HPLC Fingerprint Characteristics of Active Materials of Garlic and Other Allium Species

The bioactive molecules of garlic are classified according to their enzymatic activities as either alliinase activators or alliinase inactivators. The alliinase activation reaction system is mainly composed of sulfur-containing compounds, whereas the alliinase inactivation system is mainly composed of amino acid-based materials. The purpose of this study was to develop an effective way to digitally express features of complex active compounds of garlic as a basis for quality control. HPLC was used to develop the fingerprints of plants from different Allium species and different geographical regions according to whether the compounds were sulfur containing or based on amino acids. Using the Shannon equation, I values of sulfur-containing compounds from garlic ranged from 3.55 to 3.94, whereas I values of sulfur-containing compounds from other Allium plants, onions, leek, and Welsh onion, ranged from 3.38 to 3.53. The I values of amino acid-based compounds from garlic ranged from 3.67 to 3.91, whereas I values of these compounds from other Allium plants ranged from 3.88 to 3.99. This method effectively distinguished garlic from different species of Allium plants. This method also provided a way to digitally monitor the presence of complex active compounds of garlic and may allow evaluation of quality. This method may also provide a theoretical basis for quality control of bioactive compounds from other medicinal plants.     

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。     

GC-MS法测定大蒜中的挥发性物质

大蒜(AlliumsatiuvmL.)是多年生草本百合科植物大蒜的鳞茎,按皮的颜色不同可分为紫皮蒜和白皮蒜两种。大蒜原产于意大利的西西里岛,约在两千多年前传入我国。大蒜不仅是极佳的调味食品,而且还有很好的药用功能。近年来,科学家研究证明,大蒜是一种健康食品,有助人体防病保健、延年益寿,是药食兼优的佳品,对人体具有多种药用价值。大蒜具有一种强烈的蒜臭气味,这种特殊的气味由许多复杂的硫化物组成。这类有机硫化物可促进消化,健胃整肠,强化抗菌作用,消肿止痛,改善机体机能的功能,大蒜中还含有乙烷硫代磺酸乙酯和二烯丙基三硫化物等,能阻断强烈致癌物质亚硝胺类在胃部的形成和积累,可预防胃癌、食道癌、肝癌、鼻咽癌的发生。本试验采用"同时蒸馏-萃取方法"(simultaneousdistillationandextraction,SDE)提取白皮和紫皮大蒜的挥发性成分,经GC-MS分析,确定了化合物的化学组成和相对百分含量。     

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。     

气相色谱-质谱法测定大蒜挥发油的组成

采用改进的水蒸汽蒸馏法从山东金乡大蒜中提取挥发油。实验确定了气相色谱-质谱法分析大蒜油的条件,并对大蒜挥发油的化学成分进行了定性分析,共鉴定出20种物质。用峰面积归一化法对各物质的相对含量进行了测定,结果表明含硫化合物约占挥发油总成分的95%以上,其中含量最高的是大蒜新素,约占挥发油总量的三分之一。对低温储藏半年的挥发油进行分析的结果表明样品在低温下可稳定存放。     

The Effect of Crataegus Fruit Pre-Treatment and Preservation Methods on the Extractability of Aroma Compounds during Liqueur Production

The leaves, inflorescences, and fruits of hawthorn have long been known for their therapeutic properties. A wide range of hawthorn products, including liqueurs, are manufactured, due to the technological potential of the raw material as well as the richness of its volatile compounds. This study aimed to determine the effect of the liqueur production method and various methods of fruit preservation on the quantitative and qualitative composition of volatile compounds in the liqueurs produced. Hawthorn fruits saturated with sucrose and non-saturated with sucrose, fresh or preserved through one of three methods: freezing, air-drying, and freeze-drying, were used for liqueur preparation. The samples were analyzed using a gas chromatograph–mass spectrometer. They were found to contain 54 volatile compounds classified into 12 groups of chemicals. All 54 identified volatile compounds were detected in the liqueur made from hawthorn fruits non-saturated with sucrose and preserved by freeze-drying. In this liqueur type, 12 of the identified volatile compounds occurred in the highest concentration when compared to the other treatments. Among all volatiles, the following compounds were present in the analyzed liqueurs in the highest concentrations: dodecanoic acid ethyl ester (11.782 g/100 g), lactones (6.954 g/100 g), five monoterpenes (3.18 g/100 g), two aromatic hydrocarbons (1.293 g/100 g), isobensofuran (0.67 g/100 g), alcohol—2-methyl-2-propanol (0.059 g/100 g), and malonic ester (0.055 g/100 g). Among all analyzed liqueurs, the one made from the fruits non-saturated with sucrose and frozen was characterized by the smallest diversity of volatiles, which were present in the lowest concentrations in that liqueur.     

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.     

Optimization of Headspace Solid-Phase Micro-Extraction Conditions (HS-SPME) and Identification of Major Volatile Aroma-Active Compounds in Chinese Chive (Allium tuberosum Rottler)

In order to rapidly and precisely identify the volatile compounds in Chinese chive (Allium tuberosum Rottler), seven key parameters of headspace solid-phase micro-extraction conditions (HS-SPME) from Chinese chive were optimized. A total of 59 volatile compounds were identified by using the optimized method, including 28 ethers, 15 aldehydes, 6 alcohols, 5 ketones, 2 hydrocarbons, 1 ester, and 2 phenols. Ethers are the most abundant, especially dimethyl trisulfide (10,623.30 μg/kg). By calculating the odor activity values (OAVs), 11 volatile compounds were identified as the major aroma-active compounds of Chinese chive. From the analysis of the composition of Chinese chive aroma, the “garlic and onion” odor (OAV = 2361.09) showed an absolute predominance over the other 5 categories of aroma. The results of this study elucidated the main sources of Chinese chive aroma from a chemical point of view and provided the theoretical basis for improving the flavor quality of Chinese chive.     

Analysis of sulfur-containing compounds in crude oils by comprehensive two-dimensional gas chromatography with sulfur chemiluminescence detection

This paper reports an analytical method for separating, identifying, and quantifying sulfur-containing compounds in crude oil fraction (IBP-360 degrees C) samples based on comprehensive two-dimensional gas chromatography coupled with a sulfur chemiluminescence detector. Various sulfur-containing compounds and their groups were analyzed with one direct injection. 3620 peaks were detected including 1722 thiols/thioethers/ disulfides/1-ring thiophenes, 953 benzothiophenes, 704 dibenzothiophenes, and 241 benzonaphthothiophenes. The target sulfur compounds and their groups were identified based on the group separation feature and structured retention of comprehensive two-dimensional gas chromatography as well as standard substances. The quantitative analysis of major sulfur-containing compounds and total sulfur was based on the linear response of the sulfur chemiluminescence detector using the internal standard method. The sulfur contents of target sulfur compounds and their groups in 4 crude oil fractions were also determined. The recoveries for standard sulfur-containing compounds were in the range of 90-102%. The quantitative result of total sulfur in the Oman crude oil fraction sample was compared with those from ASTM D 4294 standard method (total S by X-ray fluorescence spectrometry), the relative deviation (RD%) was 4.2% and the precision of the method satisfactory.     

Solid-phase microextraction in the analysis of food taints and off-flavors

Selected food taints and off flavors, for which solid phase microextraction (SPME) has been used as a method for volatiles isolation, are the subject of review. Compounds responsible for musty and earthy odor off-flavors and taints in foods are discussed. This group contains haloanisoles, geosmin, and methylisoborneol. Chlorophenols are discussed as precursors of chloroanisoles and compounds impairing the flavor of food. Also described are volatile phenolic compounds responsible for medicinal off flavors, mainly ethyl phenols and vinyl phenols. Sulfur compounds that contribute to off-flavor are also discussed. Finally, a group of volatile compounds being the products of lipid oxidation are summarized. A short review of the formation, occurrence, and information on odor properties of all of these groups of compounds is given. Examples of SPME use for the analysis of compounds belonging to all described groups are shown. Elaboration of method parameters, fiber selection, experimental conditions, and quantitation of compounds are subjects of interest. Also, applications of SPME as a method for introduction of volatiles in mechanical olfaction technologies are shortly outlined.     

柠檬果茶中游离态和键合态挥发性成分分析

以柠檬果茶为研究对象,建立了顶空固相微萃取前处理结合气相色谱质谱联用技术测定其中挥发性化合物的分析方法。采用开水冲泡对样品进行提取,通过Amberlite XAD-2大孔吸附树脂对柠檬果茶中的糖苷类挥发性组分键合,分离游离态和键合态化合物,甲醇溶剂作为洗脱剂对键合态化合物进行洗脱,Almondsβ-D-葡萄糖苷酶对其酶解。使用气质联用对样品中游离态和键合态挥发性成分进行检测,其结果根据数据库匹配和对比文献保留时间定性,内标法进行定量。结果表明,柠檬果茶中含有游离态物质24种,键合态物质16种,主要为(+)-柠檬烯、1-辛醇、橙花醇、(-)-4-萜品醇、alpha-松油醇等。方法为花果茶干燥工艺提供参考。     

Diallyl Trisulfide,the Antifungal Component of Garlic Essential Oil and the Bioactivity of Its Nanoemulsions Formed by Spontaneous Emulsification

The aim of this study was to evaluate the chemical compounds of garlic essential oil (EO), and determine the antifungal efficacy of garlic EO and its major components, diallyl trisulfide and its nanoemulsions against wood-rotting fungi, Trametes hirsuta and Laetiporus sulphureus. GC-MS analysis revealed that the major constituents of garlic EO were diallyl trisulfide (39.79%), diallyl disulfide (32.91%), and diallyl sulfide (7.02%). In antifungal activity, the IC₅₀ value of garlic EO against T. hirsuta and L. sulphureus were 137.3 and 44.6 μg/mL, respectively. Results from the antifungal tests demonstrated that the three major constituents were shown to have good antifungal activity, in which, diallyl trisulfide was the most effective against T. hirsuta and L. sulphureus, with the IC₅₀ values of 56.1 and 31.6 μg/mL, respectively. The diallyl trisulfide nanoemulsions showed high antifungal efficacy against the examined wood-rotting fungi, and as the amount of diallyl trisulfide in the lipid phase increases, the antifungal efficacy of the nanoemulsions increases. These results showed that the nanoemulsions and normal emulsion of diallyl trisulfide have potential to develop into a natural wood preservative.     

汽油馏分的硫化物形态分布研究

采用气相色谱和硫化学发光检测(GC-SCD)技术,经过对色谱条件的优化,建立了汽油馏分中硫化物形态分布的测定方法。用标准物质的保留时间辅以化学法脱除硫醇、硫醚的方法对107个硫化物进行了定性;标准硫化物保留时间重复测定结果的相对标准偏差(RSD)≤0.25%。用内标法对主要的硫化物和总硫含量进行了定量,方法的加标回收率为96%~115%;同一样品重复测定5次,含硫大于7 mg/kg的硫化物组分重复测定结果的RSD≤8.9%。所建立的方法可用于不同装置的汽油馏分的硫化物形态分布规律的研究。     

Simultaneous speciation of selenium and sulfur species in selenized odorless garlic (Allium sativum L. Shiro) and shallot (Allium ascalonicum) by HPLC-inductively coupled plasma-(octopole reaction system)-mass spectrometry and electrospray ionization-tandem mass spectrometry

The simultaneous speciation of selenium and sulfur in selenized odorless garlic (Allium sativum L. Shiro) and a weakly odorous Allium plant, shallot (Allium ascalonicum), was performed by means of a hyphenated technique, a HPLC coupled with an inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) equipped with an octopole reaction system (ORS). The aqueous extracts of them contained the common seleno compound that was identified as gamma-glutamylmethylselenocysteine by an electrospray ionization-tandem mass spectrometry (ESI-MS/MS). Normal garlic contains alliin as the major sulfur-containing compound, which is the biological precursor of the garlic odorant, allicin. Alliin, however, was not detected in the extracts of the selenized odorless garlic. At least, four unidentified sulfur-containing compounds were detected in odorless garlic and shallot. Moreover, these Allium plants showed chemopreventive effects against human leukemia cells.     

A novel system for purge-and-trap with thermal desorption: Optimization using tomato juice volatile compounds

A system for purge-and -trap with thermal desorption was developed and optimized to moniotor aroma compounds at ambient temperatures. Canned tomato juice volatiles were used as a model system to develop and evaluate the method. Volatile components were first adsorbed on insert-traps packed with Tenax-TA polymer, then thermally desorbed directly inside a gas chromatograph injector. Volatile matgerials occuring in Very low amounts could be entrained and subsequently chrfomatographed, with sensitivity limited by the purity of the sweep gas. Quantitative measurement of tomato juice volatiles was linear with sample size upn to 100 gram samples. The amount of trapped volatiles was proportional to trapping time; howver, low-and intermediate-boilers broke through the trap after one hour while high-boilers continued to be retained. Apurge gas flow rate of 20ml/min gave optimum results mediate-biolers. Optimum recovery of volatile compounds was obtained with a desorption temperature of 200°c for 5 min. Coefficients of variation from triplicate runs were relatively small. The method showed promise for a simple, sensitive, and reproducibel flavor volatiles collection system for the accurate analysis of tomato compounds.     

