Synthesis and antiproliferative properties of novel naringenin derivatives

Article abstract of DOI:10.1007/s00044-017-1966-y

In order to improve the antiproliferative activity of naringenin, a naturally occurred flavonoid in citrus fruits, a series of naringenin derivatives with a tertiary amino side chain were prepared. The antiproliferative activities of these naringenin derivatives were evaluated on four human cancer cell lines, namely, MCF-7, HCT116, Hela, and A549. Compounds 4a, 9a, and 10a exhibited remarkably enhanced growth inhibition activity. Based on the observed results, the structure–activity relationship of these derivatives was discussed.

Full text of DOI:10.1007/s00044-017-1966-y

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res
DOI 10.1007/s00044-017-1966-y
ORIGINAL RESEARCH
Synthesis and antiproliferative properties of novel naringenin
derivatives
Su-You Liu1 Jiang Zeng1 Kun-Jian Peng2 Li-Chao Zhang1 Li-Jun Liu2
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Zhi-Yong Luo2 Da-You Ma1
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Received: 1 March 2016 / Accepted: 19 June 2017
© Springer Science+Business Media, LLC 2017
Abstract In order to improve the antiproliferative activity
of naringenin, a naturally occurred flavonoid in citrus fruits,
a series of naringenin derivatives with a tertiary amino side
chain were prepared. The antiproliferative activities of these
naringenin derivatives were evaluated on four human cancer
cell lines, namely, MCF-7, HCT116, Hela, and A549.
Compounds 4a, 9a, and 10a exhibited remarkably enhanced
growth inhibition activity. Based on the observed results,
the structure–activity relationship of these derivatives was
discussed.
et al. 1997; Heo et al. 2004). Owing to its low-toxicity,
(Moon et al. 2006) the anticancer activity of NG is espe-
cially attractive. Both in vitro and in vivo studies had
revealed that NG can effectively inhibit the growth of
several types of human tumor cell lines (Kanno et al. 2005;
Arul and Subramanian 2013; Sabarinathan et al. 2010).
Mechanistic studies indicated that the proapoptotic activity
of NG on cancer cell lines may involve the inhibition of
PI3K/Akt signaling pathways and caspase-3 activation
(Sabarinathan and Vanisree 2013; Bak et al. 2011; Park
et al. 2008). However, the antineoplastic activity of NG is
not strong enough for clinical application. Furthermore, the
clinical potential of NG is seriously restricted by its low oral
bioavailability (Semalty et al. 2010; Felgines et al. 2000).
Several NG derivatives had been designed in order to
improve the anticancer potential (Yoon et al. 2013; Lee
et al. 2007; Liu et al. 2013; Kim et al. 2007). For instance,
NG derivatives modified at position 7 with bulky sub-
stituents exhibited enhanced inhibitory effects on HCT116
human colon cancer cells and Human Lung epithelial
carcinoma A549 cells (Yoon et al. 2013; Lee et al. 2007).
In this study, eleven NG derivatives with an aliphatic
tertiary amino side chain were synthesized. Their anti-
proliferative effects were evaluated on four human cancer
cell lines, namely MCF-7, HCT116, Hela, and A549. Based
on the observed results, the structure–activity relationship of
these derivatives was discussed.
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Keywords Naringenin Antiproliferative activity
Synthesis Derivatives
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Introduction
Naringenin (NG) is one of the most abundant flavonoids in
citrus fruits (Kawaii et al. 1999). It has been shown to exert
a variety of biological effects, such as antioxidant, anti-
inflammatory, cholesterol-lowing, antitumor, etc (Lee et al.
1999; Chen et al. 2002; Fuhr et al. 1993; Benavente-Garcia
* Zhi-Yong Luo
luozhiyong@csu.edu.cn
* Da-You Ma
Material and methods
Chemistry
madayou@csu.edu.cn
1
School of Pharmaceutical Sciences, Central South University,
Changsha 410013, China
2
All chemicals were of analytical grade and used as received
unless otherwise stated. 1H and 13C NMR spectra were
School of Life Sciences, Central South University, Changsha
410013, China

Med Chem Res
recorded on a Bruker DRX 400 NMR instrument. MS were
recorded on a Qstar mass spectrometer.
2H, H-1′′), 5.37 (dd, J = 12.4, 14.4 Hz, 1H, H-2), 6.05 (d, J
= 2.4 Hz, 1H, H-8), 6.08 (d, J = 2.4 Hz, 1H, H-6), 6.97 (d, J
= 8.0 Hz, 2H, H-3′, 5′), 7.39 (d, J = 8.0 Hz, 2H, H-2′, 6′).
