【作者】 孟鹏；

【导师】 郑宝东；

【作者基本信息】 福建农林大学 ， 农产品加工及贮藏工程， 2013， 博士

【摘要】 金柑在尤溪已有300多年的栽培历史,营养丰富,果皮可与果肉一起食用,具有很高的观赏、食用和药用价值。目前对尤溪金柑有效成分的研究主要集中在黄酮类物质、挥发油、多糖等方面,而对金柑中柠檬苦素类化合物的研究鲜有报道。近年来,柠檬苦素类化合物已成为国内外研究的热点,该类物质具有抗癌、抑菌、抗氧化等活性。本文以福建尤溪金柑为原料,对金柑中柠檬苦素类化合物的提取、分离纯化、检测、分析鉴定、氧化动力学特征及抑菌活性进行了系列研究,旨在为开发金柑资源的保健功能和药理功能提供理论依据。主要研究结果如下：(1)研究建立了金柑中柠檬苦素和诺米林的UPLC检测体系,该检测体系中柠檬苦素和诺米林在1μg/mL～1780μg/mL和1μg/mL～1720μg/mL浓度范围内呈现出良好的线性关系,R2均为0.9999,加标回收率分别为97.19%～100.06%和95.35%-99.83%,相对标准偏差(RSD)分别为0.74%-2.25%和0.80%～3.36%,检出限分别为1.65μ g/g和1.28μg/g。UPLC检测体系保证分离度的同时,大大缩短了分析时间,减少了溶剂消耗,降低了分析成本,具有高效、合理、准确和重复性好等特点,可以用于金柑、柑橘、柚子、橙等植物中柠檬苦素类化合物的检测。(2)研究了夹带剂种类、夹带剂浓度、夹带剂添加量、萃取压力、萃取时间、二氧化碳流量、萃取温度7个单因素对柠檬苦素得率的影响,选取萃取压力、萃取时间、萃取温度3个因素,采用响应面分析法优化了超临界二氧化碳萃取金柑中柠檬苦素的工艺条件。最佳工艺条件为：萃取压力为34MPa,萃取温度为50℃,萃取时间为2.5h,在此优化条件下柠檬苦素最大得率为1.2g/kg。(3)运用了重结晶法对超临界二氧化碳萃取物进行了分离、纯化,得到了纯度较高的两种单体物质。通过红外吸收光谱(IR)、一维核磁共振(1D NMR)、二维核磁共振(2D NMR)等光谱学分析,解析了这两种柠檬苦素单体物质,鉴定了其结构,并经超高效液相色谱-串联三重四极杆质谱和超高效液相色谱-串联四极杆-飞行时间高分辨质谱进一步验证,确认为柠檬苦素和诺米林。(4)金柑柠檬苦素0.04%的添加量在猪油中能表现出较好的抗氧化效果。与抗氧化剂PG、BHT、Vc和VE比较,金柑柠檬苦素的抗氧化作用较低,但依然能使猪油的货架期寿命延长了近40%。油脂的抗氧化动力学研究结果表明,添加柠檬苦素的猪油氧化反应过程由一级反应转变为零级反应,速率常数为0.0135h-1,约为空白的1/10,说明猪油中柠檬苦素的添加降低了反应速率,改变了氧化反应历程,起到了抗氧化作用。(5)金柑柠檬苦素对金黄色葡萄球菌、志贺氏菌、沙门氏菌、枯草芽孢杆菌、大肠杆菌、黑曲霉和啤酒酵母具有一定的抑制作用。抑菌效果依次为：枯草芽孢杆菌>金黄色葡萄球菌>大肠杆菌>黑曲霉>志贺氏菌>沙门氏菌>啤酒酵母。最小抑菌浓度分别为：1.25mg/mL、1.25mg/mL、1.25mg/mL、2.50mg/mL、2.50mg/mL、2.50mg/mL、5.00mg/mL。最小杀菌浓度分别为：1.25mg/mL、2.50mg/mL、2.50mg/mL、2.50mg/mL、2.50mg/mL、5.00mg/mL、5.00mg/mL。金柑柠檬苦素在不同温度下的抑菌活性保持稳定,酸碱度对其抑菌活性影响显著。在酸性条件下,抑菌活性较强；碱性条件下抑菌活性不稳定,在强碱条件下,几乎无抑菌活性。更多还原

