Isolation of lycopene from crude tomato extract via selective inclusion in deoxycholic acid

Deoxycholic acid has been used as host in the separation of C-40 carotenoid isomers. The methodology was successfully applied to recover almost pure lycopene from commercial tomato paste.     

Chromatographic performance on a C30-bonded stationary phase of monohydroxycarotenoids with variable chain length or degree of desaturation and of lycopene isomers synthesized by various carotene desaturases.

Selectivity towards geometric isomers is a superior feature of a C30 polymeric stationary phase. Therefore, lycopene isomers synthesized in Escherichia coli transformants by catalysis of divers carotene desaturases were separated on this stationary phase. Due to their spectral characteristics and by co-chromatography with nuclear magnetic resonance-characterized carotene standards, some of them could be identified. Most of the lycopene isomers were cyclized by lycopene cyclase yielding mainly 9Z, 13Z and all-E beta-carotene. In contrast, 7,9,7',9'Z prolycopene is accumulating since it cannot be converted by this enzyme. Finally several acyclic hydroxycarotenoids with a chain of 30, 40 and 45 carbon atoms differing in the length of the polyene chain from 9 to 13 were separated on the C30 stationary phase. Longer retention times were observed when the length of the molecule increased and also when the conjugated double bond system was extended. Corresponding monocyclic carotenoids were less retained on the C30 stationary phase and derivatives with an epsilon-ionone end group eluted earlier than with a beta-end group.     

Application of analytical and preparative high-speed counter-current chromatography for separation of lycopene from crude extract of tomato paste

Lycopene was isolated from 100 mg of crude extract of tomato paste containing about 9% of lycopene. Analytical high-speed counter-current chromatography (HSCCC) was first used for the systematic selection of the two-phase solvent system. Then preparative HSCCC separation was performed with a nonaqueous solvent system composed of n-hexane-dichloromethane-acetonitrile at an optimum volume ratio of 10:3.5:6.5. This yielded 8.6 mg of lycopene at over 98.5% purity as determined by HPLC analysis.     

Cis-trans isomerizations of beta-carotene and lycopene: a theoretical study

The all-trans to mono-cis isomerizations of polyenes and two C40H56 carotenes, beta-carotene and lycopene, at the ground singlet (S0) and triplet (T1) states are studied by means of quantum chemistry computations. At the S0 state of polyenes containing n acetylene units (Pn), we find that the energy barrier of the central C=C rotation decreases with n. In contrast, however, at the T 1 state, the rotational barrier increases with n. For the C40H56 carotenes, the rotational barriers of lycopene are lower than those of their beta-carotene counterparts. This difference renders the rotational rates of lycopene to be 1-2 orders of magnitude higher than those of beta-carotene at room temperature. For both these carotenes, the barrier is lowest for the rotation toward the 13-cis isomer. The relative abundances are in the following order: all-trans > 9-cis > 13-cis > 15-cis. Although the 5-cis isomer of lycopene has the lowest energy among the cis isomers, its formation from the all-trans form is restricted, owing to a very large rotational barrier. The possible physiological implications of this study are discussed.     

低温制备高纯度番茄红素异构体及其在食用油中的异构化及降解研究

该文通过将低温C18色谱柱和C30色谱柱组合构建了可用于番茄红素异构体纯化的正交分离方法.研究表明,当色谱柱温低于-20 ℃时,普通C18色谱柱对番茄红素异构体的分离度得到大幅增加.研究了番茄红素的溶解度与分离度之间的关系,并通过该正交方法最终制备了7种纯度均高于97％的番茄红素异构体.相比于单独使用C18柱或C30柱...     

Degradation kinetic (D100) of lycopene during the thermal treatment of concentrated tomato paste

Heat treatments can cause degradation in tomatoes of lycopene which has important antioxidant effects. No information about decimal reduction time (D₁₀₀) of lycopene is available. D-value is the time required at a given temperature to reduce 90% of the molecule. This study for the first time determine the kinetic of lycopene thermal degradation. The content was measured at regular intervals of pasteurization using canned tomato paste to determinate D value. Microbiological analysis was carried out to verify product stability after packaging. Yeasts, molds and lactic acid bacteria were determined. The pasteurization time allowed to observe a loss of the red color. Lycopene content, after an increase at 8 min, decreased at 32 min of pasteurization. D₁₀₀ value was calculated at 75 min; a diminution of 90% in lycopene content in the concentrated tomato paste was observed. Microbiological analysis confirmed the stability of products after 8 min of pasteurization.     

