Evaluation of Hypoglycemic and Genotoxic Effect of Polyphenolic Bark Extract from Quercus sideroxyla

Abstract

Quercus sideroxyla is a wood species whose bark has phenolic compound and should be considered to be bioactive; the hypoglycemic and genotoxic properties of Q. sideroxyla bark were evaluated in this study. Total phenolic compound was determined in crude extract (CE) and organic extract (OE). The OE has the highest amount of phenols (724.1 ± 12.0 GAE/g). Besides, both CE and OE demonstrated effect over the inhibition of α-amylase in vitro. Hypoglycemic activity was assessed by glucose tolerance curve and the area under curve (UAC); OE showed the highest hypoglycemic activity. In addition, diabetes was induced by streptozotocin (65 mg/kg) and the extracts (50 mg/kg) were administered for 10 days; OE showed hypoglycemic effect compared with diabetic control and decreased hepatic lipid peroxidation. Acute toxicity and genotoxicity were evaluated in CE; results of acute toxicity did not show any mortality. Besides, the comet assay showed that CE at a dose of 100 mg/kg did not show any genotoxic effect when evaluated at 24 h, whereas it induced slight damage at 200 mg/kg, with the formation of type 1 comets.

Figure 1

Glucose tolerance test in rats (a). Area under the glucose curve (b). ^∗ p ≤ 0.05, significant difference compared with the control group. CE: crude extract at doses 200, 100, and 50 mg/kg; OE: organic extract at doses 50 and 25 mg/kg.

Figure 2

Hepatic lipid peroxidation assay in diabetic rats treated with CE50 and OE50 extracts during 10 days. a: significant difference versus control nondiabetic group; b: versus diabetic control group (p ≤ 0.05), Fisher-LSD test. CE: crude extract 50 mg/kg; OE: organic extract 50 mg/kg.

Figure 3

Comet assay images in cell blood of mice (400x). (a) Comet type 0, (b) comet type 3, (c) comet type 1, and (d) comet types 1 and 2.