Synthesis of 7-(2-Bromoethoxy)-5-hydroxy-2-(4-
hydroxyphenyl)chroman-4-one (1)
Synthesis of 7-methoxy-5-hydroxy-2-[4-(2-choloropropoxy)
A mixture of NG (2.72 g, 10 mmol), potassium carbonate
(0.69 g, 5 mmol) and 1,2-dibromoethane (21.6 mL, 250
mmol) in 100 mL DMF was stirred at 50 °C for 3 days. The
resultant mixture was cooled to room temperature and fil-
trated. The filtrate was mixed with 1 L H2O, and then
extracted with ethyl acetate (150 mL × 3). The organic layer
was dried over Na2SO4 and concentrated. The residue was
purified with a silica gel column and was eluted with Pet-
roleum ether/EtOAc (2:1) to afford 1 (0.95 g, 25%): mp
180.0–181.0 °C. 1H nuclear magnetic resonance (NMR)
(400 MHz, dimethylsulfoxide (DMSO)-d6): δ 2.73 (dd, J =
2.4, 17.2 Hz, 1H, H-3cis), 3.33 (m, 1H, H-3trans), 3.78 (t, J
= 5.2 Hz, 2H, H-2′′), 4.38 (t, J = 5.2 Hz, 2H, H-1′′), 5.49
(dd, J = 2.4, 14.4 Hz, 1H, H-2), 6.10 (d, J = 1.6 Hz, 1H, H-
8), 6.12 (d, J = 1.6 Hz, 1H, H-6), 6.79 (d, J = 8.4 Hz, 2H,
H-3′,5′), 7.33 (d, J = 8.4 Hz, 2H, H-2′,6′), 9.61 (s, 1H, 4′-
OH), 12.10 (s, 1H, 5-OH).
phenyl]chroman-4-one (8)
According to same procedure as preparation of 7, Com-
pound 8 was obtained as a white solid, yield 24%: mp
88.0–90.0 °C. 1H NMR (400 MHz, CDCl3):δ 2.22–2.28 (m,
2H, H-2′′), 2.79 (dd, J = 3.2, 17.2 Hz, 1H, H-3cis), 3.10
(dd, J = 13.2, 17.2 Hz, 1H, H-3trans), 3.78 (t, J = 6.4 Hz,
2H, H-3′′), 3.81 (s, 3H, OCH3), 4.14 (t, J = 6 Hz, 2H, H-1′′),
5.37 (dd, J = 3.2, 13.2 Hz, 1H, H-2), 6.04 (d, J = 2.4 Hz, 1H,
H-8), 6.07 (d, J = 2.4 Hz, 1H, H-6), 6.95–6.97 (m, 2H, H-3′,
5′), 7.37–7.39 (m, 2H, H-2′, 6′).
General procedure for the preparation of 3a–3d, 4a–4c, 9a,
9b, 10a, 10b
To a solution of the halide compound (1, 2, 7 or 8, 1 mmol)
in 5 mL DMF, a secondary amine (5 mmol) was added. The
resulting solution was stirred at 80 °C for 70 min, then
cooled to room temperature. The solution was diluted with
30 mL H2O and extracted with ethyl acetate (10 mL × 3).
The combined organic phase was concentrated and the
resulting residue was purified on a silica gel column eluted
with Petroleum ether/EtOAc to afford the substituted
product.
Synthesis of 7-(3-chloropropoxy)-5-hydroxy-2-(4-
hydroxyphenyl)chroman-4-one (2)
According to same procedure as preparation of 1, com-
pound 2 was obtained as a pale yellowish solid, yield 58%,
mp 96.0–98.0 °C. 1H NMR (400 MHz, CDCl3): δ 2.19–2.25
(m, 2H, H-2′′), 2.79 (dd, J = 3.2, 17.2 Hz, 1H, H-3cis), 3.09
(dd, J = 10.2, 17.2 Hz, 1H, H-3trans), 3.71 (t, J = 6.4 Hz,
2H, H-3′′), 4.13 (t, J = 6.0 Hz, 2H, H-1′′), 5.36 (dd, J = 2.8,
12.8 Hz, 1H, H-2), 6.04 (d, J = 2.4 Hz, 1H, H-8), 6.07 (d, J
= 2.4 Hz, 1H, H-6), 6.87–6.91 (m, 2H, H-3′, 5′), 7.32–7.35
(m, 2H, H-2′, 6′).
7-(2-Diethylaminoethoxy)-5-hydroxy-2-(4-hydroxyphenyl)
chroman-4-one (3a)
White solid, yield 62%, Rf = 0.35 (MeOH/CH2Cl2 = 1:10,
1
Synthesis of 7-methoxy-5-hydroxy-2-[4-(2-bromoethoxy)
v/v), mp 121.0–123.0 °C. H NMR (400 MHz, DMSO-d6):
phenyl]chroman-4-one (7)
δ 0.95 (t, J = 6.8 Hz, 6H, H-2′′′), 2.49–2.54 (tetra, J = 6.8
Hz, 4H, H-1′′′), 2.70–2.75 (m, 3H, H-3cis), 3.33–3.35 (m,
1H, H-3trans), 4.06 (t, J = 6.4 Hz, 2H, H-1′′), 5.48 (dd, J =
2.8, 12.8 Hz, 1H, H-2), 6.06 (d, J = 2.0 Hz, 1H, H-8), 6.08
(d, J = 2.0 Hz, 1H, H-6), 6.79 (d, J = 8.8 Hz, 2H, H-3′, 5′),
7.32 (d, J = 8.8 Hz, 2H, H-2′, 6′), 9.60 (s, 1H, 4′-OH),
12.10 (s, 1H, 5-OH). 13C NMR (100 MHz, DMSO-d6): δ
12.1 (C-2′′′), 42.3 (C-3), 47.1 (C-1′′′), 51.2 (C-2′′), 67.3 (C-
1′′), 78.8 (C-2), 94.4 (C-8), 95.2 (C-6), 102.8 (C-4a), 115.4
(C-3′, 5′), 128.6 (C-2′,6′), 128.9 (C-1′), 158.0 (C-4′),
163.1 (C-8b), 163.4 (C-5), 166.9 (C-7), 197.1 (C=O). IR
(KBr, cm−1) Vmax: 3421.4, 3122.3, 2970.9, 1634.9, 1568.9,
1514.6, 1398.1, 1161.2, 1087.4, 838.8. HRMS (ESI)
m/z [M + H]+ calcd. for C21H26O5N, 372.1811; found
372.1808.
To a solution of 7-methoxy-5-hydroxy-2-(4-hydroxyphenyl)
chroman-4-one (4.29 g, 15 mmol) in 150 mL acetone,
potassium carbonate (2.07 g, 15 mmol) and 1,2-dibro-
moethane (56.4 g, 0.3 mol) was added successively. The
resulting mixture was stirred at 80 °C for 60 h. Acetone was
removed by rotavaper. 100 mL ethyl acetate was added to the
residue, and washed by H2O (20 mL × 3). The organic
solution was concentrated. The residue was purified with a
silica gel column and was eluted with Petroleum ether/EtOAc
1
5:1 to afford 7 (1.14 g, 19%): mp 125.5–126.7 °C. H NMR
(400 MHz, CDCl3): δ 2.79 (dd, J = 2.4, 16.4 Hz, 1H, H-
3cis), 3.09 (dd, J = 13.6, 16.4 Hz, 1H, H-3trans), 3.66 (t, J
= 6.0 Hz, 2H, H-2′′), 3.81(s, 3H, OCH3), 4.32 (t, J = 6.0 Hz,

Med Chem Res
7-(2-Morpholinoethoxy)-5-hydroxy-2-(4-hydroxyphenyl)
chroman-4-one (3b)
(d, J = 2.4 Hz, 1H, H-6), 6.78 (d, J = 8..4 Hz, 2H, H-3′,5′),
7.32 (d, J = 8.4 Hz, 2H, H-2′,6′), 12.02 (br, 1H, 5-OH). 13C
NMR (100 MHz, DMSO-d6): δ 41.9 (C-3), 45.3 (N-CH3),
57.2 (C-2′′), 66.4 (C-1′′), 78.5 (C-2), 94.1 (C-8), 94.9 (C-6),
102.5 (C-4a), 115.0 (C-3′, 5′), 128.3 (C-2′, 6′), 128.6 (C-1′),
157.6 (C-4′), 162.8 (C-8b), 163.1 (C-5), 166.6 (C-8), 196.7
(C=O). IR (KBr, cm-1) Vmax: 34.25.3, 3137.9, 2951.5,
1634.9, 1572.8, 1518.4, 1401.9, 1277.7, 1165.0, 1087.4,
838.8. HRMS (ESI) m/z [M + H]+ calcd. for C19H22O5N,
344.1498; found 344.1496.
White solid, yield 90%, Rf = 0.45 (ethyl acetate/petroleum
1
ether = 2:1, v/v), mp 192.5–193.5 °C. H NMR (400 MHz,
DMSO-d6): δ 2.44 (t, J = 4.4 Hz, 4H, H-1′′′), 2.66 (t, J =
6.4 Hz, 2H, H-2′′), 2.74 (dd, J = 2.8, 17.2 Hz, 1H, H-3cis),
3.34 (dd, J = 12.8, 17.2 Hz, 1H, H-3trans), 3.56 (t, J = 4.4
Hz, 4H, H-2′′′), 4.13 (t, J = 5.6 Hz, 2H, H-1′′), 5.48 (dd, J
= 2.8, 12.8 Hz, 1H, H-2), 6.08 (d, J = 2.0 Hz, 1H, H-8),
6.10 (d, J = 2.0 Hz, 1H, H-6), 6.79 (d, J = 8.8 Hz, 2H, H-3′,
5′), 7.32 (d, J = 8.8 Hz, 2H, H-2′, 6′), 9.60 (s, 1H, 4′-OH),
12.10 (s, 1H, 5-OH). 13C NMR (100 MHz, DMSO-d6): δ
42.3 (C-3), 53.8 (C-1′′′), 56.9 (C-2′′), 66.3 (H-2′′′), 66.5 (C-
1′′), 78.9 (C-2), 94.5 (C-8), 95.4 (C-6), 102.9 (C-4a), 115.5
(C-3′, 5′), 128.7 (C-2′, 6′), 129.0 (C-1′), 158.1 (C-4′), 163.2
(C-8b), 163.5 (C-5), 166.9 (C-7), 197.3 (C=O). IR (KBr,
cm−1) Vmax: 3440.8, 2959.2, 2924.3, 2862.14, 1643.9,
1522.3, 1440.8, 1306.8, 1172.5, 1115.1, 831.7, 590.3.
HRMS (ESI) m/z [M + H]+ calcd. for C21H24O6N,
386.1604; found 386.1603.
7-(3-Diethylaminopropoxy)-5-hydroxy-2-(4-hydroxyphenyl)
chroman-4-one (4a)
Pale yellowish oil, 39.0%, Rf = 0.35 (MeOH/CH2Cl2 =
1
1:10, v/v),. H NMR (400 MHz, CDCl3): δ 1.05 (t, J = 7.2
Hz, 6H, H-2′′′), 1.90-1.96 (m, 2H, H-2′′), 2.56–2.65 (m, 6H,
H-1′′′, H-3′′), 2.77 (dd, J = 2.8, 17.2 Hz, 1H, H-3cis), 3.08
(dd, J = 12.8, 17.2 Hz, 1H, H-3trans), 4.00 (t, J = 6.0 Hz,
2H, H-1′′), 5.33 (dd, J = 2.8, 12.8 Hz, 1H, H-2), 6.02 (d, J
= 2.4 Hz, 1H, H-8), 6.05 (d, J = 2.4 Hz, 1H, H-6),
6.83–6.86 (m, 2H, H-3′, 5′), 7.29–7.32 (m, 2H, H-2′, 6′),
12.00 (br, 1H, 5-OH). 13C NMR (100 MHz, CDCl3): δ 10.7
(C-2′′′), 25.7 (C-2′′), 43.0 (C-3), 46.4 (C-1′′′), 48.8 (C-3′′),
66.6 (C-1′′), 79.0 (C-2), 94.4 (C-8), 95.5 (C-6), 103.0 (C-
4a), 116.0 (C-3′,5′), 127.8 (C-2′,6′), 129.3 (C-1′), 157.3 (C-
4′), 162.9 (8b), 164.0 (C-5), 167.2 (C-7), 196.2 (C=O). IR
(KBr, cm−1) Vmax: 3163.6, 2969.6, 2918.6, 1649.1, 1564.0,
1513.0, 1455.1, 1390.4, 1298.5, 1267.9, 1159.0, 1090.9,
832.2, 736.9, 594.0. HRMS (ESI) m/z [M + H]+ calcd. for
C22H28O5N, 386.1967; found 386.1962.
7-(2-(Piperidin-1-yl)ethoxy)-5-hydroxy-2-(4-
hydroxyphenyl)chroman-4-one (3c)
White solid, yield 71%, Rf = 0.35 (MeOH/CH2Cl2 = 1:10,
1
v/v), mp 168.0–170.0 °C. H NMR (400 MHz, DMSO-d6):
δ 1.35–1.39 (m, 2H, H-3′′′), 1.41–1.49 (m, 4H, H-2′′′, 4′′′),
2.39 (t, J = 2.0 Hz, 4H, H-1′′′, 5′′′), 2.61 (t, J = 6.0 Hz, 2H,
H-2′′), 2.73 (dd, J = 3.2, 17.2 Hz, 1H, H-3cis), 3.33 (dd, J
= 12.8, 17.2 Hz, 1H, H-3trans), 4.11 (t, J = 5.6 Hz, 2H, H-
1′′), 5.47 (dd, J = 2.8, 12.8 Hz, 1H, H-2), 6.07 (d, J = 2.4
Hz, 1H, H-8), 6.09 (d, J = 2.4 Hz, 1H, H-6), 6.79 (d, J =
8.8 Hz, 2H, H-3′, 5′), 7.32 (d, J = 8.8 Hz, 2H, H-2′, 6′), 9.61
(s, 1H, 4′-OH), 12.10 (s, 1H, 5-OH). 13C NMR (100 MHz,
DMSO-d6): δ 23.9 (C-3′′′), 25.5 (C-2′′′, 4′′′), 42.0 (C-3′′′, 5′′′),
54.3 (C-1′′′), 57.0 (C-2′′), 66.3 (C-1′′), 78.6 (C-2), 94.2 (C-8),
95.1 (C-6), 102.5 (C-4a), 115.1 (C-3′, 5′), 128.3 (C-2′, 6′),
128.7 (C-1′), 157.7 (C-4′), 162.8 (C-8b), 163.2 (C-5), 166.6
(C-7), 196.8 (C=O). IR (KBr, cm−1) Vmax: 3433.0, 3118.5,
2935.9, 1638.8, 1576.7, 1522.3, 1440.8, 1196.1, 1168.9,
1087.4, 834.9. HRMS (ESI) m/z [M + H]+ calcd. for
C22H26O5N, 384.1811; found 384.1810.
7-(3-Morpholinopropoxy)-5-hydroxy-2-(4-hydroxyphenyl)
chroman-4-one (4b)
Pale yellowish oil, yield 76%, Rf = 0.36 (ethyl acetate/pet-
1
roleum ether = 2:1, v/v), H NMR (400 MHz, CDCl3): δ
1.97 (m, 2H, H-2′′), 2.52–2.55 (m, 6H, H-1′′′, H-3′′), 2.75
(dd, J = 2.8, 17.2 Hz, 1H, H-3cis), 3.07 (dd, J = 13.2, 17.2
Hz, 1H, H-3trans), 3.75 (t, J = 4.4 Hz, 4H, H-2′′′), 4.01 (t,
J = 6.4 Hz, 2H, H-1′′), 5.30 (dd, J = 2.8, 13.2 Hz, 1H, H-2),
6.00 (d, J = 2.0 Hz, 1H, H-8), 6.04 (d, J = 2.0 Hz, 1H, H-6),
6.83 (d, J = 8.4 Hz, 2H, H-3′, 5′), 7.27 (d, J = 8.4 Hz, 2H,
H-2′, 6′), 12.00 (br, 1H, 5-OH). 13C NMR (400 MHz,
CDCl3): δ 25.7 (C-2′′), 43.0 (C-3), 53.5 (C-1′′′), 55.2 (C-3′′),
66.4 (C-2′′′), 66.6 (C-1′′), 78.9 (C-2), 94.5 (C-8), 95.4 (C-6),
103.0 (C-4a), 115.7 (C-3′, 5′), 127.9 (C-2′, 6′), 129.7 (C-1′),
156.7 (C-4′), 162.9 (C-8b), 163.9 (C-5), 167.2 (C-7), 196.1
(C=O). IR (KBr, cm−1) Vmax: 3425.2, 3188.3, 2955.3,
2850.5, 2807.8, 1646.6, 1572.8, 1518.4, 1440.8, 1301.0,
1165.0, 1095.2, 834.9. HRMS (ESI) m/z [M + H]+ calcd. for
C22H26O6N, 400.1760; found 400.1757.
