陈皮黄酮对苹果汁氧化褐变的抑制作用

The effect of flavonoids of Pericarpium Citri Reticulatae on oxidative browning of apple juice

从陈皮中提取得到总黄酮,将其分成石油醚、乙酸乙酯、乙醇和水四个不同的极性部分,分别测定其中的黄酮含量并研究各提取物在同一浓度下对苹果多酚氧化酶的抑制作用,对效果较好的提取物进行柱层析和薄层层析分离并鉴定结构,测定单体黄酮对苹果汁酶促氧化褐变的抑制作用。实验结果表明:陈皮总黄酮分为四个极性部分后,各部分黄酮含量大小为:乙酸乙酯部分>水部分>石油醚部分>乙醇部分,1 mg/mL的各提取物均能抑制苹果多酚氧化酶的活性,其中乙酸乙酯部分效果最显著,该部分经进一步分离得到黄酮单体化合物5-羟基-3,7,3′,4′-四甲氧基黄酮和5-羟基-3,6,7,8,3′,4′-六甲氧基黄酮,它们能降低苹果汁中多酚氧化酶(PPO)、过氧化物酶(POD)和苯丙氨酸解氨酶(PAL)的活性,抑制总酚含量上升,具有一定的抑制果汁褐变作用。

Petroleum ether,ethyl acetate,ethanol and water were used in flavonoids extract from Pericarpium Citri Reticulatae. The flavonoid content in each of the above extracts solvent was determined and their inhibition effects on apple polyphenol oxidase（PPO）were also studied at a given concentration. The extract which had strong inhibition effect on PPO was further isolated by column chromatography（CC）and thin layer chromatography（TLC）. The structures of monomeric flavonoids were identified and their inhibition on the oxidative browning of apple juice were studied. The results showed that the order of the flavonoid content in each solvent part was ：ethyl acetate 〉 water 〉petroleum ether 〉 ethanol. These extracts could inhibit the PPO activity at the concentration of 1 mg/mL. Ethyl acetate had the best effect and two flavonoid compounds of 5-hydroxy-3,7,3′,4′-tetramethoxflavone and 5-hydroxy-3,6,7,8,3′,4′-hexamethoxyflavone were obtained. These two flavonoid compounds can reduce the activities of polyphenol oxidase（PPO）,peroxidase（POD）,phenylalanine ammonialyase（PAL）and inhibit the increase of the total phenols in apple juice. Therefore,they have some inhibition abilities on the oxidative browning of fruit juice.