Antidiabetic Effects of Yam (Dioscorea batatas) and Its Active Constituent, Allantoin, in a Rat Model of Streptozotocin-Induced Diabetes

Abstract

The objective of this study was to investigate the therapeutic efficacies of crude yam (Dioscorea batatas) powder (PY), water extract of yam (EY), and allantoin (the active constituent of yam) in streptozotocin (STZ)-induced diabetic rats with respect to glucose, insulin, glucagon-like peptide-1 (GLP-1), C-peptide, glycated hemoglobin (HbAlc), lipid metabolism, and oxidative stress. For this purpose, 50 rats were divided into five groups: normal control (NC), diabetic control (STZ), and STZ plus treatment groups (STZ + PY, STZ + EY, and STZ + allantoin). After treatment for one-month, there was a decrease in blood glucose: 385 ± 7 in STZ, 231 ± 3 in STZ + PY, 214 ± 11 in STZ + EY, and 243 ± 6 mg/dL in STZ + allantoin, respectively. There were significant statistical differences (p < 0.001) compared to STZ (100%): 60% in STZ + PY, 55% in STZ + EY, and 63% in STZ + allantoin. With groups in the same order, there were significant decreases (p < 0.001) in HbAlc (100% as 24.4 ± 0.6 ng/mL, 78%, 75%, and 77%), total cholesterol (100% as 122 ± 3 mg/dL, 70%, 67%, and 69%), and low-density lipoprotein (100% as 29 ± 1 mg/dL, 45%, 48%, and 38%). There were also significant increases (p < 0.001) in insulin (100% as 0.22 ± 0.00 ng/mL, 173%, 209%, and 177%), GLP-1 (100% as 18.4 ± 0.7 pmol/mL, 160%, 166%, and 162%), and C-peptide (100% as 2.56 ± 0.10 ng/mL, 129%, 132%, and 130%). The treatment effectively ameliorated antioxidant stress as shown by a significant decrease (p < 0.001) in malondialdehyde (100% as 7.25 ± 0.11 nmol/mL, 87%, 86%, and 85%) together with increases (p < 0.01) in superoxide dismutase (100% as 167 ± 6 IU/mL, 147%, 159%, and 145%) and reduced glutathione (100% as 167 ± 6 nmol/mL, 123%, 141%, and 140%). The results indicate that yam and allantoin have antidiabetic effects by modulating antioxidant activities, lipid profiles and by promoting the release of GLP-1, thereby improving the function of β-cells maintaining normal insulin and glucose levels.

Antioxidant and Antitumor Activities of the Extracts from Chinese Yam (Dioscorea opposite Thunb.) Flesh and Peel and the Effective Compounds

“…Allantoin has been known to enhance the efficacy and desirability of cosmetic creams with antioxidative and antiinflammatory activities. Recent researches also indicate that allantoin has the effects of antidiabetic, memory‐enhancing, and antihypertension (Niu and others ; Chen and others ; Go and others ). To effectively exploit the value of yam and yam peel on health protection, it is significant to investigate the principal component in yam and yam peel, which have the effect of antioxidant activity in vitro and antitumor in vivo .…”

Effects of Rhizome Extract of <em>Dioscorea Batatas </em>and Its Active Compound, Allantoin, on the Regulation of Myoblast Differentiation and Mitochondrial Biogenesis in C2C12 Myotubes

“…Allantoin is the main active compound in yam and has been reported to have antidiabetic effects with plasma glucose-lowing action and glucose uptake-enhancing action in muscle tissue [11,18,40]. Under diabetic conditions including insulin resistance, hyperglycemia is a risk factor for age-related loss of muscle mass in sarcopenia, which induces muscle synthesis reduction, chronic inflammation, and mitochondrial dysfunction [41].…”

“…In modern pharmacology, yam has been studied for its effects on asthma [6], cancer [7][8][9], diabetes [10,11], and liver damage [12], as well as its antioxidation, antiinflammation, and antiaging effects [13,14]. Yam contains various compounds such as dioscin [15], steroidal saponins [15,16], saponins, gallic acid, vanillic acid [13], allatoin [11], and protodioscin [17].…”

“…Yam contains various compounds such as dioscin [15], steroidal saponins [15,16], saponins, gallic acid, vanillic acid [13], allatoin [11], and protodioscin [17]. Allantoin, a diureide of glyoxylic acid, is an active and abundant component of yam [9,11,18]. In vivo studies have shown allantoin to have anti-asthmatic [18], anti-diabetic [11,19] and anti-hypertensive [20] activities, as well as memory-enhancing effects in Alzheimer's disease [21].…”

“…Allantoin, a diureide of glyoxylic acid, is an active and abundant component of yam [9,11,18]. In vivo studies have shown allantoin to have anti-asthmatic [18], anti-diabetic [11,19] and anti-hypertensive [20] activities, as well as memory-enhancing effects in Alzheimer's disease [21].…”