基于木质纤维素生物利用的多功能糖苷酶研究进展

木质纤维素是一种重要的可再生资源,多功能糖苷水解酶对于木质纤维素的高效利用具有重要意义。文中总结了近年来针对木质纤维素生物利用的多功能糖苷水解酶的研究现状,对比了多功能糖苷水解酶与纤维小体多酶复合体、传统单一功能糖苷水解酶在结构、催化特性等方面的特点和优势,指出了多功能糖苷水解酶在未来发展中的重要地位和广泛发展前景。     

Immunohistochemical investigation of cotton carpel tissue exposed to xylanolytic hydrolases of Aspergillus flavus

Cotton carpel tissue (35–45 days post-anthesis) that had been treated with a mixture of xylanolytic hydrolases derived from Aspergillus flavus was subjected to immunocytochemical analysis. Microscopic examination of treated tissues revealed severe degradation of the secondary wall structure. Control tissue cells revealed the presence of high concentrations of xylans/arabinoxylans throughout the cell wall, as well as significant concentrations of arabinogalactan proteins in secondary wall structure. Carpel cells treated with a mixture of A. flavus-produced xylanolytic hydrolases showed a much reduced presence of labeling by xylan-specific antibodies on the inner wall surface, suggesting a severe loss of these plant polysaccharides in the secondary wall structure. Carpel exposure to a purified 14 kD endoxylanase from A. flavus also resulted in a severe reduction of xylans from secondary wall structure, although penetration of the tissue was not as dramatic. Arabinogalactan proteins were not as severely affected by the xylanolytic hydrolases. Comparison of control tissue with hydrolase-treated tissue stained with toluidine blue revealed an apparent reduction in wall thickness, supporting the conclusion of secondary wall structure degradation. Interestingly, the pectins could only be detected in the samples treated with xylanolytic enzymes, indicating that the pectins were being masked by xylans. These results are consistent with the conclusion that the xylanolytic hydrolase complex of A. flavus is a critical factor for host cell wall maceration and may represent another important fungal virulence factor, in addition to pectolytic hydrolase activities.     

石榴皮化学成分及生物活性研究进展

目的研究石榴(Punica granatum L.)皮的化学成分及其抗补体活性。 方法通过硅胶柱、Sephadex LH-20、RP-C18反相硅胶等色谱柱分离纯化,运用NMR和MS等波谱学方法鉴定化合物的结构,并采用抗补体经典途径溶血方法,测定石榴皮化学成分的抗补体活性。 结果从石榴皮乙醇提取物的乙酸乙酯和正丁醇部分分离得到14个化合物,包括5个黄酮苷类,即山柰酚-3-O-β-d-吡喃葡萄糖苷(1)、槲皮素-3-O-β-d-吡喃葡萄糖苷(2)、山柰酚-3-O-β-d-吡喃木糖苷(3)、柚皮素-7-O-β-d-吡喃葡萄糖苷(4)和山柰酚-3-O-β-d-芸香糖苷(5),以及9个其他类型化合物,即5-羟甲基糠醛(6)、正丁基-O-β-d-吡喃果糖苷(7)、3, 3′-二甲基鞣花酸-4-O-β-d-吡喃葡萄糖苷(8)、roseoside (9)、3-O-(β-d-吡喃葡萄糖基)-1-(3-甲氧基-4-羟基苯基)-1-丙酮(10)、3-O-(β-d-吡喃葡萄糖基)-1-(3, 5-二甲氧基-4-羟基苯基)-1-丙酮(11)、5-羟甲基呋喃-3-羧酸(12)、(1′R, 3′S, 5′R, 8′S, 2Z, 4E)-dihydrophaseic acid 3′-O-β-d-glucopyranoside (13)和没食子酸(14)。石榴皮乙酸乙酯部分有抗补体活性(100 μg/mL时,抑制率为51.73%)。 结论化合物3、4、7和9~13均为首次从石榴中分离得到,乙酸乙酯部分有抗补体活性,活性成分有待进一步阐明。本研究丰富了石榴的化学成分基础,为进一步开发利用石榴皮的药用价值提供了一定的实验依据。     

Total plant sterols,steryl ferulates and steryl glycosides in milling fractions of wheat and rye

The total plant sterol, steryl ferulate and steryl glycoside contents in wheat and rye milling fractions show that there are significant differences in both sterol content and composition between various milling fractions collected from a commercial mill. Total sterols were analysed by gas chromatography after acid and alkaline hydrolyses. The steryl conjugates were first extracted with acetone, fractionated on solid phase extraction (SPE) cartridges and then analysed individually (steryl glycosides by gas chromatography and steryl ferulates by reverse phase-high performance liquid chromatography with UV detection. Differences in sterol contents of the wheat samples were greater than in the rye samples. The highest total sterol content was found in wheat germ, but surprisingly high sterol contents, that were comparable to bran, were found in some flour fractions. Contents of steryl ferulates were high in the bran fractions contributing up to 17% of total sterols. The variation in the content of steryl glycosides in the samples was lower and contributed less than 10% of total sterols. These results show that much of the bioactive components may be lost when certain flour fractions produced in common flour milling procedures are discarded. However, some of these fractions with significantly high sterol contents could possibly be introduced into milling products used in breadmaking and the food industry without greatly compromising consumer acceptability.     

