PT  - JOURNAL ARTICLE
AU  - Tohru Okuda
AU  - Emiko Kawai
AU  - Jun Harada
AU  - Eri Inoue
AU  - Masashi Hisamoto
AU  - Fumie Saito-Watanabe
TI  - Inhibition of Polyphenol Oxidase by Quercetin Derivatives in Grape Skin
AID  - 10.5344/ajev.2018.17115
DP  - 2018 Jul 05
TA  - American Journal of Enology and Viticulture
PG  - ajev.2018.17115
4099  - http://www.ajevonline.org/content/early/2018/06/29/ajev.2018.17115.short
4100  - http://www.ajevonline.org/content/early/2018/06/29/ajev.2018.17115.full
AB  - Polyphenol oxidase (PPO) inhibitors were isolated from grape skin and identified as quercetin derivatives. Among the inhibitors isolated, quercetin-3-glucoside (Q3Glc) was the most potent. Kinetic analysis of the inhibitory activity towards PPO was carried out with authentic Q3Glc using catechol as substrate. The inhibition was reversible and the inhibitory mechanism obtained from Lineweaver-Burk plots indicated that Q3Glc is a competitive inhibitor, and the inhibitory constant. (Ki) was 84.6 µM.