冷柱头程序升温进样-气相色谱/质谱法研究新鲜大蒜中的有机硫化合物

采用冷溶剂提取新鲜大蒜中的有机硫化合物,结合冷柱头程序升温进样,对大蒜原始组分进行了气相色谱/质谱分析 。该法实现了从提取到色谱分离的“冷过程”,因而可以准确地鉴定大蒜提取液在热分解前的原始组分。分析结果表明, 在大蒜提取液中含有3-乙烯基-1,2-二硫杂-5-环己烯及其异构体2-乙烯基-1,3-二硫杂-4-环己烯两种主要组分以及少量 的S-甲基甲烷硫代亚磺酸酯、二烯丙基二硫醚、二烯丙基三硫醚。对大蒜的冷溶剂提取液和水蒸气蒸馏提取的大蒜油中 的有机硫化合物进行了比较,对一些主要有机硫化合物的形成进行了初步探讨。     

α-氨基膦酸酯衍生物的合成及其表征

合成了一系列N端含有均三唑并噻二唑的α-氨基膦酸酯衍生物, 其结构经过红外、核磁共振氢谱、磷谱、质谱和高分辨质谱等确证.     

新型富勒烯衍生物的激光质谱结构表征

对3种电化学方法合成的新型结构富勒烯衍生物进行了激光质谱表征,确认了1,2加成以及[5,6]开环富勒烯衍生物结构.质谱结果发现了富勒烯以及富勒烯衍生物与氧的结合峰,核磁共振结果进一步证明了富勒烯衍生物的结构,为含有C60结构衍生物的研究提供了有力的表征手段.     

气相色谱-质谱结合准确质量测定快速鉴定合成大麻素

采用气相色谱-质谱（GC-MS）结合准确质量测定方法,利用保留指数、特征碎片丰度以及高分辨准确质量数据信息,快速鉴定样品中的合成大麻素组分。建立了JWH-018、JWH-073等12种合成大麻素标准物质的分析信息数据库,检测限达到了2.5~30 ng/mL,并成功利用该方法对未知样品进行了检测,确认样品中含有“JWH-081和JWH-018”合成大麻素组分。结果表明方法可以满足合成大麻素快速鉴定的要求。     

含有28个氨基酸的复杂多肽的串级质谱全序列分析研究

利用MALDI-TOF/TOF MS和ESI-MS/MS对一种含有多达28个氨基酸的复杂合成多肽成功进行了全序列测定. 通过调节激光强度、碰撞诱导解离(CID)能量等质谱参数以及依据不同序列分析软件, 获得了涵盖所有b型和y型碎片离子的串级质谱图. 结果显示这种方法可以有效地解决de novo测序方法遇到的谱峰过于复杂导致运算死机等问题. 通过讨论如何对含有超过20个氨基酸片断的多肽进行合格串级质谱实验, 为蛋白质组学肽段序列测定提供了新的方法和思路.     

液相色谱-质谱联用技术分析固相合成胸腺五肽及其副产物

利用反相高效液相色谱(RP-HPLC)与电喷雾质谱(ESI-MS/MS)联用技术,分析用芴甲氧羰基(Fmoc)固相合成方法在WANG树脂上手工合成的胸腺五肽(H2N-Arg-Lys-Asp-Val-Tyr-COOH)粗产物,RP-HPLC结果显示:合成粗产物含有一个主要成分,三个次要成分和多个微量成分;与之联用的电喷雾质谱同步得出相应的某些信息,可对各成分的结构进行分析。结果证明,粗产物中的主成分即为目标五肽,另外几个主要副产物为五肽合成过程中去保护未完全的副产物。     

N-(1,3,2-二氧杂环己烷磷酸酯-2-取代亚甲基)硫代磷酰胺的合成和ESI质谱研究

本文合成了N-(1,3,2-二氧杂环己烷磷酸酯-2-取代亚甲基)硫代磷酰胺，利用核磁共振谱、阳离子ESI质谱和ESI多级质谱鉴定了化合物的结构，对质谱的碎裂规律进行了解释，结果显示ESI多级质谱可以用于N-(1,3,2-二氧杂环己烷磷酸酯-2-取代亚甲基)硫代磷酰胺的结构解析。     