7-(2-Dimethylanimoethoxy)-5-hydroxy-2-(4-hydroxyphenyl)
chroman-4-one (3d)
White solid, yield 30%, Rf = 0.35 (MeOH/CH2Cl2 = 1:10,
1
v/v), mp 165.0–167.0 °C. H NMR (400 MHz, DMSO-d6):
δ 2.16 (s, 6H, NCH3), 2.73 (dd, J = 2.4, 17.2 Hz, 1H, H-
3cis), 3.30 (dd, J = 12.8, 17.2 Hz, 1H, H-3trans), 3.32 (t, J
= 5.6 Hz, 2H, H-2′′) 4.08 (t, J = 5.6 Hz, 2H), 5.47 (dd, J =
2.4, 12.8 Hz, 1H, H-2), 6.07 (d, J = 2.4 Hz, 1H, H-8), 6.09

Med Chem Res
7-(3-(Piperidin-1-yl)propoxy)-5-hydroxy-2-(4-
hydroxyphenyl)chroman-4-one (4c)
6.07 (d, J = 2.0 Hz, 1H, H-6), 6.94–6.98 (m, 2H, H-3′, 5′),
7.36–7.39 (m, 2H, H-2′, 6′), 12.03 (s, 1H, 5-OH). 13C NMR
(100 MHz, CDCl3): δ 43.1 (C-3), 54.0 (C-1′′′), 55.6
(OCH3), 57.5 (C-2′′), 65.8 (C-2′′′), 66.8 (C-1′′), 78.9 (C-2),
94.1 (C-8), 95.0 (C-6), 103.0 (C-4a), 114.8 (C-3′,5′), 127.7
(C-2′,6′), 130.5 (C-1′), 159.1 (C-4′), 162.8 (8b), 164.0 (C-5),
167.8 (C-7), 195.9 (C=O). IR (KBr, cm-1) Vmax: 3436.9,
3126.2, 2951.5, 2869.9, 2800.0, 1627.2, 1572.8, 1514.6,
1301.0, 1207.8, 1153.4, 1114.6, 1087.4. HRMS (ESI)
m/z [M + H]+ calcd. for C22H26O6N, 400.1760; found
400.1758.
Pale yellowish oil, yield 81%, Rf = 0.35 (MeOH/CH2Cl2 =
1:10, v/v), 1H NMR (400 MHz, CDCl3): δ 1.47 (br, 2H, H-
3′′′), 1.62–1.68 (m, 4H, H-2′′′), 1.96–2.03 (m, 2H, H-2′′),
2.52–2.55 (m, 6H, H-1′′′, 3′′), 2.75 (dd, J = 2.8, 17.2 Hz,
1H, H-3cis), 3.07 (dd, J = 13.2, 17.2 Hz, 1H, H-3trans),
3.98 (t, J = 6.0 Hz, 2H, H-1′′), 5.31 (dd, J = 2.8, 13.2 Hz,
1H, H-2), 5.98 (d, J = 2.0 Hz, 1H, H-8), 6.03 (d, J = 2.0 Hz,
1H, H-6), 6.82 (d, J = 7.2 Hz, 2H, H-3′, 5′), 7.27 (d, J = 7.2
Hz, 2H, H-2′, 6′), 12.01 (br, 1H, 5-OH). 13C NMR (100
MHz, CDCl3): δ 23.9 (C-3′′′), 25.1 (C-2′′′), 25.8 (C-2′′),
43.0 (C-3), 54.3 (C-1′′′), 55.6 (C-3′′), 66.6 (C-1′′), 79.0 (C-
2), 94.4 (C-8), 95.5 (C-6), 103.0 (C-4a), 115.9 (C-3′,5′),
127.8 (C-2′,6′), 129.3 (C-1′), 157.3 (C4′), 162.9 (C-8b),
5-Hydroxy-7-methoxy-2-(4-(3-diethylaminopropoxy)phenyl)
chroman-4-one (10a)
Pale yellowish oil, yield 45%, Rf = 0.45 (MeOH/CH2Cl2 =
163.9 (C-5), 167.1 (C-7), 196.2 (C=O). IR (KBr, cm−1
)
1
1:10, v/v), H NMR (400 MHz, CDCl3): δ 1.05 (t, J = 7.2
Vmax: 3440.1, 3123.3, 2927.5, 2856.3, 2799.4, 1642.4,
1571.2, 1514.2, 1439.5, 1297.1, 1158.2, 1087.1, 837.9.
HRMS (ESI) m/z [M + H]+ calcd. for C23H28O5N,
398.1967; found 398.1964.
