Modulation of the antioxidant/pro-oxidant balance,cytotoxicity and antiviral actions of grape seed extracts

Grape seed extracts (GSEs) were investigated in yeast cells harbouring defects in their antioxidant system (regarding the cellular growth and growth recovery from H₂O₂ insult). GSEs antioxidant activity was detected in wild-type and mutant strains Δcta1, Δgsh1 and Δoye2glr1, while pro-oxidant activity in Δsod1 cells was seen. Assessment of proliferation of prostate cancer PC3 and HBV-replicating HepG2 2.2.15 cells treated with GSEs has shown higher cytotoxicity of red grape seed extract (RW) than white grape seed extract (WW) subjective to dose and period of administration. No antiviral effect was detected by measuring the secreted virion particles in HepG2 2.2.15 cells treated with GSEs. The GSEs play a dual antioxidant/pro-oxidant role in vivo according with the cellular antioxidant system deficiencies and exhibit cytotoxic properties in PC3 and HepG2 2.2.15 cell lines, but no antiviral action against HBV.     

谷胱甘肽对无机盐的增味特性研究

Kokumi味能赋予食物浓厚感、持续感和复杂感。目前关于kokumi味呈味肽与无机盐之间的增味特性方面的研究还未见报道。文章通过单因素实验与正交实验探究增味度、温度、pH对具有kokumi味的谷胱甘肽与无机盐体系的增味特性的影响,结果显示:谷胱甘肽与NaCl体系在温度为40℃、pH 7.0时的增味强度效果最佳,增味度为20;谷胱甘肽与CaCl₂体系在温度为40℃、pH 6.5时的增味效果最佳,增味度为15;谷胱甘肽与KCl体系在温度为45℃、pH 7.0时的增味效果最佳,增味度为15。该研究成果能为调味品的开发提供新的开发思路和理论依据。     

酿酒酵母生产谷胱甘肽的营养条件研究

通过L9(34)正交实验考查了培养基中的葡萄糖浓度、尿素浓度和磷酸二氢钾浓度对酿酒酵母KH37合成谷胱甘肽的影响。结果表明,葡萄糖浓度为影响谷胱甘肽产量的主要因素,其次是尿素浓度和磷酸二氢钾浓度。最优培养基组成为:35g/L葡萄糖、100mg/L尿素和250mg/L磷酸二氢钾。方差分析表明,葡萄糖浓度对谷胱甘肽产量的影响作用显著,而其他2个因素(尿素和磷酸二氢钾)对谷胱甘肽产量无显著影响。     

产谷胱甘肽酵母菌株培养基优化

目的筛选对谷胱甘肽产量影响显著的碳源和氮源,考察其浓度对产量的影响。方法通过单因素实验和正交试验确定最佳碳源、氮源和无机盐浓度。结果最佳培养基的基本组成：2．5％葡萄糖,1％酵母粉,0．3％硫酸铵,0．03％硫酸镁,1．2g／L磷酸氢二钾和1．8g／L磷酸二氢钾。结论确定了最优培养基组成。     

Effect of the Lycium barbarum polysaccharides administration on blood lipid metabolism and oxidative stress of mice fed high-fat diet in vivo

Epidemiological and experimental studies have suggested that high dietary fat intake of mice is associated with many physically degenerative diseases. Since oxidative stress and abnormal lipid metabolism have been speculated to be critical mechanisms underlying degenerative diseases, we hypothesized that a high-fat (HF) diet might induce oxidative stress or lipid oxidation and subsequently contribute to the high risk of some diseases such as cardiovascular and cerebrovascular ones. To test this hypothesis, male kunming mice were placed on either a HF diet or a normal laboratory diet for 30 consecutive days. This investigation demonstrated that blood fat [low density lipoprotein (LDL), total cholesterol (TC), triacylglycerols (TAG), high density lipoprotein (HDL)], blood sugar (blood glucose and liver glycogen) and oxidative stress (activities of antioxidant enzymes and levels of non-enzymic antioxidants) of mice fed high-fat diet (group II) were significantly increased or decreased (P < 0.05, P < 0.01) when compared with the control group (I). The present study revealed that HF diet induced oxidative stress and provided novel evidence regarding the link between high dietary fat and increased risk of degenerative diseases. The administration of Lycium barbarum polysaccharides did not show any effect on the body weight of the experimental mice, but significantly decreased the levels of LDL, TC, TAG, blood glucose and thiobarbituric acid reactive substances (TBARS) or increased the activities of antioxidant enzymes (P < 0.05, P < 0.01) when compared with mice in HF group (II). These findings were further supported by significantly increased non-enzymic antioxidants levels (P < 0.05, P < 0.01), suggesting that L. barbarum polysaccharides showed a noticeable inhibition against lipid oxidation induced by free radicals caused by HF diet intake (groups III, IV, V) on the basis of their antioxidant activities.     

