• Nutrition Research and Practice
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• 제11권5호
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• pp.430-434
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• 2017

BACKGROUND/OBJECTIVE: Chronic hyperglycemia induces oxidative stress via accumulation of reactive oxygen species (ROS) and contributes to diabetic complications. Hyperglycemia induces mitochondrial superoxide anion production through the increased activity of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. This study aimed to determine whether fisetin and luteolin treatments suppress the oxidative stress by modulating the expression of sirtuins (SIRTs) and forkhead box O3a (FOXO3a) under hyperglycemic conditions in human monocytes. MATERIALS/METHODS: Human monocytic cells (THP-1) were cultured under osmotic control (14.5 mmol/L mannitol), normoglycemic (NG, 5.5 mmol/L glucose), or hyperglycemic (HG, 20 mmol/L glucose) conditions, in the absence or presence of fisetin and luteolin for 48 h. To determine the effect of fisetin and luteolin treatments on high glucose-induced oxidative stress, western blotting and intracellular staining were performed. RESULTS: Hyperglycemic conditions increased the ROS production, as compared to normoglycemic condition. However, fisetin and luteolin treatments inhibited ROS production under hyperglycemia. To obtain further insight into ROS production in hyperglycemic conditions, evaluation of p47phox expression revealed that fisetin and luteolin treatments inhibited p47phox expression under hyperglycemic conditions. Conversely, the expression levels of SIRT1, SIRT3, SIRT6, and FOXO3a were decreased under high glucose conditions compared to normal glucose conditions, but exposure to fisetin and luteolin induced the expression of SIRT1, SIRT3, SIRT6, and FOXO3a. The above findings suggest that fisetin and luteolin inhibited high glucose-induced ROS production in monocytes through the activation of SIRTs and FOXO3a. CONCLUSIONS: The results of our study supports current researches that state fisetin and luteolin as potential agents for the development of novel strategies for diabetes.

• Nutrition Research and Practice
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• 제15권5호
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• pp.591-603
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• 2021

BACKGROUND/OBJECTIVES: Unregulated inflammatory responses caused by hyperglycemia may induce diabetes complications. Hesperetin, a bioflavonoid, is a glycoside in citrus fruits and is known to have antioxidant and anticarcinogenic properties. However, the effect of inflammation on the diabetic environment has not been reported to date. In this study, we investigated the effect of hesperetin on proinflammatory cytokine secretion and its underlying mechanistic regulation in THP-1 macrophages with co-treatment LPS and hyperglycemic conditions. MATERIALS/METHODS: THP-1 cells differentiated by PMA (1 µM) were cultured for 48 h in the presence or absence of hesperetin under normoglycemic (5.5 mM/L glucose) or hyperglycemic (25 mM/L glucose) conditions and then treated with LPS (100 ng/mL) for 6 h before harvesting. Inflammation-related proteins and mRNA levels were evaluated by enzyme-linked immunosorbent assay, western blot, and quantitative polymerase chain reaction analyses. RESULTS: Hesperetin (0-100 µM, 48 h) treatment did not affect cell viability. The tumor necrosis factor-α and interleukin-6 levels increased in cells co-treated with LPS under hyperglycemic conditions compared to normoglycemic conditions, and these increases were decreased by hesperetin treatment. The TLR2/4 and MyD88 activity levels increased in cells co-treated with LPS under hyperglycemic conditions compared to normoglycemic conditions; however, hesperetin treatment inhibited the TLR2/4 and MyD88 activity increases. In addition, nuclear factor-κB (NF-κB) and Acetyl-NF-κB levels increased in response to treatment with LPS under hyperglycemic conditions compared to normoglycemic conditions, but those levels were decreased when treated with hesperetin. SIRT3 and SIRT6 expressions were increased by hesperetin treatment. CONCLUSIONS: Our results suggest that hesperetin may be a potential agent for suppressing inflammation in diabetes.