Hz, 6H, H-2′′′), 1.98 (m, 2H, H-2′′), 2.56–2.58 (m, 4H, H-1′′′),
2.63 (t, J = 7.4 Hz, 2H, H-3′′), 2.78 (dd, J = 3.2, 17.2 Hz, 1H,
H-3cis), 3.09 (dd, J = 13.6, 17.2 Hz, 1H, H-3trans), 3.80 (s,
3H, OCH3), 4.03 (t, J = 6.0 Hz, 2H, H-1′′), 5.36 (dd, J = 2.8,
12.8 Hz, 1H, H-2), 6.04 (d, J = 2.4 Hz, 1H, H-8), 6.07 (d, J =
2.4 Hz, 1H, H-6), 6.94 (d, J = 8.8 Hz, 2H, H-3′,5′), 7.36 (d, J
= 8.8 Hz, 2H, H-2′,6′), 12.04 (s, 1H, 5-OH). 13C NMR (100
MHz, CDCl3): δ 11.6 (C-2′′′), 26.8 (C-2′′), 43.1 (C-3), 46.9
(C-1′′′), 49.2 (C-3′′), 55.6 (OCH3), 66.3 (C-1′), 79.0 (C-2),
94.1 (C-8), 95.0 (C-6), 103.0 (C-4a), 114.7 (C-3′,5′), 127.6 (C-
2′,6′), 130.1 (C-1′), 159.4 (C-4′), 162.8 (C-8b), 164.0 (C-5),
167.8 (C-7), 196.1 (C=O). IR (KBr, cm-1) Vmax: 3444.7,
3130.5, 2964.8, 2923.4, 1642.7, 1570.2, 1515.0, 1397.6,
1297.5, 1204.3, 1156.0, 1090.4, 834.9. HRMS (ESI) m/z [M
+ H]+ calcd. for C21H30O5N, 400.2124; found 400.2121.
5-Hydroxy-7-methoxy-2-(4-(2-diethylaminoethoxy)phenyl)
chroman-4-one (9a)
Pale yellowish oil, 72%, Rf = 0.45 (MeOH/CH2Cl2 = 1:10,
1
v/v), H NMR (400 MHz, CDCl3): δ 1.08 (t, J = 7.2 Hz,
6H, H-2′′′), 2.63-2.69 (m, 4H, H-1′′′), 2.78 (dd, J = 2.8,
17.2 Hz, 1H, H-3cis), 2.90 (t, J = 6.4 Hz, 2H, H-2′′), 3.10
(dd, J = 12.8, 17.2 Hz, 1H, H-3trans), 3.80 (s, 3H, OCH3),
4.08 (t, J = 6.4 Hz, 2H, H-1′′), 5.36 (dd, J = 2.8, 12.8 Hz,
1H, H-2), 6.04 (d, J = 2.0 Hz, 1H, H-8), 6.06 (d, J = 2.0 Hz,
1H, H-6), 6.95 (d, J = 8.8 Hz, 2H, H-3′,5′), 7.36 (d, J = 8.8
Hz, 2H, H-2′,6′), 12.03 (s, 1H, 5-OH). 13C NMR (100 MHz,
CDCl3): δ 11.8 (C-2′′′), 43.1 (C-3), 47.8 (C-1′′′), 51.7 (C-2′′),
55.6 (OCH3), 66.7 (C-1′), 79.0 (C-2), 94.1 (C-8), 95.0 (C-6),
103.1 (C-4a), 114.8 (C-3′, 5′), 127.6 (C-2′, 6′), 130.3 (C-1′),
159.3 (C-4′), 162.9 (C-8b), 164.1 (C-5), 167.9 (C-7), 196.0
(C=O). IR (KBr, cm-1) Vmax: 2970.9, 1642.7, 1572.8,
1518.4, 1444.7, 1374.8, 1293.2, 1250.5, 1153.4, 1091.3,
1025.2, 827.2, 737.9. HRMS (ESI) m/z [M + H]+ calcd. for
C22H28O5N, 386.1967; found 386.1961.
5-Hydroxy-7-methoxy-2-(4-(3-morpholinopropoxy)phenyl)
chroman-4-one (10b)
White solid, yield 85%, Rf = 0.40 (ethyl acetate/petroleum
1
ether = 2:1, v/v), mp 126.9–127.9 °C, H NMR (400 MHz,
CDCl3): δ 2.00 (m, 2H, H-2′′), 2.52 (m, 6H, H-1′′′, 3′′), 2.78
(dd, J = 2.4, 17.2 Hz, 1H, H-3cis), 3.09 (dd, J = 13.2, 17.2
Hz, 1H, H-3trans), 3.74 (t, 4H, H-2′′′), 3.80 (s, 3H, OCH3),
4.05 (t, J = 6.0 Hz, 2H, H-1′′), 5.36 (dd, J = 2.4, 12.4 Hz,
1H, H-2), 6.04 (d, J = 2.0 Hz, 1H, H-8), 6.06 (d, J = 2.0 Hz,
1H, H-6), 6.94 (d, J = 8.4 Hz, 2H, H-3′, 5′), 7.36 (d, J = 8.4
Hz, 2H, H-2′, 6′), 12.03 (s, 1H, 5-OH). 13C NMR (400
MHz, CDCl3): δ 26.3 (C-2′′), 43.1 (C-3), 53.7 (C-1′′′), 55.4
(C-3′′), 55.6 (OCH3), 66.2 (C-1′′), 66.9 (C-2′′′), 78.9 (C-2),
94.2 (C-8), 95.0 (C-6), 103.1 (C-4a), 114.7 (C-3′, 5′), 127.6
(C-2′, 6′), 130.3 (C-1′), 159.4 (C-4′), 162.8 (C-8b), 164.1
5-Hydroxy-7-methoxy-2-(4-(2-morpholinoethoxy)phenyl)
chroman-4-one (9b)
White solid, yield 82%, Rf = 0.40 (ethyl acetate/petroleum
1
ether = 2:1, v/v), mp 101.6–102.7 °C, H NMR (400 MHz,
CDCl3): δ 2.60 (br, 4H, H-1′′′), 2.78 (dd, J = 3.2, 17.2 Hz,
1H, H-3cis), 2.83 (t, J = 5.6 Hz, 2H, H-2′′), 3.08 (dd, J =
13.2, 17.2 Hz, 1H, H-3trans), 3.75 (t, J = 4.4 Hz, 4H, H-2′′′),
3.80 (s, 3H, OCH3), 4.15 (t, J = 5.6 Hz, 2H, H-1′′), 5.36 (dd,
J = 3.2, 13.2 Hz, 1H, H-2), 6.04 (d, J = 2.0 Hz, 1H, H-8),
(C-5), 167.9 (C-7), 195.9 (C=O). IR (KBr, cm−1) Vmax
:
3433.0, 3126.2, 2955.3, 2846.6, 1631.1, 1580.6, 1522.3,
1382.5, 1273.8, 1207.8, 1157.3, 1087.4, 819.4. HRMS

Med Chem Res
(ESI) m/z [M + H]+ calcd. for C23H28O6N, 414.1917;
Results and discussion
found 414.1913.
