Elsevier

Nutrition

Volume 25, Issue 2, February 2009, Pages 134-141
Nutrition

Brief communication
Hypoglycemic effect of hot-water extract of adzuki (Vigna angularis) in spontaneously diabetic KK-Ay mice

https://doi.org/10.1016/j.nut.2008.08.001Get rights and content

Abstract

Objective

Recently, we reported that 40% ethanol fraction of hot-water extracts of adzuki (Vigna angularis; EtEx.40) suppressed the postprandial blood glucose level and serum insulin level in normal mice and streptozotocin-induced type 1 diabetic rats. The present study examined the hypoglycemic effect of EtEx.40 on blood glucose, insulin concentrations, organ weight, serum composition, and hepatic lipid content in spontaneously diabetic KK-Ay/Ta Jcl mice, a model for type 2 diabetes.

Methods

To investigate the prevention of type 2 diabetes by EtEx.40 ingestion, 4-wk-old non-diabetic KK-Ay mice were fed an AIN-76 diet containing 5000 mg of EtEx.40/kg of body weight per day (EtEx.40) or an AIN-76 diet without EtEx.40 for 8 wk. Furthermore, to investigate the improvement of type 2 diabetes, 7-wk-old diabetic KK-Ay mice were fed EtEx.40 for 4 wk.

Results

Compared with the control group, EtEx.40 supplementation had a significant effect in lowering blood glucose levels, water intake, serum insulin levels, urinary glucose, urinary microalbumin/creatinine ratio, liver triacylglycerol, and total cholesterol levels. Similar results were observed in 7-wk-old diabetic KK-Ay mice fed EtEx.40 for 4 wk. These effects were also found after short-term administration of EtEx40. Overall, EtEx.40 improved several diabetic symptoms in KK-Ay mice.

Conclusion

EtEx.40 obtained from hot-water adzuki extracts showed preventive and ameliorative effects on the progression of diabetes in genetically diabetic KK-Ay mice. In the present study, we conclude that the preventive and ameliorative effects by EtEx.40 were due to the modulation of blood glucose levels and the protective effect against oxidative damage in diabetes mellitus.

Introduction

Recently, there has been an increase in the prevalence of type 2 diabetes because of the promotion of high-grade meals, rapidly changing lifestyles, and hereditary elements. Consequently, diabetes is becoming a serious health problem worldwide. The percentage of patients with type 2 diabetes is highest among 50 to 60 y olds.

Adzuki beans (Vigna angularis) are an ingredient known well in East Asia. In Japan, adzuki beans are used mainly for the production of confectioneries such as youkan, manjuu, amanatto, etc. In the case of food processing, heat treatment of adzuki beans results in a large amount of hot-water extracts (HWEs), which are usually discarded. However, HWEs are known to contain various polyphenols. In recent research, many extracts and natural products, such as polyphenols, have been reported to improve the symptoms of diabetes [1], [2], [3]. We also previously reported that HWEs of adzuki were fractionated using HP-20 column chromatography, and its 40% ethanol fraction (EtEx.40) was found to suppress the elevation of blood glucose and plasma insulin levels after oral administration in mice and rats with streptozotocin-induced diabetes [4]. The present study examined the antidiabetic effects of EtEx.40 in spontaneously diabetic KK-Ay mice, which are a model for type 2 diabetes.

Section snippets

Preparation of test materials

Adzuki beans harvested in Tokachi, Hokkaido, Japan, were boiled and the HWEs of adzuki (15 L) obtained. We concentrated the HWE to 100 times by a plate heat exchanger (Izumi Food Machinery Co. Ltd., Hyogo, Japan). Thirty milliliters of concentrated HWE was subjected to open-column chromatography on a Diaion HP-20 (Mitsubishi Chemical Co. Ltd., Tokyo, Japan, column size 5 φ × 300 mm, resin wet volume 400 g) and eluted stepwise with 5 L of distilled water and 40% ethanol. The respective fractions

Ingestion of EtEx.40 suppresses development of type 2 diabetes

The parameters of growth and food consumption in the first experiment are presented in Figure 1A and Table 2. There were no differences in body weights and food intakes of all groups. However, water intake was inclined to increase until the final day of the experiment in both groups, but that of the mice fed the EtEx.40 (Ex) diet was lower than that of the cellulose (CEL) group during the feeding period (Table 2). As shown in Figures 1B-1 and 1B-2, blood glucose levels of the diabetic mice fed

Discussion

We demonstrated for the first time that EtEx.40 suppresses the development of spontaneous diabetes in KK-Ay mice. In addition, this phenomenon was observed after only short-term administration of EtEx.40.

