C.-T. Yen et al. / Bioorg. Med. Chem. Lett. 20 (2010) 1037–1039
1039
Table 2
Table 3
Inhibitory effects of compounds on superoxide anion generation and elastase release
by human neutrophils in response to FMLP/CB
Cytotoxic effects of 1-analogs
Compd
KB
Cancer cell line (IC50 valuea,
lM)
Compd
Superoxide anion
IC50
M)a or (Inh%)
Elastase release
IC50
M)a or (Inh%)
KBvin
A549
DU-145
(
l
(l
1a
1b
1c
1g
1i
1j
1m
7
10.0 1.3
6.6 2.21
7.7 3.5
15.2 1.41
18.9 1.11
11.3 0.78
5.4 0.29
>20
NDb
8.1 1.2
8.2 0.72
Brazilein (1)
Brazilin (2)
4.0 0.42
4.6 0.63
14. 2 1.32
16.7 0.41
11.3 1.53
13.5 1.12
7.8 0.65
>20
11.0 0.47
7.1 0.44
17.5 0.67
18.1 1.54
11.0 0.67
9.1 0.75
>20
NDb
1a
1b
1c
1d
1e
1f
1g
1h
1i
1j
1k
1l
1m
1n
7
18.71 2.82
1.2 0.02
(40.87 3.49)***
1.9 0.31
3.28 0.51
13.25 1.14
(11.39 4.76)
15.50 2.40
13.6 1.09
(26.76 6.60)*
(35.54 1.71)***
8.37 0.41
16.9 0.42
17.9 0.9
16.5 1.56
NDb
18.3 0.26
6.4 0.67
>20
>20
1.65 0.09
(14.14 5.70)*
(16.37 3.71)
(ꢀ7.00 4.90)
4.65 1.31
(18.61 6.29)*
23.94 5.48
4.35 0.91
(33.38 7.75)**
16.16 0.40
19.72 4.44
19.69 5.82
NTb
15.3 1.04
9.4 0.49
>20
>20
>20
8
9
9.8 1.28
>20
10.6 0.42
>20
10
10.5 0.48
7.6 0.73
>20
13.8 1.26
Paclitaxelc
1.55 ꢁ 10ꢀ3
1.09 ꢁ 10ꢀ3
1.93 ꢁ 10ꢀ3
2.35 ꢁ 10ꢀ3
a
b
c
8.76 1.51
Data are expressed as mean SD (n = 3).
ND: not determined.
Positive control.
11.83 2.00
16.54 1.70
10.06 0.60
NTb
8
9
1.90 0.32
8.38 0.02
4.52 1.21
0.7 0.4
(43.71 2.00)***
10.25 0.14
(35.76 2.60)*
Table 1).6b Comparison of 1 to its synthetic intermediates 2 and
7–10 showed that the epoxy ketone 8 had comparable or enhanced
10
DPIc
PMSFc
activity, while the reduced diol 9 was inactive (IC50 > 20
addition, trimethylbrazilin 10 was more active than 2 with IC50
values of 10–15 M against all four human cancer cell lines. The
enhanced cytotoxicity of epoxide analog 8 could account for its
lM). In
130.9 2.91
a
IC50 represents the 50% inhibitory concentration of the compound. If 50%
inhibition was not reached at any test dose, the percentage of inhibition obtained at
a test dose of 10 g/mL is given in parentheses (Inh%). Results are presented as
l
l
mean S.E.M. (n = 3–5). *p <0.05, **p <0.01, and ***p <0.001 compared with the
twofold greater potency than
generation.
1 against superoxide anion
control value.
b
Abnormal absorption at OD 405 and 550 nm.
DPI and PMSF were used as positive controls.
c
Acknowledgments
the data showed that the former did provide better activity against
either superoxide anion generation or elastase release.
Among the eight compounds (1g–n) containing ether substitu-
ents, 1g (tri-methoxy) and 1j (di-ethoxy) displayed potent effects
This investigation was supported by a Grant CA 17625 from Na-
tional Cancer Institute, NIH, USA (K.H.L.), and by the National Sci-
ence Council, Taiwan (Y.-C.W.) and KMU-EM-97-2.1.b (Y.-C.W.).
in the superoxide anion assay (IC50 4.7 and 4.4
Analog 1j (di-ethoxy) also showed moderate effect (IC50
M) against elastase release, as did 1k (di-benzoxy) (IC50
M). Compounds 1l–n (allyl and prenyl ethers) were nonselec-
lM, respectively).