T肽的合成:合成方法的比较研究

本文用Fmoc-及Boc-固相多肽合成法合成了T肽, 结果表明BOC法得率略高于Fmoc法, 但其纯度没有Fmoc法好, 在两种合成T肽方法中, 均得到一个副产物, 经质谱分析证明, 在BOC法中的副产物是侧链仍含有一个苄基保护的T肽; 在Fmoc法中的副产物是侧链仍含有一个叔丁基保护的T肽。     

大蒜油环糊精包合物的制备

制备并鉴定温江大蒜油环糊精包合物。以大蒜油的平均利用率和包合物产率为指标,通过正交实验考查大蒜油与环糊精的投料比、包合温度、包合时间对包合工艺的影响,得出最佳包合工艺:投料比1∶8、包合温度60℃、包合时间2 h,此时挥发油的平均利用率为62.3%,包合物收率为72.1%。使用薄层色谱法对包合物进行鉴定,结果显示大蒜油与环糊精包合后,没有显示与大蒜油有相同的斑点,而大蒜油与环糊精的混合物有相同斑点。     

超高效液相色谱-高分辨质谱法检验4种酰胺类合成大麻素同分异构体

同分异构现象在合成大麻素中普遍存在，因其结构与性质上的差异并不显著，当同时存在时分离鉴定较为困难，为公安实践中合成大麻素的检验鉴定带来了一定的挑战。本研究利用超高效液相色谱-高分辨质谱技术(UHPLC-HRMS)建立了5F-EMB-PICA与5F-MDMB-PICA、ADB-BINACA与AB-PINACA这2对酰胺类合成大麻素同分异构体的检验方法。选用Hypersil GOLD C₁₈色谱柱(100 mm×2.1 mm, 1.9μm)进行UHPLC分离，以含0.1%甲酸的甲醇溶液和含10 mmol/L甲酸铵的0.1%甲酸水溶液为流动相进行梯度洗脱。高分辨质谱采用一级质谱全扫描/数据依赖二级质谱扫描(Full MS/dd-MS²)进行检验。结果表明，采用上述仪器条件，能够实现4种合成大麻素同分异构体的分离分析，5F-EMB-PICA和5F-MDMB-PICA的分离度为2.06, ADB-BINACA和AB-PINACA的分离度为1.22,均达到了有效分离的目的。研究进一步开展了方法学指标考察，5F-EMB-PICA、5F-MDMB-PICA、...     

选择离子流动管质谱法测定大蒜酶解液顶空中17种有机硫化合物

采用选择离子流动管质谱(SIFT-MS)法,顶空取样后,以H3O+,NO+或O2+为初始离子,定量分析了17种大蒜酶解液挥发性有机硫化合物。结果表明:有机硫化合物主要为二烯丙基硫醚、甲基烯丙基硫醚、硫代亚磺酸酯和硫醇,其中二烯丙基二硫醚浓度为137 g/m3,二烯丙基三硫醚浓度为13.4 g/m3,甲基烯丙基二硫醚浓度为8.98 g/m3,它们分别占17种有机硫化合物总含量的77.3%,7.58%和5.08%(相对含量);本研究采用顶空取样方法测出大蒜素的浓度为5.63 g/m3,相对含量为3.20%。     

Determination of added sulfites in dried garlic with a modified version of the optimized Monier-Williams method

The optimized Monier-Williams method is slightly modified so that it could be applied for determining sulfite content in dried garlic. Dried garlic sample is directly acidified in a reactor at a pH below 3. At this pH level, the alliinase enzyme activity is irreversibly blocked, and the sulfur-containing amino acids such as alliin (the most abundant) present in dried garlic cannot be transformed into corresponding thiosulfinates such as allicin, which is absent in dried garlic. This prevents allicin from reacting with added sulfites and being probably converted to S-allyl thiosulfate, which is not volatile and has no taste. It is found that at a pH below 2.4 and at boiling water temperature, allicin produces sulfur dioxide in adequate quantity to explain the false-positive results when utilizing the optimized Monier-Williams method with allicin suppression for unsulfited dried garlic samples. Finally, when garlic samples are stabilized in a phosphoric acid buffer at a final pH around 2.4, no sulfite is produced during the Monier-Williams distillation, which is further proof there are no naturally occurring sulfites in unsulfited dried garlic under these mild conditions.     

