Pvt. Ltd, Baroda) in normal saline (freshly prepared) by i.p. route. Control animals were injected with normal saline. Fasting blood glucose was measured 3 days later to confirm the diabetic status of the animals.

 

Estimation of blood glucose level: The blood samples were collected by tail puncture and the blood glucose level was estimated with  glucometer (Accuchek sensor).

 

Statistical analysis Statistical analysis was done by student’s t-test. The difference were considered to be significant at  p< 0.05.

 

RESULT:

(i)                  In normal rats- This experiment was carried out to show the effect of orally administered peel extract on blood glucose level in normal rats. Peel extract 50 and100 mg/kg body weight (group II and III) decreased the blood glucose level significantly (* P<0.05) at 7^th and 10^th day, respectively. The effect was compared to the normal control (group I). (Table 1)

 

(ii)                In diabetic rats- This experiment was carried out to show the effect of orally administered peel extract on blood glucose level in diabetic rats. Peel extract at 50 and 100 mg/kg body weight (group III and IV) decreased the blood glucose level significantly on 10^th day and showed antihyperglycaemic effect. The effect was compared to the diabetic control (group I). (Table 2)

 

DISCUSSION:

In this study P. granatum peel extract (100 mg/kg) significantly decreased blood glucose level in both normal and alloxan induced diabetic rats.

Alloxan monohydrate, chemically 2,4,5,6-tetra-oxy-pyrimidine, generates superoxide free radicals which are responsible for rapid destruction of β- cells¹¹.Glibenclamide (a sulphonylurea drug) is known to lower the blood glucose level by stimulating β- cells to release insulin ¹².

In the present study the peel extract of P. granatum showed marked blood glucose lowering effect in both normal and diabetic animals. This effect may be possible due to increased peripheral utilization. Inhibition of the proximal tubular reabsorption mechanism for glucose in kidney can also contribute towards blood glucose lowering effect⁸.

Studies are underway to further elucidate the mechanism of blood glucose lowering effect of the peel extract of P.granatum.

 

ACKNOWLEDGEMENT:

The authors are thankful to Dr. K. D. Ameta, Asst. Professor, Department of Horticulture, Rajasthan College of Agriculture, Udaipur (Raj.) for taxonomical identification of the drug sample.

 

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Received on 26.11.2011          Modified on 07.01.2012

Accepted on 14.01.2012         © RJPT All right reserved