References and notes
a
8.4
8.8
l
l
1. Lockhart, I. M.. In Ellis, G. P., Ed.; The Chemistry of Heterocylic Compounds;
Chromenes, Chromanones and Chromones; John Wiley & Sons: New York,
1977.
tive, but with only weak inhibitory effects in both assays (IC50 10–
2. Malhotra, S.; Sharma, V. K.; Parmar, V. S. J. Chem. Res. 1988, 179.
3. Farkas, L.; Gottsegen, A.; Norgradi, M. Tetrahedron 1970, 26, 2787.
4. Huang, Y. D.; Zhang, J.; Pettus, T. Org. Lett. 2005, 26, 5841.
5. Davis, F.; Chen, B. C. J. Org. Chem. 1993, 58, 1751.
6. (a) Kim, D. S.; Baek, N. I.; Oh, S. R.; Jung, K. Y.; Lee, I. S.; Lee, H. K. Phytochemistry
1997, 46, 177; b Lai, W. C. Master Thesis, Kaohsiung Medical University, July
2007.
7. Ye, M.; Xie, W. D.; Lei, F.; Meng, Z.; Zhao, Y. N.; Su, H.; Du, L. J. Int.
Immunopharmacol. 2006, 6, 426.
8. Zhao, Y. N.; Pan, Y.; Tao, J. L.; Xing, D. M.; Du, L. J. Pharmacology 2006, 76, 76.
9. Kabbash, A.; Yagi, A.; Ishizu, T.; Haraguchi, H.; Fujioka, T.; Moustafa, S. M.; El-
Bassuony, A. A. Saudi Pharm. J. 2008, 16, 25.
10. Hu, J.; Yan, X.; Wang, W.; Wu, H.; Hua, L.; Du Lijun. Tsinghua Sci. Technol. 2008,
13, 474.
11. Hikino, H.; Taguchi, T.; Fujimura, H.; Hiramatsu, Y. Planta Med. 1977, 31, 214.
12. Bae, I. K.; Min, H. Y.; Han, A. R.; Seo, E. K.; Lee, S. K. Eur. J. Pharmacol. 2005, 513,
237.
13. Nagai, M.; Nagumo, S.; Lee, S. M.; Eguchi, I.; Kawai, K. I. Chem. Pharm. Bull. 1986,
34, 1.
14. Tolman, R. L.; Chin, A. C. WO Patent 0,193,864, Dec 13, 2001.
15. Mar, W.; Lee, H. T.; Je, K. H.; Choi, H. Y.; Seo, E. K. Arch. Pharmacol. Res. 2003, 26,
147.
20 M). These findings suggest that 1g and 1j merit further inves-
tigation as potential anti-inflammatory compounds.
Furthermore, among the synthetic intermediates 7–10 (Table
1), the epoxy ketone 8 was significantly potent and selective
l
(IC50 1.9
was moderately active in both anti-inflammatory assays (IC50 8.4
and 10.3 M), while the tetracyclic 10 was potent only against
superoxide anion generation (IC50 4.5 M).
lM) against superoxide anion generation. The diol 9
l
l
In conclusion, among all screened compounds, including ester
(1a–d), carbamate (1e and 1f), and ether (1g–n) derivatives, the
preliminary structure–activity relationship were addressed in the
order: a) ester > ether > carbamate; b) ethyl = methyl > allyl = pre-
nyl > benzyl. In particular, the most potent analog 1b was 65-fold
more active than PMSF, the positive control, in the elastase release
assay.
Anti-cancer activity: The homoisoflavonoids 1a–n as well as the
synthesized 1, 2 and intermediates 7–10 were examined for
in vitro cytotoxic activity against four human cancer lines. Table
3 lists the IC50 values obtained with test compounds compared
to the anticancer drug paclitaxel as a positive control. Among the
14 derivatives (1a–n), seven compounds (1a–c, 1g, 1i, 1j, and
1m) showed moderate potency against the tested human cancer
16. Namikoshi, M.; Nakata, H.; Yamada, H.; Nagai, M.; Saitoh, T. Chem. Pharm. Bull.
1987, 35, 2761.
17. Venkateswarlu, S.; Panchanula, G. P.; Guraiah, M. B.; Subbaraju, G. V.
Tetrahedron 2005, 61, 3013.
18. Siddaiah, V.; Rao, C. V.; Venkateswarlu, S.; Krishnaraju, A. V.; Subbaraju, G. V.
Bioorg. Med. Chem. 2006, 14, 2545.
19. Gao, G. Y.; Li, D. J.; Keung, W. M. Bioorg. Med. Chem. 2003, 11, 4069.
20. Hosoda, S.; Hashimoto, Y. Bioorg. Med. Chem. Lett. 2007, 17, 5414.
21. Chang, H. L.; Chang, F. R.; Chen, J. S.; Wang, H. P.; Wu, Y. H.; Wang, C. C.; Wu, Y.
C.; Hwang, T. L. Eur. J. Pharmacol. 2008, 586, 332.
22. Hwang, T. L.; Yeh, S. H.; Leu, Y. L.; Chern, C. Y.; Hsu, H. C. Br. J. Pharmacol. 2006,
148, 78.
cell lines with IC50 values of 5–18
much less active than paclitaxel.
lM; however, they all were
In our previous study, the parent compound 1 showed moder-
ate cytotoxic activity against six cancer cell lines (IC50 8–34 M,
l