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New Phloroglucinol Derivatives from the Fruit Tree Syzygium jambos and Their Cytotoxic and Antioxidant Activities Guo-Qiang Li, Yu-Bo Zhang, Peng Wu, Neng-Hua Chen, ZhongNan Wu, Li Yang, Rui-Xia Qiu, Guo-Cai Wang, and Yao-Lan Li J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.5b04293 • Publication Date (Web): 10 Nov 2015 Downloaded from http://pubs.acs.org on November 16, 2015
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Journal of Agricultural and Food Chemistry
New Phloroglucinol Derivatives from the Fruit Tree Syzygium jambos and Their Cytotoxic and Antioxidant Activities Guo-Qiang Li,†,§ Yu-Bo Zhang,†,§ Peng Wu,†,ǁ,§ Neng-Hua Chen,† Zhong-Nan Wu,† Li Yang,† Rui-Xia Qiu,‡ Guo-Cai Wang,*,† Yao-Lan Li*,† †
Institute of Traditional Chinese Medicine and Natural Products, College of Pharmacy, Jinan University, Guangzhou 510632, P. R. China
‡
Department of Food Science and Engineering, Jinan University, Guangzhou 510632, P. R. China
ǁ
International Institute for Translational Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou 510006, P. R. China
1
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ABSTRACT: Seven new phloroglucinol derivatives (1–7) were isolated from the
2
fruit tree Syzygium jambos together with four known triterpenoids (8–11) and two
3
known flavones (12–13). According to the spectroscopic analyses (IR, ESIMS,
4
HRESIMS, 1D and 2D NMR), the structures of compounds 1–7 were elucidated as
5
jambone A (1), jambone B (2), jambone C (3), jambone D (4), jambone E (5),
6
jambone F (6), and jambone G (7). All the isolates were determined for their cytotoxic
7
activities on melanoma cells by MTT assay, and compounds 10 and 11 showed potent
8
activities. Moreover, compounds 1‒2, 4‒7 and 12‒13 exhibited weak antioxidant
9
activities under FRAP and DPPH radical-scavenging assays.
10 11
KEYWORDS: Syzygium jambos, phloroglucinol derivatives, structure identification,
12
cytotoxic activity, antioxidant activity
2
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■ INTRODUCTION
14
The genus Syzygium (Myrtaceae) which consists of 500 species is mainly distributed
15
in tropical America and Austrilia.1 In the south of China, there are about 70 species of
16
Syzygium including Syzygium jambos (L.) Alston, and many of them are used as the
17
edible and medicinal plants. Different parts of the plants have different
18
pharmacological actions in the system of traditional medicine. The fructification is a
19
kind of common fruit in folk, and it is seen as a tonic for the brain and liver.2 The
20
barks are applied to treat asthma, bronchitis and hoarseness.2 The leaves are used as
21
the source of herbal tea in China, and their decoctions are not only used as a diuretic,
22
but also used for the treatment of rheumatism and sore eyes.2 The seeds are used to
23
treat catarrh, diarrhea, diabetes and dysentery, and the flowers can reduce fever.2
24
Syzygium jambos (Eugenia jambos) is a fruit tree which originated in Southeast Asia
25
and naturalized in India.1 Previous investigations on S. jambos had led to the isolation
26
of phenols,3,4 flavonoids5-7 and triterpenoids.8,9 The modern pharmacological studies
27
had found that the extract of S. jambos possessed anti-dermatophytic,9
28
anti-bacterial,3,10 anti-inflammatory,3,11 anti-nociceptive,1 anti-oxidant12 and liver
29
protective13 activities.
30
In our efforts to study the Chinese medicines, the chemical constituents of S.
31
jambos was investigated, leading to the isolation of seven new phloroglucinol
32
derivatives (1‒7), four known triterpenoids (8‒11) and two known flavones (12‒13).
33
These isolates were tested for their cytotoxic activities on melanoma cells by MTT 3
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assay.
Furthermore,
their
antioxidant
35
2,2-diphenyl-1-picryhydrazyl
36
antioxidant power (FRAP) assays.