【Abstract】 Kumquat had more than300years cultivation histories in the Youxi. It’s nutrition is rich, including the Vitamin, mineral substance, amino acid, fructose, pectin and so on. The peel and the fruit pulp may edible together. It has very high watching, edible and medicinal value. Currently, the Youxi kumquat active ingredient research mainly focuses on flavonoids, volatile oils, polysaccharides and so on, while limonoids in kumquat rarely reported. In recent years, limonoids has become a hot research, the substance has the activity of anticancer, antibacterial and antioxidant.In this paper, Fujian Youxi kumquat as raw material, the limonoids extraction, purification, detection, analysis and identification, the oxidation kinetics and the antibacterial activity were studied. The studies provide a theoretical basis for the development of the health and pharmacological functions of kumquat.Results of the study are as follows,(1) UPLC detection system of limonin and nomilin was established. The method had good linear relationship in the range of1μg/mL～1780μg/mL for limonin(R2=0.9999) and1μg/mL～1720μg/mL for nomilin(R2=0.9999). Recovery ratios were97.19%-100.06%and95.35%-99.83%, and relative standard deviations were0.74%-2.25%and0.80%-3.36%, detection limit were1.65μg/g and1.28μg/g respectively. UPLC detection system greatly reduced the analysis time, the solvent consumption, the cost analysis in the condition of guarantee of the degree of seperation. The method possesses merits of efficient, reasonable, accuracy and resproducibility, it can be used for the detection of limonin and nomilin in kumquat, orange, grapefruit and other plants.(2) Effect on the limonin yield by the cosolvent type, cosolvent concentration, dosage of cosolvent, extraction pressure, extraction time, extraction temperature and CO2flow rate were studied. Extraction pressure, extraction time, extraction temperature were selected as main effect factors. Response surface methodology (RSM) was applied to optimize the process conditions for supercritical carbon dioxide extraction of limonin in kumquat. The optimal process conditions for supercritical carbon dioxide extraction were as follows:extraction pressure34MPa, extraction time2.5h, extraction temperature50℃. Under the certain condition, the yield of limonin was up to1.2g/kg.(3) The kumquat supercritical carbon dioxide extracts were isolated and purified by the recrystallization method, two high purity monomer substances were obtained. The substances identified as limonin and nomilin by infrared absorption spectrometry (IR), one-dimensional NMR (1D NMR), two-dimensional nuclear magnetic resonance (2D NMR), and with UPLC-MS/MS and UPLC-QTOF-MS furth verification.(4) Kumquat limonin showed good antioxidant effect on lard when the dosage is0.04%. Compared with antioxidants PG, BHT, VC, VE, the antioxiant activity of the limonin is low, but it still can make the shelf life of lard life extension for nearly40%. Oil oxidation kinetics studies showed that the oxidation reactions process of lard which adding the limonin, changing from one-level reaction to zero-level reaction, the constant of reaction rate is0.0135h-1,1/10of the blank lard approximately. The results showed that the kumquat limonin which added to lard reduced the reaction rate, changed the oxidizing reaction course and played the oxidation resistance role.(5) The antibacterial experiment in vitro showed that the kumquat limonin had inhibitory effect on Staphylococcus aures, Salmonella, Shigella, Escherichia coli, Bacillus subtilis, Aspergillus niger and Saccharomyces cervisiae. The inhibiting order of the kumquat limonin was Bacillus subtilis> Staphylococcus aures> Escherichia coli> Aspergillus niger> Shigella> Salmonella> Saccharomyces cervisiae. The minimum inhibition concentrations(MIC) were1.25mg/mL、1.25mg/mL、1.25mg/mL、2.50mg/mL、2.50mg/mL、2.50mg/mL、5.00mg/mL respectively. The minimum bactericidal concentration(MBC) were given as below:1.25mg/mL、2.50mg/mL、2.50mg/mL、2.50mg/mL、2.50mg/mL、5.00mg/mL、5.00mg/mL. The antibacterial activity of kumquat limonin remained stable at different temperatures, but pH affected its antibacterial activity significantly. The kumquat limonin had strong antibacterial activity under the acidic condition, but unstable under alkaline conditions. Under strong alkaline conditions, its had almost no antibacterial activity.更多还原