| 摘要: |
| 研究了提取溶剂及其浓度、提取温度和有无氮气保护及提取时间对山杏种皮黑色素提取效果的影响,并对提取的山杏种皮黑色素与人工合成的多巴黑色素的理化性质进行了比较。结果表明,该黑色素适宜于用0.5mol/L NaOH在60 ℃下提取2次,每次12 h,提取宜在氮气下进行,以防止黑色素的过度氧化。在该工艺条件下,经过酸水解和进一步有机溶剂洗涤及反复沉淀纯化以后,可从5 g山杏种皮中得到黑色素237 mg,得率为4.73%;山杏种皮黑色素中总多酚含量较高,约为262 mg/g。山杏种皮黑色素与合成多巴黑色素的理化性质非常相似,不溶于水和常见的有机溶剂,在1 mol/L KOH溶液中完全溶解,pH小于3时发生沉淀,可被KMnO4、K2Cr2O7、NaClO和H2O2氧化漂白,多酚定性反应呈阳性;在紫外-可见光区没有吸收峰,红外光谱中在3 400 cm-1附近和1 650～1 620cm-1各有一个强的吸收带。 |
| 关键词: 山杏 种皮 黑色素 提取工艺 理化性质 |
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| 基金项目:国家林业局“948”项目(2004-4-52) |
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| Isolation of melanin from testae of Prunus ameniaca Linn |
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| Abstract: |
| Melanin was extracted from testae of Prunus ameniaca first and the effective extraction of melanin was explored.The result showed the melanin was suitable to be extracted twice with 0.5 mol/L NaOH at 60 ℃ for 12 h,and the operation should be carried out under nitrogen to avoid excessive oxidation.After acid hydrolysis,further purification with organic solvents and repeated precipitation,4.73% yield of melanin was obtained.The melanin from testae of Prunus ameniaca contained higher total phenolic content,about 262 mg gallic acid equivalents per gramme.The physicochemical properties of the melanin from testae of Prunus ameniaca showed a strong similarity to these of synthetic DOPA melanin.They were insoluble in both water and common organic solvents but dissolved only in alkali,while precipitated in alkaline FeCl3 and when pH is below 3,and were bleached in KMnO4,K2Cr2O7,NaClO and H2O2,and produced a blue color with FeSO4/ferricyanide.In the ultraviolet and visible range of wavelengths the melanin absorption spectrum represents the decreasing line.The infrared spectra had the same strong absorption peaks as the broad band at 3 400 cm-1 and at 1650-1620 cm-1,respectively. |
| Key words: Prunus ameniaca,testae,melanin,isolation,physicochemical property |
