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

采用重复层析技术从生姜根茎中分离得到11种姜酚类化合物，分别为姜酚、姜辣素和脱氢姜二酮，取代基的碳链长度为8~12。通过5种方法评价了化合物的抗氧化活性：1)DPPH自由基清除活性；2)在乙醇-缓冲体系中对亚油酸自氧化的抑制作用；3)对亚油酸甲酯自氧化的抑制作用；4)用油稳定指数法评价其在通气和加热条件下对亚油酸甲酯氧化的抑制作用；以方法1和方法5为基础的这些成分的抗氧化活性顺序为：姜辣素[类似或等同]姜辣素和脱氢姜二酮。对亚油酸自氧化的抑制作用顺序为shogaol&gt；姜辣素&gt；脱氢姜二酮，而方法3和方法4的化合物的活性顺序为脱氢姜二酮&gt；姜辣素[类似或相同]shogaol。对于不同烷基链长的人参醇类化合物，基于方法2的相关活性与较长的烷基链长显著相关。这一发现也适用于不同烷基链长的阿魏酸酯。此外，使用方法1-4测量了肉桂酸相关化合物的作用。基于方法1、3和4，3，4-二羟基苯基的咖啡酸的活性最强，而基于方法2的4-羟基-3-甲氧基苯基的苯甲酸的活性最强。这些结果表明，不仅抗氧化剂清除自由基的能力，而且抗氧化剂由于烷基上的取代基与底物的亲和力也可能与抗氧化剂的活性有关。

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.