Tertiary amino group is a common moiety in drugs. Intro-
duction of a tertiary amino group could enhance the
hydrophilicity of a chemical entity through the corre-
sponding salt form and in the meanwhile may improve its
bioactivity. Here, we attempted to introduce a tertiary amino
moiety to NG. As we know, the 7-hydroxy group of NG can
be selectively alkylated. As shown in Scheme 1, nucleo-
philic substitution with 1,2-dibromoethane or 1-bromo-3-
chloropropane gave alkylated halo-intermediate 1 and 2
respectively, which were further substituted with a sec-
ondary amine to afford tertiary amino group bearing NG
derivatives 3a–3d, 4a–4c. 7-methylated NG 6 was obtained
using methyl iodide as electrophile. Further alkylation with
1,2-dibromoethane or 1-bromo-3-chloropropane give the 4′
substituted halo-intermidiates 7 and 8, respectively. In a
similar manner, tertiary amino group bearing NG deriva-
tives 9a, 9b, 10a, and 10b were also obtained using a
secondary amine. Meanwhile, compound 5, a NG derivative
bearing an amide side chain at 7-hydroxy group was also
prepared (Scheme 1).
The antiproliferative activities of the synthesized NG
derivatives were evaluated by MTT method on four human
cancer cell lines, namely, MCF-7 human breast cancer cells,
HCT116 human colon cancer cells, Hela human cervical
cancer cell and A549 human Lung epithelial carcinoma
cells. The growth inhibitory rate at 100 μM (GI100μM) and
GI50 value for each compound on each cell line were col-
lected. As shown in Table 1, NG showed very weak anti-
proleferative activity to these four cancer cell lines even at
100 μM concentration (entry 13, Table 1). As we expected,
the tertiary amino side chain bearing NG dereivatives
generally exihibited much stronger growth inhibitory effect
on these cell lines than NG did while the amide side chain
bearing compound 5 did not show any enhanced activity
(entry 1–11 and 12, Table 1). Among these compounds, 10a
exhibited the most potent growth inhibitory activity to the
tested cancer cell lines with GI50 value of 15.0, 6.0, 8.7 and
11.4 μM to MCF7, HCT116, Hela and A549, respectively
(entry 10, Table 1). Further SAR analysis indicated that: (1)
the distance between N and O on the side chain has an
notable influence on the antiproliferative activity, namely,
the compounds with three methlenes between N and O
(compounds 4a, 10a, entry 5 and 10, Table 1) showed
stronger activity than the compounds with two methlenes
between N and O (compound 3a, 9a, entry 1 and 8,
Table 1); (2) a morphlino group is not a good tertiary amino
moiety for the side chain, since the morpholino group
bearing compounds 3b, 4b, 9b, and 10b (entry 2, 6, 9, 11,
Table 1) showed much higher GI50s than corresponding
diethyl amino group bearing compounds 3a, 4a, 9a, and
10a did (entry 1, 5,8, 10, Table 1).
