弱碱水解丙二酰基型大豆异黄酮的研究

本实验采用碱法将丙二酰基大豆异黄酮水解为葡萄糖苷型大豆异黄酮。通过正交实验得到最佳碱水解条件为:PH=11.0,水解温度65℃,水解时间1h。水解前样品中大豆异黄酮的含量分别是:D:16.12%,G:14.49%,MD:33.62%,MG:35.77%,水解后样品中大豆异黄酮的含量分别是:D:46.86%,G:47.34%,MG:5.80%,MD:nd。     

迎春花叶抑菌活性物研究

采用硅胶柱层析(CC)、薄层层析(TLC)和重结晶等技术,从迎春花叶乙酸乙酯萃取物中分离到一强抑菌活性单体。经理化检测和波谱分析数据鉴定属裂环烯醚萜葡糖苷类(secoiridoid glucosides)的迎春花素(jasminin)。该单体在强酸性环境中不稳定,高温、紫外光处理后抑菌活性稳定,对金黄色葡萄球菌的最小抑菌浓度(MIC)为均为1mg/ml,对痢疾杆菌、大肠杆菌的最小抑菌浓度为0.5mg/ml,对三个受试菌的最小杀菌浓度(MBC)为2mg/ml。     

On the glucoside analysis: Simultaneous determination of free and esterified steryl glucosides in olive oil. Detailed analysis of standards as compulsory first step

This work covers two important gaps in the field of micronutrient databases: herein we describe a short and easy protocol that allows the analysis of both free and esterified steryl gulcosides in olive oil. By utilising accurate quantitative methods we achieve a better understanding of olive oil composition and health promoting properties. The procedure consists of isolating the fraction of interest through solid phase extraction, and using gas chromatography–flame ionisation detection for both identification and quantification of the derivatised species. Additionally, mass-spectrometry detection has been utilised for confirming the identity of the individual esterified steryl glucosides in some cases.     

甜叶菊功能性成分研究进展

甜叶菊含有多种功能性成分,包括糖苷类化合物、黄酮类化合物、绿原酸类等。甜菊糖苷作为甜味剂在食品、医药行业有重要的应用价值,黄酮类和绿原酸类物质也具有抗氧化、抗炎、抗癌等活性,具有开发潜力。本文对这三种物质在甜叶菊中的提取分离应用进行了综述。      

紫斑牡丹籽饼粕单萜苷类成分的分离鉴定

目的:研究紫斑牡丹榨油后的籽饼粕单萜苷类化学成分的分离鉴定,探索油用牡丹籽油制备过程中的副产物——牡丹籽饼粕的研究开发价值。方法:采用硅胶、凝胶柱色谱以及半制备高效液相色谱等技术进行分离纯化,综合运用波谱学方法鉴定化合物的结构。结果:从油用牡丹籽饼粕中共分离的8个单萜苷类化合物,分别鉴定为β-gentiobiosyl-paeoniflorin(1)、白芍苷(2)、氧化白芍苷(3)、牡丹酮-1-O-β-D-吡喃葡萄糖苷(4)、白芍苷R1(5)、paeonifanin(6)、8-O-去苯甲酰白芍苷(7)、牡丹皮苷F(8)。结论:上述8个化合物均为首次从紫斑牡丹榨油后的牡丹籽饼粕中分离得到。结果表明油用牡丹籽饼粕中含有大量的单萜苷类化合物,具有重要的研究开发价值。     

In‐gel detection and study of the role of flavonol 3‐glucosidase in the bitter taste generation in tartary buckwheat

The present study demonstrated that flavonol 3‐glucosidase (f3g) is an important cause of bitter taste generation in tartary buckwheat (Fagopyrum tataricum) flour using the f3g complement test. To screen the f3g deletion line, which must have little bitter taste, an in‐gel method to detect individual f3g isozymes in tartary buckwheat seeds was developed. The f3g isozymes in tartary buckwheat seed were stained using a rutin–copper complex on the native–PAGE gel. This method was able to clearly detect as little as 1.4 ng of individual f3g isozymes within 20 min following electrophoresis. With this method, screening of the f3g deletion line can be conducted efficiently and will result in a better taste in tartary buckwheat flour. Copyright © 2004 Society of Chemical Industry     

Effects of solar ultraviolet radiation and canopy manipulation on the biochemical composition of Sauvignon Blanc grapes

Background and Aims: New Zealand is exposed to relatively high solar ultraviolet (UV) radiation; such high irradiances of UV radiation having the potential to change the biochemical composition of plants. The aim of this study was to investigate the effects of UV radiation and the role of canopy leaves on berry biochemical composition in Vitis vinifera var. Sauvignon Blanc. Sauvignon Blanc is the major grape variety grown in New Zealand. Methods and Results: Leaves were removed from around the fruiting zones of vines and screens that altered UV radiation exposures were placed over the grape bunches. Samples taken throughout development were analysed for changes in total phenolic compounds (including flavonols), amino acids and methoxypyrazines. Total phenolic compounds increased substantially in response to UV‐B exposure and this was reflected in changes taking place within the skins of the berries. Flavonol levels were determined by UV‐B radiation exposure and accumulated to maximum concentrations at veraison, subsequently declining to harvest. UV radiation did not have a significant effect on the majority of amino acids or methoxypyrazine concentrations. The most noticeable change in amino acid and methoxypyrazine accumulation was caused by the presence of leaves over the fruiting zone, retaining these leaves maintained significantly higher concentrations in the berries at harvest. Conclusions: UV‐B radiation determines the composition of flavonols in the skins of grapes. Amino acid and methoxypyrazine concentrations are not predominantly determined by UV‐B, but retention of leaves over the fruiting zone promotes their accumulation in berries. Significance: Canopy manipulations are routinely used commercially in the vineyard to help control vigour and reduce disease pressure. The findings presented here are important for viticulturists to understand how management of the vine leaf canopy can determine the biochemical composition of the grapes and can therefore, ultimately affect wine quality.     

乙二醇葡糖苷的分离纯化

以葡萄糖和乙二醇为原料,以磷酸为催化剂,制备了乙二醇葡糖苷。采用萃取的方法对乙二醇葡糖苷进行初步分离,再用G15交联葡聚糖凝胶进行层析柱分离,以质量分数0.2‰的迭氮化钠溶液做流动相,体积流量为0.9 mL/min,可使乙二醇与乙二醇葡糖苷完全分离,实现除去乙二醇的目的。     

Purification of citrus limonoids and their differential inhibitory effects on human cytochrome P450 enzymes

Recent studies demonstrated that citrus limonoids and flavonoids possess numerous health promoting properties. In the present study, glucosides of limonoids and flavonoids were purified from citrus molasses and limonoid aglycones from citrus seeds. Glucosides were separated on styrene (divinylbenzene), Q‐sepharose resins with increasing concentration of sodium chloride. A pH‐dependent cold precipitation was carried out for the isolation of naringin in large quantity. Major aglycones such as limonin and nomilin were isolated from seeds by direct crystallization and minor limonoids were purified by vacuum liquid chromatography. The structures of the isolated compounds were confirmed by NMR spectra. Individual limonoids were tested for O‐dealkylase and hydroxylase activities of human cytochrome P450 (CYP) isoenzymes such as CYP1A2, CYP1B1, CYP3A4 and CYP19, using ethoxyresorufin, methoxyresorufin and dibenzylfluorescein as substrates. Partial to high inhibition of CYPs was observed in dose‐dependent assays. Significant (P < 0.001) reductions in enzyme activities were observed with purified compounds above 2 µmol. Kinetic analyses indicated that limonin glucoside inhibited CYP19 competitively (IC₅₀, 7.1 µ mol L^?1), whereas Nomilinic acid glucoside inhibited it noncompetitively (IC₅₀, 9.4 µ mol^?1). Nomilinic acid glucoside was the most potent limonoid, with an overall IC₅₀ of < 10 µ mol, for all the enzymes tested. The differential inhibition of CYPs can be ascribed to structural variations of the limonoid nucleus. Limonoid inhibition of key CYPs involved in carcinogenesis supports growing evidence that citrus limonoids act as anticancer agents. Copyright © 2007 Society of Chemical Industry