37
■ MATERIALS AND METHODS
(DPPH)
capabilities
radical-scavenging
were and
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evaluated
by
ferric-reducing
38
General Apparatus and Chemicals. A Jasco V-550 UV/VIS spectrophotometer
39
was applied for recording ultraviolet absorption spectra. IR spectroscopy were
40
scanned using a Bruker EQUINOX 55 spectrometer with KBr pellets. The 1D and 2D
41
NMR spectra were measured on a Bruker AVANCE-500 NMR spectrometer (500
42
MHz for 1H NMR; 125 MHz for 13C NMR). The ESIMS data were obtained using an
43
AB SCIEX 4000 Q-Trap mass spectrometer. HRESIMS data were determined on an
44
AB SCIEX Triple TOF 5600+ mass spectrometer. Analytical HPLC was performed
45
with a Dionex chromatograph with a P680 pump, a PDA-100 photodiode array
46
detector, and a Cosmosil C18 column (4.6 × 250 mm, 5 µm). Preparative HPLC was
47
performed on an Agilent 1100 LC series with a DAD detector using a preparative
48
Cosmosil C18 column (20 × 250 mm, 5 µm). Silica gel (200-300 mesh, Qingdao
49
Marine Chemical Inc., Qingdao, China), Sephadex LH-20 (Pharmacia Biotech,
50
Uppsala, Sweden) and reverse phase C-18 (50 µm, YMC, Kyoto, Japan) were used to
51
perform column chromatography (CC). The precoated silica gel GF254 plate for TLC
52
was purchased from Yantai Chemical Industry Research Institute (Yantai, China). All
53
reagents were provided by Tianjin Damao Chemical Company (Tianjin, China).
54
3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT),
55
acid,
2,4,6-tris(2-pyridyl)-s-triazine
(TPTZ)
and
L-ascorbic
2,2-diphenyl-1-picrylhydrazyl 4
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(DPPH) were purchased from Sigma (St. Louis, USA).
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Plant Material. The leaves of S. jambos were collected in May 2012 from
58
Guangzhou, Guangdong, China. This plant was authenticated by Prof. Guang-Xiong
59
Zhou of the College of Pharmacy, Jinan University. A voucher specimen (NO.
60
20120524) is deposited in the Institute of Traditional Chinese Medicine and Natural
61
Products, College of Pharmacy, Jinan University (Guangzhou, China).
62
Extraction and Isolation. The air-dried and powdered leaves (10 kg) of S.
63
jambos were extracted thrice with 95% EtOH at 70°C. The solution was evaporated
64
under reduced pressure to get a residue (700 g). The residue was firstly suspended in
65
water, and then partitioned with petroleum ether, ethyl acetate, and n-butyl alcohol,
66
respectively. The ethyl acetate part (250 g) was loaded to a silica gel CC
67
(CHCl3/MeOH, 100:0 to 0:100, v/v) to give five fractions (1–5). Fraction 1 (45 g) was
68
separated by a reversed silica gel (MeOH/H2O, 30:70 to 100:0, v/v) and Sephadex
69
LH-20 (CHCl3/MeOH, 50:50, v/v) CC to obtain compounds 8 (11 mg), 9 (7 mg) and
70
11 (16 mg). Fraction 2 (3 g) was purified by Sephadex LH-20 CC (MeOH) and
71
preparative HPLC (MeOH/H2O, 65:35, v/v) to afford compounds 5 (13 mg) and 10
72
(14 mg). Fraction 3 (30 g) was separated by reversed silica gel (MeOH/H2O, 30:70 to
73
100:0, v/v) and Sephadex LH-20 (MeOH) CC to achieve compounds 1 (12 mg), 3 (10
74
mg) and 4 (22 mg). Fraction 3 was further purified by preparative HPLC (MeOH/H2O,
75
75:25, v/v) to afford compounds 2 (15 mg), 6 (8 mg) and 7 (16 mg). Fraction 5 (28 g)
76
was chromatographed twice on reversed silica gel CC (MeOH/H2O, 50:50 to 100:0,
77
v/v) and Sephadex LH-20 CC (MeOH) to yield compounds 12 (12 mg) and 13 (9 mg). 5
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Jambone A (1): red gum; UV (MeOH) λmax 205, 226, 286 nm; IR (KBr) νmax 3200,
79
2927, 1700, 1620, 1525, 1459, 1394, 1253, 1170, 1078, 1024, 987, 828, 733, 525
80
cm-1; 1H and
81
(calcd for C24H35O4, 387.2535).
