• The Korean Journal of Food And Nutrition
• /
• v.30 no.6
• /
• pp.1222-1228
• /
• 2017

In the current study, we investigated the inhibitory activity of water soluble ${\beta}-glucan$ from oat (Avena sativa) against various digestive enzymes such as ${\alpha}-glucosidase$, sucrase, maltase and glucoamylase. Inhibition of these enzymes involved in the absorption of disaccharide can significantly decrease the post-prandial increase of blood glucose level after a mixed carbohydrate diet. The ${\beta}-glucan$ had the highest documented rate of small intestinal sucrase inhibitory activity (2.83 mg/mL, $IC_{50}$) relevant for potentially managing post-prandial hyperglycemia. Furthermore, we evaluated the effects of ${\beta}-glucan$ on the level of post-prandial blood glucose in animal model. The post-prandial blood glucose levels were tested two hours after sucrose/starch administration, with and without ${\beta}-glucan$ (100, and 500 mg/kg-body weight). The maximum blood glucose levels (Cmax) of ${\beta}-glucan$ administration group were decreased by about 23% (from $219.06{\pm}27.82$ to $190.44{\pm}13.18$, p<0.05) and 10% (from $182.44{\pm}13.77$ to $165.64{\pm}10.59$, p<0.01) in starch and sucrose loading test, respectively, when compared to control in pharmacodynamics study. The ${\beta}-Glucan$ administration significantly lowered the mean, maximum, and minimum level of post-prandial blood glucose at 30 min after meal. In view of the foregoing, it is felt that our findings suggest that ${\beta}-glucan$ from oat serves to reduce post-prandial blood glucose rise secondary to slower absorption of glucose in the small intestine, via carbohydrate hydrolyzing enzymes inhibition.

• Nutrition Research and Practice
• /
• v.3 no.4
• /
• pp.272-278
• /
• 2009

Postprandial hypoglycemic effect of mulberry leaf (Morus alba L.) was compared in two animal models: Goto-Kakizaki (GK) rats, a spontaneous non-obese animal model for type II diabetes, and their counterpart control Wistar rats. First, the effect of a single oral administration of mulberry leaf aqueous extract (MLE) on postprandial glucose responses was determined using maltose or glucose as substrate. With maltose-loading, MLE reduced peak responses of blood glucose significantly in both GK and Wistar rats (P < 0.05), supporting the inhibition of $\alpha$-glucosidase by MLE in the small intestine. With glucose-loading, MLE also significantly reduced blood glucose concentrations, measured at 30 min, in both animal models (P < 0.01), proposing the inhibition of glucose transport by MLE. Next, dried mulberry leaf powder (MLP) was administered for 8 weeks by inclusion in the diet. By MLP administration, fasting blood glucose was significantly reduced at weeks 4 and 5 (P < 0.05), but then returned to values that were similar to those of the control at the end of experimental period in GK rats. Insulin, HOMA-IR, C-reactive protein, and triglycerides tended to be decreased by MLP treatment in GK rats. All other biochemical parameters were not changed by MLP administration in GK rats. Collectively, these findings support that MLE has significant postprandial hypoglycemic effect in both non-obese diabetic and healthy animals, which may be beneficial as food supplement to manage postprandial blood glucose. Inhibitions of glucose transport as well as $\alpha$-glucosidase in the small intestine were suggested as possible mechanisms related with the postprandial hypoglycemic effect of MLE.

• Korean journal of food and cookery science
• /
• v.28 no.1
• /
• pp.25-32
• /
• 2012

This study was carried out to evaluate biological activities concerning extracts according to extraction methods from unripened fruit of Rubus coreanus Miq. The extraction methods were HWE (hot water extraction for 4 hr at $100^{\circ}C$), SFE (extraction for 3 hr at $40^{\circ}C$ under 300 bar, 100% of $CO_2$ fluid), USE (ultrasonification extraction for 4 hr at $50^{\circ}C$ with water), USE+HWE (hot water extraction for 2 hr at $100^{\circ}C$ after ultrasonification process for 2 hr), VE (vacuum extraction for 4 hr at $90^{\circ}C$ under 0.9 bar with water). VE extract showed the highest contents of total polyphenol ($178.78{\pm}3.79\;mg/g$) and total flavonoid ($40.93{\pm}0.68\;mg/g$). $IC_{50}$ values of DPPH radical scavenging activity, linoleic acid peroxidation inhibition activity and LDL (low density lipoprotein) oxidation inhibition activity of HWE extract showed the lowest $35.39{\pm}0.25{\mu}g/mL$, $12.61{\pm}0.31{\mu}g/mL$ and $1.31{\pm}0.02{\mu}g/mL$ among other all extracts, respectively. $IC_{50}$ values of ${\alpha}$-glucosidase inhibitory activities of VE and HWE extracts showed lower $14.34{\pm}0.20{\mu}g/mL$ and $15.83{\pm}0.20{\mu}g/mL$ than those of other extracts, respectively. Specifically, HWE and VE extracts have relatively better biological activities than other extracts; these could be potentially used as a bioactive source for health functional foods.

• Journal of Life Science
• /
• v.33 no.10
• /
• pp.783-790
• /
• 2023

Modern people have an increased incidence of metabolic diseases due to changed eating habits, and diabetes is considered the most significant metabolic disease. Given that existing diabetes treatments are accompanied by side effects, the aim of this study was to identify traditional natural products that have anti-diabetic activity. The potential anti-diabetic and antioxidant activities of natural products were examined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay, α-glucosidase assay, and protein tyrosine phosphatase 1B (PTP1B) inhibition assay. Methanol extracts of Ulmus davidiana var. japonica, Acer tegmentosum branches, Nelumbo nucifera seeds, and Carthamus tinctorius seeds were found to have high anti-diabetic activity and further fractionated with solvents using ethyl acetate and butanol. Consequently, the ethyl acetate fraction of C. tinctorius seeds (MG-11-E) with high α-glucosidase and PTP1B inhibitory activity was selected. MG-11-E was subjected to preparative thin layer chromatography, and fraction #6 showed high α-glucosidase and PTP1B inhibitory activity. Fraction #6 was analyzed and fractionated via high performance liquid chromatography with 50% methanol as the mobile phase, and anti-diabetic activity was observed in the sample that eluted after 4 min as a single peak. The α-glucosidase inhibitory activity exhibited by this sample seemed to be greater than the PTP1B inhibitory activity; thus, it was concluded that a greater anti-diabetic therapeutic effect may be achieved by combining this agent with natural products that inhibit PTP1B activity.

• Journal of Life Science
• /
• v.28 no.6
• /
• pp.688-696
• /
• 2018

Hemp seed (Cannabis sativa L.; HS), an annual herbaceous plant in the Cannabis genus, has been reported to play various biological functions in immunity increase, atherosclerosis, constipation, hyperlipidemia prevention, anti-inflammatory, and anti-cancer. In recently years, as superfood, the growing interest in the health care benefits of hemp seed has led to increased consumption. In this study, we investigated the effect of an ethanol extract of HS fermented with lactic acid bacteria (Lactobacillus plantarum KCTC 3107, L. plantarum KCTC 3108, L. brevis BHN-LAB128, L. paracasei BHN-LAB129). An antibacterial activity against Staphylococcus aureus and Bacillus cereus were 13.99 mm and 15.17 mm, respectively. The ethanol extracts of fermented hemp seed by lactic acid bacteria that the contents of total polyphenol, total flavonoid content, DPPH radical scavenging activity, SOD-like activity, and ${\alpha}$-glucosidase inhibitory activity were increased compared to non-fermented hemp seed. Also, tyrosinase inhibitory activity of the fermented hemp seed (FHS), known to melanin increasing substance was increased. In these results, we suggested that FHS have effects of anti-oxidant, ${\alpha}$-glucosidase inhibitory activity, and tyrosinase inhibitory activity. Hence, we proposed that FHS has possible to development as functional foods and cosmetics.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.39 no.11
• /
• pp.1573-1579
• /
• 2010

This research was performed to determine the antioxidant activity, nitrite scavenging activity, and its inhibitory activity on angiotensin converting enzyme (ACE), xanthine oxidase, $\alpha$-glucosidase, and elastase of hot water extract from pine bud (WPB). Antioxidant activity of WPB was measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and superoxide dismutase (SOD)-like activity. DPPH radical scavenging activity and SOD-like activity of WPB were remarkably increased in a dose-dependent manner, and were about 71.4 and 85.4% at 2 mg/mL, respectively. The xanthine oxidase and ACE inhibitory activities were about 70.9 and 51.9% at 2 mg/mL of WPB, respectively. Nitrite scavenging activity of WPB was about 59.1, 53.8, and 39.5% on pH 1.2, 3.0, and 6.0 at 2 mg/mL, respectively. The WPB also showed elastase and $\alpha$-glucosidase inhibitory effects. These results revealed that pine bud have strong antioxidant activity and positive effects on the inhibition of xanthine oxidase, ACE, and elastase.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.44 no.11
• /
• pp.1637-1644
• /
• 2015

