Figures index : Concurrent Accumulation of Myricetin and Gallic Acid Putatively Responsible for the Umami Taste of a Specialized Old Oolong Tea : Science and Education Publishing

Figures index

Journal of Food and Nutrition Research. 2013, 1(6), 164-173 doi:10.12691/jfnr-1-6-8

Figure 1. Tea leaves and infusions of a fresh oolong tea and the umami tea. Tea leaves were shown before and after tea preparation. After tea preparation (95°C for 15 min), the tea infusions were kept at room temperature for 30 min prior to photographing

Figure 2. Liquid chromatography profiles (0-75 min) of infusions of the fresh oolong tea (A) and the umami tea (B) at 280 nm; In comparison with the fresh oolong tea, major phenolic compounds apparently decreased and increased in the umami tea were indicated by down and up arrows, respectively

Figure 3. Liquid chromatography profiles (0-75 min) of infusions of the intermediate umami teas after baking for 2, 3 and 4 years at 280 nm, Amplification of each profile from 40 to 65 min is shown in an inserted panel within the diagram; AFTGs represents acylated flavonol tetraglycosides identified previously [12]

Figure 4. Contents of glutamate in the tea samples during the conversion of umami tea; Contents of glutamate in the fresh oolong tea, umami tea and intermediate umami teas after baking for 2, 3 and 4 years were analyzed and compared. Data are mean ± SEM (n = 3)

Figure 5. Chemical structures of tea phenolic compounds used for molecular modeling; Gallic acid, myricetin, quercetin, three catechins (GC, EGC and EGCG), and two flavonol glycosides (K-3G and M-Gal) were selected for molecular docking to the umami receptor in this study

Figure 6. Binary docking of myricetin and gallic acid to the umami receptor compared with that of glutamate and IMP, the known umami ligand and enhancer, respectively. The right panels show the modes of the umami receptor (in ribbon structure) with or without the docking of ligands and enhancers (in pink and green ball-and-stick, respectively). The magnified docking sites are shown in the left panels along with the labeled distance between the two lobes of the binding cavity

Figure 7. Detailed molecular interactions of myricetin-gallic acid (A) or glutamate-IMP (B) within the binding cavity of the umami receptor; Molecular interactions between the two sets of binary docking molecules (ligand and enhancer) and the umami receptor shown in Figure 6 are illustrated in more details. Ligands and enhancers are depicted in pink and green ball-and-stick, respectively. Residues belonging to the upper lobe, the lower lobe and the hinge region are labeled in blue, red and black. Hydrogen bonding is shown in green dashed lines, and -stacking or -cation interaction is designated in orange lines

Figure 8. Docking of major catechins to the binding cavity in the umami receptor along with their corresponding molecular interactions; Three representative catechins, GC (A), EGC (B) and EGCG (C), depicted in pink ball-and-stick, are selected for the docking modeling in company with gallic acid, depicted in green ball-and-stick, except for EGCC. Detailed molecular interactions of the three catechins within the binding cavity of the umami receptor are shown in the right panels along with the distance between the two lobes of the binding cavity labeled in the left panels

Figure 9. Docking of tea flavonol compounds to the binding cavity in the umami receptor along with their corresponding molecular interactions; Three representative flavonol compounds, quercetin (A), K-3G (B) and M-Gal (C), depicted in pink ball-and-stick, are selected for the docking modeling in company with gallic acid, depicted in green ball-and-stick. Detailed molecular interactions of the three flavonol compounds within the binding cavity of the umami receptor are shown in the right panels along with the distance between the two lobes of the binding cavity labeled in the left panels