13
C NMR data see Tables 1 and 2; HRESIMS m/z 387.2526 [M+H]+
82
Jambone B (2): red gum; UV (MeOH) λmax 204, 232, 286 nm; IR (KBr) νmax 3238,
83
2927, 2854, 1700, 1627, 1525, 1459, 1450, 1292, 1147, 1112, 723, 615 cm-1; 1H and
84
13
85
C25H35O4, 399.2535).
C NMR data see Tables 1 and 2; HRESIMS m/z 399.2530 [M-H]- (calcd for
86
Jambone C (3): red gum; UV (MeOH) λmax 204, 227, 286 nm; IR (KBr) νmax 3238,
87
3009, 2930, 2854, 1705, 1630, 1525, 1463, 1395, 1249, 1171, 1076, 1023, 725, 526
88
cm-1; 1H and
89
(calcd for C24H37O4, 389.2692).
13
C NMR data see Tables 1 and 2; HRESIMS m/z 389.2688 [M+H]+
90
Jambone D (4): red gum; UV (MeOH) λmax 204, 227, 286 nm; IR (KBr) νmax 3387,
91
3006, 2931, 2854, 1717, 1697, 1680, 1624, 1510, 1453, 1142, 724, 668, 446 cm-1; 1H
92
and
93
C25H37O4, 401.2692).
13
C NMR data see Tables 1 and 2; HRESIMS m/z 401.2675 [M-H]- (calcd for
94
Jambone E (5): red gum; UV (MeOH) λmax 205, 227, 249, 294 nm; IR (KBr) νmax
95
3400, 3013, 2958, 2855, 1665, 1621, 1584, 1506, 1424, 1365, 1272, 1167, 1067, 1071,
96
846, 728, 554 cm-1; 1H and
97
409.2376 [M-H]- (calcd for C26H33O4, 409.2379).
13
C NMR data see Tables 1 and 2; HRESIMS m/z
98
Jambone F (6): red gum; UV (MeOH) λmax 207, 230, 251, 297 nm; IR (KBr) νmax
99
3461, 2928, 2857, 1657, 1622, 1585, 1460, 1420, 1357, 1296, 1166, 1067, 846, 554 6
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cm-1; 1H and
13
C NMR data see Tables 1 and 2; HRESIMS m/z 425.2672 [M+H]+
101
(calcd for C27H37O4, 425.2692).
102
Jambone G (7): red gum; UV (MeOH) λmax 204, 228, 248, 294 nm; IR (KBr) νmax
103
3400, 2929, 2856, 1661, 1621, 1584, 1510, 1423, 1358, 1271, 1164, 1115, 1067, 978,
104
846, 771, 727, 551 cm-1; 1H and
105
413.2683 [M+H]+ (calcd for C26H37O4, 413.2692).
13
C NMR data see Tables 1 and 2; HRESIMS m/z
106
Cells. The melanoma SK-MEL-28 and SK-MEL-110 cells, as well as normal Vero
107
cells were provided by Sun Yat-Sen University Cancer Center and maintained in
108
DMEM medium (Gibco) containing 5% fetal bovine serum (Gibco) at 37°C in air
109
with 5% CO2.
110
3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay.
111
According to the early study,14 MTT assay was used to assess the cytotoxicities of
112
compounds. The cells (3000 per well) were cultivated in 96-well plates for 24 h to
113
obtain 80% confluent monolayer. The medium was then replaced with new medium
114
containing different concentrations of compounds, and the medium without
115
compounds as control. After incubation for 72 h, medium was replaced by 10 µL of
116
the MTT, and the cells were further incubated for another 4 h to allow MTT formazan
117
formation. Following incubation, the medium was replaced by DMSO (100 µL) to
118
dissolve the formazan crystals in each well. Absorbance was detected by a microplate
119
reader (Thermo Scientific, USA) at 570 nm. Each assay was performed three times,
120
and calculated the concentration giving 50% inhibition (IC50). Cisplatin was used as
121
the positive control. 7
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FRAP Assay. FRAP assay of compounds was estimated in triplicate according to
123
our previous report.15 10 mM TPTZ was dissolved into 40 mM HCl. The 25 mL of
124
0.3 M acetate buffer, 2.5 mL of 20 mM FeCl3 solution and 2.5 mL of 10 mM TPTZ
125
solution were mixed to prepare FRAP reagent. 20 µL of sample (100 µM) and 180 µL
126
of FRAP reagent were added to a 96-well microplate. In the darkness, the mixture was
127
shaken adequately and allowed to stand for 5 min at room temperature. And then, the
128
absorbance was detected at 593 nm with a multi-mode detection microplate reader.