微乳体系中番茄红素稳定性的研究

番茄红素的抗氧化性很强,人体内番茄红素的含量与人的寿命相关,但它对光和氧十分敏感限制了它的使用。微乳作为生物活性物质载体具有极大的应用潜力。本文研究番茄红素在食品级微乳体系中的稳定性。     

Chromatographic determination of the effect of storage on lycopene

A reverse-phase high-performance liquid chromatography (HPLC) method for the determination of lycopene in an alkaline lipid phase is described, and pigment stability in stored tomato sausage is reported. To avoid and replace the use of nitrite, lycopene from tomato products is added to minced meat and a tomato sausage with natural color is produced. Tomato sausage with and without nitrite were smoked in a smoking compartment and stored (4 degrees C and 8 degrees C) for 25 and 17 days, respectively. Among other factors, the quality of the tomato sausage depends on stability of lycopene during process and storage. Lycopene, being lipophilic, is extracted together with the polar and neutral fat in food. Efforts to purify lycopene from the fatty content will result in loss of pigment. The triacylglycerides obstruct the detection of lycopene by spectrophotometry or by HPLC with diode-array detection. To solve this problem, the triacylglycerides are hydrolyzed to free fatty acids just before analyzing lycopene on a column tolerating alkaline samples. At the end of the storage, loss of pigment in the sausage without nitrite was 26% stored at 4 degrees C and 19% at 8 degrees C. Corresponding results for the sausage with nitrite added as well as tomato paste show the loss of pigment is 20% and 45%. For each type of fatty food extracted, it is important to minimize the use of alkaline solutions because the HPLC equipment may be susceptible to alkaline conditions.     

Direct determination of lycopene content in tomatoes (Lycopersicon esculentum) by attenuated total reflectance infrared spectroscopy and multivariate analysis

Lycopene is a potent antioxidant that has been shown to play critical roles in disease prevention. Efficient assays for detection and quantification of lycopene are desirable as alternatives to time- and labor-intensive methods. Attenuated total reflectance infrared (ATR-IR) spectroscopy was used for quantification of lycopene in tomato varieties. Calibration models were developed by partial least-squares regression (PLSR) using quantitative measures of lycopene concentration from liquid chromatography as reference method. IR spectra showed a distinct marker band at 957 cm(-1) for trans Carbon-Hydrogen (CH) deformation vibration of lycopene. PLSR models predicted the lycopene content accurately and reproducibly with a correlation coefficient (sigma) of 0.96 and standard error of cross-validation <0.80 mg/100 g. ATR-IR spectroscopy allowed for rapid, simple, and accurate determination of lycopene in tomatoes with minimal sample preparation. Results suggest that the ATR-IR method is applicable for high-throughput quantitative analysis and screening for lycopene in tomatoes.     

Synthesis, stereochemistry, and photochemical and thermal behaviour of bis-tert-butyl substituted overcrowded alkenes

In order to study the structural limits in the design of molecular motors, a tert-butyl substituted analogue was prepared. The unexpected photochemical and thermal isomerisation processes and the stereochemistry of new overcrowded alkene are described. The bis tert-butyl substituted alkenes were synthesised in a five-step sequence with an overall yield of 7.5%. Structural assignments of the isomers based on experimental data were supported by calculations of all four isomers of the alkene. X-Ray crystal analysis showed a strongly twisted alkene (torsion angle 39 degrees ) for a less stable photochemically generated cis-isomer.     

The ability of spectrum autocorrelation models to predict the lycopene concentration in foods through visible spectroscopic data

We developed a novel computerized approach based on lag-k autocorrelation coefficients (LCCs) and linear models (LMs) to estimate the concentration of lycopene in foods by the spectroscopy. The LCCs were calculated using the data obtained using whole visible scans from 400 to 600 nm (vide supra) of lycopene standards and food samples (ketchup, tomato juice and tomato sauce). The chaotic parameter (CP) was then transferred into a LM to estimate the concentration of lycopene compound. The integrated LCC/visible spectroscopy method developed can be considered as a satisfactory analytical technique able to estimate lycopene concentration in food samples in a fast accurate way, with a mean prediction error lower than 5.7% and a mean correlation coefficient higher than 0.957.     

