Abstract

Calophyllum brasiliense (Cb) belongs to the Clusiaceae family and it is generally used for diabetes treatment. The aim of this study was to evaluate the anti-diabetic effect of Cb’s hydroethanolic extract (CBE) on diabetic induced rats by streptozotocin and evaluate the content of polyphenols and tannins of the extract. The polyphenols and tannins evaluation in the extract were determinated by a spectrophotometer in 760 nm and isocratic HPLC system and reverse phase column (C18). The induction of diabetes was performed by intraperitoneal injection of streptozotocin (55 mg/kg) and was confirmed by a histopathological analysis. The total content of polyphenols and tannins (gallic acid) in CBE was 0.025 ± 0.0028 mg/mL (4.77%) and 8.262 ± 0.417 µg/mL, respectively. According to the oral glucose tolerance test that was performed both in normal and diabetic mice, the treatment with 500 mg/kg of CBE appeared to significantly reduce the blood glucose levels compared to the untreated group (P < 0.001). The treatment of diabetic mice with 500 mg/kg of CBE for 30 days significantly improved  diabetes clinical symptoms (polydipsia, polyuria, polyphagia and weight loss) (P < 0.001). After the urinary glucose analysis, it was found that the treatment with 500 mg/kg of CBE significantly decreased the urinary glucose levels at an average of 177.55 ± 17.8 mg/dL (32.40%) (P < 0.001). In relation to the blood glucosemeasurements, it was shown that the groups treated with 500 mg/kg CBE and 3 mg/kg of Glibenclamide had significantly lower levels of blood glucose when compared to non-treated group (P < 0.001) 24.09% (143.36 ± 19.6 mg/dL) and 36.04% (200.08 ± 14.9 mg/dL), respectively). The histopathological analysis revealed an increase in the number of endocrine cells in the islets of Langerhans in the groups treated with CBE500 and insulin. Therefore, it was concluded that the treatment with 500 mg/kg of CBE exhibited anti-diabetic activity.

Key words: Calophyllum brasiliense, polyphenols, diabetes, clinical parameters.