Synthesis of chrysin derivatives and screening of antitumor activity

Article abstract of DOI:10.1080/10286020.2019.1586677

A series of aromatic or long-chain chrysin derivatives (1–10) were synthesized by esterification of chrysin and acyl chloride. The chemical structures of these compounds were determined by mass spectrum (MS), ¹H NMR, and ¹³C NMR spec

Full text of DOI:10.1080/10286020.2019.1586677

Journal of Asian Natural Products Research
ISSN: 1028-6020 (Print) 1477-2213 (Online) Journal homepage: https://www.tandfonline.com/loi/ganp20
Synthesis of chrysin derivatives and screening of
antitumor activity
Ni Chen, Ru Wang, Liu-Jun Lu, Li-Jian Yan, Li-Li Bai, Yan Fu, Ying Wang, De-
Qian Peng, Xun Chen, Can-Hong Wang, Juan Li & Ke Zhao
To cite this article: Ni Chen, Ru Wang, Liu-Jun Lu, Li-Jian Yan, Li-Li Bai, Yan Fu, Ying Wang,
De-Qian Peng, Xun Chen, Can-Hong Wang, Juan Li & Ke Zhao (2019): Synthesis of chrysin
derivatives and screening of antitumor activity, Journal of Asian Natural Products Research, DOI:
10.1080/10286020.2019.1586677
To link to this article: https://doi.org/10.1080/10286020.2019.1586677
Published online: 19 Mar 2019.
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JOURNAL OF ASIAN NATURAL PRODUCTS RESEARCH
https://doi.org/10.1080/10286020.2019.1586677
Synthesis of chrysin derivatives and screening of
antitumor activity
a
a
a
a
a
a
a
Ni Chen , Ru Wang , Liu-Jun Lu , Li-Jian Yan , Li-Li Bai , Yan Fu , Ying Wang ,
a
a
b
a
a
De-Qian Peng , Xun Chen , Can-Hong Wang , Juan Li and Ke Zhao
a
b
School of Pharmacy, Hainan Medical College, Haikou 571100, China; Hainan Branch Institute of
Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical
College, Haikou 570311, China
ABSTRACT
ARTICLE HISTORY
A series of aromatic or long-chain chrysin derivatives (1–10) were
synthesized by esterification of chrysin and acyl chloride. The
chemical structures of these compounds were determined by
mass spectrum (MS), H NMR, and C NMR spectra. Though aro-
matic chrysin derivatives (1–9) with a rigid structure were hard to
dissolve in common organic solvents, the long-chain chrysin
derivative (10) with a flexible structure had better solubility, and
its anticancer activity (IC50 ¼ 14.79 lmol/L) against liver cancer
cell lines was 5.4 times better than chrysin (IC50 ¼ 74.97 lmol/L),
which showed superposition of pharmacological activity.
Received 29 November 2018
Accepted 21 February 2019
1
13
KEYWORDS
Chrysin derivative;
anticancer; liver cancer cell;
superposition
1. Introduction
Cancer is an intractable disease, and the cases are increasing worldwide, so the
screening of potential anticancer agents has been an urgent problem [1,2]. In this
regard, chrysin (5,7-dihydroxyflavone) (Figure 1) is one of natural flavonoids that are
ubiquitous in plants. It has an extensive pharmacological activities with low toxicity
and high efficacy such as anti-inflammatory [3,4], anti-oxidant [5], anti-human
immunodeficiency virus (HIV) [6], anti-anxiolytic effect [7], aromatase inhibitor [8],
and anticancer [9,10]. However, solubility of chrysin is extremely poor, and its 5,7-
hydroxy groups are easily glycosylated which limit its clinical application. Therefore,
CONTACT De-Qian Peng
pengdeqian2004@163.com; Xun Chen
chenxunchenpei@163.com; Can-Hong Wang
xinzhuangjianpo@163.com
ß 2019 Informa UK Limited, trading as Taylor & Francis Group

2
N. CHEN ET AL.
Figure 1. Synthesis of chrysin derivatives.
