新疆药桑枝条中抗氧化活性成分sanggenon A的分离鉴定

Separation and Identification of the Antioxidant Compound Sanggenon A from Xinjiang Medicine Mulberry Branches

【目的】分离鉴定新疆药桑枝条中的抗氧化活性成分,揭示其抗氧化功效的物质基础,为发现新的天然抗氧化成分及新疆药桑的开发利用提供理论依据。【方法】将新疆药桑枝条利用70%乙醇冷浸的方法提取,滤液低温减压浓缩;TLC(薄层层析)与DPPH(1,1-二苯基-2-苦基苯肼)相结合的方式进行活性检测;以紫外显色、10%硫酸乙醇显色的方式进行物质检测;在活性跟踪下通过不同有机溶剂萃取分段、多次硅胶柱层析、凝胶柱层析及薄层层析,对新疆药桑枝条中抗氧化活性成分进行分离纯化。将分离得到的化合物以氘代氯仿为溶剂,TMS(四甲基硅烷)为内标,利用MS(质谱)及NMR(核磁共振)技术进行波谱测定及结构解析。以人工合成抗氧化剂BHT(2,6-二叔丁基-4-甲基苯酚)为对照,进行清除DPPH自由基、OH自由基及总还原力的测定。【结果】从新疆药桑枝条乙酸乙酯萃取部分中分离得到1种易溶于甲醇及乙酸乙酯的深黄色粉末,根据其理化性质初步判断为黄酮类化合物。结合其理化性质并通过MS,~1H-NMR,^(13)CNMR,DEPT的波谱数据分析,确定其为已知化合物sanggenon A(桑根酮A),分子式为C_(25)H_(24)O_7,分子量为436。抗氧化活性研究表明,其清除DPPH自由基和OH自由基的IC_(50)值分别为50.3和96.5 mg·L^(-1)(对照BHT分别为64.2和231.6 mg·L^(-1)),总还原力也明显高于对照。【结论】本文首次从桑树的枝条中分离得到该物质,拓展了提取分离该物质的原材料来源,可为新疆地区广泛种植的林业资源的开发利用提供理论基础。

【Objective】Xinjiang medicine mulberry branches are characterized by their strong antioxidation,but have been untapped as by-products which are annually and largely produced in sericulture.Study on separating and identifying antioxidant active component from Xinjiang medicine mulberry branches can reveal their physical basis of antioxidation,and provide a theoretical foundation for discovery of new natural antioxidant component and for exploitation of Xinjiang medicine mulberry.【Method 】 The components in medicine mulberry branches are extracted with 70% ethanol and concentrated by reducing pressure at low temperature.Together with DPPH（1,1-diphenyl-2 picrylhydrazyl）,TLC（ thin layer chromatography） was applied in activity detection,while ultraviolet spectrophotometry was used to detect the active substances with 10% sulfuric acid-ethanol solution coloration.Based on the activity tracking,separation and purification of the antioxidant compound in medicine mulberry branches were achieved by different organic solvents extraction and segmentation,repeated silica gel column chromatography,gel column chromatography and thin-layer chromatography.With deuterated chloroform as the solvent and TMS（tetramethylsilane） as the internal standard substance,the MS（ mass spectra） and NMR（nuclear magnetic resonance） techniques were employed to make spectrum and structure analysis on the compound,and then DPPH free radical and OH free radical scavenging,as well as the total reducing power assay are proceeded with the synthetic antioxidant BHT as a control.【Results】The deep yellow powder,freely soluble in methanol and ethyl acetate,was separated from Xinjiang medicine mulberry branches with ethyl acetate extraction.According to its physical and chemical properties,the powder is classified as flavonoids by preliminary judgment,and then with spectral data analysis by MS,^1H-NMR,^13C-NMR,and DEPT,it was finally identified as the known compound,sanggenon A,and its molecular formula is C_（25）H_（24）O_7,with the molecular weight of 436 Dalton.The antioxidant activity study showed that the IC_（50） values of scavenging DPPH radical and OH radical were 50.3 mg·L^-1 and 96.5 mg·L^-1,respectively（the IC_（50） values of the control BHT were 64.2 mg·L^-1 and 231.6 mg·L^-1,respectively）.The total reducing power is significantly higher than the control BHT.【Conclusion】The antioxidant component,Sanggenon A,is firstly separated from mulberry branches in this study,which expands the sources of raw materials for extraction and separation of the component.In addition,this study provides theoretical basis for the further study of Sanggenon A and for exploitation of medicine mulberries that,as a forestry resource,are widely cultivated in the region of Xinjiang.The mechanism of the Sanggenon A production in mulberry branches remains further study.