• Food Science and Industry
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• v.40 no.2
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• pp.46-58
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• 2007

제2형 당뇨병은 대사성 질환으로 간, 근육 그리고 지방 조직 세포에서 인슐린 작용의 장애로 나타나는 인슐린 저항성으로 혈당의 이용이 감소하여 혈당이 높아짐에도 불구하고 췌장의 베타세포에서 인슐린 분비가 충분하지 못할 때 유발된다. 서구에서는 비만 등으로 인해 인슐린 저항성이 증가하면 인슐린 분비가 높은 고인슐린혈증을 나타내어 당뇨병으로의 진전은 늦다. 하지만 우리나라를 비롯한 아시아의 사람들은 인슐린 저항성이 증가할 때 인슐린 분비가 충분치 못해 혈청 인슐린 농도가 정상인과 비슷하거나 더 낮은 상태에서 당뇨병으로 진전된다. 이러한 차이는 우리나라를 비롯한 아시아 사람들에게서 제2형 당뇨병의 발생이 급격하게 증가할 것이라는 보고되었다. 결국 당뇨병은 간, 근육 및 지방조직에서의 인슐린 작용의 장애와 췌장의 베타세포에서 인슐린 분비의 부족의 복합적인 장애에 의해서 나타나고 이것은 공통적으로 각 조직에서의 인슐린/insulin growth factor (IGF)-1 신호전달의 장애와 관련이 있다. 베타세포에서의 인슐린분비 자체는 인슐린/IGF-1 신호전달과 관계가 없지만 간접적으로 관련이 있다. 인슐린 분비능은 베타세포의 증식과 생존에 의한 베타세포의 양과 밀접한 관련이 있는데 인슐린/IGF-1 신호전달은 베타세포의 증식과 생존을 조절한다. 그러므로 혈당 조절에 관여하는 기능성 식품은 인슐린 작용을 향상시키는 인슐린 민감성 특성을 가지거나, 혈당이 높아질 때 인슐린 분비를 촉진시키는 insulinotropic 작용을 하는 성질을 가지고 있어야 하겠다. 전자의 대표적인 약은 1999년에 미국 FDA에서 승인 받은 peroxisome proliferator-activated receptor $(PPAR)-{\gamma}$ agonist 인 thiazolidinedione 계통의 약물인 troglitazone, pioglitazone, rosiglitazone 등이 있고, 후자는 2007년에 승인 받은 Exenatide는 glucagon like peptide (GLP)-1 agonist이다. 이 두 가지 약은 모두 자연계에 존재하는 동식물에서 유래된 것으로 식품에도 많이 다양한 종류의 인슐린 민감성 물질이나 insulinotropic 작용을 하는 물질이 함유되어 있을 것이다. 이러한 기능 이외에 혈당조절 약이나 식품으로 사용되는 것은 탄수화물의 소화를 방해하는 것으로 탄수화물 소화효소인 a-amylase 또는 maltase의 활성을 억제하여 식후 혈당의 급격한 상승을 방지하는 것이 있다. 우리나라 사람들은 탄수화물의 섭취가 너무 많아서 실제로 이러한 식품이나 약의 효능이 높지 않을 것이다. 혈당을 조절하는 기능성 식품은 이 세 가지 효능 중 일부를 가지고 있는 것이 될 수 있다. 이러한 기능을 스크리닝하기 위해서 3가지 단계를 거쳐야 한다. 먼저 시험관에서 또는 세포 실험을 통해서 앞서 언급한 3가지 기능을 가지고 있는 지 여부를 각각 조사한다. 이중에서 효과가 있는 것은 당뇨 동물 모델을 사용하여 in vivo에서 혈당 강하기능과 혈당 강하기전을 조사하는 실험을 한다. 효과가 있는 식품이 우리가 전통적으로 식품으로 섭취해 왔다면 독성 검사를 거쳐야 할 필요가 없지만 한약재이거나 특수 식품의 경우에는 in vivo 실험 전에 GLP 기관에서 반드시 독성 실험을 거쳐 독성 유무를 확인할 필요가 있다. 동물 실험에서 효과적인 것은 인체 실험을 거쳐 혈당 조절 기능성 식품으로 식약청에서 허가를 받을 수 있겠다. 결론적으로 식품에는 항당뇨 특성을 가진 물질들이 함유되어 있는 것들이 상당히 많다. 혈당 조절기능이 있는 기능성 식품으로 개발할 때 고려해야 할 것은 1) 그 양이 혈당 강하 기능성 식품으로 지정받을 수 있을 정도로 충분히 함유되어 있느냐, 2) 혈당을 강하시키는 기전이 단순히 당의 배설을 촉진시켜서 혈당을 저하시키는 것이 아니라, 인슐린 작용을 촉진시키거나, 포도당 자극에 의한 인슐린 분비를 촉진시키거나 탄수화물의 소화 흡수를 억제시킴으로 혈당을 강하시키는 지 등을 파악하는 것이다. 이러한 조건을 만족시키는 식품은 지속적으로 섭취할 때 당뇨병을 예방하거나 진전을 지연시킬 수 있는 혈당조절기능이 있는 기능성 식품으로 개발 가능성이 있겠다.