there were lots of reports to solve these problems. Zou et al. found that nitric oxide-
donating derivatives of chrysin showed vasculoprotective effects [11]. Some chrysin
derivatives showed stronger anticancer activity than chrysin such as 5,7-diacetyl
chrysin [12], iodo-chrysin derivatives [13,14], amino acid chrysin derivatives [15],
long-chain chrysin derivatives [16], chrysin benzoates [17], and N-chrysin derivatives
[
18]. Fonseca et al. found that the selenium-containing chrysin derivatives showed
antioxidant and anticancer activities in vitro [19]. Some chrysin derivatives (chrysin
containing piperazines [20] and chrysin containing N-derivatives [21]) showed anti-
bacterial activity. Either chrysin derivatives or chrysin nitric oxide (NO)-donating
derivatives showed a-glucosidase inhibitory activity [22]. Valdez-Calder oꢀ n et al. syn-
thesized chrysin containing 2-mercaptopyridine or 5-(trifluoromethyl)-2-mercaptopyr-
idine, and some of them inhibited larval development [23].
As we know, aromatic compounds also have extensive pharmacological activities
with low toxicity and high efficacy. Therefore, introducing aromatic groups into the
basic skeleton of chrysin will give the resulting compounds that not only improve the
solubility of the compounds but also play synergistic anticancer effect. Thereby, the
compounds will increase solubility and efficacy [4].
In this paper, a series of aromatic or long-chain groups were introduced into the
skeleton of chrysin by esterification of chrysin and acyl chloride and got 10 chrysin
derivatives (1–10). The anticancer activity of long-chain chrysin derivative was better
than chrysin against liver cancer cell lines.
2. Results and discussion
2.1. Synthesis
The procedures for the synthesis of these compounds in this paper by the reaction of
chrysin and acyl chloride are shown in Figure 1. A series of aromatic groups with

JOURNAL OF ASIAN NATURAL PRODUCTS RESEARCH
3
rigid structures were introduced into the chrysin skeleton through esterification. In
the process of reaction, an appropriate amount of triethylamine was added as a bind-
ing acid agent to neutralize the hydrochloric acid generated by the reaction, so that
the reaction was carried forward, and the yield of the target product was improved,
and aromatic chrysin derivatives were obtained (1–9). However, these compounds
were hard to dissolve in common organic solvents (n-hexane, ethyl acetate, methanol,
ethanol, dimethyl sulfoxide, etc.) and that may be due to the strong rigid structure of
aromatic compounds. Therefore, a flexible long-chain chrysin derivative was synthe-
sized (10), which had good solubility in dimethylsulphoxide. Moreover, the hydrogen
of 5-OH group bonded with the carbonyl group and formed a relatively stable six-
member ring, with the result that the 5-OH group of chrysin is not more active than
its 7-OH group [24]. Consequently, substitutions with acyl chloride at the 7-position
of chrysin were gained at low reaction temperature.
2
.2. Structural characterization
1
Among all compounds, H NMR spectral analysis indicated that the 5-position phen-
olic hydroxyl proton peak of chrysin was in the lowest field (d 11.69–12.77) due to
the electron-withdrawing effect of the carbonyl group on the 4-position and the six-
membered ring between the hydroxyl group and carbonyl group. The proton peaks
13
in the aromatic ring were located in d 6.57–8.39. The C NMR spectra showed that
peaks of the 4-position carbonyl and ester groups of chrysin occurred in the low-
est field.
2
.3. Antitumor activity
Chrysin has extensive pharmacological activities, and aromatic compounds have
excellent anticancer activities. It is supposed to be introduced into the skeletal struc-
ture of chrysin to obtain aromatic chrysin derivatives with an enhanced therapeutic
effect according to the superposition of the pharmacological activity. In this paper,
we synthesized 9 aromatic chrysin derivatives (1–9), which became less soluble in
common organic solvents, resulting in limiting the anticancer activity of these com-
pounds. The flexible long-chain chrysin derivative (10) had better solubility in dime-
thylsulphoxide and showed better anticancer activity (IC50 ¼ 14.79 lmol/L) than that
of chrysin (IC50 ¼ 74.97 lmol/L). The results showed that the flexible long-chain
chrysin derivative had the superposition of pharmacological activity.