7-Diethylaminocarbonylmethoxy-5-hydroxy-2-(4-
hydroxyphenyl)chroman-4-one (5)
To a solution of NG (272 mg, 1 mmol) in 20 mL acetone,
was added N,N-diethyl-2-chloro-acetoamide (150 mg, 1
mmol), potassium carbonate (69 mg, 0.5 mmol) and potas-
sium iodide (16 mg, 0.1 mmol). The resulting mixture was
stirred at 45 °C for 2 days. 40 mL H2O was added to the
mixture. The precipitates collected by filtration was washed
with ethyl acetated to afford 5 (240 mg, 62%) as white
solid: Rf = 0.55 (ethyl acetate/petroleum ether = 2:1, v/v),
mp 229.5–230.7 °C, 1H NMR (400 MHz, DMSO-d6): δ
1.02 (t, J = 7.2 Hz, 3H, CH3a), 1.13 (t, J = 7.2 Hz, 3H,
CH3b), 2.71 (dd, J = 2.8, 17.2 Hz, 1H, H-3cis), 3.28 (m, 4H,
NCH2), 3.31 (dd, J = 12.8, 17.2 Hz, 1H, H-3trans), 4.86 (s,
2H, H-1′′), 5.48 (dd, J = 2.8, 12.8 Hz, 1H, H-2), 6.04 (d, J
= 2.0 Hz, 1H, H-8), 6.07 (d, J = 2.0 Hz, 1H, H-6), 6.79 (d,
J = 8.0 Hz, 2H, H-3′,5′), 7.32 (d, J = 8.0 Hz, 2H, H-2′,6′),
9.57 (s, 1H, 4′-OH), 12.07 (s, 1H, 5-OH). 13C NMR (100
MHz, DMSO-d6): δ 13.2 (CH3a), 14.3 (CH3b), 42.3
(NCH2), 66.2 (C-1′′), 78.9 (C-2), 94.6 (C-8), 95.5 (C-6),
102.9 (C-4a), 115.4 (C-3′, 5′), 128.7 (C-2′, 6′), 129.0 (C-1′),
157.9 (C-4′), 163.0 (C-8b), 163.1 (C-5), 165.6 (C-7), 166.6
(2′′-C=O), 197.2 (4-C = O). IR (KBr, cm-1) Vmax: 3231.0,
2974.8, 2932.0, 1634.9, 1576.7, 1518.4, 1448.5, 1161.2,
1141.7, 1087.4, 842.7. HRMS (ESI) m/z [M + H]+ calcd.
for C21H24O6N, 386.1604; found 386.1607.
Antiproliferative assay
Cell growth inhibition was analyzed using 3-(4,5-dime-
thylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)
assay. Briefly, cells cultured overnight on 96-well plates
were washed twice with PBS, administered media con-
taining different concentrations of NG derivatives and
incubated for 48 h. Twenty microliter of MTT stock solu-
tion (5 mg/mL) were added to each well, followed by
incubation for an additional 4 h. Blue formazans were
eluted from cells by the addition of 100 μL of DMSO with
gentle shaking for 10 min at room temperature. Absorben-
cies were measured at 570 nm using an enzyme-linked
immunosorbent assay reader. Data were collected from
three separate experiments and the percentage of NG deri-
vatives induced cell growth inhibition was determined by
comparison to DMSO-treated control cells. Growth inhibi-
tion rate was calculated in the following way: GI (%) = (A0
– A1)/A0*100, where A0 is the absorbance of the control, A1
is the absorbance of tested samples. The GI50 values were
calculated using SPSS software.

Med Chem Res
Scheme 1 Synthesis of naringenin derivatives
Table 1 Antiproliferative
Entry Compound MCF-7
GI100 μM GI50
HCT116
Hela
A549
GI100 μM GI50
activity of NG derivatives on
human cancer cell lines, GI100μM
(%), GI50 (μM)
GI100 μM GI50
GI100 μM GI50
1
3a
44
0
>100
>100
>100
>100
26.5
93
55
91
93
92
82
92
89
85
90
29
19
20
22.3
107.0
35.1
43.7
11.0
75.7
12.9
10.5
68.8
6.0
94
0
55.2
>100
63.9
66.3
25.1
>100
28.7
10.0
>100
8.7
92
16
93
86
92
28
92
94
22
91
16
1
52.0
2
3b
>100
48.6
3
3c
48
35
99
19
88
99
11
99
30
0
93
88
92
0
4
3d
87.3
5
4a
20.6
6
4b
>100
44.4
>100
25.1
7
4c
93
92
8
8
9a
19.7
17.7
9
9b
>100
15.0
>100
11.4
10
11
12
13
10a
94
11
6
10b
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
5
Naringenin
4
0
0
GI100μM (%) = Growth inhibition rate at 100 μM; GI50 (μM) = Median growth inhibition concentration (μM)
Conclusion
The mechanism behind the enhanced sensitivity of these
NG derivatives towards cancer cells will be further
In summary, by attaching a tertiary amino side chain on 7-
hydroxy group or 4′-hydroxy group of naringenin, several
novel NG derivatives were prepared. Some of these nar-
ingenin derivatives exhibited remarkably enhanced anti-
proliferative activity to four tested human cancer cell lines.
explored.
Acknowledgements This work was partially supported by the grants
from the National Natural Science Foundation of China (No.
20672147, No. 21472247).

Med Chem Res
Compliance with ethical standards
Kawaii S, Tomono Y, Katase E, Ogawa K, Yano M (1999) HL-60
differentiating activity and flavonoid content of the readily
extractable fraction prepared from citrus juices. J Agric Food
Chem 47:128–135
Conflict of interest The authors declare that they have no competing
interests.
Kim H, Lee E, Kim J, Kim J, Lim H, Lee C-H, Ahn J-H, Chong Y,
Lim Y (2007) Binding study of naringenin derivatives and cyclin
dependent kinase 2. Bull Korean Chem Soc 28:1413–1415
Lee E-R, Kang Y-J, Choi H-Y, Kang G-H, Kim J-H, Kim B-W, Han
YS, Nan S-Y, Paik H-D, Park Y-S, Cho S-G (2007) Induction of
apoptotic cell death by synthetic naringenin derivatives in human
lung epithelial carcinoma A549 cells. Biol Pharm Bull
30:2394–2398
Lee SH, Park YB, Bae KH, Bok SH, Kwon YK, Lee ES, Choi MS
(1999) Cholesterol-lowering activity of naringenin via inhibition
of 3-hydroxy-3-methylglutaryl coenzyme A reductase and acyl
coenzyme A: cholesterol acyltransferase in rats. Ann Nutr Metab
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