酸碱粗提配合超声破碎法制取可溶性长牡蛎(Crassostrea gigas)黑色素的研究

虽然牡蛎黑色素已经提取鉴定成功,但因为大部分实验需要用到黑色素的水溶液,而天然黑色素不溶于水,致使天然长牡蛎(Crassostrea gigas)黑色素的功效验证工作难以开展。本课题组探究总结出一套有效方法,对可溶性长牡蛎黑色素进行制取。首先选用酸碱法,从黑色长牡蛎中提取出天然长牡蛎黑色素,将其溶于氢氧化钠溶液中,利用超声细胞破碎仪进行处理,用盐酸中和至中性,离心取上清并干燥后得到一种黑色可溶性固体;再将该黑色固体分别用激光粒度测试仪、红外光谱仪和紫外光谱扫描仪进行检验后,发现天然长牡蛎黑色素经过超声降解处理后,颗粒粒度大幅下降,其溶解性大幅提高。红外光谱则显示出1630nm左右有明显的峰值,说明超声降解处理并未破坏真黑色素吲哚环等官能团;紫外吸光图谱的比较则显示天然长牡蛎黑色素破碎后,吸收峰仍然出现在210nm左右,但吸收值明显升高,说明超声降解法可以将难溶于水的天然长牡蛎黑色素降解为可溶于水的小颗粒可溶性黑色素,从而提高了紫外吸收值。可溶性牡蛎黑色素的制备成功对推动牡蛎黑色素的功能研究具有重要意义。

THE PREPARATION OF SOLUBLE PACIFIC OYSTER MELANIN USING THE PH-SHIFT PROCESSING AND ULTRASONIC-ASSISTED PROCEDURE

Oyster melanin has been extracted and identified successfully. Due to its poor solubility, it is difficult to validate the efficacy of natural oyster melanin because most of experiments need melanin solution. To this end, we introduce a method which can get the soluble melanin of Pacific oyster (Crassostrea gigas). Firstly, the method of acid and alkali was chosen to extract the natural oyster melanin from oysters with black shells, then the extracted melanin was dissolved in sodium hydroxide solution, the solution was processed by the ultrasonic cell disruptor and balanced out with hydrochloric acid, the supernatant liquid was retained after centrifuge and the solvable melanin was got after drying. The natural oyster melanin and the solvable melanin was tested by laser particle size tester, infrared spectrometer, and ultraviolet spectrum scanner inspection, respectively. We found that the grain size of the oyster melanin has fallen dramatically, which greatly increased solubility. Infrared spectroscopy results showed that the absorption curve of the solvable melanin solution has an obvious peak around 1630 nm, which hinting that the ultrasonic degradation process does not destroy the indole ring functional groups of eumelanin. The results of UV absorbance spectrum shows that the absorption peak of the solvable oyster melanin still appeared around 210 nm but its absorption value was significantly higher than that of natural oyster melanin, suggesting that the ultrasonic degradation can make the natural oyster melanin to degrade into the small grained soluble melanin. The success of acquiring the soluble Pacific oyster melanin is important to validate the efficacy of oyster melanin in animal testing.