To develop health-functional food ingredients for improvement of diabetes, we examined biological activities, including total contents of polyphenols and flavonoids, antioxidant activity, and inhibition of ${\alpha}$-glucosidase and pancreatic lipase activities of ethanol extracts from unripe fruit of Momordica charantia L. cultivated in Hamyang, Korea. Ethanol extracts were tested using different ethanol concentrations (0%, 30%, 50%, and 70%) and temperatures ($50^{\circ}C$ and $70^{\circ}C$). Experimental results showed that total polyphenol and flavonoid contents were achieved concentrations of 7.77 mg/g (tannic acid), 7.66 mg/g (gallic acid), and 10.66 mg/g (rutin). The hydroxyl radical scavenging, ABTS cation radical scavenging, and FRAP activities were 82.19%, 42.82%, and 0.19 under the same conditions, respectively. The highest inhibitory activities of ${\alpha}$-glucosidase and pancreatic lipase were achieved in the 70% ethanol extract at $70^{\circ}C$. These results will be useful for development of health functional foods for anti-diabetes using 70% ethanol extract from unripe fruit of bitter melon.

• Korean Journal of Food Science and Technology
• /
• v.47 no.2
• /
• pp.254-260
• /
• 2015

The effect of the extraction solvent on the physiological properties of the peel of the Korean pear (Pyrus pyrifolia cv. Niitaka) was evaluated. The total phenol content was highest in the 80%(wt) methanol extract, whereas flavonoid content was highest in the 80% ethanol extract. The antioxidant activities of the extracts were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging abilities, and their reducing power. The water and 80% methanol extracts of the pear peel had highest DPPH and ABTS radical scavenging activities, and reducing power, respectively. The inhibition of ${\alpha}$-glucosidase was highest in the 80% methanol extract, and alcohol dehydrogenase activity was highest in the water extract. All three extracts had similar antimicrobial activity. Because water, 80% ethanol, and 80% methanol extracts exhibited high activities in different assays of physiological properties, each solvent could be used for specific purposes.

• The Korean Journal of Food And Nutrition
• /
• v.28 no.2
• /
• pp.295-301
• /
• 2015

Biological compounds such as crude saponin and total polyphenol were determined in Allium hookeri roots and leaves. In addition, activities of DPPH radical scavenging activity, hydroxyl radical scavenging activity, ${\alpha}$-amylase inhibition activity and nitrite scavenging were detected in concentrates of 70% ethanol extracts of Allium hookeri roots and leaves. The crude saponin content of the roots and leaves were 4.28 mg/g, and 4.17 mg/g, respectively. Total polyphenol and total flavonoid content was higher in leaves than roots. Furthermore the DPPH radical scavenging activity and hydroxyl radical scavenging activities of leaves was higher than roots. For ${\alpha}$-glucosidase inhibitory activity, 70% ethanol extracts of Allium hookeri roots and leaves showed 60% activity inhibition at a 10 mg/mL concentration. Nitrite scavenging abilities under acidic conditions were most effective for Allium hookeri leaves extracts. These results suggested that Allium hookeri leaves might be used as the components of health functional food.

• Nutrition Research and Practice
• /
• v.4 no.6
• /
• pp.486-491
• /
• 2010

Tight control of blood glucose is the most important strategy for the treatment of diabetes mellitus. Here, we investigated the beneficial effects of Welsh onion on fasting and postprandial hyperglycemia. Inhibitory activities of hot water extracts from the green stalk and white bulb, which are the edible portions of the Welsh onion, and the fibrous root extract against yeast ${\alpha}$-glucosidase were measured in vitro. To study the effects of Welsh onion on postprandial hyperglycemia, a starch solution (1 g/kg) with and without Welsh onion fibrous root extract (500 mg/kg) or acarbose (50 mg/kg) was administered to streptozotocin-induced diabetic rats after an overnight fast. Postprandial plasma glucose levels were measured and incremental areas under the response curve were calculated. To study the hypoglycemic effects of chronic feeding of Welsh onion, five-week-old db/db mice were fed an AIN-93G diet or a diet containing either Welsh onion fibrous root extract at 0.5% or acarbose at 0.05% for 7 weeks after 1 week of adaptation. Fasting plasma glucose and blood glycated hemoglobin were measured. Compared to the extract from the edible portions of Welsh onion, the fibrous root extract showed stronger inhibition against yeast ${\alpha}$-glucosidase, with an $IC_{50}$ of 239 ${\mu}g/mL$. Oral administration of Welsh onion fibrous root extract (500 mg/kg) and acarbose (50 mg/kg) significantly decreased incremental plasma glucose levels 30-120 min after oral ingestion of starch as well as the area under the postprandial glucose response curve, compared to the control group (P < 0.01). The plasma glucose and blood glycated hemoglobin levels of the Welsh onion group were significantly lower than those of the control group (P < 0.01), and were not significantly different from those fed acarbose. Thus, we conclude that the fibrous root of Welsh onion is effective in controlling hyperglycemia in animal models of diabetes mellitus.