Figure 1.
(Oxyresveratrol-4-O-b-D-glucopyranosyl-3′-O-b-D-glucopyranoside or 2, 4, 3′, 5′-tetrahydroxystilbene).
Figure 2.
3D (A) and 2D profiles (B) of E30 fraction on analytic and prepared HPLC-DAD.
Figure 3.
3D(A),2D(B) profiles on HPLC and UV-visible spectra(C)of MA.
Figure 4.
Consecutive UV-Vis spectra obtained in the oxidation of 0.5 mmol/L L-tyrosine by mushroom tyrosinase in the absence sample (a), in presence of 2 mmol/L mulberroside A (b) or oxyresveratrol (c) for 12 min.
Spectra scans were repeatedly at a speed of 300 nm/30 s in 2 min intervals.
Figure 5.
Using N-acetyl-L-tyrosine as a substrate, because of the presence of an acetate group on the N-group of an amino acid, intracyclization of dopaquinone to leukodopachrome is blocked.
Figure 6.
The change in the content of N-acetyl-L-tyrosine as a substrate for tyrosinase in the absence of sample (A), in the presence of 175.9 µmol/L MA (B) or oxyresveratrol (C) during 60 min. HPLC analysis of the redox reaction of p-benzoquinone and L-DOPA in the absence of sample (D), or in the presence of mulberroside A (E), or in the presence of oxyresveratrol (F) at 245 nm. HPLC profiles of the redox reaction of p-benzoquinone and L-DOPA in the absence of PBS (G), mulberroside A (H) or oxyresveratrol (I) at different reaction times of 0, 10, 20 and 30 min.
Figure 7.
Inhibition effects of mulberroside A (blue line) and oxyresveratrol (red line) on the monophenolase activity of mushroom tyrosinase.
Figure 8.
The reversible inhibitory reaction of Mulberroside A (Left) and oxyresveratrol (Right) on monophenolase of mushroom tyrosinase.
Figure 9.
Determination of the inhibitory type and inhibition constant of MA (Left) and oxyresveratrol (Right) on monophenolase of mushroom tyrosinase.
(A) Lineweaver-Burk plots for inhibition of MA or oxyresveratrol on monophenolase. (B) and (C)represent the plots of slope and intercept versus the concentration of MA for determining the inhibition constant KI and KIS.
Table 1.
Inhibition effect of mulberroside A and of oxyresveratrol on the monophenolase activity of the mushroom tyrosinase.
Figure 10.
Inhibition effects of mulberroside A (blue) and oxyresveratrol (red) on the diphenolase activity.
Figure 11.
The inhibitory mechanism of Mulberroside A (a) and oxyresveratrol (b) on diphenolase of mushroom tyrosinase was reversible.
Figure 12.
Inhibition constant of MA (a) and oxyresveratrol (b) on diphenolase of mushroom tyrosinase.
(A) Lineweaver-Burk plots for inhibition of MA on diphenolase. (B) The plots of slope versus the concentration of mulberroside A for determining the inhibition constants KI, respectively.
Table 2.
Inhibition effects of MA and of OR on the diphenolase activity of the mushroom tyrosinase.