Abstract
Postprandial hyperglycemia and oxidative stress are important factors that worsen the health condition of patients with type 2 diabetes. We recently showed that extracts from Ceiba pentandra mitigate hyperglycemia in dexamethasone- and high diet/streptozotocin-induced diabetes. Herein, we evaluated the postprandial regulatory properties and the antioxidant effects of the aqueous (AE) and methanol (ME) extracts from the stem bark of Ceiba pentandra. The phytochemical analysis of AE and ME was performed using the LC-MS technique and the total phenolic and flavonoid assays. Both extracts were tested for their ability to inhibit superoxide anion (O2•ـ), hydrogen peroxide (H2O2), protein oxidation, alpha-amylase, and alpha-glucosidase activities. The mode of enzyme inhibition was also determined in a kinetic study. AE and ME were both rich in phenolic and flavonoid compounds. ME was 2.13 and 1.91 times more concentrated than AE in phenolic and flavonoid compounds, respectively. LC-MS allowed the identification of 5 compounds in both extracts. ME and AE inhibited O2•ـ with IC50 of 51.81 and 34.26 μg/ml, respectively. On H2O2, they exhibited IC50 of 44.84 and 1.78 μg/ml, respectively. Finally, they exhibited IC50 of 120.60 and 140.40 μg/ml, respectively, in the inhibition of protein oxidation induced by H2O2, while showing IC50 of 39.26 and 97.95 μg/ml on the protein oxidation induced by AAPH. ME and AE inhibited alpha-amylase with IC50 of 6.15 and 54.52 μg/ml, respectively. These extracts also inhibited alpha-glucosidase, demonstrating IC50 of 76.61 and 86.49 μg/ml. AE exhibited a mixed noncompetitive inhibition on both enzymes, whereas ME exhibited a competitive inhibition on α-amylase and a pure noncompetitive inhibition on α-glucosidase. These results demonstrate that ME and AE scavenge reactive oxygen species and prevent their effects on biomolecules. Besides, ME and AE inhibit carbohydrate digestive enzymes. These properties may contribute to reduce postprandial hyperglycemia and regulate glycemia in diabetic patients.
Highlights
Diabetes mellitus is becoming a serious and leading health threat in low- and middle-income countries
Reactive oxygen species (ROS) and mostly superoxide anion are generated from the mitochondrial respiratory chain, and their excessive production may result in oxidative stress
The present study showed that both extracts and mostly the methanol extract successfully scavenged superoxide anion, suggesting that these plant extracts could be useful tools in the fight against oxidative stress-induced tissue damages
Summary
Diabetes mellitus is becoming a serious and leading health threat in low- and middle-income countries. It is one of the largest global health emergencies of the 21st century with increasing prevalence. The main strategy in the management of diabetes is the achievement of an adequate glycemic control. Fasting glycemia is routinely measured as a determinant of glycemic control, but necessary, it is insufficient. To achieve an effective blood glucose control, postprandial glycemia should be taken into consideration. The loss of postprandial glycemic control has been shown to be an early step of glucose homeostasis disorder that occurs earlier than fasting glycemia impairment [2, 3]. Recent evidences have demonstrated that postprandial hyperglycemia is an independent
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