• Biomolecules & Therapeutics
• /
• 제26권2호
• /
• pp.201-209
• /
• 2018

G protein-coupled receptor 119 (GPR119) is expressed in the pancreas and gastrointestinal tract, and its activation promotes insulin secretion in the beta cells of the pancreatic islets as well as the secretion of glucagon-like peptide-1 (GLP-1) in intestinal L cells, consequently improving glucose-stimulated insulin secretion. Due to this dual mechanism of action, the development of small-molecule GPR119 agonists has received significant interest for the treatment of type 2 diabetes. We newly synthesized 1,2,4-triazolone derivatives of GPR119 agonists, which demonstrated excellent outcomes in a cyclic adenosine monophosphate (cAMP) assay. Among the synthesized derivatives, YH18968 showed cAMP=2.8 nM; in GLUTag cell, GLP-1secretion=2.3 fold; in the HIT-T15 cell, and insulin secretion=1.9 fold. Single oral administration of YH18968 improved glucose tolerance and combined treatment with a dipeptidyl peptidase 4 (DPP-4) inhibitor augmented the glucose lowering effect as well as the plasma level of active GLP-1 in normal mice. Single oral administration of YH18968 improved glucose tolerance in a diet induced obese mice model. This effect was maintained after repeated dosing for 4 weeks. The results indicate that YH18968 combined with a DPP-4 inhibitor may be an effective therapeutic candidate for the treatment of type 2 diabetes.

• Journal of the Korean Wood Science and Technology
• /
• 제47권4호
• /
• pp.498-508
• /
• 2019

This study was carried out to investigate the potential of Korean red pine (Pinus densiflora) inner bark extracts as an antidiabetic agent. The ethyl acetate soluble fraction of the bark extracts was chromatographed on a Sephadex LH-20 column to yield five compounds, which structures were elucidated by NMR spectroscopy. The isolated compounds were (+)-catehin, (-)-epicatechin, taxifolin, taxifolin-3'-O-${\beta}$-D-(+)-glucose and $\tilde{n}$-courmaric acid. The antidiabetic activity of the different fractions, including the crude extracts and isolated compounds, was evaluated by ${\beta}$-cells insulin secretion and glucose uptake in skeletal muscle cells. The insulin secretion was 128% for taxifolin at $25{\mu}g/mL$. However, the other samples had no effect on this test. For the glucose uptake activity assay, $1{\mu}M$ insulin and 2 mM metformin were used as controls. Both the crude extract and taxifolin showed relatively low activity values, but the other samples yielded glucose uptake values over 260%. ${\rho}$-courmaric acid showed the highest uptake (270%). The results confirmed that Korean red pine extracts may be used as a hypoglycemic agent.

• BMB Reports
• /
• 제52권5호
• /
• pp.295-303
• /
• 2019

Breakthroughs in stem cell technology have contributed to disease modeling and drug screening via organoid technology. Organoid are defined as three-dimensional cellular aggregations derived from adult tissues or stem cells. They recapitulate the intricate pattern and functionality of the original tissue. Insulin is secreted mainly by the pancreatic ${\beta}$ cells. Large-scale production of insulin-secreting ${\beta}$ cells is crucial for diabetes therapy. Here, we provide a brief overview of organoids and focus on recent advances in protocols for the generation of pancreatic islet organoids from pancreatic tissue or pluripotent stem cells for insulin secretion. The feasibility and limitations of organoid cultures derived from stem cells for insulin production will be described. As the pancreas and gut share the same embryological origin and produce insulin, we will also discuss the possible application of gut organoids for diabetes therapy. Better understanding of the challenges associated with the current protocols for organoid culture facilitates development of scalable organoid cultures for applications in biomedicine.

• 대한의생명과학회지
• /
• 제12권3호
• /
• pp.217-224
• /
• 2006

It has been reported that the dysfunctions of podocytes are associated with the development of diabetic nephropathy. In addition, insulin-like growth factors (IGFs) are associated with the development of diabetic nephropathy. However, it is not yet known about the effect of high glucose on IGF-I, -II secretion, and IGF binding proteins (IGFBPs) expression in the podocytes. Thus, this study was conducted to examine the effect of high glucose on IGF system and its involvement of protein kinase C (PKC) and mitogen activated protein kinases (MAPKs) in podocytes. In this study, high glucose (25 mM) increased IGF-I and IGF-II secretion (P<0.05), which was blocked by SB 203580 (a p38 MAPK inhibitor) but not by PD 98059 (a p44/42 MAPK inhibitor). In addition, high glucose-induced stimulation of IGFs was blocked by bisindolylmaleimide I and staurosporine (protein kinase C inhibitors). High glucose also increased IGFBP-l expression, which was blocked by bisindolylmaleimide I and SB 203580. In conclusion, high glucose alters IGFs secretion and IGFBP expression via PKC and p38 MAPK pathways in podocytes.