Validated liquid chromatographic method for quantitative determination of allicin in garlic powder and tablets

In the present study, an RP high performance liquid chromatographic method was developed and validated for the determination of allicin in garlic powder and tablets. Chromatographic separation was carried out on an RP-18(e )column (125 mm x 4 mm), using a mobile phase, consisting of methanol-water (50:50 v/v), at a flow rate of 0.5 mL/min and UV detection at 220 nm. Ethylparaben was used as the internal standard. The assay was linear for allicin concentrations of 5.0-60.0 microg/mL. The RSD for precision was <6.14%. The accuracy was above 89.11%. The detection and quantification limits were 0.27 and 0.81 microg/mL, respectively. This method was used to quantify allicin in garlic powder samples. The results showed that the method described here is useful for the determination of allicin in garlic powder and tablets.     

High-performance ion-pair chromatography method for simultaneous analysis of alliin,deoxyalliin, allicin and dipeptide precursors in garlic products using multiple mass spectrometry and UV detection

The quality of garlic and garlic products is usually related to their alliin content and allicin release potential. Until now no analytical method was able to quantify simultaneously allicin, its direct precursor alliin (S-allyl-L-cysteine sulfoxide), SAC (S-allyl-L-cysteine) as well as various dipeptides that apparently serve as storage compounds in garlic. It is well known that all these intermediates are involved in the allicin biosynthetic pathway. A simple and rapid HPLC method suitable for routine analysis was developed using eluents containing an ion-pairing reagent. Particularly, heptanesulfonate as ion-pairing reagent guarantees a sufficient separation between alliin and the more retained dipeptides at very low pH. Allicin was eluted after 18 min on a 150 x 3 mm column. Synthetic reference compounds were characterized by the same chromatographic method using a diode-array UV detector and an ion trap mass spectrometer (electrospray ionization) in the multiple MS mode. In routine analysis of garlic bulbs, powders and other products, the diode-array detector is sufficient for a relevant quantification. Our method has been used in studies to improve the quality of garlic and its derived products.     

Copolymerization of 2,2-diallyl-1,1,3,3-tetraethylguanidinium chloride and alkyl methacrylates

Radical copolymerization of 2,2-diallyl-1,1,3,3-tetraethylguanidinium chloride with methyl methacrylate and allyl methacrylate in the bulk and methanol solution in the presence of azobis-isobutyric acid dinitryle at 70–90°C has been studied. Copolymerization of 2,2-diallyl-1,1,3,3-tetraethylguanidinium chloride with methyl methacrylate or allyl methacrylate in the bulk proceeds with formation of random copolymers enriched in methacrylate units; in the copolymerization of 2,2-diallyl-1,1,3,3-tetraethylguanidiny chloride with methyl methacrylate in methanol, the copolymerization constants of the monomers become close. The kinetic parameters of the reaction have been studied, the relative activities of the monomers have been determined. It has been found that 2,2-diallyl-1,1,3,3-tetraethylguanidinium chloride is copolymerized with allyl methacrylate or methylmethacrylate to form pyrrolidinium structures in the cyclolinear polymer chain. At high degrees of conversion of the copolymerization of 2,2-diallyl-1,1,3,3-tetraethylguanidinium chloride with allyl methacrylate, the viscosity increases and the side polymer chains are crosslinked by “allyl bonds” to form insoluble copolymers, swelling in benzene and DMSO.     

Garlicnins B(1), C(1), and D, from the fraction regulating macrophage activation of Allium sativum

Several novel sulfides from acetone extracts of bulbs of garlic (Allium sativum L.), were identified and investigated. These were named garlicnins B(1) (1), C(1) (2), and D (3), and they were found to have the ability to control macrophage activation. Garlicnins B(1) (1) and C(1) (2) possess a new skeleton of cyclic sulfoxide and their structures of garlicnins B(1) (1) and C(1) (2) were characterized as 3,4-dimethyltetrahydrothiophene-S-oxide derivatives carrying the substitutions of a propenyl and a sulfenic acid, and an allyldithiine and a 1-propene-sulfenic acid (a), respectively. The mechanism of the proposed production of these compounds is discussed. Garlicnin D (3), dithiine-type, was estimated to be derived by addition of (a)+allyl thiosulfenic acid (b) derived from allicin. The identification of these novel sufoxides from onion and garlic accumulates a great deal of new chemistry to the Allium sulfide field, and future pharmacological investigations aid the development of natural, healthy foods and anti-cancer agents that could potentially prevent or combat disease.     

