气介式超声强化西兰花热风干燥过程中硫苷分解代谢途径相关物质的变化

为探究气介式超声对西兰花热风干燥过程中硫苷分解代谢的影响,本文研究了西兰花小花球在气介式超声联合热风干燥（20 kHz,60 ℃,125.2和180.1 W/dm2）过程中的干燥特性以及硫苷、萝卜硫素、抗坏血酸、Fe2+和酚酸含量以及黑芥子酶、体外抗氧化活性的变化规律。结果表明:相比于单独热风干燥,超声处理不仅可以加快干燥进程（125.2和180.1 W/dm2超声处理下干燥时间分别比单独热风干燥缩短11.1%和17.8%）,同时,超声联合热风干燥过程中3-吲哚甲基硫苷含量增加且黑芥子酶活力增强。180.1 W/dm2气介式超声联合热风干燥终点样品中3-吲哚甲基硫苷、萝卜硫素含量和黑芥子酶活力分别比单独热风干燥终点的样品高出10.7%、26.0%和15.2%,Fe2+含量比单独热风干燥终点的样品低8.1%,表明超声处理减少了Fe2+对硫苷酶促降解的干扰,能够促进4-甲基硫氧丁基硫苷降解形成萝卜硫素,但超声处理对西兰花干燥过程中抗坏血酸含量、游离酚酸含量和体外抗氧化活性变化影响不明显。本研究表明气介式超声联合热风干燥既能加快西兰花干燥进程,又能促进4-甲基硫氧丁基硫苷的转化,并对生物活性成分具有一定的保护作用。     

A chemical basis for differential acceptance ofErysimum cheiranthoides by twoPieris species

Wormseed mustard,Erysimum cheiranthoides, is unacceptable as a host for the cabbage butterfly,Pieris rapae. However, it is preferred for oviposition byPieris napi oleracea in the greenhouse. Isolation and identification of the oviposition stimulants toP. napi oleracea were accomplished by C₁₈ open-column chromatography, TLC, ion-exchange chromatography, HPLC, UV, and NMR spectroscopy. Glucoiberin and glucocheirolin were identified as the most active stimulants. The extracted glucoiberin was as stimulatory as glucocheirolin, although its concentration in theErysimum plants was about 10 times lower than that of glucocheirolin. These glucosinolates were only weak stimulants toP. rapae. Furthermore,P. rapae was strongly deterred by the cardenolides, erysimoside and erychroside, fromE. cheiranthoides, andP. napi oleracea was less sensitive to these compounds. No other deterrent toP. napi oleracea was detected in this plant species. The results explain the differential acceptance ofE. cheiranthoides by these twoPieris species.     

菜籽粕脱毒方法及其特点

简要概括了菜籽粕脱毒技术的研究现状,详细介绍了各种脱毒方法的机理及特点等。     

Oviposition stimulants and deterrents regulating differential acceptance ofIberis amara byPieris rapae andP. napi oleracea

Iberis amara (Cruciferae) contains both stimulants and deterrents that are involved in regulating oviposition byPieris rapae andP. napi oleracea. The most active deterrents toP. rapae isolated from butanol extracts of the plant were found to be 2-O--d-glucosyl cucurbitacin I and 2-O--d-glucosyl cucurbitacin E. However,P. napi oleracea was behaviorally insensitive to these compounds and was only weakly deterred by other individual fractions of the butanol extract. Stimulant activity of the postbutanol water extract ofI. amara was associated with glucosinolates. The most abundant of these was identified as sinigrin, and a relatively minor component was shown to be glucoiberin. The isolated sinigrin was more stimulatory toP. rapae than was the glucoiberin-containing fraction, butP. napi oleracea was stimulated as strongly by the glucoiberin fraction, even though the concentration of this compound was much lower. The contrasting responses of the twoPieris species to the deterrents and stimulants inI. amara can explain the differential acceptance of the plant by these butterflies.     

The Cellular and Subcellular Organization of the Glucosinolate–Myrosinase System against Herbivores and Pathogens

Glucosinolates are an important class of secondary metabolites in Brassicales plants with a critical role in chemical defense. Glucosinolates are chemically inactive but can be hydrolyzed by myrosinases to produce a range of chemically active compounds toxic to herbivores and pathogens, thereby constituting the glucosinolate–myrosinase defense system or the mustard oil bomb. During the evolution, Brassicales plants have developed not only complex biosynthetic pathways for production of a large number of glucosinolate structures but also different classes of myrosinases that differ in catalytic mechanisms and substrate specificity. Studies over the past several decades have made important progress in the understanding of the cellular and subcellular organization of the glucosinolate–myrosinase system for rapid and timely detonation of the mustard oil bomb upon tissue damage after herbivore feeding and pathogen infection. Progress has also been made in understanding the mechanisms that herbivores and pathogens have evolved to counter the mustard oil bomb. In this review, we summarize our current understanding of the function and organization of the glucosinolate–myrosinase system in Brassicales plants and discuss both the progresses and future challenges in addressing this complex defense system as an excellent model for analyzing plant chemical defense.     