• Laboraroty Animal Research
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• 제34권4호
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• pp.195-202
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• 2018

Hyperglycemia is one of the major risk factors for stroke. Hyperglycemia can lead to a more extensive infarct volume, aggravate neuronal damage after cerebral ischemia. ${\alpha}$-Synuclein is especially abundant in neuronal tissue, where it underlies the etiopathology of several neurodegenerative diseases. This study investigated whether hyperglycemic conditions regulate the expression of ${\alpha}$-synuclein in middle cerebral artery occlusion (MCAO)-induced cerebral ischemic injury. Male Sprague-Dawley rats were treated with streptozotocin (40 mg/kg) via intraperitoneal injection to induce hyperglycemic conditions. MCAO were performed four weeks after streptozotocin injection to induce focal cerebral ischemia, and cerebral cortex tissues were obtained 24 hours after MCAO. We confirmed that MCAO induced neurological functional deficits and cerebral infarction, and these changes were more extensive in diabetic animals compared to non-diabetic animals. Moreover, we identified a decrease in ${\alpha}$-synuclein after MCAO injury. Diabetic animals showed a more serious decrease in ${\alpha}$-synuclein than non-diabetic animals. Western blot and reverse-transcription PCR analyses confirmed more extensive decreases in ${\alpha}$-synuclein expression in MCAO-injured animals with diabetic condition than these of non-diabetic animals. It is accepted that ${\alpha}$-synuclein modulates neuronal cell death and exerts a neuroprotective effect. Thus, the results of this study suggest that hyperglycemic conditions cause more serious brain damage in ischemic brain injuries by decreasing ${\alpha}$-synuclein expression.

• 생명과학회지
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• 제33권11호
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• pp.851-858
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• 2023

Unique cartilage matrix-associated protein (UCMA)은 γ-카르복실화(Gla) 잔기가 풍부한 간외 비타민 K 의존 단백질이다. UCMA는 조골세포 분화를 촉진하고 뼈 형성을 강화한다고 보고되고 있지만 고혈당 스트레스 하에서 조골세포에 미치는 영향에 대해서는 아직 알려진 바가 없다. 본 연구에서는 고혈당 조건하에서의 MC3T3-E1 조골세포에서 UCMA 효과를 조사하기 위해 MC3T3-E1 조골세포를 높은 포도당에 노출한 후 재조합 UCMA 단백질을 처리하였다. MC3T3-E1 세포에서 활성 산소종(ROS)의 생성은 고혈당 조건하에서 증가했으나 UCMA 단백질 처리 후 감소했음을 CellROX 및 MitoSOX 염색으로 확인하였다. 또한 고혈당 조건에서 UCMA 단백질을 함께 처리한 MC3T3-E1 세포에서 정량적 중합효소 연쇄반응 결과, 항산화 유전자인 nuclear factor erythroid 2-related factor 2 와 superoxide dismutase 1 발현이 증가하였다. 동일 조건하에서 UCMA 단백질 처리에 의해 heme oxygenase-1 발현 감소와 함께 세포질에서 핵으로의 전위가 감소되었고, 미토콘드리아 분열에 관여하는 dynamin-related protein 1 발현이 증가하였으며, AKT 신호 활성은 억제되었다. 종합적으로 UCMA는 고혈당에 노출된 조골세포에서 ROS 생성을 완화하고, 항산화 유전자 발현을 증가시키고, 미토콘드리아 역학에 영향을 미치며, AKT 신호를 조절하는 것으로 보인다. 본 연구는 UCMA의 세포 메커니즘에 대한 이해를 돕고, 대사 장애 관련한 골 합병증에 대한 새로운 치료제로서의 잠재적 사용 가능성을 제시하고 있다.

• 한국식품영양과학회지
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• 제39권9호
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• pp.1257-1262
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• 2010

본 연구는 지골피, 동충하초, 가시오가피의 복합추출물을 고포도당 조건(4.5 g/L)에서 배양한 HepG2 세포를 이용하여 당대사 관련 주요 효소인 glucokinase, acetyl CoA carboxylase의 활성을 RT-PCR과 western blotting 방법을 이용하여 측정하였다. 복합추출물을 HepG2 세포에 24시간 처리한 후 GK mRNA와 protein의 발현 양을 측정한 결과 각각 $168{\pm}0.04%$, $182.4{\pm}0.03%$로 증가하였으며, ACC 효소의 활성은 고포도당으로 배양하였을 때 ACC mRNA 및 protein 발현 양은 각각 $127.3{\pm}0.02%$, $126.7{\pm}0.24%$로 증가 하였다. 결론적으로 지골피, 동충하초, 가시오가피의 복합추출물이 GK 및 ACC mRNA 발현을 증가시킴으로써 항당뇨 효과를 나타냄을 관찰하였다.

