女贞果实的抗氧化性测定

Determination of Antioxidant Activity of Extracts from Ligustrum lucidum Fruit

以南京产女贞果实为原料,考察不同提取剂对女贞果实不同部位(全果、果皮、核壳和果仁)提取所得提取液对DPPH自由基的清除效果,比较向阳面和向阴面不同生长期女贞果实的乙醇提取液对DPPH自由基的清除效果,研究固体状乙醇提取物的抗氧化性,测定女贞果实抗氧化的主要化学成分和固体状乙醇提取物的感官指标。结果表明:极性溶剂提取液表现出较强的清除DPPH自由基的能力;不同提取剂对女贞果实不同部位的提取物清除DPPH自由基能力的顺序为:甲醇、水的提取物为果皮>全果>核壳>果仁,丙酮、乙酸乙酯、乙醇的提取物为果皮>全果>果仁>核壳;提取物在低浓度区对DPPH自由基的清除作用与浓度成正相关,且斜率大大高于高浓度区,而高浓度区对DPPH自由基的清除作用与浓度的关系较复杂,表现为与提取剂密切相关。另外果实以成熟初期的提取物对DPPH自由基清除率最高,在成熟中期和过成熟期后均有不同程度下降,而且向阳面生长果实提取物对DPPH自由基的清除率显著高于向阴面果实提取物。抗氧化比较实验得到所制备的固体状女贞全果乙醇提取物抗氧化效果(IC50=5.38～10.46)与VC(IC50=8.59)相当,低于茶多酚(IC50=1.70)。另外,水溶性好、呈深咖啡色固体状的乙醇提取物有望成为一种新型高效抗氧化剂。

The DPPH radical scavenging effects of different solvent extracts from different parts of Ligustrum lucidum fruit growing in Nanjing were comparatively investigated.Moreover,the effects of sunlight illumination and growth period on the DPPH free radical scavenging activity of ethanol extract from whole Ligustrum lucidum fruit were examined,and the lyophilized ethanol extract from whole Ligustrum lucidum fruit was subjected to sensory evaluation and comparison with VC and tea ployphenols in free radical scavenging capacity.Polar and non-polar solvents were employed to extract Ligustrum lucidum fruit,and the extracts derived from polar solvent extraction showed stronger DPPH free radical scavenging capacity.Solvents and fruit parts both made a difference to DPPH free radical scavenging capacity.The same solvent extracts from different fruit parts obtained with methanol,ethanol or water were ranked in the following order starting with the strongest：peel 〉whole fruit〉 shell〉 kernel.For acetone,ethyl acetate and ethanol extracts,the order was peel 〉whole fruit 〉kernel〉 shell.All five solvent extracts from whole fruit showed a positive correlation between DPPH free radical scavenging activity and concentration in the lower concentration range,and the slopes were much higher than those in the higher concentration range.However,the concentration-effect relationship in the higher concentration range was complicated and closely associated with solvent type.The highest DPPH free radical scavenging activity of Ligustrum lucidum fruit was observed at the early ripening stage,followed by different decreases at the middle and post ripening stages.The ethanol extract from Ligustrum lucidum fruit exposed to sunlight revealed significantly higher DPPH free radical scavenging activity than that from Ligustrum lucidum fruit unexposed to sunlight.The lyophilized ethanol extract from whole Ligustrum lucidum fruit had a DPPH free radical scavenging capacity（IC50= 5.3810.46） equivalent to that（IC50 = 8.59） of VC but lower than that（IC50 = 1.70） of tea polyphenols.The solid water-soluble ethanol extract in dark brown is a potential effective antioxidant.