• Journal of Microbiology and Biotechnology
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• 제29권6호
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• pp.905-912
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• 2019

Bioethanol has attracted much attention in recent decades as a sustainable and environmentally friendly alternative energy source. In this study, we compared the production of bioethanol by Candida molischiana and Saccharomyces cerevisiae at different initial concentrations of cellobiose and glucose. The results showed that C. molischiana can utilize both glucose and cellobiose, whereas S. cerevisiae can only utilize glucose. The ethanol yields were 43-51% from different initial concentrations of carbon source. In addition, different concentrations of microcrystalline cellulose (Avicel) were directly converted to ethanol by a combination of Trichoderma reesei and two yeasts. Cellulose was first hydrolyzed by a fully enzymatic saccharification process using T. reesei cellulases, and the reducing sugars and glucose produced during the process were further used as carbon source for bioethanol production by C. molischiana or S. cerevisiae. Sequential culture of T. reesei and two yeasts revealed that C. molischiana was more efficient for bioconversion of sugars to ethanol than S. cerevisiae. When 20 g/l Avicel was used as a carbon source, the maximum reducing sugar, glucose, and ethanol yields were 42%, 26%, and 20%, respectively. The maximum concentrations of reducing sugar, glucose, and ethanol were 10.9, 8.57, and 5.95 g/l, respectively, at 120 h by the combination of T. reesei and C. molischiana from 50 g/l Avicel.

• Biomolecules & Therapeutics
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• 제5권4호
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• pp.364-368
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• 1997

Onion (Allium cepa Linn) has been reported to have hypoglycemic activity in human and several animal models. In the present study, we performed intraperitoneal glucose tolerance test (IPGTT) in young (1.5mo) and aged (5 mo) rats treated with onion in order to determine whether aging can influence on the anti-hy-perglycemic effect of onion. In addition, we investigated the hypoglycemic effect of onion in streptozotocin- induced diabetic rats treated with aqueous extracts of onion (500 mg/kg, i.p., daily) for 4 weeks. Blood glucose level was determined in fasted and fed rats by using a glucometer (Johnson & Johnson). In glucose tolerance test, blood glucose level was maximally increased 15 min after glucose load (2 g/kg, i.p.), and recovered to the basal level 3 hr after glucose challenge in young and old rats. The maximum blood glucose levels of young and aged rat were 184$\pm$7.49 and 225.2$\pm$ 12.55 mg/dl, respectively. A single i.p. injection of aqueous extract of onion (1 g/kg) 30 min before glucose challenge significantly decreased blood glucose levels at 15, 30, 60, 90 min after glucose load in aged rats, while the administration of onion did not show any significant effect in young rats. In onion-treated diabetic rats, significant hypoglycemic effect (p<0.05) was observed, and the effect was greater in fasted rats than in fed. In conclusion, these results suggest that anti-hyperlycemic effect of onion can be changed by age and fasting.

• 대한수의학회지
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• 제44권4호
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• pp.497-505
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• 2004

The proliferation of mesangial cells has been associated with the development of diabetic nephropathy. The cell proliferation has been regulated by diverse growth factors. Among them, insulin like growth factors(IGFs) are also involved in the pathogenesis of diabetic nephropathy. However, it is not yet known about the effect of high glucose on IGF-I and IGF-II secretion and the relationship between high glucose-induced secretion of IGFs and PKC or oxidative stress in the mesangial cells. Thus, we examined the mechanisms by which high glucose regulates secretion of IGFs in mesangial cells. High glucose(25 mM) increased IGF-I and IGF-II secretion. High glucose-induced increase of IGF-I and IGF-II secretion were blocked by taurine($2{\times}10^{-3}$ M), N-acetyl cystein(NAC, $10^{-5}M$), or GSH($10^{-5}M$) (antioxidants), suggesting the role of oxidative stress. High glucose-induced secretion of IGF-I and IGF-II were blocked by H-7, staurosporine, and bisindolylmaleimide I(protein kinase C inhibitors). On the other hand, high glucose also increased lipid peroxide (LPO) formation in a dose dependent manner. In addition, high glucoseinduced stimulation of LPO formation was blocked by PKC inhibitors. These results suggest that PKC is responsible for the increase of oxidative stress in the action of high glucose-induced secretion of IGF-I and IGF-II in mesangial cells. In conclusion, high glucose stimulates IGF-I and IGF-II secretion via PKCoxidative stress signal pathways in mesangial cells.

