高效液相色谱-串联质谱法测定蜂蜜中的甲基乙二醛

目的建立一种蜂蜜中甲基乙二醛的高效液相色谱-串联质谱法的测定方法。方法采用高效液相色谱-串联质谱法测定蜂蜜中的甲基乙二醛,蜂蜜样品直接用水提取,2,3-二氨基萘为衍生化试剂,常温下避光反应8 h以上,以0.1%甲酸水-乙腈为流动相,色谱柱分离,通过质谱电喷雾离子源,正离子模式进行定性和定量分析。结果甲基乙二醛的线性范围为0.05~1.0μg/m L,相关系数0.999以上,线性良好,检出限为0.2 mg/kg,定量限为0.5 mg/kg。回收率92.4%~97.5%之间,相对标准偏差(relative standard deviation,RSD)均小于1.3%。结论该方法的精密度、回收率均满足要求,适用于大批量样品的快速检测。     

Methylglyoxal: A newly detected and potentially harmful metabolite in the blood of ketotic dairy cows

Ketosis causes serious economic losses for the modern dairy industry because it is a highly prevalent metabolic disease among cows in high-producing herds during the transition period. Due to some striking similarities between diabetes in humans and ketosis in dairy cows, there is potential for the use of methylglyoxal (MGO)—commonly used in human diabetics—as a biomarker in dairy cattle. However, currently no data are available about the presence of MGO in the serum of dairy cattle or about the characteristics of its production or its potential contribution in the pathogenesis of ketosis. To determine the potential origin and pathway of formation of MGO, cows in different metabolic conditions [i.e., non-subclinically ketotic dairy cows in early lactation (n = 7), subclinically ketotic dairy cows in early lactation (n = 8), overconditioned dry cows (BCS >4.25, n = 6), and nonlactating heifers (n = 6)] were selected. Serum MGO concentrations were determined and correlated with indicators of the glucose and lipid metabolism and with haptoglobin (Hp) as an inflammatory marker. The serum MGO concentrations in subclinically ketotic cows (712.60 ± 278.77 nmol/L) were significantly greater than in nonlactating heifers (113.35 ± 38.90 nmol/L), overconditioned dry cows (259.71 ± 117.97 nmol/L), and non-subclinically ketotic cows (347.83 ± 63.56 nmol/L). In serum of lactating cows, concentrations of glucose and fructosamine were lower than in heifers and were negatively correlated with MGO concentrations. Even so, concentrations of metabolic and inflammatory markers such as dihydroxyacetone phosphate, nonesterified fatty acids, β-hydroxybutyrate, acetone, and Hp were remarkably higher in subclinically ketotic cows compared with nonlactating heifers; these metabolites were also positively correlated with MGO. In human diabetics elevated MGO concentrations are stated to originate from both hyperglycemia and the enhanced lipid metabolism, whereas higher MGO concentrations in subclinically ketotic cows were not associated with hyperglycemia. Therefore, our data suggest MGO in dairy cows to be a metabolite produced from the metabolization of acetone within the lipid metabolization pathway and from the metabolization of dihydroxyacetone phosphate. Furthermore, the highly positive correlation between MGO and Hp suggests that this reactive compound might be involved in the proinflammatory state of subclinical ketosis in dairy cows. However, more research is needed to determine the potential use of MGO as a biomarker for metabolic failure in dairy cows.     

食品中甲基乙二醛的来源、毒性及其清除剂研究进展

生物体内存在多种活性羰基化合物(reactive carbonyl species,RCS),其中甲基乙二醛(methylglyoxal,MG)是人体内最主要的RCS,它是机体内源性代谢产物,也能在食品加工和贮藏过程中产生,尤其在含糖量高的焙烤食品和加入高果糖玉米糖浆的碳酸饮料中含量较高。除了具有直接的细胞毒性,MG也参与体内蛋白质和核酸的糖化反应,引起羰基应激,诱发组织病理损伤,加剧慢性退行性疾病的恶性发展。本文概述了食品加工中MG的产生、健康危害及其清除等方面的国内外研究进展,为清除MG功能食品的研发提供理论依据。     

1,2-丙二醇空气选择氧化合成α-羟基丙酮和丙酮醛

采用电解银催化剂,选择催化氧化1,2-丙二醇联产α-羟基丙酮和丙酮醛。研究了反应条件对产物组成的影响。实验结果表明,以电解银催化氧化1,2-丙二醇可以同时得到α-羟基丙酮和丙酮醛,当温度为360℃,氧醇比为0.25,液时空速为8.73h-1时,单程转化率36%,它们的选择性之和接近100%。氧醇比是选择性氧化合成α-羟基丙酮和丙酮醛的关键因素。     

Methylglyoxal Content in Drinking Coffee as a Cytotoxic Factor

Abstract: A causal relationship between metabolic syndrome and methylglyoxal (MG) has been suggested. Consumption of coffee and other types of beverages has been known to produce MG, thus resulting in both nutritional and health concerns. The purpose of this study was to determine the ideal combination of coffee, cream, and sugar in order to minimize MG consumption. Four types of black coffee were tested: espresso, bold, mild, and a decaffeinated mild roast. Sugar and/or cream were added to the coffee samples to test whether MG levels were altered. Using high-performance liquid chromatography, the concentration of MG in various coffee samples was determined. The espresso coffee sample was found to contain the highest level of MG at 230.9 μM. The bold coffee roast had the 2nd highest amount of MG, followed by the mild and decaffeinated varieties. Adding cream to bold coffee significantly reduced its MG level in comparison to the coffee sample without cream. On the other hand, the addition of sugar to the bold coffee did not further increase the MG level in the samples. The cellular damaging effect of MG was shown as there were decreased numbers of cultured HEK-293 cells after 24 h of MG treatment (100 and 300 μM), which is consistent with an increased cell apoptosis induced by MG treatment (100 and 300 μM). Due to the overconsumption of exogenous MG, drinking an excess of any type of coffee poses health risks.     

2,5-二甲基-4-羟基-3(2H)-呋喃酮的合成研究

天然产物2,5-二甲基-4-羟基-3(2H)-呋喃酮在香料工业中占有重要地位。今采用作者提出的化学反应路径选择因子对呋喃酮的合成方法进行计算比较,确定了以丙酮醛为原料,通过偶联反应合成中间体苏式3,4-二羟基-2,5-己二酮,再由成环反应制备产物呋喃酮的合成路线。考察了各个因素对偶联反应、成环反应的影响,得出较为合适的条件。并针对文献中呋喃酮分离条件苛刻、难工业化的缺点,摸索得到了较简便的呋喃酮的分离提纯方法,有利于实现呋喃酮的工业化生产。