• Journal of the Korea Convergence Society
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• v.11 no.10
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• pp.155-162
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• 2020

This study wanted to confirm the relevance between body mass index(BMI) and insulin resistance and beta-cell function based on abdominal obesity in obese middle-aged men. This study targeted 797 obese middle-aged men who had undergone health checkups at general hospitals in Gyeonggi-do from January 2018 to June 2020. There were 327 in the group with abdominal obesity and 470 in the group without abdominal obesity. Glucose(p<0.001), HbA1c(p=0.003), insulin(p<0.001), HOMA-IR(p<0.001) was different between groups. BMI was a factor affecting insulin resistance and beta cell function regardless of the with or without of abdominal obesity. BMI was associated with the onset of disease of insulin resistance and beta cell functional degradation regardless of the with or without of abdominal obesity. Therefore, it is considered necessary to manage the indicators of the BMI through exercise programs and regular checkups for health management of middle-aged obese men.

• Journal of the Korea Convergence Society
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• v.11 no.9
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• pp.267-276
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• 2020

The purpose of this study was to investigate the relationship between VAI, insulin resistance, and pancreatic beta cell function according to the prevalence of metabolic syndrome in obese adults. From 2017 to 2019, 1,797 obese adults who received medical checkups at a general hospital in Bundang. Diagnosis of metabolic syndrome is NCEP-ATP III. HOMA index was used for insulin resistance and pancreatic beta cell function. VAI was higher in the metabolic syndrome than in the control(p<.001). As the number of risk factors for metabolic syndrome increased, the VAI value was higher(p<.001). The prevalence of metabolic syndrome increased as the VAI quartile increased(p<.001). VAI was also shown to be related to HOMA-IR and HOMA-β in the control, but not in the metabolic syndrome.

• Korean Journal of Clinical Laboratory Science
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• v.52 no.4
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• pp.327-334
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• 2020

The present study was conducted to assess the relationship between metabolic syndrome, metabolic syndrome score, homeostasis model assessment of insulin resistance (HOMA-IR), and beta-cell function (HOMA-B) in obese Korean adults. The study included 1,860 adults aged 20 years or older from the 2010 Korean National Health and Nutrition Examination Survey (KNHANES) data. Metabolic syndrome and metabolic syndrome score (MSS) were positively associated with HOMA-IR (both P<0.001). HOMA-B levels of elevated blood pressure (P<0.001) and elevated fasting blood glucose group (P<0.001) were significantly lower than the normal group. However, the HOMA-B levels of abdominal obesity (P=0.003) and reduced high-density lipoprotein cholesterol group (P=0.030) were significantly higher than the normal group. Nevertheless, metabolic syndrome (P<0.001) and MSS (P<0.001) were inversely associated with the HOMA-B levels. In conclusion, metabolic syndrome and MSS were positively associated with insulin resistance and inversely associated with beta-cell function in Korean adults with obesity.

