654
L. Zhang et al.
Arch. Pharm. Chem. Life Sci. 2007, 340, 650–655
7,8,39,49,59-Pentamethoxyflavone 3
2(R,S)-59-Hydroxy-7,8,39,49-tertramethoxyflavan (l) 2
Compound 13 (0.50 g, 1.12 mmol) was stirred in MeOH (5 mL) in
the presence of 10% Pd-C (0.80 g, 0.75 mmol Pd0) under a hydro-
gen atmosphere at room temperature for 12 h. The catalyst was
filtrated and washed with EtOAc. The filtrate was concentrated
in vacuo and purified by column chromatography silica gel to
give The natural flavan racemate (l) 2 (0.32 g, 82.6%) as a oil. 1H-
NMR (300 MHz, CDCl3) d: 2.01 (1H, m), 2.18 (1H, m), 2.74 (1H, m),
2.88 (1H, m), 3.85 (6H, m), 3.88 (6H, s), 5.02 (1H, dd, J1 = 2.5 Hz, J2 =
9.6 Hz), 5.80 (1H, s), 6.49 (1H, d, J = 8.5 Hz), 6.76 (1H, d, J = 8.5 Hz),
6.59 (1H, d, J = 1.7 Hz), 6.65 (1H, d, J = 1.8 Hz). 13C-NMR (CDCl3) d:
24.1, 29.4, 55.4, 55.8, 60.3, 60.5, 77.1, 101.4, 104.2, 105.3, 115.1,
123.0, 134.6, 136.8, 137.5, 148.3, 148.7, 151.2, 152.2. MS (ESI) m/z:
347 [M+H]+. Anal. Calcd. for C19H22O6: C, 65.88; H, 6.40. Found: C,
65.81; H, 6.37.
Compound 12a (2.20 g, 5.64 mmol) was refluxed for 6 h in 10 mL
of acetic acid. The mixture then was poured onto 120 mL of ice
water to precipitate the flavone. After purification by column
chromatography over silica gel (n-hexane : EtOAc = 5 : 1), the nat-
ural flavone 3 was obtained (1.52 g, 72.4%) as a white solid: mp.
205–2068C (lit [10] mp 2068C). 1H-NMR (300 MHz, CDCl3) d: 3.94
(3H, s), 3.97 (6H, s), 4.02 (3H, s), 4.05 (3H, s), 6.80 (1H, s), 7.07 (1H,
d, J = 9.0 Hz), 7.21 (2H, s), 7.97 (1H, d, J = 9.0 Hz). 13C-NMR (CDCl3)
d: 56.1, 56.2, 56.3, 60.7, 61.5, 103.5, 106.1, 109.9, 118.1, 120.5,
126.7, 136.7, 141.3, 150.5, 153.5, 156.7, 162.6, 177.5. MS (ESI) m/z:
395 [M+Na]+. Anal. Calcd. for C20H20O7: C, 64.51; H, 5.41. Found: C,
64.49; H, 5.38.
59- Benzyloxy-7,8,39,49-tertramethoxyflavone 13
Compound 12b (1.20 g, 2.58 mmol) was refluxed for 6 h in acetic
acid (50 mL). The mixture then was poured onto 120 mL of ice
water and 10% NaOH was used to adjusted the pH 6–7. Then,
the mixture was extracted with EtOAc (3650 mL). The organic
layer was washed by brine (2630 mL) and dried over anhydrous
Na2SO4. After filtration, the liquid was concentrated and the resi-
due could be purified by column chromatography over silica gel
(n-hexane : EtOAc = 5 : 1) to give 13 (0.84 g, 72.6%) as a yellow
Cytotoxicity assays
SGC-7901, BEL-7402, HeLa, and HL-60 cell lines were obtained
from Chinese Academy of Medical Sciences (Beijing, China). Cells
were cultured in RPMI-1640 medium (Sigma, USA) supple-
mented with 10% heat-inactivated fetal calf serum (HyClone,
USA), 2 mmol/L glutamin (GIBCO, USA), 100 KU/L penicillin and
100 g/L streptomycin (GIBCO, USA) at 378C in 5% CO2. SGC-7901,
BEL-7402, HeLa, and HL-60 cells were plated at 56103 cells per
96-well cell culture plate, and incubated for 24 h at 378C. The
various concentrations of series of the test compounds were
then added to growth medium. As a control group, DMSO (end-
concentration of 0.1%) was added to growth medium. After 72 h
treatment, cell viability was determined by MTT assay [18]. The
percentage of cell growth inhibition was calculated as follows:
1
solid: mp. 155–157 C. H-NMR (300 MHz, CDCl3) d: 3.96 (6H, s),
3.99 (3H, s), 4.01 (3H, s), 5.24 (2H, s), 6.69 (1H, s), 7.06 (1H, d, J =
9.0 Hz), 7.19 (1H, d, J = 1.8 Hz), 7.24 (1H, d, J = 1.8 Hz), 7.33–7.49
(5H, m), 7.95 (1H, d, J = 9.0 Hz ). MS (ESI) m/z: 471 [M+Na]+. Anal.