• 동아시아식생활학회지
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• 제12권5호
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• pp.364-369
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• 2002

본 연구는 천연 자원인 뽕나무에서 혈당강하 효능을 가진 뽕잎(상엽)의 열수 추출법을 이용하여 상엽 추출물의 공정화 확립과 Formulation 개발을 위해 상엽 추출물과 silk peptide 및 한약재를 첨가한 시제품을 동물실험을 통하여 Formulation을 최종 결정하여 제품화하여 기능성 음료를 개발하고자 하였다. 연구 결과, 상엽 추출의 최적 조건은 상엽 크기는 3mm 이하로 하고, 2/3 정도 packing된 면포자루로 포장된 상엽을 사용하며, 상엽 사용량은 50~100 g/L, 추출 온도는 9$0^{\circ}C$, 추출 시간은 2 hr으로 하였으며 이때 수율은 20~25%였다. 또한 시료 배합에 따른 혈당강하 실험을 통하여 상엽 추출물과 silk peptide 의 농도는 각각 1%, 0.1%일 때 혈당강하 작용이 가장 우수하였으며 부재료로 사용된 둥글레는 상엽추출물의 10% 첨가한 경우가 혈당강하작용이 가장 컸으며, polydextrose도 효과가 있으므로 첨가하는 것이 바람직하다고 사료된다.

• Biomolecules & Therapeutics
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• 제22권1호
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• pp.47-54
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• 2014

The present study was aimed to evaluate the antioxidant defense system of cinnamaldehyde in normal, diabetic rats and its possible protection of pancreatic ${\beta}$-cells against its gradual loss under diabetic conditions. In vitro free radical scavenging effect of cinnamaldehyde was determined using DPPH (1,1-diphenyl-2-dipicrylhydrazyl), superoxide radical, and nitric oxide radical. Streptozotocin (STZ) diabetic rats were orally administered with cinnamaldehyde at concentrations of 5, 10 and 20 mg/kg body weight for 45 days. At the end of the experiment, the levels of plasma lipid peroxides and antioxidants such as vitamin C, vitamin E, ceruloplasmin, catalase, superoxide dismutase, reduced glutathione and glutathione peroxidase were determined. A significant increase in the levels of plasma glucose, vitamin E, ceruloplasmin, and lipid peroxides and significant decrease in the levels of plasma insulin and reduced glutathione were observed in the diabetic rats. Also the activities of pancreatic antioxidant enzymes were altered in the STZ-induced diabetic rats. The altered enzyme activities were reverted to near-normal levels after treatment with cinnamaldehyde and glibenclamide. Histopathological studies also revealed a protective effect of cinnamaldehyde on pancreatic ${\beta}$-cells. Cinnamaldehyde enhances the antioxidant defense against reactive oxygen species produced under hyperglycemic conditions and thus protects pancreatic ${\beta}$-cells against their loss and exhibits antidiabetic properties.

• The Korean Journal of Pain
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• 제35권2호
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• pp.160-172
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• 2022

