4058
Q. Yan et al. / Bioorg. Med. Chem. Lett. 19 (2009) 4055–4058
1
itor with IC50 value of 0.05 mmol/L. These observations, together
0.16
0.12
0.08
0.04
0.00
with the inhibitory effects of compounds 8, 11 and 12, indicated
that a 30-configuration of hydroxyl group might contribute to the
increase of inhibitory effects on mushroom tyrosinase.
The inhibition mechanism of compounds 12, 12a and 12b on
mushroom tyrosinase for the oxidation of L-DOPA was determined.
Figure 3A showed the relationship of enzyme activity with its con-
centration in the presence of different concentrations of compound
12. The results showed that the plots of V versus [E] gave a family
of straight lines with different slopes but they intersected one an-
other in the Y-axis. In the presence of compounds 12a and 12b, the
kinetics of the enzyme, were shown in Figure 3B and C. The plots of
V versus [E] gave a family of parallel straight lines with the same
slopes. These results demonstrated that the inhibitory effect of
compound 12 on the tyrosinase was reversible, whereas the inhibi-
tion of compounds 12a and 12b were irreversible, suggesting that
barbiturate and thiobarbiturate moieties of 5-benzyli-
2
3
4
0
2
4
6
8
[E](μM)
1
0.16
0.12
0.08
0.04
0.00
-0.04
-0.08
2
3
dene(thio)barbiturate-b-D-glycosides effectively inhibited the en-
zyme by binding to its binuclear active site irreversibly.
4
In conclusion, the present investigation reported the inhibitory
effects of 5-benzylidene(thio)barbiturate-b-
diphenolase activity of mushroom tyrosinase for the oxidation of
-DOPA. Compound 12b was found to be the most potent tyrosi-
D-glycosides on the
L
nase inhibitor with IC50 value of 0.05 mmol/L. SARs analysis indi-
cated that (1) 5-benzylidene thiobarbiturate substructures were
efficacious for the inhibitory activity; (2) the lipophilic property
of acetylated sugar moiety facilitated inhibitory potency; (3) the
hydroxyl group of 30-configuration contributed to the increase of
inhibitory effects. The inhibition mechanism study revealed that
2
4
6
8
[E](μM)
5-benzylidene(thio)barbiturate-b-
inhibitors. All these results suggested that 5-benzylidene(thio)bar-
biturate-b- -glycosides might be utilized for the development of
D-glycosides were irreversible
1
D
2
0.16
0.12
0.08
0.04
0.00
new candidate for treatment of dermatological disorders related
to tyrosinase.
3
4
Acknowledgment
This work was supported by the Natural Science Foundation of
Guangdong Province, China (2004B30101007) and the Open Pro-
ject of the State Key Laboratory of Biocontrol (2007-01).
Supplementary data
2
4
6
8
10
[E](μM)
Supplementary data associated with this article can be found, in
Figure 3. The effect of concentrations of tyrosinase on its activity for the catalysis
of -DOPA at different concentration of compounds 12 (A), 12a (B) and 12b (C). The
L
concentrations of compounds 12, 12a and 12b for curves 1–4 are 0, 0.5, 0.8 and
1.0 mmol/L, respectively.
References and notes
1. Sánchez-Ferrer, A.; Rodríguez-López, J. N.; García-Cánovas, F.; García-Garmona,
F. Biochim. Biophys. Acta 1995, 1247, 1.
2. Friedman, M. J. Agric. Food Chem. 1996, 44, 631.
3. Khan, K. M.; Mughal, U. R.; Khan, M. T. H. Bioorg. Med. Chem. 2006, 14, 344.
4. Shiino, M.; Watanabe, Y.; Umezawa, K. Bioorg. Med. Chem. 2001, 9, 1233.
5. Ley, J. P.; Bertram, H. J. Bioorg. Med. Chem. 2001, 9, 1879.
6. Maeda, K.; Fukuda, M. J. Pharm. Exp. Therap. 1996, 276, 765.
7. Funayama, M.; Arakawa, H.; Yamamoto, R.; Nishino, T. Biosci. Biotech. Biochem.
1995, 59, 143.
8. Sugimoto, K.; Nishmura, T.; Nomura, K.; Sugimoto, K.; Kuriki, T. Chem. Pharm.
Bull. 2003, 51, 798.
9. Yi, W.; Cao, R. H.; Wen, H.; Yan, Q.; Zhou, B. H. Bioorg. Med. Chem. Lett. 2008, 18,
6490.
10. Li, J.; Liu, P.; Na, D. Q.; Wu, X. N. J. Health Toxicol. 2001, 15, 110.
11. Liu, J. B.; Cao, R. H.; Yi, W.; Ma, C. M.; Wan, Y. Q.; Zhou, B. H.; Ma, L.; Song, H. C.
Eur. J. Med. Chem. 2009, 44, 1773.
12. Wen, H.; Lin, C. L.; Que, L.; Ge, H. Eur. J. Med. Chem. 2008, 43, 166.
13. Flecher, H. G.; Hudson, C. S. J. Am. Chem. Soc. 1947, 69, 921.
14. Ness, R. K.; Flecher, H. G.; Hudson, C. S. J. Am. Chem. Soc. 1951, 73, 959.
15. Oulmi, D.; Maillard, P.; Guerquin-Kern, J. L.; Huel, C. J. Org. Chem. 1995, 60, 1554.
16. Jyothish, K.; Avirah, R. R.; Ramaiah, D. Org. Lett. 2006, 8, 111.
17. Hu, Y.; Chen, Z. C.; Le, Z. G. Synth. Commun. 2004, 34, 4521.
inhibitory activity. These results, together with the above-men-
tioned inhibitory effects of compounds 1–2, 1a and 2a, suggested
that the lipophilic property of acetylated sugar moiety facilitated
inhibitory potency on mushroom tysosinase. To further investigate
the inhibitory effect of the position of glycoside at the aromatic
ring of 5-benzylidenethiobarbiturate, compounds 8b, 9b and 10b
bearing a glycoside moiety of 40-, 20- and 30-configuration were
examined for their tyrosinase inhibitory activities. As shown in Fig-
ure 3, compounds 8–10b all exhibited potent inhibitory effects
with the tendency of 40-(8b, IC50 = 0.23 mmol/L) > 20-(9b,
IC50 = 0.43 mmol/L) > 30-configuration (10b, IC50 = 0.87 mmol/L).
In addition, incorporation of additional hydroxyl group onto posi-
tion-2 of aromatic ring of compound 8b to give compound 11b
(IC50 = 0.28 mmol/L) showed slightly lower inhibitory activity,
whereas compound 12b having additional hydroxyl group of
30-configuration was found to be the most potent tyrosinase inhib-