高速逆流色谱法分离β-谷甾醇和菜油甾醇的研究

利用高速逆流色谱法 ,并选用V(庚烷 )∶V(乙腈 )∶V(乙酸乙酯 ) =5∶5∶1溶剂体系 ,成功地分离了混合植物甾醇标准品中的 β 谷甾醇和菜油甾醇。经过HPLC检测 ,一次性分离可得到质量分数为 97%的 β 谷甾醇和质量分数为 91%的菜油甾醇产品 ,收率分别可达 5 6 %和 5 0 %。该方法简便、重现性好 ,可作为高纯度 β 谷甾醇和菜油甾醇标准品的制备分离方法     

Identification of chemical oviposition stimulants from rice grain forSitophilus zeamais motschulsky (Coleoptera,Curculionidae)

Chemical components stimulating oviposition bySitophilus zeamais in rice grain were isolated from rice bran and were found to be a mixture of ferulates, diglycerides, and free sterols. Oviposition preference of the species can be induced by synergistic action of these compounds.     

重组酿酒酵母生物合成菜油甾醇

菜油甾醇作为甾体药物（孕酮、雄烯二酮、氢化可的松等）的重要合成前体已受到国内外研究学者的广泛关注。首先通过生物信息学分析,筛选了10种不同来源的7-脱氢胆固醇还原酶DHCR7,并采用CRISPR/Cas9基因编辑技术将酿酒酵母（Saccharomyces cerevisiae）内源的ERG5基因替换成不同来源的DHCR7基因,构建了菜油甾醇合成菌株。结果发现整合来源于Pangasianodon hypophthalmus DHCR7的菌株Zw507表现出最高的菜油甾醇的产量216.93 mg/L。进一步筛选了10种酵母内源启动强度较强的启动子来与PhDHCR7基因进行组合,结果显示以TEF1p为启动子时菜油甾醇的产量最高可达253.35 mg/L。为了进一步提高菜油甾醇产量,增加了DHCR7表达盒在酵母基因组上的拷贝数。当拷贝数为3个时,菜油甾醇的产量达到最高302.27 mg/L。最终,通过5 L发酵罐进行补料分批发酵,实现了916.88 mg/L菜油甾醇产量。该菌株可作为后续甾体药物生物合成的优良底盘细胞。     

Side-chain autoxidation of stigmasterol and analysis of a mixture of phytosterol oxidation products by chromatographic and spectroscopic methods

Although the structure of phytosterols is closely related to cholesterol, there is a gap in knowledge concerning the formation and occurrence of oxidation products from phytosterols. The main objective of this study was to isolate and characterize some side-chain oxidation products formed after autoxidation of stigmasterol. Another objective was to highlight the difficulties in the analysis of phytosterol and a mixture of their oxidation products by GC. Pure stigmasterol was oxidized at 120°C for 72 h in an air-ventilated oven. Preparative TLC separated the oxidation products, and the products were characterized with GC-MS and NMR. In addition to the common ring-structure oxidation compounds, three semipolar oxidation products—24-ethylcholest-5,22-dien-3β,25-diol, 24-ethylcholest-5,22-dien-3β,24-diol, and 24-ethyl-5,22-choladien-3β-ol-24-one—were characterized for the first time by TLC, GC-MS, and NMR. Moreover, the results of the analysis of a large number of oxidation products from sitosterol, campesterol, and stigmasterol by capillary column GC indicated that further efforts and optimization are required in this area.     

Characterization of side-chain oxidation products of sitosterol and campesterol by chromatographic and spectroscopic methods

Based on the cholesterol-lowering effects of phytosterols, known since the 1950s, extra phytosterol amounts have been added to certain food products for almost 10 yr. Literature reports on oxidation of phytosterols in general are limited, and data on side-chain oxidation of these compounds are scarce. The aim of this study was to investigate and characterize autoxidation products from a mixture of the two phytosterols sitosterol and campesterol. A commercial mixture of the two sterols was oxidized for 72 h at 120°C in an air-ventilated oven. The oxidation products were separated by preparative TLC and identified and characterized with GC-MS. The following oxidation products were identified from the two phytosterols: 24-methylcholest-5-en-3β,24-diol, 24-methylcholest-5-en-3β,25-diol, 24-methylcholest-4-en-6α-ol-3-one, 24-methylcholest-4-en-6β-ol-3-one, 24-ethylcholest-5-en-3β,24-diol, 24-ethylcholest-5-en-3β, 25-diol, 24-ethylcholest-4-en-6α-ol-3-one, 24-ethylcholest-4-en-6β-ol-3-one. Full-scan mass spectra of these compounds are reported for the first time as their trimethylsilyl-ether derivatives.     

