【作者】 梁清蓉；

【导师】 钱和；

【作者基本信息】 江南大学 ， 食品科学与工程， 2005， 硕士

【摘要】 番石榴叶作为治疗腹泻、咳嗽等症的中草药,已经有几百年的应用历史。现代研究表明,正是番石榴叶中的酚类物质赋予它多种药用功效。本论文主要针对番石榴叶中酚类物质的提取工艺、分离鉴定、以及它们的抗氧化和抑菌活性进行了研究。首先探讨了溶剂法和酶法对番石榴叶酚类物质提取率的影响,并对其提取工艺进行了研究。通过单因素实验,确定了丙酮水溶液为较佳的提取溶剂,并发现提取时间、提取温度、溶剂浓度和原料粒度对提取率有较大的影响;通过正交实验和极差分析,确定了丙酮水溶液最佳的工艺参数为:提取温度60℃,提取时间1hr,溶剂浓度为50%,原料粒度为40目,在该工艺条件下得到的总酚含量即没食子酸当量（GAE: gallic acid equivalent）为143 mg GAE/g。另外,探讨了酶法对提取番石榴叶中酚类物质的影响,结果表明纤维素酶、果胶酶、碱性蛋白酶对酚类物质的提取率没有效果;而酸性蛋白酶有助于提高番石榴叶酚类物质的提取率,但提高的效率和幅度有限。其次对番石榴叶中酚类物质进行了分离纯化和鉴定。选用聚酰胺、硅胶、DA201、NKA、NKA-9、D3520和D4020等树脂进行了静态吸附实验。综合考虑它们的吸附率和解吸率,选用DA201进行柱分离。对DA201柱预分离得到的组分,进一步通过聚酰胺柱分离,得到组分A和B。利用RP-HPLC分析这两个组分,并将结果与标准品的液相色谱信息比较,发现样品中至少有7种酚类物质:没食子酸、原儿茶酸、阿魏酸、山奈素、咖啡酸、绿原酸、槲皮素等。接着又通过HPLC-ESIMS进行分析。根据液相色谱和质谱信息,证实样品中含有槲皮素、山奈素、金丝桃甙、异槲皮酮、番石榴苷和山奈素甙。其中还发现有三种未见文献报道的物质存在于番石榴叶提取物中,其具体结构有待鉴定。最后,利用DPPH自由基比色法测定了番石榴叶提取物的抗氧化活性。通过测定提取物的自由基清除率和EC₅₀,发现番石榴叶提取物具有抗氧化活性,其中的粗丙酮提取物有更佳的抗氧化性。另外还用滤纸片扩散法对番石榴叶提取物抗菌活性进行了研究,结果发现提取物对沙门氏菌、大肠杆菌、金黄色葡萄球菌等致病菌有较强的抑制作用。更多还原

【Abstract】 Guava leaf has been used for centruries as a herb for the treatment of diarrhea, cough andother diseases. Phenolics have been thought to be the main active compounds in guava leafwhich contribute to these pharmaceutical characters. In this study, our attention was much paidto the extraction, separation, identification of the phenolic compounds in guava leaf as well astheir antioxidative and antimicrobial activity.Firstly, the extraction processes of polyphenolic compounds from dry guava leaf includingsolvent extraction, enzymatic assisted extraction were discussed. It was found that the extractionrecovery was greatly impressed by different solvents, solvent concentration, extractingtemperature, extracting time and particle size of guava leaf. After one single test and a L9(34)orthogonal test, the optimum extracting condition were obtained 50% acetone solution,extraction temperature 60℃, extraction time 1hr, 40 Mu and the total phenols was 143 mg GAE(gallic acid equivalent)/g.Secondly, phenolics in guava leaf extract were purified and then identified. Several resinsincluding polyamide, silica gel, DA201, NKA, NKA-9, D3520, D4020 were investigated bycomparing their absorption and desorption rate. It was found that DA201 was proper for crudepurificating phenols in guava leaf extract. After first being separated through DA201 column, thecollection extract was further purified through polyamide coloumn. By UV screening, fraction Aand B were obtained. Identification of flavonoids and flavonoid glycosides in A and B wascarried out by means of HPLC-UV and HPLC-MS analysis. By using HPLC-UV, two knownphenolics (gallic acid and quercetin) and five new reported ones (procatechuic acid, chlorogenicacid, caffeic acid, kaempferol, ferulic acid) were identified in guava leaf extract. By usingLC-MS, two flavonoids (quercetin and kaempferol) and four flavonoid glycosides (three knowncomponents, quercetin 3-O-alpha-L-arabinoside, quercetin 3-O-beta-D-glucoside, quercetin3-O-beta-D-galactoside, along with one novel compound, kaempferol-glycoside) and three otherunknown compounds have been identified in the fractions.Finally, the antioxidant activity of guava leaf extracts was determined at ambienttemperature by means of a 2, 2-diphenyl-1-picrylhydryzyl (DPPH.) colorimetry with detectionscheme at 515 nm. It’s shown that guava leaf had high antioxidant activity, which wascomparable to that of ascorbic acid and quercetin (natural antioxidant). Crude acetone guava leafextract has higher antioxidative activity than water, alcoholic extract. What’s more, antimicrobialactivity of the guave leaf extract was also studied, and the result was shown that it was effectivein inhibiting the growth of Escherichia coli, Staphylococcus aureus, Salmonella.更多还原