129
The calibration curve was established by using different concentrations (0.15–1.5 mM)
130
of FeSO4·7H2O solution. The positive group was preformed using ascorbic acid. The
131
FRAP value of sample was expressed as the concentration (µM) generating an
132
absorbance increase equivalent to 1 mM Fe2+ solution.
133
DPPH Radical Scavenging Capacity Assay. The antioxidant activities were also
134
assessed by the scavenging activity of stable DPPH free radicals.15,16 100 µL of the
135
sample at different concentrations (0–500 µM in ethanol) was added to 100 µL of
136
DPPH solution (200 µM in ethanol) in a 96-well microplate. The mixture was shaken
137
vigorously and incubated for 30 min in the darkness. The absorbance of the mixture
138
was recorded at 517 nm by using a microplate reader, and ascorbic acid was
139
considered as the positive control. The scavenging capacity of DPPH was calculated
140
in the following way: scavenging activity (%) = 100 × (Acontrol–Asample)/Acontrol, Asample:
141
the absorbance of sample, Acontrol: the absorbance of control. Each assay was
142
determined in triplicate and calculated the concentration scavenging 50% of DPPH
143
radical (SC50). 8
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■ RESULTS AND DISCUSSION
146
The 95% ethanol extract of the leaves of S. jambos was separated by repeated silica
147
gel, ODS, Sephadex LH-20 CC and preparative HPLC to afford seven new
148
compounds, along with six known ones, which were identified as jambone A (1),
149
jambone B (2), jambone C (3), jambone D (4), jambone E (5), jambone F (6),
150
jambone
151
3β-O-trans-p-coumaroylalphitolic acid (10),19 3β-O-cis-p-coumaroylalphitolic acid
152
(11),19
153
6-desmethyl-sideroxylin (13)21 (Fig. 1).
G
(7),
oleanolic
acid
(8),17
betulinic
5,7-dihydroxy-6,8-dimethyl-4′-methoxyflavone
acid
(9),18
(12),20
154
Compound 1 was obtained as red gum. Its molecular formula, C24H34O4, was
155
established on the basis of HRESIMS (m/z 387.2526 [M+H]+, calcd for C24H35O4,
156
387.2535). The IR spectrum suggested the presence of hydroxyl (3200 cm-1), alkyl
157
(2927 cm-1), carbonyl (1700 cm-1), and aromatic ring (1620, 1525 cm-1) functionalities.
158
The 1H NMR spectrum showed a set of double-bond signals at δH 5.23-5.37 (6H,
159
overlapped), indicating the presence of three disubstituted double bonds. The four
160
characteristic proton signals at δH 2.77 (4H, overlapped) suggested the presence of
161
two doubly allylic methylenes. The 13C NMR and DEPT spectra revealed the presence
162
of 24 carbon signals, including a ketonic carbon (δC 207.3), twelve olefinic carbons
163
(δC 95.7-165.9), ten methylenes (δC 21.4-44.8) and a methyl (δC 14.6). All the data of 1
164
were
165
(Z,Z,Z,Z)-1-(2',4',6'-trihydroxyphenyl)octadeca-6,9,12,15-tetraen-l-one,22 except for
similar
to
those
of
the
known
compound
9
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166
the absence of a double bond at C-6, -7 and the presence of two methylenes at δC 30.6,
167
30.6, suggesting that the double bond at C-6, -7 was hydrogenated in 1. This was
168
confirmed by the HMBC correlations between H-8 (δH 2.03) and C-6 (δC 30.6)/C-10
169
(δC 128.7). With the aid of HSQC, 1H-1H COSY, and HMBC experiments, the 1H and
170
13
171
olefinic double bonds were indicated by the chemical shifts observed in the 13C NMR
172
spectrum for the signals of the doubly allylic methylenes (δC 26.4, C-11; δC 26.3,
173
C-14).23 Thus, the structure of 1 was elucidated and named as jambone A.