• Asian-Australasian Journal of Animal Sciences
• /
• 제2권3호
• /
• pp.216-217
• /
• 1989

• 대한핵의학회:학술대회논문집
• /
• 대한핵의학회 1972년도 제11차 학술대회
• /
• pp.70.2-70.2
• /
• 1972

• 한국식품영양학회지
• /
• 제23권2호
• /
• pp.233-239
• /
• 2010

Phenolic acid concentrates of rice bran(RB-ex) and hydroxycinnamic acids were investigated for their anti-hyperglycemic activities through glucose uptake and glucokinase activity using HepG2 cells and stimulatory effects on insulin secretion using HIT-T15 cells. RB-ex was prepared as an ethylacetate extract after alkaline hydrolysis and hydroxycinnamic acids, found as major compositions of RB-ex, such as ferulic acid(FA), sinapic acid(SA) and p-coumaric acid(p-CA) were investigated to compare with the properties of RB-ex. The properties of glucose uptake in HepG2 cells were examined in the absence of insulin and two different glucose concentrations(5.5 mM and 25 mM). RB-ex and FA showed anti-hyperglycemic activities through the increase of glucose uptake and the stimulation of glucokinase activity in HepG2 cells. RB-ex exhibited higher glucose uptakes with higher glucose concentrations, whereas FA exhibited the same increasing effects on both concentrations of glucose. RB-ex and FA exhibited doubled glucokinase activities relative to control. In the presence of insulin in the 25 mM glucose-containing medium, the levels of glucose uptake were increased in all treatments compared with control. As stimulatory effects of samples on insulin secretion were estimated, RB-ex and FA stimulated insulin secretion at a concentration of 25 ${\mu}g/m{\ell}$ and in particular, FA showed the highest amount of insulin-release in HIT-T15 cells. Antioxidative effects on HIT-T15 cells, RB-ex and hydroxycinnamic acids, excluding p-CA, showed inhibitory activities of 78% to 80% at a concentration of 100 ${\mu}g/m{\ell}$. On the basis of these results, we conclude that RB-ex and FA could help decrease blood glucose levels and prevent the cell damages via antioxidant activity.

• 생명과학회지
• /
• 제11권5호
• /
• pp.476-482
• /
• 2001

다시마의 열수출물이 당뇨병의 치료에 효과가 있는지를 알아보기 위하여 alloxan으로 처리하여 실험적으로 당뇨병을 유발한 후 glucose의 초기 인산화에 관여하는 glu-cokinase와 hexokinase의 활성을 살펴본 결과 다음과 같은 결론을 얻었다. 1. Alloxan 주사에 의해 체중과 공복시의 glucose 및 insulin 분비가 증가되었으나, 다시마 투여에 의해 공복시의 insulin 분비가 유의성있게 감소하였으며 체중과 공복시의 glucose의 유의성은 없었으나 대조군에 비하여 감소하였다. 2. Alloxan 주사에 의해 혈청중 glucosecl가 정상군에 비하여 현저하게 증가되었으나 다시마 투여에 의해 현저히 감소되었다. Insulin 치의 상승과 분비 지연도 다시마 투여군에서는 정상군과 유사한 경향을 보였다. 3. Glucokinase와 hexokinase의 활성은 alloxan 주사에 의해 현저히 감소되었으나, 다시마 투여에 의해 유의성있게 상승되었다. 이상의 결과로 다시마는 alloxan으로 유발된 당뇨병에서 glcuose 인산화 glucokinase와 hexokinase의 활성을 증가시키는 것으로 나타나 당뇨병의 치료에 효과가 있는 것으로 여겨진다.

