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African Journal of Biotechnology

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Blood glucose lowering effect of aqueous extract of Graptophyllum pictum (Linn) Griff. on alloxan-induced diabetic rats and its acute toxicity in mice

SO Olagbende-Dada, SO Ogbonnia, HAB Coker, GE Ukpo

Abstract


This study was aimed at evaluating the claimed anti-diabetic property of the aqueous extract of Graptophyllum pictum leaf and to establish an effective dose for the extract. It also attempted to unravel if the extract could be acutely toxic to mice. The anti-diabetic study was carried out on alloxan-induced diabetic Wistar rats. After diabetic induction, the rats were divided into 5 groups. Groups 1 to 3 were orally administered 100, 150 and 200 mg/kg body weight extract by gastric probe for four weeks; group
4 was administered 10 mg/kg body weight metformin, a well known hypoglycemic drug, while group 5 served as control and received the vehicle of administration (distilled water). The fasting blood glucose level (FBGL) of the rats was checked before commencement of treatment and weekly during the drug administration period using Roche Accu-chek Active Glucometer. The percentage change in FBGL before commencement of treatment and during the treatment period was calculated and expressed
graphically. The acute toxicity of the extract was studied in 4 groups of Swiss albino mice which were orally administered high doses (1 to 4 g/kg) of the extract. The results obtained from the anti-diabetic study showed a significant reduction (P < 0.05) in the mean fasting blood glucose level in all the three groups of animals treated with the plant extract when compared to the control; and it exhibited effective anti-diabetic potency when compared with metformin (a standard anti-diabetic drug); the effective dose was established at 100 mg/kg. The LD50 could not be determined as none of the treated mice died during the acute toxicity study. These findings suggest that the aqueous extract of the leaves of G.
pictum possess hypoglycemic effect which is comparable to metformin and can be safely administered orally without any immediate unwanted effect. However, this calls for detailed studies to elucidate the therapeutic and long term toxicological profiles of the extract.

Key words: Diabetes, Graptophyllum pictum, aqueous extract, hypoglycemic, metformin.




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