• Korean Journal of Food Science and Technology
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• v.35 no.3
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• pp.488-492
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• 2003

Yeast cell wall mutant, Saccharomyces cerevisiae IS2 was screened by the NTG treatment of Saccharomyces cerevisiae KCTC 7911. The mutant was highly resistant to zymolase, which specifically degrades ${\beta}$-1,3-D-glucose chain of ${\beta}$-glucan and mechanical disruption by glass beads. These phenomena demonstrate that the yeast mutant has cell wall structure different from the wild-type. The ${\beta}$-glucan of yeast mutant and wild-type strains was recovered by sequential extraction with NaOH. The injection of ${\beta}$-glucan into the abdominal cavity of mouse resulted in an increase in the number of peritoneal immune cells, NO (nitric oxide) production, and phagocytic activity of macrophage. The number of immune cells was found to be $3.90{\times}10^6\;cells/10\;mL$ and $5.48{\times}10^6\;cells/10\;mL$ with the wild-type and mutant ${\beta}$-glucan, respectively. The effect on the NO production and phagocytic activity of mutant ${\beta}$-glucan were 1.69 and 1.43-fold higher than those of wild-type. These results indicate that the immuno-stimulating activity of alternated ${\beta}$-glucan from mutant yeast is higher than that of wild-type.

• Journal of Life Science
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• v.31 no.11
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• pp.969-979
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• 2021

Type 2 diabetes is a serious chronic metabolic disease, and the goal of diabetes treatment is to keep blood glucose at a normal level and prevent complications from diabetes. Hyperglycemia is a key pathologic feature of type 2 diabetes that mainly results from insulin resistance and pancreatic β-cell dysfunction. Chronic exposure of β-cells to elevated glucose concentrations induces glucotoxicity. In this study, we examined whether an 80% ethanol extract of Oxya chinensis sinuosa Mishchenko (OEE) protected INS-1 pancreatic β-cells against glucotoxicity-induced apoptosis and oxidative stress. Pretreatment with a high concentration of glucose (high glucose = 30 mM) induced glucotoxicity and apoptosis of INS-1 pancreatic β cells. Treatment with OEE significantly increased cell viability. Treatment with 0.01-0.20 mg/ml OEE dose dependently decreased intracellular reactive oxygen species, lipid peroxidation, and nitric oxide levels and increased insulin secretion in high glucose-pretreated INS-1 β cells. OEE also significantly increased the activities of antioxidant enzymes in response to high-glucose-induced oxidative stress. Moreover, OEE treatment significantly reduced the expressions of pro-apoptotic proteins, including Bax, cytochrome C, caspase-3, and caspase-9, and increased anti-apoptotic Bcl-2 expression. Apoptotic cells were identified using Annexin-V/propidium iodide staining, which revealed that treatment with OEE significantly reduced high-glucose-induced apoptosis. These findings implicate OEE as a valuable functional food in protecting pancreatic β-cells against glucotoxicity-induced apoptosis and oxidative stress.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.7
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• pp.949-955
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• 2011

[ ${\beta}$ ]Glucan is a polysaccharide expressed on the cell walls of fungi. It is known that ${\beta}$-glucan is recognized by a family of C-type lectin receptors, dectin-1, which is expressed mainly on myeloid immune cells, including macrophages, neutrophils and dendritic cells. Raw 264.7 cells were treated with ${\beta}$-glucan from Schizophyllum commune. ${\beta}$-Glucan was not cytotoxic up to 400 ${\mu}g$/mL as measured by MTT assay. To measure the activity of macrophages, NO and TNF-${\alpha}$ assays were performed in Raw 264.7 cells. Treatment with ${\beta}$-glucan for 24 hr significantly increased production of NO and TNF-${\alpha}$ compared with control groups (p<0.05), indicating activation of macrophages. To measure inhibition of breast cancer cell proliferation, MTT assay was performed in MDA-MB-231 cells. Cell viability was significantly decreased in the group treated with 400 ${\mu}g$/mL of ${\beta}$-glucan for 48 hr (p<0.05) compared to the control group. However, tumor volume was decreased in the groups administered 200 ${\mu}g$ of ${\beta}$-glucan/mouse compared to the control group. These results indicate that ${\beta}$-glucan inhibits breast cancer cell growth through the induction of apoptosis.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.44 no.1
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• pp.95-101
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• 2018

The epidermis which is stratified by epithelial tissue renewal based on keratinocyte differentiation protects the organism from various environmental insults by forming a physical barrier. Autophagy is a mechanism which mediates lysosomal delivery and degradation of protein aggregates, damaged organelles and intracellular microorganisms. Recent reports have shown that autophagy has critical roles for proper terminal differentiation to stratum corneum via removing metabolic organelles and nuclei. However, whether increasing autophagy can activate epidermal differentiation is unknown. Here, we screened a library of natural single compounds and discovered that betaine specifically increased the LC3 positive cytosolic punctate vesicles and LC3-I to LC3-II conversion in HaCaT human keratinocyte cell line, indicating increased autophagy flux. mTOR pathway, which negatively regulates autophagy, was not affected by betaine treatment, suggesting betaine-induced autophagy through an mTOR-independent pathway. Betaine-induced autophagy was also observed in primary human keratinocyte and skin equivalent. Furthermore, epidermal thickness was increased in skin equivalent under betaine treatment. Overall, our finding suggests that betaine as a novel regulator of autophagy may induce epidermal turnover and improve the skin barrier abnormality of the aged epidermis.