3. Experimental
3.1. General experimental procedures
NMR spectra were recorded by a Bruker AVANCE III HD 400 MHz spectrometer
with tetramethylsilane as an internal standard (Bruker, F €a llanden, Switzerland). Mass
spectrum analysis was conducted on a V.G. ZAB-HS spectrometer (VG instruments,
U.K.). The chemical reaction was performed using a concentrated thermostatic heat-
ing magnetic stirrer (Henan Yuhua, Henan, China) and a 78-1 magnetic heating

4
N. CHEN ET AL.
agitator (Eventful instrument, Changzhou, China). The solvent was removed using an
RE-2000B rotary evaporator (Shanghai Yirong, Shanghai, China). The reaction was
monitored using a WFH-204B portable ultraviolet lamp (Shanghai Chitang,
Shanghai, China).
Chrysin and triethylamine were purchased from Shanghai Bide Pharmaceutical
Technology Co., Ltd. (Shanghai, China) and Tianjin Beichen Founder Reagent
Factory (Tianjin, China), respectively; benzoyl chloride, 4-nitrobenzoyl chloride, 4-flu-
orobenzoyl chloride, 4-methylbenzoyl chloride, 3,4,5-trimethyl benzoyl chloride, 4-
methoxybenzoyl chloride, myristoyl chloride, 4-chlorbenzoyl chloride, 4-bromoben-
zoyl chloride, and 4-iodobenzoyl chloride were purchased from J&K Scientific Co.,
Ltd. (Beijing, China); petroleum ether, ethyl acetate, dichloromethane, and acetone
were purchased from Xilong Scientific Co., Ltd. (Guangdong, China); 4A molecular
sieve was purchased from Sinopharm Chemical Reagent Co., Ltd. (Beijing, China).
3.2. Chemistry
The synthesis of compound 1 [25]: chrysin (1.0 g, 3.9 mmol), dissolved in an appro-
priate amount of acetone, was added to the reaction flask in an ice-salt bath. Benzoyl
chloride (1.4 mL, 11.8 mmol) in acetone was added dropwise to the mixture solution
ꢀ
at about 0 C, then followed the equivalent amount of triethylamine, while maintain-
ing the same temperature. The resulting mixture was stirred for 2 h, and the reaction
was completed. Deionized water (10 mL) was added and stirred for 10 min. The
ꢀ
resulting mixture was concentrated through the rotary evaporation apparatus (45 C),
then transferred the liquid to the separatory funnel and extracted with ethyl acetate
for five times. The organic layers were dried by anhydrous Na SO and recrystallized
2
4
in ethyl acetate to gain the yellow chrysin derivative (1.6 g; yield ¼ 83.3%; R ¼ 0.38
f
(
petroleum ether:ethyl acetate ¼ 12:1)). A similar procedure was utilized to synthesize
other chrysin derivatives 2–10.
3
.2.1. 7-O-benzoyl chrysin (1)
1
Yield ¼ 83.3%, R ¼ 0.38 (petroleum ether:ethyl acetate ¼ 12:1); H NMR (400 MHz,
f
0
0
00
CDCl ) d 12.75 (s, 1H, -OH), 8.21 (d, 2H, J ¼ 7.6 Hz, H-2 , 6 ), 7.89 (d, 2H,
3
0
0
00
0
0
0
00
J ¼ 7.2 Hz, H-2 , 6 ), 7.67 (t, 1H, J ¼ 7.2 Hz, H-4 ), 7.51–7.58 (m, 5H, H-3 , 4 , 5 , 3 ,
0
0
13
5
), 7.00 (s, 1H, H-3), 6.74 (s, 1H, H-6), 6.71 (s, 1H, H-8). C NMR (101 MHz,
CDCl ) d 183.0(C-4), 164.8(Ar-CO-), 164.3(C-2), 162.1(C-5), 157.0(C-7), 156.5(C-9),
3
00 0 0 00 00 0 0 00
1
1
34.2(C-4 ), 132.3(C-1 ), 131.1(C-4 ), 130.4(C-3 , 5 ), 129.3(C-3 , 5 ), 129.0(C-1 ),
00
00
0
0
28.9(C-2 , 6 ), 126.5(C-2 , 6 ), 109.1(C-3), 106.3(C-6), 105.7(C-8), 101.3(C-10); elec-
þ
trospray ionization (ESI)-MS: m/z 359.2 [M þ H] .