Genotype and growing location effects on phytosterols in canola oil

There is little information available about phytosterols in canola (Brassica napa L.) oil and the effects of genotype and growing locations from Virginia and the mid-Atlantic region of the United States, a potential area for the establishment of domestic production to provide edible oil. Our objectives were to characterize the phytosterols, phospholipids, unsaponifiable matter, and FA in oil from Virginia-grown canola. Among 11 canola genotypes grown at two locations during 1995–1996 significant variations existed for oil content and FA profiles, but not for contents of phospholipids, unsaponifiable matter, total phytosterols, campesterol, stigmasterol, and β-sitosterol, Total phytosterol content in the oil of Virginia-grown canola varied from 0.7 to 0.9% with a mean of 0.8%. This concentration compared favorably with oil from Canadian canola, which typically contains 0.5 to 1.1% total phytosterols. The mean contents of brassicasterol, campesterol, stigmasterol, β-sitosterol, Δ⁵-avenasterol, and Δ⁷-stigmatenol as percentages of total phytosterols in Virginia-grown canola were: 9.7, 32.0, 0.6, 49.3, 4.99, and 3.5%, respectively. Growing location did not affect phytosterols in Virginia-grown canola oil but had significant effects on contents of phospholipids, and saturated (myristic, stearic, and arachidic) and unsaturated (palmitoleic, linoleic, linolenic, eicosenoic, and erucic) FA.     

红树林植物露兜簕果实的化学成分研究

在对露兜簕果实研究中分离得到6个化合物,利用MS、NMR等波谱方法鉴定为菜油甾醇、过氧化麦角甾醇、Cholest-4-en-3-one、β-谷甾醇、油酸甘油酯、正十六烷醇。     

重组解脂亚罗酵母合成菜油甾醇

菜油甾醇是一种具有重要生理活性的植物甾醇。为构建合成菜油甾醇的工程菌株,通过敲除解脂亚罗酵母polf菌株中麦角固醇合成基因ERG5,促进麦角-5,7,24-三烯醇的体内积累,进而表达经密码子优化的非洲爪蟾DHCR7基因,使麦角-5,7,24-三烯醇在DHCR7和polf胞内ERG4的共同催化作用下,转化成菜油甾醇,最后利用GC-MS对重组菌株的发酵产物进行检测分析。结果表明,重组菌株polf-ERG5--DHCR7+(PED)合成菜油甾醇的产量达0.485 mg/g(以细胞干重计)。重组解脂亚罗酵母合成菜油甾醇菌株的成功构建,为生物合成法合成植物甾醇提供了新思路。     

Kinetic Studies of Phytosterol Adsorption on Zeolite

Abstract

Equilibrium isotherms of sterol adsorption on zeolite show the characteristics of irreversible equilibrium adsorption. First order and second order surface adsorption control mechanisms as well as micropore diffusion control model failed to satisfactorily describe the kinetics of sterol adsorption on zeolite. From the analysis of adsorption data, it was found that macropore diffusion control model satisfactorily describes the kinetics of sterol adsorption on zeolite. The effect of temperature on the diffusivity during adsorption was found to conform to the Eyring equation. It was shown that a change in temperature has a negligible effect on the selectivity of sterol adsorption on zeolite.     

Analysis of tocopherols and phytosterols in vegetable oils by HPLC with evaporative light-scattering detection

Methods were developed for the separation, detection, and quantification of tocopherols and phytosterols by high-performance liquid chromatography with an evaporative light-scattering detector. Four tocopherols— α, β, γ and δ—and four phytosterols—campesterol, β-sitosterol, brassicasterol, and stigmasterol—were analyzed in soybean, sunflower, low-erucic acid rapeseed (LEAR) and corn oils. The use of an evaporative light-scattering detector, in conjunction with modification of methods from the literature to prepare and analyze tocopherols and phytosterols by HPLC, showed consistent results between trials and levels of these minor constituents. Presented at the Annual American Oil Chemists' Society Meeting, May 3–7, 1989, Cincinnati, OH.