二烯丙基硫醚化合物的合成

二烯丙基一硫醚（DS）,二烯丙基二硫醚（DDS）,二烯丙基三硫醚（DTS）和二烯丙基四硫醚（DTTS）等是大蒜提取液中的主要有效成分,具有十分广泛独特的生理药理活性。作者以甲酸、丙三醇为超始原料合成了这些化合物,烯丙基硫醚化合物总含量达83%,其中DDS,DTS含量分别达30%。产物均GC-MS鉴定确证。合成方法简单,原料易得,反应步骤少,实用性较强。     

Rapid determination of volatile compounds in grapes by HS-SPME coupled with GC-MS

Volatile compounds of grapes are responsible of varietal aroma. At the moment, methods used for analysis of these compounds are solvent-based, time-consuming and generally require large amounts of sample. In order to obtain an appropriate technique to study grape volatile compounds, HS-SPME method has been developed. The optimal sampling conditions were: 70 °C for 20 min with a 65-μm PDMS/DVB fibre. Sixteen volatile compounds have been quantified in pulp and skins of Muscat grapes. Terpenes, mainly linalool, geraniol and nerol, have been the volatiles present in the highest concentration, since these compounds contribute, to a larger extent, to the aroma of Muscat grapes and wines. So the proposed technique can be used for the characterisation of grape varieties or cultivars and for the determination of the aromatic maturity of grapes.     

The Effects of Antioxidants on the Changes in Volatile Compounds in Heated Welsh Onions (Allium fistulosum L.) during Storage

Welsh onion (Allium fistulosum L.) is usually used to enhance the flavor characteristics of various foods. Volatile compounds in Welsh onions, including sulfur-containing compounds, may vary during heat process and storage. Accordingly, the changes in the volatile compounds in Welsh onions, subjected to heat and antioxidant (ascorbic acid and glutathione) treatments during storage, are investigated in the present study. The majority of sulfur-containing compounds in Welsh onions showed significant differences between the untreated Welsh onions and heated Welsh onions. During the heating of the Welsh onions, some sulfur-containing compounds, such as 2-methylthiirane, 1-(methyldisulfanyl)prop-1-ene, 1-[[(E)-prop-1-enyl]disulfanyl]propane, 1-(propyltrisulfanyl)propane, 1-[[(E)-prop-1-enyl]trisulfanyl]propane, and (methyltetrasulfanyl)methane, showed significant differences between the untreated and heated Welsh onions (p < 0.05). In addition, partial least square discriminant analysis (PLS-DA) was applied to discriminate the heated Welsh onion samples added with different antioxidants. The heated Welsh onion samples added with ascorbic acid was mainly associated with 2-phenylacetaldehyde, acetic acid, methylsulfanylmethane, prop-2-ene-1-thiol, undecan-2-one, and (2E,4E)-deca-2,4-dienal. Moreover, the key volatile compounds in the heated Welsh onion samples added with glutathione were 3-ethylthiophene, 1-(methyldisulfanyl)-1-methylsulfanylpropane, 1-methylsulfanylpentane, 2-prop-2-enylsulfanylpropane, and 1-propan-2-ylsulfanylbutane.     

Volatiles Emission by Crotalaria nitens after Insect Attack

Plants are known to increase the emission of volatile organic compounds upon the damage of phytophagous insects. However, very little is known about the composition and temporal dynamics of volatiles released by wild plants of the genus Crotalaria (Fabaceae) attacked with the specialist lepidopteran caterpillar Utetheisa ornatrix (Linnaeus) (Erebidae). In this work, the herbivore-induced plant volatiles (HIPV) emitted by Crotalaria nitens Kunth plants were isolated with solid phase micro-extraction and the conventional purge and trap technique, and their identification was carried out by GC/MS. The poly-dimethylsiloxane/divinylbenzene fiber showed higher affinity for the extraction of apolar compounds (e.g., trans-β-caryophyllene) compared to the Porapak™-Q adsorbent from the purge & trap method that extracted more polar compounds (e.g., trans-nerolidol and indole). The compounds emitted by C. nitens were mainly green leaf volatile substances, terpenoids, aromatics, and aldoximes (isobutyraldoxime and 2-methylbutyraldoxime), whose maximum emission was six hours after the attack. The attack by caterpillars significantly increased the volatile compounds emission in the C. nitens leaves compared to those subjected to mechanical damage. This result indicated that the U. ornatrix caterpillar is responsible for generating a specific response in C. nitens plants. It was demonstrated that HIPVs repelled conspecific moths from attacked plants and favored oviposition in those without damage. The results showed the importance of volatiles in plant–insect interactions, as well as the choice of appropriate extraction and analytical methods for their study.