3
.2.2. 7-O-(4-methylbenzoyl)chrysin (2)
1
Yield ¼ 61.1%, R ¼ 0.33 (petroleum ether:ethyl acetate ¼ 12:1); H NMR (400 MHz,
f
00
00
CDCl ) d 12.73 (s, 1H, -OH), 8.08 (d, 2H, J ¼ 8.0 Hz, H-2 , 6 ), 7.88 (d, 2H,
3
0
0
0
0
0
J ¼ 7.2 Hz, J ¼ 7.2 Hz, H-2 , 6 ), 7.49–7.57 (m, 3H, H-3 , 4 , 5 ), 7.31 (d, 2H, J ¼ 7.6 Hz,
00
00
H-3 , 5 ), 6.98 (s, 1H, H-3), 6.72 (s, 1H, H-6), 6.69 (s, 1H, H-8), 2.46 (s, 3H, -CH ).
3
1
3
C NMR (101 MHz, CDCl ) d 182.9(C-4), 164.7(ArCO-), 164.3(C-2), 162.0(C-5),
3

JOURNAL OF ASIAN NATURAL PRODUCTS RESEARCH
5
00 0 0 00 00
56.9(C-7), 156.5(C-9), 145.1(C-4 ), 132.2(C-1 ), 131.1(C-4 ), 130.4(C-3 , 5 ),
1
1
1
00
0
0
0
0
00
00
29.5(C-1 ), 129.2(C-3 , 5 ), 126.5(C-2 , 6 ), 126.2(C-2 , 6 ), 109.0(C-3), 106.2(C-6),
þ
05.7(C-8), 101.3(C-10), 21.9(C-CH ); ESI-MS: m/z 373.3 [M þ H] .
3
0
0
0
3
.2.3. 7-O-(3 ,4 ,5 -trimethylbenzoyl)chrysin (3)
1
Yield ¼ 79.4%, R ¼ 0.52 (petroleum ether:ethyl acetate ¼ 12:1); H NMR (400 MHz,
f
0
0
CDCl ) d 12.77 (s, 1H, -OH), 7.93 (d, 2H, J ¼ 7.6 Hz, H-2 , 6 ), 7.52-7.60 (m, 3H, H-
3
0
0 0 00 00
3
8
, 4 , 5 ), 7.00 (s, 1H, H-3), 6.95 (s, 2H, H-2 , 6 ), 6.76 (s, 1H, H-6), 6.71 (s, 1H, H-
00
00
00 13
), 2.47 (s, 6H, 2 ꢁ CH -3 , 5 ), 2.43 (s, 3H, -CH -4 ). C NMR (101 MHz, CDCl3)
3
3
d 183.0(C-4), 167.4(Ar-CO-), 164.9(C-2), 162.2(C-5), 157.0(C-7), 156.2(C-9), 140.6(C-
0
0
0
0
00 00 0 0 0 0 00 00
4
6
2
), 136.0(C-3 , 5 ), 132.3(C-1 ), 131.1(C-4 ), 129.3(C-3 , 5 ), 129.2(C-1 ), 129.0(C-2 ,
), 126.6(C-2 , 6 ), 109.2(C-3), 106.3(C-6), 105.6(C-8), 101.2(C-10), 21.3(CH -C 00),
0
0
3
4
þ
0.2(2 ꢁ CH -C 00 00); ESI-MS: m/z 401.4 [M þ H] .
