台灣產荔枝花主要抗氧化成份之分離、鑑定與分析及其抑制LPS誘發RAW264.7細胞一氧化氮生成之探討

Isolation, identification and analysis of the major antioxidant compounds in the flower of lychee (Litchi chinensis Sonn.) cultivated in Taiwan and their suppression for NO production in LPS-stimulated RAW 264.7 cells.

許全翔(Chuan-Hsiang Hsu)

指導教授 ： 林昭田 ； 楊登傑

中山醫學大學/健康管理學院/應用化學系碩士班/碩士(2011年)

https://doi.org/10.6834/CSMU.2011.00158

摘要

荔枝 (Litchi chinensis Sonn.) 屬無患子科 (Sapindaceae family)荔枝屬（Litchi）植物，為一種台灣重要的經濟作物，於三月下旬開花，六月下旬成熟。荔枝花一般都以廢棄物處理。我們先前的研究發現荔枝花的丙酮萃取物含有豐富的多酚類和極佳抗氧化力。因此本研究繼續將丙酮萃取物依次進行液液分離、矽膠管柱層析、LH-20管柱層析，所得的區分物均評估總酚與總類黃酮含量，及進行抗氧化活性測試 (總抗氧化力 (trolox equivalent antioxidant capacity, TEAC) 、DPPH (2,2-diphenyl-1-picrylhydrazyl hydrate) 自由基的清除能力和延遲Cu2+誘導LDL (low density lipoproteins) 的氧化能力) 。丙酮萃取物經液液萃取 (水、正丁醇、乙酸乙酯、正己烷) 以乙酸乙酯區分物的抗氧化活性較佳，且總酚及總類黃酮含量較高；再將此區分物經矽膠管柱層析得到13個區分，以第10~12區分物之抗氧化活性較好且總酚與總類黃酮含量較高；由第10~12區分再經 Sephadex LH-20管柱層各得到3個區分，以三者的第2區分最好；此三者之區分利用半製備型HPLC分離纯化得到兩個主要的抗氧化物質，經由Mass與NMR (nuclear magnetic resonance) 進行結構鑑定，確認荔枝花之主要抗氧化物質為表兒茶素(－)-epicatechin和原花青素proanthocyanidin A2。經由HPLC定量，凍乾的荔枝花 (－)-epicatechin 與proanthocyanidin A2含量分別為 5.48 及11.07 (mg/g of dry weight) 。

關鍵字

荔枝花 ； 抗氧化 ； 表兒茶素

並列摘要

Litchi (Litchi chinensis Sonn.) belonging to Sapindaceae family is one of the important commercial crops in Taiwan, which blooms in late March and fruit matures in late June. The flower is usually considered as disposable byproducts. Our pervious study found that acetone extract of litchi flower had a notable amount of phenol and also exhibited good antioxidant capacity. In the investigation, the acetone extract was further separated through liquid-liquid partition, silica gel column chromatography and Sephadex LH-20 column chromatography in turn. The amounts of phenol and flavonoid in each collected fraction were determined; the antioxidant activities for each fraction were also assayed with Trolox equivalent antioxidant capacity (TEAC), scavenging ability on 2, 2-diphenyl-2-picrylhydrazyl hydrate (DPPH) radicals and inhibition of Cu2+-induced oxidation of human low density lipoprotein (LDL).
The acetone extract of litchi flower was separated by liquid-liquid partition into n-hexane, ethyl acetate, n-butanol, and water fractions. The ethyl acetate fraction had the highest phenol and flavonoid levels as well as antioxidant capacities. Thirty sub-fractions could be obtained after the ethyl acetate fraction was subjected to silica gel column chromatography. The sub-fractions 10~12 with higher phenol and flavonoid levels and antioxidant capacities were applied to Sephadex LH-20 column chromatography. Each sub-fraction (10, 11 and 12) could be further separated into three minor parts, and the minor-part 2 from each sub-fraction was the best, which could be isolated two major compounds by semi-preparative high performance liquid chromatography (HPLC). (-)-Epicatechin and proanthocyanidin A2 identified with Mass and nuclear magnetic resonance (NMR) were the major antioxidant compounds in litchi flower; their amounts were 5.48 and 11.07 (mg/g dry weight), respectively.

並列關鍵字

litchi flower ； antioxidant ； epicatechin

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