• 생명과학회지
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• 제17권5호
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• pp.687-693
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• 2007

사람의 섬유아세포인 GM10을 사용하여 glucose의 배양조건에 다른 물질대사 및 IGFBP-3 발현을 살펴본 결과, glucose 농도에 따른 glucose 소비와 triglyceride 축적 수준은 고농도 glucose 배양 조건에서 증가한 반면, 총 단백질 함량은 고농도 glucose배양 조건에서 시간의 경과에 따라 감소하였다. 또한 고농도 glucose 배양 조건에서 5일 동안 배양한 세포 배양액내의 유리아미노산 함량은 저농도보다 고농도 glucose 배양 조건에서 높게 나타났다. IGFBP-3 단백질 수준과 mRNA수준은 저농도 glucose배양 조건에서 증가하였으나, IGFBP-3 단백질 분해효소에 따른 영향은 없었다. 이상의 결과에서 glucose 배양조건에 따른 물질대사는 부분적으로 세포를 이용한 당뇨병 모델 실험에서 in vivo와 같은 결과를 얻지 못하였지만, IGFs와 같은 세포 성장인자에 대한 연구를 통해 세포수준의 당뇨병 모델화가 가능하다고 여겨진다.

• 대한의생명과학회지
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• 제7권4호
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• pp.161-166
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• 2001

Most mammalian cells take up glucose by passive transport proteins in the plasma membranes. The best known of these proteins is the human erythrocyte glucose transporter, GLUT1. High levels of heterologous expression far the transporter are necessary for the investigation of its three-dimensional structure by crystallization. To achieve this, the baculovirus expression system has become popular choice. However, Spodoptera frugiperda Clone 9 (Sf9) cells, which are commonly employed as the host permissive cell line to support baculovirus replication and protein synthesis, grow well on TC-100 medium that contains 0.1% D-glucose as the major carbon source, suggesting the presence of endogenous glucose transporters. Furthermore, very little is known of the endogenous transporters properties of Sf9 cells. Therefore, human GLUT1 antibodies would play an important role for characterization of the GLUT1 expressed in insect cell. However, the successful use of such antibodies for characterization of GLUT1 expression m insect cells relies upon their specificity for the human protein and lack of cross-reaction with endogenous transporters. It is therefore important to determine the potential cross-reactivity of the antibodies with the endogenous insect cell glucose transporters. In the present study, the potential cross-reactivity of the human GLUT1 antibodies with the endogenous insect cell glucose transporters was examined by Western blotting. Neither the antibodies against intact GLUT1 nor those against the C-terminus labelled any band migrating in the region expected fur a protein of M$_r$ comparable to GLUT1, whereas these antibodies specifically recognized the human GLUT1. Specificity of the human GLUT1 antibodies tested was also shown by cross-reaction with the GLUT1 expressed in insect cells. In addition, the insect cell glucose transporter was found to have very low affinity for cytochalasin B, a potent inhibitor of human erythrocyte glucose transporter.

• 대한한의학회지
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• 제31권2호
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• pp.1-18
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• 2010

Objective: The water extract of Chilgi-tang (CGT) has been traditionally used in treatment of heart diseases caused by stress in Oriental Medicine. However, little is known about the mechanism by which CGT rescues neuronal cells from injury damage. Therefore, this study was designed to evaluate the protective effects of CGT on Neuro-2A cells by glucose deprivation-induced cell death. Methods: We investigated how cell death induced by glucose deprivation was associated with increased reactive oxygen species (ROS) generation. Result: The CGT treatment prior to glucose deprivation insult significantly reduced the number of cell deaths and the glucose deprivation-induced increase in ROS. Nitric oxide (NO) was also attenuated by CGT treatment. In addition, we demonstrated that the anti-cell death effect of CGT was blocked by heme oxygenase-1 (HO-1) activation. Finally, pretreatment of cells with a hemin, HO-1 inducer, reduced glucose deprivation-induced cell death. In contrast, pretreatment of cells with a ZnPP, HO-1 activity inhibitor, attenuated CGT-induced inhibition of cell death. Conclusions: These findings indicate that ROS plays an important role in glucose deprivation-induced cell death and that CGT may prevent glucose deprivation-induced cell death by inhibiting the ROS generation through HO-1 activation in Neuro-2A cells.

