荔枝果实不同部位提取物的总黄酮含量及其稳定性、抗氧化、美白活性分析

Analysis of total flavonoids content, stability, antioxidant and whitening activities of extracts from different parts of litchi fruit

中文关键词:  荔枝果实  总黄酮  抗氧化活性  酪氨酸酶活性

英文关键词:litchi fruit  total flavonoids  antioxidant activity  tyrosinase activity

中文摘要:

      目的 探究荔枝果实不同部位多酚提取物(果肉、鲜干果核、鲜干果壳)中总黄酮含量及其稳定性、抗氧化及美白活性。方法 通过亚硝酸钠显色法测定荔枝果实不同部位多酚提取物中的黄酮类物质含量, 并以紫外分光光度法测定其对1,1-二苯基-2-苦基肼(1,1-diphenyl-2-picrylhydrazyl, DPPH)自由基的清除能力、稳定性(温度、pH及光照)及对酪氨酸酶的抑制活性。结果 荔枝果实不同部位多酚提取物中均有较高的总黄酮含量, 其中荔枝果肉多酚中黄酮占比最高为93.24%; 其DPPH自由基抗氧化活性顺序是: 荔枝果肉>鲜荔枝核>干荔枝核>鲜荔枝壳>干荔枝壳; 对酪氨酸酶抑制能力分别是: 荔枝果肉>干荔枝核>鲜荔枝核>鲜荔枝壳>干荔枝壳, 其中荔枝果肉与干荔枝核的半抑制浓度(half maximal inhibitory concentration, IC50)分别为0.197与0.241, 均优于熊果苷(IC50为0.343)。在同等温度、pH、自然光条件下, 荔枝果实总黄酮稳定性顺序分别是: 干荔枝壳>干荔枝核>鲜荔枝壳>鲜荔枝核>荔枝果肉。结论 荔枝果实不同部位多酚提取物均具有一定DPPH抗氧化活性、稳定性与酪氨酸酶抑制活性, 且其DPPH抗氧化活性和酪氨酸酶抑制活性均与其总黄酮含量和成分相关。荔枝果肉和荔枝壳、荔枝核等废弃物均可成为天然抗氧化剂与美白成分的原料来源, 为拓展荔枝果实在食品及日化行业的应用提供参考。

英文摘要:

      Objective To explore the total flavonoid content and stability, antioxidant and whitening activities of polyphenol extracts from different parts of litchi fruit (pulp, fresh and dried seeds, and fresh and dried pericarps). Methods The flavonoid content of polyphenol extracts from different parts of litchi fruits was determined by sodium nitrite colorimetry, and their scavenging ability to 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals, stability (temperature, pH and natural light) and inhibitory activity against tyrosinase were determined by UV spectrophotometry. Results The total flavonoid content was relatively high in polyphenol extracts from different parts of litchi fruit, with the highest percentage of flavonoids in the polyphenols of lychee pulp at 93.24%; the diminishing sequence of their DPPH antioxidant activity was litchi pulp, fresh litchi seeds, dried litchi seeds, fresh litchi pericarps, and dried litchi pericarps; Also, litchi pulp had the strongest inhibitory ability to tyrosinase, followed by dried litchi seeds, fresh litchi seeds, fresh litchi pericarps, dried litchi pericarps. Among them, litchi pulp and dried litchi seeds had strongest inhibitory activity, with the half maximal inhibitory concentration (IC50) of 0.197 and 0.241, respectively, and both better than arbutin (IC50 was 0.343); besides, the results showed that the descending order of stability from dried litchi pericarps, dried litchi seeds, fresh litchi pericarps, fresh litchi seeds, and litchi pulp, under the same conditions of temperature, pH and natural light. Conclusion There are certain DPPH antioxidant activity, stability and tyrosinase inhibitory activity in polyphenol extracts from different parts of litchi fruit, and their DPPH antioxidant activity and tyrosinase inhibitory activity are both related to their total flavonoid content and composition. Litchi pulp and the usually discarded litchi pericarps and seeds can be a source of raw materials for natural antioxidants and whitening ingredients, providing a reference for expanding the application of litchi fruit in the food and daily chemical industry.