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

1999 Fiscal Year Final Research Report Summary

• Project/Area Number: 10660133
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 食品科学・栄養科学
• Research Institution: Osaka City University
• Principal Investigator: KIKUZAKI Hiroe Osaka City University, Faculty of Human Life Science, Lecturer, 生活化学部, 講師 (60291598)
• Project Period (FY): 1998 – 1999
• Keywords: ginger / gingerol / shogaol / dehydrogingerdione / ferulic acid related compounds / radical scavenging activity / antioxidant activity

Research Abstract

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.