毕赤酵母合成S-腺苷甲硫氨酸过程谷胱甘肽流量分析与控制

S-腺苷甲硫氨酸(S-adenosyl-L-methionine,SAM)是一种具有广阔应用前景的活性氨基酸,利用毕赤酵母催化合成是SAM主要生产方法,但SAM可被细胞转化为还原型谷胱甘肽(glutathione reduced,GSH),后者可进一步转化为氧化型谷胱甘肽(glutathione oxidized,GSSG)。该研究分析了SAM合成过程中谷胱甘肽总量的动态变化,并基于GSSG/GSH偏移,揭示了胞内氧化还原势与GSH流量变化的相关性。最后添加抗氧化剂维生素C,通过降低胞内SAM→GSH流量及改善细胞活性,进一步提高SAM产率。     

Biosynthesis of poly-gamma-glutamic acid in plants: transient expression of poly-gamma-glutamate synthetase complex in tobacco leaves

Transient expression of genes coding for the poly-gamma-glutamate (gammaPGA) synthetase system (pgs) was investigated in tobacco plants. Three genes of the pgs, pgsA, pgsB and pgsC, were separately placed under the control of the CaMV 35S promoter and introduced into tobacco leaves via Agrobacterium infection. Synthesized gammaPGA in plant tissues was detected immunologically with mouse anti-gammaPGA antiserum which specifically reacts with gammaPGA on a nitrocellulose membrane. Confirmation of gammaPGA biosynthesis in the transient expression analysis in tobacco tissue indicates that subunits of pgs complex were expressed and reassembled in a functional form.     

The methionine precursor dl-2-hydroxy-(4-methylthio)butanoic acid protects intestinal epithelial barrier function

dl-2-hydroxy-(4-methylthio)butanoic acid (HMTBA) is a source of dietary methionine (Met) that is widely used in poultry nutrition. We have previously shown that HMTBA is preferentially diverted to the transsulfuration pathway, which gives antioxidant metabolites such as taurine and glutathione. Therefore, here we hypothesize that this Met source can protect epithelial barrier function in an in vitro model of intestinal inflammation of Caco-2 cells. The results show that HMTBA prevents the increase in paracellular permeability induced by H₂O₂ or tumour necrosis factor-α. This effect can be attributed to the increased production of taurine and reduced glutathione. Similar results were obtained for dl-Met, although the protective role of the amino acid was less pronounced than that of the hydroxy analogue. In conclusion, the diversion to the transsulfuration pathway means that this Met precursor is of greater value than previously thought, due to its capacity to improve intestinal homeostasis and the quality of poultry products destined for human consumption.     

菟丝子醇提液对小鼠脑缺血再灌注损伤的保护作用

目的探讨菟丝子醇提液（AECS）对脑缺血再灌注（I/R）小鼠学习记忆障碍的改善作用,对肝脑组织中相关酶的作用及其作用机制。方法利用超声提取法制备AECS;采用暂时性阻断两侧颈总动脉的方法制备小鼠脑I/R损伤的模型,进行避暗实验,观察AECS对小鼠学习记忆功能的保护作用;生化方法测定肝脑组织中谷胱甘肽过氧化物酶（GSH-Px）活性。结果AECS中、高剂量可明显减少脑I/R小鼠避暗实验中错误次数,延长潜伏期;AECS中、高剂量能不同程度地提高肝、脑组织中GSH-Px活性。结论AECS对脑I/R所致小鼠记忆功能障碍具有保护作用,其作用机制可能为增强肝、脑组织中GSH-Px活性。