Allicin induces apoptosis in EL-4 cells in vitro by activation of expression of caspase-3 and -12 and up-regulation of the ratio of Bax/Bcl-2

Garlic (Allium sativum L.; Liliaceae) has been widely demonstrated in the role of cancer prevention, but the specific compound in garlic corresponding to this effect and its mechanisms are not clearly known. Allicin is one of the organic sulphur compounds derived from garlic. In the present study we investigated the anti-proliferative and pro-apoptotic activities of allicin in murine T-lymphocytes (EL-4) and the mechanism of inducing apoptosis in?vitro. The results showed that allicin was effective in inhibiting the proliferation of EL-4 cells in?vitro in a concentration-dependent manner. Further, allicin could induce the formation of apoptotic bodies, nuclear condensation, DNA spallation, and even activated the expression of caspase-3, -12 and cytochrome C (cyt C). Finally, allicin up-regulated the ratio of Bax/Bcl-2 and induced a mitochondrion membrane potential (MMP) decrease. Allicin induced apoptosis in EL-4 cells in a time- and concentration-dependent manner, in which the mitochondrial pathway might play a central role.     

大蒜素的检测及大蒜辣素分解机理的探讨

通过正交试验方法,研究了硫酸钡吸光比浊法测定大蒜中大蒜素含量的最佳实验条件。在选定实验条件下,体系的吸光度与硫酸根离子浓度呈线性关系,相关系数r为0.9985,相对标准偏差(RSD)为0.86%。采用高效液相色谱法对样品中二烯丙基二硫醚进行定量检测,其检测结果与吸光比浊法的结果具有一定的互补对照性。在此基础上采用红外光谱法、气相色谱-质谱法对大蒜素中含硫活性成分进行定性分析,并将四种方法结果进行对比,对大蒜辣素过热分解的机理进行了探讨,为大蒜素中不同含硫化合物之间的转化提供了依据。     

Quantitative Determination of Allicin in Allium sativum L. Bulbs by UPLC

An UPLC method for determination of allicin in garlic bulb powder has been developed and validated. Chromatographic separation and determination were performed on an Acquity UPLC BEH C₁₈ column using a mobile phase of methanol/water (50:50, v/v). Linearity between the allicin concentration and the peak area was good within the concentration ranges 2.04–510 mg L⁻¹. The method was validated over this range for both accuracy and precision. The method was successfully used for the quantitative analysis of allicin in ten garlic varieties.

     

Do garlic-derived allyl sulfides scavenge peroxyl radicals?

The chain-breaking antioxidant activities of two garlic-derived allyl sulfides, i.e. diallyl disulfide (1), the main component of steam-distilled garlic oil, and allyl methyl sulfide (3) were evaluated by studying the thermally initiated autoxidation of cumene or styrene in their presence. Although the rate of cumene oxidation was reduced by addition of both 1 and 3, the dependence on the concentration of the two sulfides could not be explained on the basis of the classic antioxidant mechanism as with phenolic antioxidants. The rate of oxidation of styrene, on the other hand, did not show significant changes upon addition of either 1 or 3. This unusual behaviour was explained in terms of the co-oxidant effect, consisting in the decrease of the autoxidation rate of a substrate forming tertiary peroxyl radicals (i.e. cumene) upon addition of little amounts of a second oxidizable substrate giving rise instead to secondary peroxyl radicals. The relevant rate constants for the reaction of ROO(.) with 1 and 3 were measured as 1.6 and 1.0 M(-1) s(-1), respectively, fully consistent with the H-atom abstraction from substituted sulfides. It is therefore concluded that sulfides 1 and 3 do not scavenge peroxyl radicals and therefore cannot be considered chain-breaking antioxidants.