Background: The authors established an in vitro model of diabetic neuropathy based on the culture system of primary neurons and Schwann cells (SCs) to mimic similar symptoms observed in in vivo models of this complication, such as impaired neurite extension and impaired myelination. The model was then utilized to investigate the effects of insulin on enhancing neurite extension and myelination of diabetic neurons. Methods: SCs and primary neurons were cultured under conditions mimicking hyperglycemia prepared by adding glucose to the basal culture medium. In a single culture, the proliferation and maturation of SCs and the neurite extension of neurons were evaluated. In a co-culture, the percentage of myelination of diabetic neurons was investigated. Insulin at different concentrations was supplemented to culture media to examine its effects on neurite extension and myelination. Results: The cells showed similar symptoms observed in in vivo models of this complication. In a single culture, hyperglycemia attenuated the proliferation and maturation of SCs, induced apoptosis, and impaired neurite extension of both sensory and motor neurons. In a co-culture of SCs and neurons, the percentage of myelinated neurites in the hyperglycemia-treated group was significantly lower than that in the control group. This impaired neurite extension and myelination was reversed by the introduction of insulin to the hyperglycemic culture media. Conclusions: Insulin may be a potential candidate for improving diabetic neuropathy. Insulin can function as a neurotrophic factor to support both neurons and SCs. Further research is needed to discover the potential of insulin in improving diabetic neuropathy.

• Applied Biological Chemistry
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• 제48권1호
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• pp.103-108
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• 2005

${\alpha}-Amylase$ 저해제는 소장에서 전분의 소화를 저해하여 포도당의 흡수를 지연시킴으로써 혈당 조절 목적으로 이용된다. 따라서 본 연구에서는 ${\alpha}-amylase$ 저해제를 탐색할 목적으로 국내 자생 목본류 약 1400여종의 70% ethanol 추출액을 대상으로 ${\alpha}-amylase$ 저해제 분포를 검색하였다. 수종의 목본류에서 ${\alpha}-amylase$ 저해제가 분포하고 있음이 확인되었으며, 그 중 활성이 비교적 높은 말채나무 기원의 저해제를 대상으로 연구를 진행하였다. 기원별 효소에 따른 저해 활성도를 살펴보면 salivary와 pancreatic ${\alpha}-amylase$, 미생물 기원의 ${\alpha}-glucosidase$에는 탁월한 저해 활성을 보인 반면 돼지 기원의 ${\alpha}-glucosidase$ 저해제에 대해서는 매우 낮은 저해 활성을 보였다. ${\alpha}-Amylase$와 ${\alpha}-glucosidase$의 kinetic을 분석하면 salivary와 pancreatic 두 효소에 모두 경쟁적 저해제로, 효모의 ${\alpha}-glucosidase$에는 비경쟁적과 반경쟁적의 혼합형 저해제로 나타났다. 또한 열과 산성에 대한 안정성을 확인한 결과 비교적 안정적인 것으로 나타났다. 본 추출물의 식이 섭취에 따른 혈당 강하 효과와 체중에 미치는 영향에서는 혈당과 체중 상승을 억제하는 효과가 확인되었고, mRNA수준에서 대퇴근 세포에 있어서 GLUT4의 발현이 증가됨을 확인하였다.

• 한국식품과학회지
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• 제46권6호
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• pp.773-777
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• 2014

고혈당으로 유도된 염증반응 모델에서 유황양파즙(onion juice)의 항염증 효능을 평가하였다. 고혈당(HG, 25 mM glucose) 조건하에서 48시간 배양된 THP-1 세포들은 정상혈당(NG, 5.5mM glucose) 조건의 세포들에 비해 유의적으로 낮은 세포 생존율을 보였으나, $50-150{\mu}L$ 유황양파즙을 함께 처리하자 NG군 수준으로 회복되었다. 이는, 유황양파즙이 고농도 당에 의한 세포독성을 완화시켜 주었음을 시사한다. 고혈당으로 유도된 HG군에서 염증성 사이토카인 TNF-${\alpha}$는 NG군의 290% 수준까지 분비되어 유의적으로 증가하였으나, $50{\mu}L$ 유황양파즙 처리로 TNF-${\alpha}$의 분비 수준이 전반적으로 저해되었으며, TNF-${\alpha}$의 발현 수준 역시 낮아져, 유황양파즙이 고혈당에 의한 염증반응을 저해하였음을 시사해 주었다. 이는 유황양파즙에서 보고된 높은 수준의 플라보노이드에 의한 효과로 일부 해석되었다. 본 연구는 식품 섭취를 통한 당뇨 및 당뇨합병증 예방의 가능성을 보여줌으로써, 식이인자의 항염증 효능에 관한 향후 연구들의 기초적 근거 자료로 활용될 수 있다.