Propriedades antidiabéticas e antioxidantes do extrato hidroetanólico de Cedrela odorata L.

Abstract

Cedrela odorata L. (cedro-rosa) was selected for the antidiabetic in vivo evaluation, based on the results obtained from an in vitro screening performed with various plants mentioned in an ethnopharmacological survey in the region of Vale do Juruena - Mato Grosso, Brazil. This screening aimed to evaluate the inhibition of alpha-glucosidase and the antioxidant capacity by DPPH radical sequestering of hydroethanolic extracts. The hydroethanolic extract of the inner stem bark of Cedrela odorata L. (HeECo) showed IC50 and DC50 in the evaluation of inhibition of alpha-glucosidase and an antioxidant capacity of 84.7 e 3.7 μg/mL, respectively, well below the positive control acarbose and vitamin C (5115.5 e 7.9 μg/mL), respectively. The fingerprint of EHeCo showed the presence of gallic acid, (-)- gallocatechin and (+)- catechins. Tests for acute and sub-chronic toxicity showed that the extract presented low toxicity at the evaluated doses. In the sub-chronic antidiabetic evaluation tests, streptozotocin-induced diabetic rats (40 mg/kg in 0.01 M citrate buffer pH 4.5 iv) and non-diabetic rats were used. Diabetic animals were treated with 250 and 500 mg/kg HeECo for 21 days and the results were compared with the vehicle-treated diabetic group - 2% DMSO (DC) and the positive control group (metformin - DMet). No changes were observed in body weight, food and water intake, urine volume, blood glucose, glucosuria and urinary urea. The triglyceride level was reduced at the two doses (N = 132 ± 15; DC = 123 ± 15; DT250 = 73 ± 10#; DT500 = 78 ± 8#; DMet = 142 ± 10 mg/dL, #p<0,05). After 21 days of treatment with HeECo, the concentration of malondialdehyde in the blood was reduced (N = 1.9 ± 0.3; DC = 5.6 ± 0.5; DT250 = 3.3 ± 0.3; DT500 = 2.9 ± 0.5#; DMet = 3.9 ± 1.0 μmol/L, #p<0.05) and the activity of superoxide dismutase (N = 42.3 ± 0.3; DC = 40.9 ± 0.7; DT250 = 60.7 ± 1.8#; DT500 = 60.8 ± 1.1#; DMet = 42.0 ± 0,4 U/L, #p<0.05) and glutathione peroxidase increased (N = 16.2 ± 0.5; DC = 11.4 ± 0.7*; DT250 = 15.6 ± 0.5#; DT500 = 14.8 ± 0.3#; DMet = 12.2 ± 0.5 103 U/L, *p<0.05 vs N, #p<0.05 vs DC). The HeECo effect on glucose tolerance was assessed after a glucose, starch and sucrose overload, the extract being administered at the same dose as in the sub-chronic experiment, 30 minutes before the carbohydrate overload. Phloridzin (DF) was used as positive control for the test in which the overload consisted of glucose, and acarbose (DA), when the overload was sucrose or starch. The extract, at both doses reduced the glycemic peak and also the area under the curve (N = 16253 ± 318; DC = 37666 ± 2347*; DT250 = 32353 ± 1467; DT500 = 27666 ± 1423#; DF = 25033 ± 1241# mg/dL x 120 minutes, *p<0.05 vs N, #p<0.05 vs DC) when the overload was glucose. When the loading was sucrose, the extract at a dose of 500 mg/kg, reduced the peak blood glucose after 30 minutes without reduction in the area under the curve (N = 138 ± 3; DC = 437 ± 39*; DT250 = 294 ± 38; DT500 = 243 ± 69#; DA = 253 ± 22# mg/dL, *p<0.05 vs N, #p<0.05 vs DC). The HeECo had no effect on blood glucose levels of the animals receiving starch. The HeECo showed antihyperglycaemic, hypolipidemic and antioxidant, showing the therapeutic potential of the inner stem bark of C. odorata in the treatment of diabetes and disease-related complications.