【作者】 袁海娜；

【导师】 姚善泾；

【作者基本信息】 浙江大学 ， 生物化工， 2010， 博士

【摘要】 异硫氰酸酯(isothiocyanates, ITCs)是硫代葡萄糖苷(glucosinolates, GLS)在植物内源黑芥子酶作用下的水解产物,主要存在于十字花科芸苔属植物中,作为天然的抗癌活性物质备受关注。ITCs在国外已基本实现商业化生产,国内对ITCs的研究还有待深入。本文对天然ITCs的制备技术、功效分析及包合技术作了较为全面的研究。具体包括以下几个方面：ITCs的溶剂萃取制备技术、超临界CO2萃取制备技术；ITCs的抗氧化性能和抗衰老作用；及利用β-环糊精(cylodextrin,CD)为壁材对ITCs的包合技术研究。本论文主要进行了如下几方面的研究：以西兰花种子为原料,采用溶剂萃取技术,得到了含量高达80%的ITCs浸膏。考察了制备方法对浸膏中二氯甲烷溶剂残留量的影响,有利于提升产品的质量,为研究产品的功效打下基础。分析了采用超临界CO2萃取技术从西兰花中制备ITCs的可行性,初步建立了ITCs的超临界CO2萃取制备技术,其ITCs得率为溶剂萃取技术的82%,但没有有机溶剂残留。研究了ITCs提取物的体外抗氧化性质。通过自由基清除系统(包括超氧阴离子自由基(02·-)、羟基自由基(OH·)和DPPH自由基(DPPH-)等)、脂质抗氧化系统和还原力三个氧化体系,较全面地考察了ITCs提取物的体外抗氧化作用。结果发现ITCs提取物具有显著的体外抗氧化活性(P<0.01)。经反相柱层析分离及GC-MS分析发现,1-异硫氰酸-4-甲磺酰基丁烷,即萝卜硫素(sulforaphane, SFN)作为一种ITCs化合物是提取物中重要的抗氧化物质。SFN对DPPH自由基的清除活性约为Vc的1/10-1/5。以苯甲基异硫氰酸酯(benzyl isothiocyanate, BITC)为对照品初步探讨了SFN的抗氧化机理。经FTIR分析发现,SFN抗氧化活性的作用原因之一可能是由于其中的(CH3-SO-CH2-)基团通过提供活泼氢而阻断了自由基及脂质过氧化的链式反应。ITCs提取物对热和光敏感,但其抗氧化稳定性高于Vc。以果蝇为实验动物,研究了ITCs提取物的抗衰老作用。ITCs提取物提高了果蝇的寿命、性活力(P<0.05)和繁殖力(P<0.05),在提高果蝇体内SOD酶活性的同时,降低了MDA的产生和积累。这些工作为拓宽ITCs的功效研究提供了依据。以p-CD为壁材,采用饱和溶液法,制备了β-CD-BITC,β-CD-PEITC (phenylethyl isothiocyanates, PEITC)和β-CD-SFN三种包合物。建立了以UV吸收光谱法定量测定BITC, PEITC和SFN的方法。采用RSD法优化了包合工艺。测定了三种包合物的包合常数k和包合比等参数。对包合物的热力学、光谱学、结构化学以及显微结构学进行了分析和表征。除了UV吸收光谱保持不变外,其FTIR、X-ray晶体结构及SEM显微结构变化说明,在疏水作用主导以及适宜的包合条件下,p-CD和ITCs之间发生了包合相互作用,而且经对包合物进行的DSC-TG热力学分析表明,包合后的ITCs热稳定性提高了。更多还原

【Abstract】 Isothiocyanates (ITCs) are abundant in cruciferous vegetables, and they are the hydrolysis products of glucosinolates (GLS) by the enzyme myrosinase. ITCs are of interest because of their chemopreventive activities. ITCs have been commercially produced abroad and have not deeply being studied in China currently. This work consisted of the following parts:(1) Preparation of ITCs extracts by using the dichloromethane solvent extraction and supercritical fluid extraction-CO2 technologies. (2) Research on the antioxidant activity and antisenescence properties of ITCs extracts. (3) Preparation and characterization of inclusion complexes of ITCs inβ-cyclodextrin cavity.The following major progresses were achieved in this work:ITCs crude extracts were prepared by methylene chloride solvent extraction method from broccoli seeds. The concentration of resulted extractum was up to 80%. The methylene chloride residue was determined and the technology was built to insure solvent residue to met safety requirements. It was favorable for further development the efficacy of ITCs extracts.The trouble was still focused on use of much organic solvents, and the consequence of contamination and safety worry was caused by the residual solvents. The supercritical fluid extraction-CO2 technology of ITCs was preliminarily constructed. The yield reached comparatively to 82% that of solvents extraction method.The antioxidant properties of ITCs extracts were evaluated by using the in vitro bioassays, including superoxide anion radical (02·-), hydroxyl radical (OH·), and 2, 2-diphenyl-l-picrylhydracyl (DPPH·) radical-scavenging methods, lipid peroxidation assay, and reducing power assay. The ITCs extracts exhibited significant antioxidant activities (P<0.01). The extracts due to purity disturbance were separated through Amberchrom CG161M reverse phase column in AKTA purifier 100 apparatus and analyzed further by GC-MS. Sulforaphane (SFN) was successfully separated and identified. The antioxidant activity of SFN was approximately one tenth to one fifth of that of vitamin C (Vc). It was experimented to be the dominating contributor to antioxidant capacity of ITCs extracts. However, there was no direct antioxidant activity found for benzyl isothiocyanate (BITC) in vitro. Therefore, the group (CH3-SO-CH2-) was the probable part to offer reactive hydrogen resulting in interdiction of free radical chain-reaction and lipid peroxidation. The antioxidant activity of ITCs extracts was sensitive to heat and light. Although its antioxidant-stability was affected by temperature and storage condition, it was more stable than Vc.The effect of ITCs extracts on senescence of melanogasters was studied. The life-span, sexual potency and reproduction ability of melanogasters were consistently improved in spite of no significant found for the prolongation of life-span. The activity of SOD enzyme was advanced and the accumulation of MDA was also inhibited in melanogasters in vivo. It is not well known about the antisenescence of ITCs extracts. This work is open to add knowledge to this area.The poor water-solubility of ITCs compounds is favorable for forming the inclusion complexes withβ-Cyclodextrin (β-CD), which is P-CD-ITC. In this work, P-CD-BITC,β-CD-PEITC (phenylethyl isothiocyanates, PEITC) andβ-CD-SFN inclusion complexes were prepared by co-precipitation processes. The UV spectrum was applied to quantity BITC, PEITC and SFN. Response surface design (RSD) was applied to optimize the preparation conditions. The association constants and inclusion ratios of three inclusion complexes were calculated. The inclusion complexes prepared were respectively analyzed by thermal methods (TG and DSC), Fourier transformation-infrared spectroscopic (FTIR), X-ray powder diffraction (XRD) and SEM micrographs means in order to characterize the inclusion behavior of ITCs andβ-CD. The results indicated that the interaction between the guest (BITC, PEITC and SFN) and host ((3-CD) molecules did occur except that the UV spectrum was kept unalterable. Hence, under proper inclusion conditions, it is the hydrophobic interaction force that forces the inclusion reaction. The thermal-stability of complexes was improved.更多还原