Insight into the Thermal Ring‐Opening Polymerization of Phospha[1]ferrocenophanes

A mixture of cis/trans isomers of phospha[1]ferrocenophanes equipped with one iPr group at the α position to the bridging PhP moiety was prepared. Both isomers (cis‐ 4 and trans‐ 4 ) were obtained as racemates and could be separated so that their thermal properties were investigated individually. The molecular structure of cis‐ 4 was determined by single‐crystal X‐ray analysis showing a tilt angle α=26.35(8)°. Interconversion between both isomers occurred in the melt at elevated temperatures and revealed that the trans isomer is thermodynamically more stable. Structural and thermodynamic data was complemented by DFT calculations (B3PW91/6‐311+G(d,p) and B3PW91‐D3(BJ)/6‐311+G(d,p)). Performance of thermal ring‐opening polymerization (ROP) of trans‐ 4 at 230 °C gave polymers and cyclic oligomers. Gel permeation chromatography (GPC) of the sulfurized polymer resulted in a molecular weight of 62.5 kDa (M_w) and a polydispersity index of 1.39 (PDI). Mass spectrometric analysis of the oligomers showed the presence of cyclic species from dimers to heptamers. After sulfurization, preparative thin layer chromatography led to the separation of three isomeric dimers. Structural characterization of these dimers by single‐crystal X‐ray analysis led to the conclusion that the Fe?Cp bond breaks during the thermal ROP process. A mechanism similar to the known mechanism of the photolytic ROP of ferrocenophanes is proposed.     

Depolarized rayleigh light scattering in absorption bands measured in lycopene solution

The depolarized scattering intensity from the polyene pigment lycopene was measured in the visible absorptiion band and was found to be in good agreement with theoretical calculations at the short wavelength part of the band whereas significant deviations were observed at the red edge of this band.     

A simple and rapid method to assess lycopene in multiple layers of skin samples

Topical application of lycopene is a convenient way to restore antioxidants depleted from the skin by UV radiation and achieve protection against premature aging and cancer. In this study, a simple, rapid and reproducible method to quantify lycopene in different skin layers was developed, validated and employed to assess this compound after skin penetration studies. Lycopene was extracted from the stratum corneum (SC) and viable epidermis and dermis (ED) by vortex homogenization and bath sonication in a mixture of acetonitrile and methanol (52:48, v/v). Lycopene was assayed by HPLC using a C₁₈ column, and acetonitrile:methanol (52:48, v/v) as mobile phase. The quantification limit of lycopene in samples of SC and ED was 35 ng/mL and the assay was linear from 35 to 2000 ng/mL. Within‐day and between‐days assays coefficients of variation and relative errors (indicative of precision and accuracy) were less than 15% (or 20% for the limit of quantification). Lycopene recovery from SC and ED was dependent on the spiked concentration: for 50 ng/mL, recoveries were 88.3 and 90.5%; for 100–1000 ng/mL, recoveries were 68.6–74.9%. This method has a potential application for lycopene quantification during formulation development and evaluation in the dermatological field. Copyright © 2009 John Wiley & Sons, Ltd.     

Dietary uptake of lycopene protects human cells from singlet oxygen and nitrogen dioxide - ROS components from cigarette smoke.

There is current interest in the health benefits of dietary carotenoids and the possible deleterious effects on certain sub-populations such as smokers. Here we report in vivo protection of human lymphocytes, conferred by dietary supplementation of lycopene rich foods against the reactive oxygen species, NO(2)(*) radical (by electron transfer) and 1(O)(2) (by energy transfer). It was found that a lycopene rich diet, maintained for 14 days, increased the serum lycopene level 10 fold compared to serum obtained after the same period, where a typical western European diet had been consumed. Relative lymphocyte protection factors of 17.6 and 6.3 against NO(2)(*) radical and 1(O)(2), respectively, were obtained, which re-enforce epidemiological data, showing protection against several chronic diseases by tomato lycopene.     

