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

采用重复色谱技术从生姜根茎中分离到11个与姜辣素相关的化合物，分别为姜辣素、姜辣素和被8 ~ 12碳链取代的脱氢姜辣二酮。通过五项指标评价了这些化合物的抗氧化活性；1) DPPH自由基清除活性，2)乙醇缓冲体系中亚油酸自氧化的抑制作用，3)亚油酸甲酯自氧化的抑制作用，4)油品稳定性指数法曝气和加热条件下亚油酸甲酯氧化的抑制作用，5)脂体氧化的抑制作用。方法1和方法5得到的抗氧化活性依次为：姜辣素、姜辣素、脱氢姜辣二酮。方法3和方法4对亚油酸自氧化的抑制作用为姜黄酮>姜黄酮>脱氢姜二酮，方法3和方法4对亚油酸自氧化的抑制作用为姜黄酮>脱氢姜二酮【相似或相等】姜黄酮。对于不同烷基链长度的ginerol相关化合物，基于方法2，烷基链越长，活性越高。这一发现也被观察到与不同长度的烷基阿魏酸酯的烷基链。此外，采用方法1-4测定肉桂酸相关化合物的作用。含3,4-二羟基苯基的咖啡酸在方法1、方法3和方法4中活性最强，含4-羟基-3-甲氧基苯基的茶酸在方法2中活性最强。这些结果表明，抗氧化剂的抗氧化活性不仅与自由基清除能力有关，还与烷基链上取代基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.