In mice fed a CEL diet, the blood glucose levels, serum insulin levels, water consumption, and urinary glucose concentrations gradually increased with increasing body weight and food intake. These observations were almost the same as those reported by Odaka et al. [10]. In this study, there

References (21)

There are more references available in the full text version of this article.

Cited by (56)

  • Identification of anthocyanin compositions in black seed coated Korean adzuki bean (Vigna angularis) by NMR and UPLC-Q-Orbitrap-MS/MS and screening for their antioxidant properties using different solvent systems

    2021, Food Chemistry
    Citation Excerpt :

    Further, many studies have reported that the presence of various saponins: azukisaponin I–VI, AZ I–IV, angulasaponin A–D; flavonoids: (+)-catechin, vitexin-4″-O-glucoside, quercetin-3-O-glucoside, quercetin-3-O-rutinoside; procyanidins: procyanidin B-1, B-3; and furanylmethyl glycoside: angularides A–D in adzuki bean (Ariga, Koshiyama, & Fukushima, 1988; Iida, Yoshiki, Kahara, Okubo, & Ohrui, 1997; Iida et al., 1999; Jiang, Zeng, David, & Massiot, 2014; Liu, Cai, & Xu, 2017). These constituents are also associated with a wide range of biological properties, such as antioxidant, anti-inflammatory, hypoglycemic, anti-hypotensive, renal cortex protective, and hepatoprotective activities (Durak, Baraniak, Jakubczyk, & Świeca, 2013; Han et al., 2004: Itoh, Kobayashi, Horio, & Furuichi, 2009; Mukai & Sato, 2009; Sato et al., 2005). Interestingly, adzuki beans exhibit various seed coat colours inclding white, yellow, green, black, and red (Hori, Sato, & Hatai, 2006).

  • Hypoglycemic efficacy and safety of Momordica charantia (bitter melon) in patients with type 2 diabetes mellitus

    2020, Complementary Therapies in Medicine
    Citation Excerpt :

    However, current treatments are unsatisfactory,2 and various alternative and complementary treatments have emerged among the population of Asia. Studies have shown that such as green tea,3 aloe,4 citrus fruits,5 and beans,6–9 have glucose lowering effect and hypolipidemic effects in animals and human studies. With the increase in popular reporting and advertisements about the beneficial effects of various alternative and complementary treatments on glucose control, many patients with diabetes use alternative and complementary treatments to improve their glucose levels or reduce diabetic complications.10

  • Isolation and identification of α-glucosidase inhibitory constituents from the seeds of Vigna nakashimae: Enzyme kinetic study with active phytochemical

    2018, Food Chemistry
    Citation Excerpt :

    For instance, Vigna angularis and V. aconitifolia species are known as metabolite crops, which are rich in tannins, polyphenols, saponins, and phytic acids and their constituents possess pharmacological properties such as strong affinities of protein and peptide as well as amylase, trypsin, and α-glucosidase inhibitions (Itoh et al., 2004, 2009; Yao et al., 2011). V. mungo and V. angularis species have also recently confirmed the antihyperglycemic and antihypolipidemic activities as well as increase of blood glucose and cholesterol in diabetic rats and high-fat-diet-fed mice (Itoh et al., 2004, 2009; Solanki & Jain, 2010). V. nakashimae is also known as excellent antidiabetic and antiobesity agent with various pharmacological activities (Son et al., 2013; Yeo et al., 2011).

View all citing articles on Scopus
View full text