3
3 , 5
3
.2.4. 7-O-(4-methoxylbenzoyl)chrysin (4)
1
Yield ¼ 94.9%, R ¼ 0.48 (petroleum ether:ethyl acetate ¼ 12:1); H NMR (400 MHz,
f
00
CDCl ) d 12.74 (s, 1H, -OH), 8.17 (dd, 1H, J ¼ 2.8, 2.4 Hz, H-2 ), 8.15 (dd, 1H,
3
00
J ¼ 2.0, 2.8 Hz, H-6 ), 7.91 (dd, 1H, J ¼ 1.2, 2.4 Hz, H-6), 7.90 (t, 1H, J ¼ 2.0 Hz, H-2),
0
0
0
00
7
.51–7.57 (m, 3H, H-3 , 4 , 5 ), 7.02 (dd, 1H, J ¼ 2.0, 2.8 Hz, H-3 ), 7.00 (m, 2H, H-3,
0
0
13
5
), 6.75 (s, 1H, H-6), 6.71 (d, 1H, J ¼ 2.0 Hz, H-8), 3.92 (s, 3H, -OCH ). C NMR
3
00
101 MHz, CDCl ) d 183.1(C-4), 164.8(Ar-CO-), 164.5(C-2), 164.0(C-4 ), 162.1(C-5),
3
(
00 00 0 0 0 0
57.0(C-7), 156.7(C-9), 132.7(C-3 , 5 ), 132.3(C-1 ), 131.2(C-4 ), 129.3(C-3 , 5 ),
1
1
1
0
0
00
00
00
26.6(C-2 , 6 ), 121.2(C-1 ), 114.2(C-2 , 6 ), 109.0(C-3), 106.3(C-6), 105.8(C-8),
01.4(C-10), 55.7(-OCH ); ESI-MS: m/z 389.6 [M þ H] .
þ
3
3
.2.5. 7-O-(4-iodobenzoyl)chrysin (5)
1
Yield ¼ 63.1%, R ¼ 0.46 (petroleum ether:ethyl acetate ¼ 5:1); H NMR (400 MHz,
f
0
0
00
CDCl ) d 12.76 (s, 1H, -OH), 8.14 (d, 2H, J ¼ 8.0 Hz, H-2 , 6 ), 7.90 (d, 2H,
3
0
0
0
0
0
00
00
J ¼ 6.8 Hz, H-2 , 6 ), 7.50–7.59 (m, 5H, H-3 , 4 , 5 , 3 , 5 ), 6.99 (s, 1H, H-3), 6.75 (s,
1
3
1
1
6
1
H, H-6), 6.71 (s 1H, H-8). C NMR (101 MHz, CDCl ) d 183.0(C-4), 164.9(Ar-CO-),
63.7(C-2), 162.2(C-5), 157.0(C-7), 156.2(C-9), 132.3(C-1 ), 132.0(C-3 , 5 ), 131.7(C-2 ,
0
3
0
00
0
00
0
00
0
0
00
0
0
00
), 131.2(C-4 ), 129.3(C-1 ), 129.3(C-3 , 5 ), 129.3(C-4 ), 126.6(C-2 , 6 ), 109.2(C-3),
þ
06.4(C-6), 105.7(C-8), 101.2(C-10); ESI-MS: m/z 485.7 [Mþ H] .
3
.2.6. 7-O-(4-bromobenzoyl)chrysin (6)
1
Yield ¼ 62.1%, R ¼ 0.48 (petroleum ether:ethyl acetate ¼ 5:1); H NMR (400 MHz,
f
00
00
CDCl ) d 12.76 (s, 1H, -OH), 8.07 (d, 2H, J ¼ 6.8 Hz, H-2 , 6 ), 7.89 (d, 2H,
3
0
0
00
00
0
0
0
J ¼ 4.2 Hz, H-2 , 6 ), 7.68 (d, 2H, J ¼ 6.8 Hz, H-3 , 5 ), 7.53–7.63 (m, 3H, H-3 , 4 , 5 ),
13
6
1
1
1
.99 (s, 1H, H-3), 6.75 (s, 1H, H-6), 6.70 (s 1H, H-8). C NMR (101 MHz, CDCl ) d
83.0(C-4), 164.9(Ar-CO-), 163.7(C-2), 162.2(C-5), 157.0(C-7), 156.2(C-9), 132.3(C-
0
3
0
00
00
00
00
00
0
0
), 132.3(C-4 ), 131.9(C-2 , 6 ), 131.2(C-3 , 5 ), 129.6(C-4 ), 129.4(C-3 , 5 ),
00
0
0
27.9(C-1 ), 126.6(C-2 , 6 ), 109.3(C-3), 106.4(C-6), 105.7(C-8), 101.2(C-10); ESI-MS:
þ
m/z 438.2 [M þ H] .