Sulfur-containing metabolites in radishes. Further exploration of glucoraphenin desulfation

Glucoraphenin (GRE), found in radishes, holds the unique structural specificity of a Michael acceptor vinyl sulfoxide site. For this reason, desulfo-GRE resulting from enzymatic desulfation is converted into thioimidate N-oxides. Under longer reaction times, a new sulfur-containing compound was isolated and characterized as a cyclic thiohydroximate.     

Biological activity of the shrubBoscia senegalensis (PERS.) LAM. ex Poir. (Capparaceae) on stored grain insects

Biological activity of leaves, fruits and extract of the African shrubBoscia senegalensis (PERS.) LAM. ex Poir. was evaluated against five stored-grain insects. When added to cowpeas at 2–4% (w/w), fresh ground fruits and leaves caused 80–100% mortality inCallosobruchus maculants (F.) adults and significantly reduced both emergence and damage of the F₁ progeny. Acetone fruit extract exhibited a potent fumigant effect onProstephanus truncatus Horn, C.maculatus, andSitotroga cerealella OLIV.; with LT₅₀ values of 3.8, 2.3, and below 1.5 hr, respectively. LC₅₀ determination forB. senegalensis fruits and leaves as well as pure methylisothiocyanate (MITC) onTribolium castaneum HERBST,Sitophilus zeamais MOTSCH. andC. maculatus showed a differential response of the insects to plant parts or MITC. Quantitative dosage ofBoscia active components and LC₅₀ values obtained for the plant tissues, compared to those of pure molecules, indicate that the biological activity ofB. senegalensis is due to the liberation of MITC from a glucosinolate precursor glucocapparin contained inBoscia fruits and leaves.     

7 种十字花科种子中黑芥子酶降解油菜籽饼粕中硫苷的产物比较分析

比较7 种十字花科植物种子中的黑芥子酶的活性,利用气相色谱-质谱法（gas chromatography-massspectrometry,GC-MS）分别测定这7 种黑芥子酶降解油菜籽饼粕中硫代葡萄糖苷（简称硫苷）的产物组分和相对含量。结果表明：7 种来源的黑芥子酶比活力存在差异（P＜0.05）,比活力由高到低依次为西兰花籽黑芥子酶（broccoli seeds myrosinase,BSm）、油菜籽黑芥子酶（rape seeds myrosinase,RPSm）、白菜籽黑芥子酶（whitecabbage seeds myrosinase,WCSm）、萝卜籽黑芥子酶（radish seeds myrosinase,RDSm）、芥蓝籽黑芥子酶（kaleseeds myrosinase,KSm）、甘蓝籽黑芥子酶（cabbage seeds myrosinase,CSm）和芥菜籽黑芥子酶（mustard seedsmyrosinase,MSm）。GC-MS比较分析7 种黑芥子酶降解油菜籽饼粕中硫苷的产物发现,RPSm降解产物有6 种,即1-丁烯基-4-异硫氰酸酯、烯丙基异硫氰酸酯、2-苯乙基异硫氰酸酯、苯丙腈、致甲状腺肿素和2,1-苯并异恶唑。CSm降解产物中1-丁烯基-4-异硫氰酸酯含量最高（33.22%）,RPSm次之,含量为32.20%,而MSm降解产物中未检测到。WCSm、KSm、MSm和CSm降解产物中检测到新组分丁基异硫氰酸酯。与RPSm降解产物相比,其他6 种黑芥子酶降解产物中恶唑类及腈类物质种类增多,有4 种恶唑类和3 种腈类,但降解产物中未检测到2,1-苯并恶唑。不同来源的黑芥子酶在相同环境下降解油菜籽饼粕中的硫苷的产物种类和相对含量存在明显差异,虽RPSm活性低于BSm,但其降解产物中恶唑类及腈类种类最少,含量最低,是较好的降解油菜籽饼粕中硫苷的酶源。     

高产酸菌株的筛选、鉴定及其混菌发酵对菜籽粕营养价值的影响

本实验从泡菜水中分离得到一株高产有机酸的乳杆菌,并将该菌株与黑曲霉混合后结合两步法处理菜籽粕,同时降解菜籽粕中的硫苷和大分子蛋白并提高总酸含量,从而提高菜籽粕的营养价值。该株乳杆菌经16S rDNA鉴定,确定为类食品乳杆菌(Lactobacillus paralimentarius)。将该菌株与黑曲霉混合后结合两步法处理菜籽粕后,其营养价值得到了一定提高,与空白对照和单菌发酵相比,总酸含量分别提高了640.54%、160.95%和112.40%;酸溶蛋白和氨基酸态含量分别从2.87%和0.12%提高到19.08%和1.23%;硫苷含量从23.09 μmol/g下降到12.65 μmol/g。结果表明,混菌发酵结合两步法有利于改善菜籽粕的营养价值,对扩大菜籽粕的利用奠定了基础。