Cardiopulmonary health indices and diabetes risk scores in undergraduate students of a private university in Nigeria

Terminalia catappa aqueous leaf extract reverses insulin resistance, improves glucose transport and activates PI3K/AKT signalling in high fat/streptozotocin-induced diabetic rats

Rising prevalence of type 2 diabetes mellitus (T2DM) in sub-Saharan Africa has necessitated surveys of antidiabetic medicinal plants. This study assessed the antidiabetic mechanism of Terminalia catappa aqueous leaf extract (TCA) in high fat/low dose streptozotocin-induced type 2 diabetic rats. T2DM was induced by a combination of high-fat diet and low dose STZ (30 mg/kg bw) and the animals were administered with TCA (400 and 800 mg/kg bw) orally daily for 28 days. Biochemical parameters and indices for diabetes including renal function tests and pancreatic histology were evaluated. Relative expression of hepatic insulin resistance, signalling and glucose transport genes were also assessed. Induction of T2DM resulted in significant (p < 0.05) weight loss, dysregulated glucose level and clearance, electrolyte imbalance and disrupted diabetic biochemical parameters. Diabetes onset also perturbed β-cell function and insulin resistance indices, damaged pancreas microanatomy, while disrupting the expression of insulin receptor substrate 1 (IRS-1), phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT) and glucose transporter isoform 4 (GLUT-4) mRNA. Oral treatment of diabetic animals with TCA significantly (p < 0.05) ameliorated alterations due to T2DM induction in a manner comparable with glibenclamide. These results suggest TCA exerts its antidiabetic action by reversing insulin resistance, improving glucose transport and activating PI3K/AKT signalling.

Terminalia catappa Extract Palliates Redox Imbalance and Inflammation in Diabetic Rats by Upregulating Nrf-2 Gene

This study aims at evaluating the ameliorative role of Terminalia catappa aqueous leaf extract (TCA) on hyperglycaemia-induced oxidative stress and inflammation in a high-fat, low dose streptozotocin-induced type 2 diabetic rat model. Experimental rats were treated orally with 400 and 800 mg/kg bw TCA daily for four weeks. Antioxidant enzyme activities, plasma glucose concentration, protein concentration, oxidative stress, and inflammation biomarkers were assayed using standard methods. Hepatic relative expressions of tumour necrosis factor-alpha (TNF-α), interleukin-six (IL-6), and nuclear factor-erythroid 2 related factor 2 (Nrf-2) were also assessed. Molecular docking and prediction of major TCA phytoconstituents' biological activity related to T2DM-induced oxidative stress were evaluated in silico. Induction of diabetes significantly (p < 0.05) reduced superoxide dismutase, glutathione-S-transferase, and peroxidase activities. Glutathione and protein stores were significantly (p < 0.05) depleted, while glucose, MDA, interleukin-six (IL-6), and tumour necrosis factor-α (TNF-α) concentrations were significantly (p < 0.05) increased. A significant (p < 0.05) upregulation of hepatic TNF-α and IL-6 expression and downregulation (p < 0.05) of Nrf-2 expression were observed during diabetes onset. TCA treatment significantly (p < 0.05) modulated systemic diabetic-induced oxidative stress and inflammation, mRNA expression dysregulation, and dysregulated macromolecule metabolism. However, only 800 mg/kg TCA treatment significantly (p < 0.05) downregulated hepatic TNF-α expression. 9-Oxabicyclo[3.3.1]nonane-2,6-diol and 1,2,3-Benzenetriol bound comparably to glibenclamide in Nrf-2, IL-6, and TNF-α binding pockets. They were predicted to be GST A and M substrate, JAK2 expression, ribulose-phosphate 3-epimerase, NADPH peroxidase, and glucose oxidase inhibitors. These results suggest that TCA ameliorates hyperglycaemia-induced oxidative stress and inflammation by activating Nrf-2 gene.