The influence of exposure to light on the phenolic content of ‘Fuji’ apple

In this study, the influence of changes in fruit lighting on individual and total phenols in ‘Fuji’ apple, as well as color development was studied. Content levels of eight quercetin glycosides, five anthocyanins, two catechins and a hydroxycinnamic acid in the skin of apples were analyzed, using high-performance liquid chromatography, tandem mass spectrometry (HPLC-MS). Total phenol, chlorophyll and carotenoid contents were determined by spectrometry. The purpose of this study was to compare content levels of those compounds in apple skin of fruit grown in different parts of the tree canopy, under and outside of the hail net. Lighting of fruit was measured during the last month before harvest. The lowest values were measured in the inner fruit and higher ones in the outer parts of the canopy, while the highest values were measured in fruit growing at the top of the tree. The hail net had no influence on the decrease of lighting in comparison to the control. Light conditions in the tree canopy influenced lower content levels of quercetin glycosides and most anthocyanins in the fruit skin in the inner part of the tree canopy, whereas fruit from the canopy top contained the highest levels of quercetin glycosides and cyanidin glycosides. Catechin, epicatechin and chlorogenic acid content levels in apple skin were independent of fruit position in the canopy or hail net usage, except for chlorogenic acid, where the content level was higher in cases when the orchard was covered with a hail net. Fruit from the top and outer parts of the canopy had a darker and redder coloration than inner fruit, while no influence of canopy position on chlorophyll and carotenoids was detected. Since quercetin glycosides and cyanidin glycosides are influential in red skin color development, better coloration of fruit from the outer and top canopy was observed. More intensive lighting stimulated a higher content level of flavonoids and, consequently, better coloration, which is an important factor in fruit quality.     

黔产竹节参总黄酮苷的提取与测定方法研究

［目的］探讨黔产竹节参黄酮苷的提取与检测方法。［方法］以80%乙醇为溶剂,研究了黔竹节参黄酮苷的提取方法,并建立了竹节参黄酮苷的测定方法。［结果］黔产竹节参黄酮苷的提取率为0.981 8%,精制黄酮苷的含量为96.2%;采用分光光度法检测黔产竹节参黄酮苷浓度,对照样品回归方程y=-0.003 00＋0.011 01x,r=0.999 30,对照样品的加标回收率为100.36%。［结论］该方法操作简便快速准确,能满足黔产竹节参中总黄酮苷的提取和检测的要求。     

苦杏仁甙的分离与鉴定

从赤峰地区山杏种仁中分离得到一种氰甙,经核磁共振、红外光谱、元素分析鉴定为苦仁甙。提取方法简便、成本低,产品纯度高。     

苦瓜皂甙的提取及含量测定

研究了苦瓜皂甙的提取工艺和测定方法,以提取温度、浸泡时间、乙醇浓度分数为考察因素,通过单因素实验确定了最佳提取条件:乙醇浓度60%,温度70℃,浸泡时间2h,料液比11∶0;通过正交实验及方差分析确定影响提取的主次因素,温度>乙醇浓度>料液比>提取时间;采用分光光度法对苦瓜中皂甙含量进定量分析。     

A new naphthalene glycoside from the roots of Smilax bockii

From the roots of Smilax bockii a new compound, 7-hydroxymethyl-1, 4, 5-trihydroxynaphthalene-4-O-beta-D-xylopyranosyl(1-->6)-beta-D-glucopyranoside, was isolated. The structure of the new compound was elucidated on the basis of spectroscopic methods.     

A new triglucosylated naphthalene glycoside from Aloe vera L.

A new triglucosylated naphthalene derivative, named aloveroside A (1), together with two known anthraquinone dimers and two 6-phenyl-2-pyrone derivatives, was isolated from the Aloe vera ethanolic extracts. The structure of 1 was established as 1-(((4-(1-O-β-D-glucopyranosyl -(1→4)-β-D-xylopyranoside)-hydroxymethyl)-1-hydroxy-8-O-α-L-rhamnopyranoside)naphthalene-2-yl)-ethanone by means of spectroscopic evidences and chemical methods. All these compounds were tested for their BACE inhibitory activity but no significant activities were found.