• Nutrition Research and Practice
• /
• 제11권3호
• /
• pp.198-205
• /
• 2017

BACKGROUND/OBJECTIVES: The anti-diabetic activity of pear through inhibition of ${\alpha}-glucosidase$ has been demonstrated. However, little has been reported about the effect of pear on insulin signaling pathway in obesity. The aims of this study are to establish pear pomace 50% ethanol extract (PPE)-induced improvement of insulin sensitivity and characterize its action mechanism in 3T3-L1 cells and high-fat diet (HFD)-fed C57BL/6 mice. MATERIALS/METHODS: Lipid accumulation, monocyte chemoattractant protein-1 (MCP-1) secretion and glucose uptake were measure in 3T3-L1 cells. Mice were fed HFD (60% kcal from fat) and orally ingested PPE once daily for 8 weeks and body weight, homeostasis model assessment of insulin resistance (HOMA-IR), and serum lipids were measured. The expression of proteins involved in insulin signaling pathway was evaluated by western blot assay in 3T3-L1 cells and adipose tissue of mice. RESULTS: In 3T3-L1 cells, without affecting cell viability and lipid accumulation, PPE inhibited MCP-1 secretion, improved glucose uptake, and increased protein expression of phosphorylated insulin receptor substrate 1 [p-IRS-1, ($Tyr^{632})$)], p-Akt, and glucose transporter type 4 (GLUT4). Additionally, in HFD-fed mice, PPE reduced body weight, HOMA-IR, and serum lipids including triglyceride and LDL-cholesterol. Furthermore, in adipose tissue, PPE up-regulated GLUT4 expression and expression ratio of p-IRS-1 ($Tyr^{632})/IRS$, whereas, down-regulated p-IRS-1 ($Ser^{307})/IRS$. CONCLUSIONS: Our results collectively show that PPE improves glucose uptake in 3T3-L1 cells and insulin sensitivity in mice fed a HFD through stimulation of the insulin signaling pathway. Furthermore, PPE-induced improvement of insulin sensitivity was not accompanied with lipid accumulation.

• 한국식품영양과학회지
• /
• 제34권9호
• /
• pp.1336-1343
• /
• 2005

일본에서는 녹나무 줄기에서 분리한 정유의 하나인 camphor는 강심제등 약용으로 사용하고 있지만, 녹나무 잎 추출물에 대한 연구도 적고 특히 항당뇨 효과에 대한 연구는 거의 없었다. 본 연구에서는 녹나무 잎 추출물이 in vitro에서 인슐린 작용, 인슐린 분비 또는 탄수화물의 소화에 효과적인지를 조사함으로 항당뇨에 효과적인지 여부를 조사하였다. 녹나무 잎을 $70\%$ 에탄올로 추출한 후 메탄올과 물을 섞은 용액으로 단계별로 XAD-4 column으로 분획 하였다. 녹나무 잎 추출물은 고농도(1 mg/mL)에서도 MTT로 측정하였을 때 세포 독성을 나타내지 않았다 녹나무 잎 추출분획 물 중 40과 $60\%$ 메탄올층은 3T3-L1 지방세포에 처리하였을 때 인슐린의 작용을 향상시켜 포도당의 흡수를 증가시키는 효과가 매우 컸다. 이 추출분획 물들은 3T3-L1 지방세포에 존재하는 인슐린의 작용을 향상시켜 인슐린을 10 nM을 처리한 것보다도 효과적으로 포도당 흡수를 증가시켰다. 또한 $40\%$ 메탄올층은 3T3-L1 섬유아세포에 분화 유도물질를 처리하였을 때 PPAR$\gamma$인 pioglitazone과 마찬가지로 지방 세포로의 분화를 촉진시키고 지방의 축적도 증가시켰다. 그러므로 $40\%$ 메탄올층에는 PPAR-$\gamma$ agonist로 작용하는 물질이 함유되어 있을 가능성이 높다. 베타세포라인인 Min6세포에 녹나무 잎 추출분획물을 처리한 후 저농도와 고농도 포도당 자극시 인슐린 분비를 측정하였을 때 두 농도에서 모두 인슐린 분비에 영향을 미치지 않았다. 또한 녹나무 잎 추출분획물은 탄수화물의 소화에 작용하는 효소인 $\alpha$-glucoamylase의 활성에 영향을 미치지 않았다. 결론적으로 녹나무 잎에는 인슐린 분비나 탄수화물의 소화에 관여하는 성분의 없지만, 인슐린 작용을 향상시키는 인슐린 민감성물질이 함유되어 있을 가능성이 높다. 특히 $40\%$ 메탄올층에는 PPAR$\gamma$ agnist로 작용하는 인슐린 민감성 물질이 존재할 가능성이 높다.