• Korean Journal of Food Science and Technology
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• v.39 no.6
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• pp.701-707
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• 2007

Anti-diabetic effect of Platycodi radix (PR) extract fractions was determined if vitro by investigating insulin-like action, insulin sensitizing action, glucose-stimulated insulin secretion, gene expression related to ${\beta}-cell$ function and mass, and ${\alpha}$-glucoamylase suppressing action. Insulin-like activity was not promoted by the treatment of PR methanol factions in 373-L1 fibroblast. However, treatment with 0, 20 and 100% PR methanol fractions along with 1 ng/mL insulin increased insulin-stimulated glucose uptake in 373-L1 adipocytes. In addition, the treatment of 0% and 100% methanol fractions along with differentiation inducers significantly increased the differentiation of 373-L1 fibroblasts to adipocytes. These fractions may contain insulin sensitizer. The 20%, 80% and 100% methanol fractions enhanced glucose-stimulated insulin secretion in Min6 cells, insulin secreting cell line. This was related to the mechanism to promote glucose sensing and ${\beta}-cell$ proliferation, which was regulated by the induction of IRS-2, glucokinase and PDX-1 genes. As expected, 20, 80 and 100% methanol fractions increased mRNA levels of IRS-2, glucokinase and PDX-1 genes. However, PR fractions did not affect the ${\alpha}-glucoamylase$ activity in vitro. These data suggested that PR extract fractions have anti-diabetic actions through improving insulin sensitization, glucose-stimulated insulin secretion, and ${\beta}-cell$ proliferation. Therefore, PR extracts can be beneficial for anti-diabetic treatment in lean diabetic patients.

• Journal of Nutrition and Health
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• v.51 no.6
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• pp.498-506
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• 2018

Purpose: Lycopene, a carotenoid with anti-oxidant properties, occurs naturally in tomatoes and pink grapefruit. Although the beneficial effects of lycopene on various disorders have been established, little attention has been paid to the possible anti-diabetic effects of lycopene focusing on ${\beta}$-cells. Therefore, this study investigated the potential of lycopene to protect ${\beta}$-cells against apoptosis induced by a cytokine mixture. Methods: For toxicity experiments, the cells were treated with 0.1 ~ 10 nM of lycopene, and the cell viability in INS-1 cells (a rat ${\beta}$-cell line) was measured using a MTT assay. To induce cytokine toxicity, the cells were treated with a cytokine mixture (20 ng/mL of $TNF{\alpha}$ + 20 ng/mL of IL-$1{\beta}$) for 24 h, and the effects of lycopene (0.1 nM) on the cytokine toxicity were measured using the MTT assay. The expression levels of the apoptotic proteins were analyzed by Western blotting, and the level of intracellular reactive oxidative stress (ROS) was monitored using a DCFDA fluorescent probe. The intracellular ATP levels were determined using a luminescence kit, and mRNA expression of the genes coding for anti-oxidative stress response and mitochondrial function were analyzed by quantitative reverse-transcriptase PCR. Results: Exposure of INS-1 cells to 0.1 nM of lycopene increased the cell viability significantly, and protected the cells from cytokine-induced death. Lycopene upregulated the mRNA and protein expression of B-cell lymphoma-2 (Bcl-2) and reduced the expression of the Bcl-2 associated X (Bax) protein. Lycopene inhibited apoptotic signaling via a reduction of the ROS, and this effect correlated with the upregulation of anti-oxidative stress response genes, such as GCLC, NQO1, and HO-1. Lycopene increased the mRNA expression of mitochondrial function-related genes and increased the cellular ATP level. Conclusion: These results suggest that lycopene reduces the level of oxidative stress and improves the mitochondrial function, contributing to the prevention of cytokine-induced ${\beta}$-cell apoptosis. Therefore, lycopene could potentially serve as a preventive and therapeutic agent for the treatment of type 2 diabetes.