3种来源黑木耳黑色素的性质及其体外抗氧化活性比较

Properties and Antioxidant Activities in vitro of Three Auricularia heimuer Melanin

该研究以黑木耳“1703”的子实体、菌丝体和发酵液为试验材料,采用碱溶酸沉法提取黑色素,采用紫外可见光谱(ultraviolet–visible spectroscopy,UV-Vis)、傅里叶变换红外光谱(Fourier transform infrared spectrometer,FTIR)、扫描电子显微镜(scanning electron microscope,SEM)、高效液相色谱(high performance liquid chromatography,HPLC)法研究黑色素的结构表征,测定黑木耳黑色素的溶解性、稳定性和体外抗氧化活性。UV-Vis结果表明3种来源黑木耳黑色素最大吸收波长均为210 nm。FTIR结果表明3种来源黑木耳黑色素均具有天然黑色素的3个特征吸收区。HPLC结果表明3种来源黑木耳黑色素均只有一个吸收峰,且保留时间基本一致。溶解性结果表明3种来源黑木耳黑色素均易溶于碱性溶液,微溶于75%乙醇溶液,难溶于水和多数有机溶剂。稳定性结果表明3种来源黑木耳黑色素均具有良好的温度稳定性和光照稳定性,Fe^(3+)能够促进黑色素溶解,Fe^(2+)和Cu^(2+)导致黑色素不稳定。体外抗氧化试验结果表明3种来源黑木耳黑色素对DPPH自由基、ABTS^(+)自由基和羟基自由基均具有较强的清除能力,其中发酵液黑色素清除能力最强。

In this study,the fruiting body,mycelium,and fermentation broth of Auricularia heimuer strain'1703'were used as experimental material.The alkali dissolution acid precipitation method was utilized to ex⁃tract melanin.The ultraviolet⁃visible spectroscopy(UV⁃Vis),Fourier transform infrared spectrometer(FTIR),scanning electron microscope(SEM)and high performance liquid chromatography(HPLC)were ap⁃plied to study the structural characterization of melanin,the solubility,stability,and antioxidant activity of melanin in vitro were determined.The UV⁃Vis results showed that the maximum absorption wavelength of three melanins was 210 nm.The FTIR results showed that the three melanins had three characteristic absorption re⁃gions of natural melanin.The HPLC results showed that there was only one absorption peak for three melanins,and the retention time was basically the same.The results showed that the melanin from the three sources was easily soluble in an alkaline solution,slightly soluble in 75%ethanol solution,and insoluble in sterile water and most organic solvents.The stability results showed that the three melanins had good temperature stability and light stability.Fe^(3+)can promote the dissolution of melanin,and Fe^(2+)and Cu^(2+)cause melanin instability.The results of in vitro antioxidant experiments showed that the three melanins had strong scavenging ability to DPPH,ABTS^(+),and OH free radical,among which the fermentation broth had the strongest melanin scavenging ability.