Calcd. for C26H24O7: C, 69.63; H, 5.39. Found: C, 69.51; H, 5.34.
Inhibition (%) = [A570(control) – A570(drug)]/A570(control)6100
59-Hydroxy-7,8,39,49-tertramethoxyflavone 4
A solution of 13 (0.26 g, 0.58 mmol) in EtOAc (10.0 mL) was
stirred in the presence of 10% Pd-C (0.02 g) under a hydrogen
atmosphere at room temperature for 10 h. The catalyst was fil-
trated and washed with EtOAc. The filtrate was concentrated in
vacuo and purified by column chromatography silica gel (n-hex-
ane : EtOAc = 5 : 1) to give the natural flavone 4 (0.19 g, 85.5%) as
a light yellow solid: mp. 211–2138C (lit [10] mp. 212–2138C). 1H-
NMR (300 MHz, CDCl3) d: 3.94 (3H, s), 3.97 (3H, s), 4.01 (3H, s),
4.05 (3H, s), 4.72 (1H, s), 6.70 (1H, s), 7.09 (1H, d, J = 9.0 Hz), 7.12
(1H, d, J = 1.8 Hz), 7.24 (1H, d, J = 1.8 Hz), 7.94 (1H, d, J = 9.0 Hz).
13C-NMR (CDCl3) d: 55.7, 56.2, 60.5, 61.3, 101.6, 105.6, 107.1,
109.8, 117.5, 120.6, 126.5, 136.7, 139.4, 150.3, 150.5, 153.1,
156.7, 163.2, 178.8. MS (ESI) m/z: 359 [M+H]+. Anal. Calcd. for
C19H18O7: C, 63.68; H, 5.06. Found: C, 63.61; H, 5.04.
References
[1] D. D. Majo, M. Giammanco, M. L. Guardia, E. Tripoli, et
al., Food Res. Intern. 2005, 38, 1161–1166.
[2] H. Y. Sohn, K. H. Son, C. S. Kwon, G. S. Kwon, S. S. Kang,
Phytomedicine 2004, 11, 666–672.
[3] T. Morikawa, F. M. Xu, H. Matsuda, M. Yoshikawa, Chem.
Pharm. Bull. 2006, 54, 1530–1534.
[4] A. F. Abdel-Razik, M. I. Nassar, E.-D. A. El-Khrisy, A.-A. M.
Dawidar, T. J. Mabry, Fitoterapia 2005, 76, 762–764.
[5] K. J. Hodgetts, Tetrahedron 2005, 61, 6860–6870.
2(R,S)-7,8,39,49,59-Pentamethoxyflavan (l) 1
[6] J. Xue, X. Zhang, X. Chen, Y. Zhang, Y. Li, Synthetic Com-
mun. 2003, 33, 3527–3536.
Compound 3 (0.81 g, 2.17 mmol) was stirred in MeOH (5 mL) in
the presence of 10% Pd-C (1.55 g, 1.45 mmol Pd0) under a hydro-
gen atmosphere at room temperature for 12 h. Pd/C was filtrated
and washed with EtOAc. After removing the solvent, the oil was
purified by column chromatography silica gel (n-hexane : EtOAc
= 10 : 1). The natural flavan racemate (l) 1, was obtained (0.64 g,
81.9%) as a oil.1H-NMR (300 MHz, CDCl3) d: 2.05 (1H, m), 2.19 (1H,
m), 2.71 (1H, m), 2.89 (1H, m), 3.85 (3H, s), 3.86 (9H, s), 3.89 (3H, s),
5.07 (1H, dd, J1 = 2.4 Hz, J2 = 9.9 Hz), 6.51 (1H, d, J = 8.5 Hz), 6.78
(1H, d, J = 8.5 Hz), 6.67 (2H, s). 13C-NMR (CDCl3) d: 24.3, 30.0, 55.9,
56.1, 60.5, 60.7, 77.5, 102.8,104.1, 115.8, 123.4, 137.2, 137.3,
148.5, 151.7, 153.1. MS (ESI) m/z: 383 [M+Na]+. Anal. Calcd. for
C20H24O6: C, 66.65; H, 6.71. Found: C, 66.61; H, 6.69.
[7] K. Oyama, T. Kondo, J. Org. Chem. 2004, 69, 5240–5246.
[8] M. C. Jimenez, M. A. Miranda, R. Tormos, Tetrahedron
1997, 53, 14729–14736.
[9] T. G. C. Bird, B. R. Brown, I. A. Stuart, A. W. R. Tyrrell, J.
Chem. Soc. Perkin Trans. I 1983, 8, 1831–1846.
[10] N. Kaneda, J. M. Pezzuto, D. D. Soejarto, A. D. Kinghorn,
et al., J. Nat. Prod. 1991, 54, 196–205.
[11] Y. K. Rao, C. V. Rao, P. H. Kishore, D. Gunasekar, J. Nat.
Prod. 2001, 64, 368–367.
i 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim