Stability to Light, Heat, and Hydrogen Peroxide at Different pH Values and DPPH Radical Scavenging Activity of Acylated Anthocyanins from Red Radish Extract
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- 作者：Hiroshi Matsufuji ; Hirotsugu Kido ; Hisashi Misawa ; Junichi Yaguchi ; Takashi Otsuki ; Makoto Chino ; Mitsuharu Takeda ; Kazuo Yamagata
- 刊名：Journal of Agricultural and Food Chemistry
- 出版年：2007
- 出版时间：May 2, 2007
- 年：2007
- 卷：55
- 期：9
- 页码：3692 - 3701
- 全文大小：305K
- 年卷期：v.55,no.9(May 2, 2007)
- ISSN：1520-5118
文摘
The stability of red radish extract to light, heat, and hydrogen peroxide at different pH values (3, 5,and 7) was examined, in which major anthocyanins were pelargonidin glycosides acylated with acombination of p-coumaric, ferulic, or caffeic acids. The light irradiation (fluorescence light, 5000 lx;at 25 
C) indicated that the red radish extract was more stable at lower pH than at higher pH. TheHPLC analyses revealed that diacylated anthocyanins in the extract were more stable to light at pH3 than monoacylated anthocyanins. No significant difference in degradation rates of acylatedanthocyanins at pH 5 was observed, whereas anthocyanins acylated with p-coumaric or ferulic acidswere more stable at pH 7 than ones with caffeic acids. The stability to heat (at 90-95 C) showeda tendency similar to that for light. The number of intramolecular acyl units contributes to stability tolight and heat at lower pH, whereas the characteristics of intramolecular acyl units influence the stabilityat higher pH. The degradation behavior of red radish extract to H2O2 were almost the same to thoseof light and heat, depending on the pH. However, HPLC analyses revealed that the stability of individualacylated anthocyanins were independent of the pH. These data suggest that the characteristics, thenumber, and the binding site of intramolecular acyl units affect the stability of anthocyanin to H2O2.DPPH radical scavenging activity of all acylated anthocyanins was higher than those of pelargonidinand perlargonidin-3-glucoside. The activity of acylated anthocyanins mostly depended on the activityof intramolecular acyl units (caffeic acid > ferulic acid > p-coumaric acid). However, the activity washighly affected by the binding site of intramolecular acyl units even if anthocyanins have commonacyl units.
C) indicated that the red radish extract was more stable at lower pH than at higher pH. TheHPLC analyses revealed that diacylated anthocyanins in the extract were more stable to light at pH3 than monoacylated anthocyanins. No significant difference in degradation rates of acylatedanthocyanins at pH 5 was observed, whereas anthocyanins acylated with p-coumaric or ferulic acidswere more stable at pH 7 than ones with caffeic acids. The stability to heat (at 90-95 C) showeda tendency similar to that for light. The number of intramolecular acyl units contributes to stability tolight and heat at lower pH, whereas the characteristics of intramolecular acyl units influence the stabilityat higher pH. The degradation behavior of red radish extract to H2O2 were almost the same to thoseof light and heat, depending on the pH. However, HPLC analyses revealed that the stability of individualacylated anthocyanins were independent of the pH. These data suggest that the characteristics, thenumber, and the binding site of intramolecular acyl units affect the stability of anthocyanin to H2O2.DPPH radical scavenging activity of all acylated anthocyanins was higher than those of pelargonidinand perlargonidin-3-glucoside. The activity of acylated anthocyanins mostly depended on the activityof intramolecular acyl units (caffeic acid > ferulic acid > p-coumaric acid). However, the activity washighly affected by the binding site of intramolecular acyl units even if anthocyanins have commonacyl units.