• Nutritional Sciences
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• 제9권1호
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• pp.3-8
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• 2006

Functional damage to microvascular endothelial cells by hyperglycemia is thought to be one of the critical risk factor.; in the impaired wound healing seen with diabetes mellitus. It is also thought that oxidative stress plays a significant role in this endothelial cell dysfunction. The present study examined the differential effects of flavonoids on endothelial cell dysfunction under high glucose conditions. Human endothelial cells exposed to 30 mmol/L glucose for 7 d were pre-treated with various flavonoids and pulse-treated with 0.2 mmol/L $H_2O_2$ for 30 min. High glucose markedly decreased cell viability with elevated oxidant generation and nuclear condensation. $H_2O_2$ insult exacerbated endothelial cytotoxicity due to chronic exposure to high glucose. (-)Epigallocatechin gallate and quercetin improved glucose-induced cell damage with the disappearnnce of apoptotic bodies, whereas apigenin intensified the glucose cytotoxicity. In addition, cell viability data revealed that these flavonoids of (-)epigallocatechin gallate and quercetin substantially attenuated both high glucose- and $H_2O_2$- induced dual endothelial damage. These results suggest that (-)epigallocatechin gallate and quercetin may be beneficial agents for improving endothelial cell dysfunction induced by high glucose and may prevent or reduce the development of diabetic vascular complications.

• 한국미생물·생명공학회지
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• 제24권4호
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• pp.385-392
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• 1996

Bacillus stearotheymophilus, a potent xylanolytic bacterium isolated from soil, was tested for the strain's strategies of pentose utilization and the evidence of substrate preferences. The strain metabolized glucose, xylose, ribose, maltose, cellobiose, sucrose, arabinose and xylitol. The efficacy of the sugars as a carbon and energy source in this strain was of the order named above. The organism, however, could not grow on glycerol as a sole growth substrate. During cultivation on a mixture of glucose and xylose or arabinose, the major hydrolytic products of xylan, B. stearothermophilus displayed classical diauxic growth in which glucose was utilized during the first phase. On the other hand, the pentose utilization was prevented immediately upon addition of glucose. Cellobiose was preferred over xylose or arabinose. In contrast, maltose and pentose were co-utilized, and also no preference on between xylose and arabinose. Enzymatic studies indicated that B. stearothermophilus possessed constitutive hexokinase, a key enzyme of the glucose metabolic system. While, the production of $^{D}$-xylose isomerase, $^{D}$-xylulokinase and $^{D}$-arabinose isomerase essential for pentose phosphate pathway were induced by xylose, xylan, and xylitol but repressed by glucose. Taken together, the results suggested that the sequential utilization of B. stearothermophilus would be mediated by catabolite regulatory mechanisms such as catabolite inhibition or inducer exclusion.

• Journal of Microbiology and Biotechnology
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• 제14권4호
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• pp.665-672
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• 2004

D-Ribose is a five-carbon sugar used for the commercial synthesis of riboflavin, antiviral agents, and flavor enhancers. Batch fermentations with transketolase-deficient B. subtilis JY1 were carried out to optimize the production of D-ribose from xylose. The best results for the fermentation were obtained with a temperature of $37^{\circ}C$ and an initial pH of 7.0. Among various sugars and sugar alcohols tested, glucose and sucrose were found to be the most effective for both cell growth and D-ribose production. The addition of 15 g/l xylose and 15 g/l glucose improved the fermentation performance, presumably due to the adequate supply of ATP in the xylose metabolism from D-xylulose to D-xylulose-5-phosphate. A batch culture in a 3.7-1 jar fermentor with 14.9 g/l xylose and 13.1 g/l glucose resulted in 10.1 g/l D-ribose concentration with a yield of 0.62 g D-ribose/g sugar consumed, and 0.25 g/l-h of productivity. Furthermore, the sugar utilization profile, indicating the simultaneous consumption of xylose and glucose, and respiratory parameters for the glucose and sucrose media suggested that the transketolase-deficient B. subtilis JY1 lost the glucose-specific enzyme II of the phosphoenolpyruvate transferase system.

• Applied Microscopy
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• 제46권3호
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• pp.140-149
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• 2016

This study intended to compare the effects of the sugar-Omija extract tea (SO) and LuoHanGuo-Omija extract tea (LO) to blood glucose levels and metabolism among streptozotocin (STZ)-induced diabetic mice and to prove the positive effects of LuoHanGuo extract as a sugar substitute. According to the results, the rate of blood glucose increase and the blood glucose level was reduced, and the weight was increased. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), triglyceride, low density lipoprotein cholesterol, and total cholesterol was decreased, and albumin, total protein, and high density lipoprotein cholesterol (HDL-C) was increased in the STZ/LO group as compared to the STZ group. Compared to the STZ/SO group, the rate of blood glucose increase and glucose tolerance was decreased. AST, ALT, and total cholesterol was decreased, and HDL-C level was high. In conclusion, the LO displayed hypoglycemic effect, prevented weight loss caused by diabetes, recovered liver function, and improved lipid metabolism. In addition, such positive effects were obviously shown during comparison with the experimental group treated with the SO. Therefore, the LO were considered as favorable food supplements that can be safely taken by persons with diabetes, obesity, hypertension, and heart disease; they have to control their sugar intake as well as their diet.