Antioxidant phytochemicals against type 2 diabetes

Abstract

Dietary phytochemicals, of which polyphenols form a considerable part, may affect the risk of obesity-associated chronic diseases such as type 2 diabetes. This article presents an overview on how phytochemicals, especially polyphenols in fruits, vegetables, berries, beverages and herbal medicines, may modify imbalanced lipid and glucose homeostasis thereby reducing the risk of the metabolic syndrome and type 2 diabetes complications.

The Mechanisms of Inhibition of Advanced Glycation End Products Formation through Polyphenols in Hyperglycemic Condition

“…Mimicking insulin activity [45] Curcuma longa (Turmeric) Curcumin Preventing free radicals and glycosylated haemoglobin (HbA) formation, protecting non-enzymatic antioxidants pools, preventing of lipid peroxidation, lowering blood glucose level [59,61,62,66] Cyperus rotundus (Nut sedge) Gallic acid, p-coumaric acid, epicatechin Reduction of protein carbonyl and thiol oxidation…”

“…Inhibitory effect on α-amylase or α-glucosidase activity, interruption of GLUT4 [59] Glycyrrhiza glabra (Licorice) Tannic acid, glycyrrhizin Inhibitory effect on α-amylase or α-glucosidase activity, interruption of GLUT4 [59] Gymnema sylvestre (Australian cowplant or Gurmari) Momordica charantia (Bitter melon) Not reported in the referenc Improve oxidative stress through lowering triglyceride, cholesterol or plasma glucose levels, stimulation of insulin secretion [84] Nigella sativa (Black seed) Quinones, Thymoquinone Decreasing of MGO-mediated glycation, scavenging reactive oxygen species, antioxidant activity [79] Phyllanthus niruni (Chanca Piedra or Child Pick-a-back)…”

“…Ellagic acid Inhibitory activity against AR in rat lens [73] Psidium guajava (Guava) Gallic acid, catechin, quercetin Chelating activity, scavenging of α-dicarbonyl compounds [89] Pterocarpus marsupium (Indian Kino Tree) Pterosupin Decreasing lipid peroxidation and supporting antioxidant defense system [59] Pueraria lobata (Kudzu) Puerarin PG-3, and puerol B Decreasing AGE-induced inflammation by inducing of the HO-1 noids with an OH group at C-3′ are stronger AGEs inhibitors than those with OH at C-3. Any hydroxyl group on positions 3′, 4′, 5, and 7 increases the AGEs inhibitory ability of the compound (l " Fig.…”

“…It is evident that different organs of the same plant produce different secondary metabolites. There is growing evidence that a remarkable alteration of Vitis vinifera (Grape) Resveratrol Preventing AGEs induced proliferation, increasing expression of GLUT-4 in muscles [47,59] Fig . 4 Proposed general pathways leading to AGEs formation, and potential sites to inhibit by phytochemicals.…”

“…(Apocynaceae), Ziziphus jujube Miller (Rhamnaceae), or Trigonella foenum-graecum L. (Fabaceae) showed protective effects on pancreatic β-cells by decreasing lipid peroxidation, amplifying insulin secretion or supporting antioxidant defense system (increasing of glutathione and beta carotene levels of plasma in diabetic rats) [59]. Enzymatic breakdown of polysaccharides (such as starches) to monosaccharide (glucose) by α-amylase or α-glucosidase in- creases the glucose level in the blood stream, resulting in an upregulation of glucose metabolism and finally in an increase of AGEs formation.…”