6
N. CHEN ET AL.
3
.2.7. 7-O-(4-chlorobenzoyl)chrysin (7)
1
Yield ¼ 77.7%, R ¼ 0.46 (petroleum ether:ethyl acetate ¼ 5:1); H NMR (400 MHz,
f
00
00
CDCl ) d 12.76 (s, 1H, -OH), 7.97 (d, 2H, J ¼ 6.8 Hz, H-2 , 6 ), 7.88–7.91 (m, 4H, H-
3
0
0 00 00 0 0 0
2
, 6 , 3 , 5 ), 7.51-7.59 (m, 3H, H-3 , 4 , 5 ), 6.99 (s, 1H, H-3), 6.75 (s, 1H, H-6), 6.70
1
3
(
s, 1H, H-8). C NMR (101 MHz, CDCl ) d 183.0(C-4), 164.9(Ar-CO-), 163.5(C-2),
3
00 0 00 00
62.2(C-5), 157.0(C-7), 156.2(C-9), 140.9(C-4 ), 132.3(C-1 ), 131.8(C-3 , 5 ), 131.2(C-
1
4
6
0
00
00
0
0
00
0
0
), 129.3(C-2 , 6 ), 129.3(C-3 , 5 ), 127.4(C-1 ), 126.6(C-2 , 6 ), 109.2(C-3), 106.4(C-
þ
), 105.7(C-8), 101.2(C-10); ESI-MS: m/z 393.6 [M þ H] .
3
.2.8. 7-O-(4-fluorobenzoyl)chrysin (8)
1
Yield ¼ 87.8%, R ¼ 0.52 (petroleum ether:ethyl acetate ¼ 12:1); H NMR (400 MHz,
f
00
CDCl ) d 12.76 (s, 1H, -OH), 8.29 (dd, 1H, J ¼ 6.8, 6.0 Hz, H-2 ), 8.23 (dd, 1H,
3
00
0
0
J ¼ 7.2, 5.6 Hz, H-6 ), 7.86 (d, 2H, J ¼ 6.8 Hz, H-2 , 6 ), 7.52 (d, 3H, J ¼ 6.8 Hz, H-3,
0
0
00 0 0 0
13
3
, 5 ), 7.13–7.25 (m, 3H, H-3 , 4 , 5 ), 7.13 (s, 1H, H-6), 6.65 (s, 1H, H-8). C NMR
00
101 MHz, CDCl ) d 176.4(C-4), 164.3(C-4 ), 163.1(Ar-CO-), 162.8(C-2), 158.0(C-5),
3
(
0 0 00 0 0
54.2(C-7), 150.6(C-9), 133.2(C-1 ), 132.0(C-4 ), 131.2(C-1 ), 129.3(C-3 , 5 ), 129.2(C-
1
3
1
0
0
00
0
0
00
00
, 5 ), 126.4(C-2 , 6 ), 126.0(C-2 , 6 ), 115.8(C-3), 114.2(C-6), 109.5(C-8), 108.8(C-
þ
0); ESI-MS: m/z 377.4 [M þ H] .
3
.2.9. 7-O-(4-nitrobenzoyl)chrysin (9)
1
Yield ¼ 12.6%, R ¼ 0.48 (petroleum ether:ethyl acetate ¼ 9:1), H NMR (400 MHz,
f
00
00
00
00
CDCl ) d 12.81 (s, 1H, -OH), 8.39 (s, 4H, H-2 , 3 , 5 , 6 ), 7.92 (dd, 1H, J ¼ 1.2,
3
0
0
0
0
13
0
1
.6 Hz, H-2 ), 7.80 (dd, 1H, J ¼ 2.0, 1.6 Hz, H-6 ), 7.52–7.59 (m, 3H, H-3 , 4 , 5 ), 7.02
(d, 1H, J ¼ 2.0 Hz, H-3), 6.78 (s, 1H, H-6), 6.73 (d, 1H, J ¼ 2.0 Hz, H-8). C NMR
(101 MHz, CDCl ) d 183.0(C-4), 165.1(Ar-CO-), 162.6(C-2), 162.4(C-5), 157.0(C-7),
3
00 00 0 0 00 00
1
1
1
55.8(C-9), 151.4(C-4 ), 134.4(C-1 ), 132.4(C-1 ), 131.6(C-4 ), 131.1(C-2 , 6 ),
29.4(C-3 , 5 ), 126.6(C-2 , 6 ), 124.0(C-3 , 5 ), 109.5(C-3), 106.5(C-6), 105.5(C-8),
01.1(C-10); ESI-MS: m/z 404.3 [M þ H] .