Comparative analysis of plant lycopene cyclases

Carotenoids are essential isoprenoid pigments produced by plants, algae, fungi and bacteria. Lycopene cyclase (LYC) commonly cyclize carotenoids, which is an important branching step in the carotenogenesis, at one or both end of the backbone. Plants have two types of LYC (β-LCY and ϵ-LCY). In this study, plant LYCs were analyzed. Based on domain analysis, all LYCs accommodate lycopene cyclase domain (Pf05834). Furthermore, motif analysis indicated that motifs were conserved among the plants. On the basis of phylogenetic analysis, β-LCYs and ϵ-LCYs were classified in β and ϵ groups. Monocot and dicot plants separated from each other in the phylogenetic tree. Subsequently, Oryza sativa Japonica Group and Zea mays of LYCs as monocot plants and Vitis vinifera and Solanum lycopersicum of LYCs as dicot plants were analyzed. According to nucleotide diversity analysis of β-LCY and ϵ-LCY genes, nucleotide diversities were found to be π: 0.30 and π: 0.25, respectively. The result highlighted β-LCY genes showed higher nucleotide diversity than ϵ-LCY genes. LYCs interacting genes and their co-expression partners were also predicted using String server. The obtained data suggested the importance of LYCs in carotenoid metabolism. 3D modeling revealed that depicted structures were similar in O. sativa, Z mays, S. lycopersicum, and V. vinifera β-LCYs and ϵ-LCYs. Likewise, the predicted binding sites were highly similar between O. sativa, Z mays, S. lycopersicum, and V. vinifera LCYs. Most importantly, analysis elucidated the V/IXGXGXXGXXXA motif for both type of LYC (β-LCY and ϵ-LCY). This motif related to Rossmann fold domain and probably provides a flat platform for binding of FAD in O. sativa, Z mays, S. lycopersicum, and V. vinifera β-LCYs and ϵ-LCYs with conserved structure. In addition to lycopene cyclase domain, the V/IXGXGXXGXXXA motif can be used for exploring LYCs proteins and to annotate the function of unknown proteins containing lycopene cyclase domain. Overall results indicated that a high degree of conserved signature were observed in plant LYCs.     

Quantum chemical characterization of the structures, thermochemical properties, and singlet-triplet splittings of didehydroquinolinium and didehydroisoquinolinium ions

Structural and energetic properties are predicted for the 21 didehydroquinolinium ion isomers and 21 didehydroisoquinolinium ion isomers in their lowest-energy singlet and triplet states by using density functional and multireference second-order perturbation theories. Singlet-triplet splittings and biradical stabilization energies are examined to gain insight into the degree of interaction between the biradical centers, with comparison being made to analogous didehydronaphthalenes and didehydropyridines.     

Preparation of highly deuterated zeaxanthin, lycopene, and β-carotene from fully deuterated mevalonate using engineered Escherichia coli

Carotenoids are important natural pigments produced by various microorganisms and plants. Specific deuterium-labeling of these compounds is invaluable in biochemical and physiochemical research. In this paper, preparation of highly deuterated zeaxanthin, lycopene, and β-carotene using engineered Escherichia coli with fully deuterated mevalonate is described. Also described are physico-chemical properties of the obtained deuterated carotenoids.     

双官能度手性和消旋苯并噁嗪的合成及热性能研究

采用无溶剂法合成了新型双酚A和双酚AF(六氟双酚A)基手性和消旋苯并噁嗪单体,利用红外光谱(FTIR)、核磁共振氢谱(1H-NMR)、旋光仪和高效液相色谱(HPLC)对单体结构和性质进行了表征,通过差式扫描量热仪(DSC)和热重分析仪(TGA)对苯并噁嗪的固化行为及聚合物的热性能进行了研究.结果表明,无溶剂法合成苯并噁嗪单体具有反应速度快、产率高、对环境友好等特点;双官能度消旋苯并噁嗪单体由内消旋和外消旋异构体组成,且内消旋苯并噁嗪单体含量高于外消旋;手性和消旋苯并噁嗪单体具有相同的开环聚合行为;由于消旋苯并噁嗪分子的立体构型不同,使得聚苯并噁嗪的自由体积减小,分子链的堆积更加致密,因而消旋聚苯并噁嗪的玻璃化转变温度(Tg)和热稳定性均高于手性聚苯并噁嗪和传统的双酚A-苯胺型聚苯并噁嗪;此外,C—F键具有高的解离能,因而双酚AF基聚苯并噁嗪的热性能显著提高.     

辛基二茂铁同分异构体纯度标准物质的定值技术研究

(2-辛基)-二茂铁、(3-辛基)-二茂铁和(4-辛基)-二茂铁是辛基二茂铁主要的3种同分异构体,由分离工业品辛基二茂铁制备而来。目前国内外金属有机化合物的标准物质有限,对这3种异构体进行高精度定值比较困难。该文首先考察标准物质候选物的均匀性和稳定性;再确定其中各杂质种类,用杂质扣除法对各候选物进行定值,重点研究了气相色谱法对各候选物中有机杂质及有机溶剂的定值技术,评定了标准物质的不确定度,为相关物质在高新技术领域的应用奠定了基础。