二甲双胍调节AMPK/SREBP-1通路及在临床中的应用进展

二甲双胍是临床上常用的降糖药物之一,除了降血糖外,还有多种医学生物价值在不断被发现而备受关注。近年研究表明,二甲双胍通过激活AMPK抑制固醇调节元件结合蛋白-1（SREBP-1）减少脂质合成,在治疗肝脏脂肪变性、改善胰岛素敏感性、预防动脉粥样硬化和心血管功能障碍、肿瘤、多囊卵巢综合征以及新型冠状病毒肺炎的辅助治疗等方面发挥一定作用。因此,本文就二甲双胍通过激活AMPK抑制SREBP-1调控糖脂质代谢的可能机制以及在临床中的应用做一综述。     

STEROL BIOSYNTHESIS BY STRAINS OF SACCHAROMYCES CEREVISIAE IN THE PRESENCE AND ABSENCE OF DISSOLVED OXYGEN

The content of sterols in Saccharomyces cerevisiae which has been harvested after anaerobic growth and then added to a complex nutrient medium, rises rapidly from ca. 1 mg/g dry yeast to ca. 10 mg in the presence of dissolved oxygen. A range of sterols, present principally as sterol esters, is formed during this period. The concentration of free sterols does not rise above 3 mg/g and esters are thought to form a reserve sterol pool. Cyclization of squalene to lanosterol in the presence of oxygen seems not to be markedly affected by oxygen concentration in contrast to demethylation and desaturation reactions on the pathway to ergosterol. When oxygen concentration falls to zero, further metabolism of preformed sterols continues, with the accumulation of episterol and ergosterol and reduction in the concentration of zymosterol and 24(28)-dehydroergosterol. During anaerobic growth a marked hydrolysis of sterol esters occurs and free sterols eventually predominate.     

A new quality parameter in tomato and tomato products: ergosterol

The poor precision of the "percentage of discarded fruits" and "Howard mold count" methods has increased the importance of ergosterol for the microbiological quality evaluation of tomato and tomato products. Ergosterol, a constituent of the cell wall of some important vegetable parasites, such as molds, has been recently recognized as a potential objective parameter useful for the characterization of the quality of processing tomatoes. Thus, 15 mg of ergosterol/kg total solids has been stated as an acceptability maximum limit of tomato products.     

玉米植物甾醇的精制、结构表征及GC-MS分析

以玉米植物甾醇粗品为研究对象,应用响应面分析法,对植物甾醇的精制工艺条件进行研究,结果表明:液料比10∶1,结晶温度1℃,养晶时间3 h,甾醇得率为68.60%,甾醇纯度为95.68%,甾醇得率与理论预测值基本一致。采用红外光谱分析法和电镜扫描法对玉米植物甾醇进行表征。采用气相色谱质谱联用仪分析精制产品中玉米植物甾醇的组成,鉴定出菜油甾醇、豆甾醇和β-谷甾醇3种植物甾醇,质量分数分别为28.57%、6.18%和65.25%。     

芝麻油脱臭馏出物中甾醇的两种提取工艺优化

旨在探索芝麻油脱臭馏出物中植物甾醇的两种提取方法,在单因素试验基础上采用正交试验优化得到溶剂法提取最佳工艺条件为:皂化时间3.5h,皂化温度80℃,加碱量8.5mL/0.5g,使用此优化工艺参数,测得甾醇总含量为8.42%;超临界CO2法提取最佳工艺条件为:CO2流量20L/h,萃取时间3h,萃取压力25 MPa,萃取温度50℃,该条件下甾醇提取率可达73.25%。两种方法从得率上和操作上相比较,超临界CO2萃取法优于溶剂法。     

Sterols of seed oils of Vernonia galamensis,Amaranthus cruentus,Amaranthus caudatus,Amaranthus hybridus and Amaranthus hypochondriacus grown in the humid tropics

Analysis of sterols of seed oils from Vernonia galamensis, Amaranthus cruentus, A caudatus, A hybridus and A hypochondriacus, the last four being exotic breeds planted in the humid tropics of Africa, is presented in this report. Identifiable sterols in all the seed oil samples include campesterol, stigmasterol, ß-sitosterol, Δ⁵-avenasterol and Δ⁷-avenasterol except for Vernonia galamensis where cholesterol was detected (63.61 mg per 100 g oil).     

营养玉米油及其关键精炼工艺技术

介绍了我国玉米油的发展现状,玉米油的营养特性及营养成分,以及在精炼过程中的关键技术。其中：双温双塔分段脱臭技术可以最大限度的减少了反式脂肪酸的形成,控制其含量≤0.3%;低温淡碱脱酸与复合吸附剂低温低用量脱色技术,可以最大限度保留植物甾醇,控制其含量在10 000 mg/kg以上。     

植物油中总甾醇测定前处理方法的研究

通过研究甾醇酯的皂化条件,确立了植物油中总甾醇测定的前处理方法.其重复测定结果的相对标准偏差仅为0.46%,人员之间重复测定结果的相对标准偏差在0.31%-0.58%之间,实验室间结果稳定性也较好,最大的相对标准偏差为6.26%,回收率在95.02%-104.29%范围内,适用于植物油中总甾醇的测定.