0
0
0
0
00
00
þ
3
.2.10. 7-O-myristyl chrysin (10)
1
Yield ¼ 95.8%, R ¼ 0.52 (petroleum ether:ethyl acetate ¼ 12:1), H NMR (400 MHz,
f
0
CDCl ) d 12.69 (s, 1H, -OH), 7.90 (dd, 1H, J ¼ 1.2, 1.6 Hz, H-2 ), 7.88 (dd, 1H,
3
0
0
0
0
J ¼ 2.0,1.6 Hz, H-6 ), 7.51–7.59 (m, 3H, H-3 , 4 , 5 ), 6.86 (d, 1H, J ¼ 2.0 Hz, H-3),
6
1
1
.73 (s, 1H, H-6), 6.57 (d, 1H, J ¼ 2.0 Hz, H-8), 2.59 (t, 2H, J ¼ 7.6 Hz, -COCH -),
2
.73-1.81 (m, 2H, -COCH CH -), 1.39-1.47 (m, 2H, -COCH CH CH -), 1.27-1.37 (m,
2
2
2
2
2
1
3
8H, -(CH ) CH ), 0.89 (dd, 3H, J ¼ 6.4, 7.2 Hz, -CH ). C NMR (101 MHz, CDCl )
2
9
3
3
3
0
00
d 183.0(C-4), 171.4(C-1 ), 164.8(C-2), 162.0(C-5), 156.9(C-7), 156.3(C-9), 132.3(C-1 ),
0 0 0 0 0
1
1
1
31.2(C-4 ), 129.3(C-3 , 5 ), 126.5(C-2 , 6 ), 109.0(C-3), 106.3(C-6), 105.6(C-8),
01.1(C-10), 34.6(C-2 ), 32.0(C-3 ), 29.2-29.8(C-4 -11 ), 25.0(C-12 ), 22.8(C-13 ),
4.2(C-14 ); ESI-MS: m/z 465.5 [M þ H] .
00
00
00
00
00
00
00
þ
3
.3. Anticancer activity
In this paper, anticancer activities of chrysin derivatives were carried out with human
liver cancer cell line HepG2 by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-

JOURNAL OF ASIAN NATURAL PRODUCTS RESEARCH
7
4
tetrazolium bromide (MTT) assay in vitro. The cell lines (approximate 10 cells) were
cultured in the 96-well plate and incubated in the CO culture box for 24 h. The
2
supernatant was absorbed, and the diluted compound in dimethyl sulfoxide (DMSO)
was added to each pore (200 lL) and got the concentration gradient of 100, 50, 25,
12.5, and 6.25 lmol/L. The solvent control group (containing 0.4% DMSO) and the
blank group (equivalent medium) were incubated for 48 h with 5 rewells at each con-
centration. The MTT solution of 5.0 g/L was added to each well for 20 lL, incubated
for 4 h, and the supernatant was discarded. After adding 150 lL DMSO and oscillat-
ing for 10 min, the absorbance OD value was measured at 570 nm with EX-800
Eliasa, and half of the inhibitory concentration (IC ) of the drug was calculated. All
50
of the compounds were repeated three times for each cell line.
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding
This research work was financially supported by the Program of Hainan Association for
Science and Technology Plans to Youth R & D Innovation (QCXM 201707 and 201808),
Scientific Research Foundation for Advanced Talents in Hainan Medical University
(XRC180004), Cultivation Foundation of Hainan Medical College (HY2015-03), and
Innovation and Entrepreneurship Training Project for College Students (201811810028,
HYCX2018028, and HYCX2018090).
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