Structure-activity relationship of antioxidative components isolated from ginger (Zingiber officinal)

从生姜根茎中分离得到11个姜酚类化合物，包括姜酚、姜烯酚和脱氢姜二酮，它们均被8~12个碳原子的烷基取代。通过五种方法评价了这些化合物的抗氧化活性; 1）清除DPPH自由基的活性，2）抑制亚油酸在乙醇-缓冲体系中的自氧化，3）抑制亚油酸甲酯的自氧化，4）使用油稳定性指数方法在通风和加热下对亚油酸甲酯氧化的抑制作用，以及5）脂质体的抗氧化作用。基于方法1和5的这些成分的抗氧化活性的顺序为姜烯酚[相似或相等]姜辣素>脱氢姜二酮。对亚油酸自氧化的抑制作用的顺序为姜烯酚>姜辣素>脱氢姜二酮，而基于方法3和4的化合物的活性的顺序为脱氢姜二酮>姜辣素[相似或相等]姜烯酚。关于具有不同烷基链长度的姜油素相关化合物，基于方法2，显著较高的活性与较长的烷基链相关。在具有不同长度烷基链的阿魏酸烷基酯的情况下也观察到这一发现。此外，使用方法1 - 4测量肉桂酸相关化合物的作用。基于方法1、3和4，具有3，4-二羟基苯基的咖啡酸显示最强活性，而基于方法2，具有4-羟基-3-甲氧基苯基的阿魏酸显示最强活性。这些结果表明，抗氧化剂的抗氧化活性不仅与其清除自由基的能力有关，而且与烷基链上的取代基所引起的抗氧化剂与底物的亲和力有关。

Eleven gingerol related compounds, gingerols, shogaols and dehydrogingerdiones substituted with an alkyl group bearing 8〜12 carbon chain length, were isolated from rhizomes of ginger (Zingiber officinale) using repeated chromatographic techniques. The antioxidant activities of these compounds were evaluated by five measurements ; 1) the DPPH radical scavenging activity, 2) the inhibitory effect on autoxidation of linoleic acid in ehtanol-buffer system, 3) the inhibitory effect on autoxidation of methyl linoleate, 4) the inhibitory effect on oxidation of methyl linoleate under aeration and heating using Oil Stability Index method and 5) the inhibitory effect on oxidation of liposome. The antioxidant activity of these constituents based on the methods 1 and 5 was in the order shogaols 【similar or equal】 gingerols > dehydrogingerdiones. The inhibitory effect on autoxidation of linoleic acid was in the order shogaols > gingerols > dehydrogingerdiones, while the activity of the compounds based on methods 3 and 4 was in the order dehydrogingerdiones > gingerols 【similar or equal】 shogaols. Concerning ginerol related compounds with different lengths of alkyl chain, significant higher activity was correlated with longer alkyl chains based on the method 2. This finding was also observed in the case of alkyl ferulates with different lengths of alkyl chain. In addition, the effects of cinnamic acid related compounds were measured using the methods 1-4. Caffeic acid with 3,4-dihydroxy phenyl group showed the strongest activity based on the methods 1, 3 and 4, while felulic acid with 4-hydroxy-3-methoxyphenyl group showed the strongest activity based on the method 2. These findings suggested that not only radical scavenging ability of antioxidant but also the affinity of the antioxidant with substrate owing to the substituents on the alkyl chain might contribute to the antioxidant activity.