C NMR signals of 1 were assigned as shown in Table 1. The Z configurations of the
174
Compound 2 was also yielded as red gum. The molecular formula was established
175
to be C25H36O4 based on HRESIMS (m/z 399.2530 [M-H]-, calcd for C25H35O4,
176
399.2535). The IR (3238, 2927, 1700, 1627 and 1525 cm-1) and UV (204, 232 and
177
286 nm) spectra of 2 revealed that it was also a phenol derivative. The 1H and
178
NMR spectra of 2 were very similar to those of 1 except for the presence of an
179
additional methyl (δH 1.85/δC 7.3) in 2 (Tables 1 and 2). The HMBC correlations
180
between H-7′ (δH 1.85) and C-2′ (δC 163.7)/C-3′ (δC 103.5) suggested the additional
181
methyl was connected to C-3′. The 1H-13C long-range correlation of H-2 (δH
182
1.63)/C-1′ (δC 105.1) in the HMBC spectrum indicated the position of the acyl chain
183
was also at C-2′. The Z configurations of the olefinic double bonds were the same as
184
those of 1 indicated by its 13C NMR spectrum. Accordingly, compound 2 was deduced
185
and named as jambone B.
13
C
186
The HRESIMS analysis of 3 showed a quasi-molecular ion peak at m/z 389.2688
187
[M+H]+ (calcd for C25H37O4, 389.2692), corresponding to a molecular formula 10
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C24H36O4. Comparison of the 1H and 13C NMR data of 3 with those of 1 showed that
189
they were similar (Tables 1 and 2). The most notable difference was the double bond
190
between C-15 (δC 128.1) and C-16 (δC 132.6) was replaced by two methylenes at δC
191
30.4 (C-15) and δC 32.6 (C-16), which was verified by the HMBC correlation of H-18
192
(δH 0.87)/C-16. The structure of 3 was deduced by analysis of the HSQC, 1H-1H
193
COSY and HMBC spectra, and all the 1H and 13C NMR data of 3 were assigned and
194
shown in Tables 1 and 2. The above evidence established the structure of compound 3
195
to be jambone C.
196
The molecular formula of 4 was established as C25H38O4 based on the
197
quasi-molecular ion m/z 401.2675 [M-H]- (calcd for C25H37O4, 401.2692). The 1H, 13C
198
NMR and DEPT spectra were similar to those of 3, except for the presence of an
199
additional signal of methyl at C-3′ in 4 (Tables 1 and 2). And this was verified by the
200
HMBC correlations between H-7′ (δH 1.90) and C-2′ (δC 163.8)/C-3′ (δC 103.5). The
201
location of the acyl chain was further confirmed by the HMBC correlation between
202
H-2 (δH 3.02) and C-1′ (δC 105.1). According to the chemical shifts of the doubly
203
allylic methylene (δC 26.5, C-11), the configurations of olefinic double bonds were
204
indicated as 9Z and 12Z.23 Thus, compound 4 was identified as jambone D.
205
Compound 5 was isolated as red gum. The HRESIMS exhibited the molecular ion
206
peak at m/z 409.2376 [M-H]- (calcd for C26H33O4, 409.2379), indicating its molecular
207
formula was C26H34O4. The spectral properties of 5 [IR νmax 1665, 1621, 1584 cm−1;
208
UV (CH3OH) λmax 205, 227, 249, 294 nm] implied the presence of a
209
5,7-dihydroxychromone chromophore. Indeed, the
13
C NMR spectrum (Table 2) 11
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210
contained all the appropriate resonances (δC 95.4, 100.7, 104.6, 108.1, 160.0, 163.1,
211
168.0, 172.2, 183.7) for this ring system.24 Comparison of the 1H and 13C NMR data
212
of 5 (Table 1) with those of 1 showed that they possessed a same long side-chain. The
213
HMBC correlations between H-1′ (δH 2.55)/H-2′ (δH 1.66) and C-2 (δC 172.2)
214
revealed the side chain was located at C-2. The
215
methylenes (δC 26.5, C-10′; δC 26.4, C-13′) revealed the olefinic double bonds were Z
216
configurations.23 Accordingly, compound 5 was deduced to be jambone E.
13
C NMR data of the doubly allylic
217
The 1D NMR data of compound 6 were in good agreement with those of
218
compound 5 (Tables 1 and 2), except for the presence of an additional methyl (δH
219
1.97/δC 7.3) in 6. The HMBC correlations between H-11 (δH 1.97) and C-5 (δC
220
160.0)/C-6 (108.8) suggested the additional methyl was connected to C-6. The
221
location of the alkyl chain was further confirmed by the HMBC correlation between
222
H-2′ (δH 1.65) and C-2 (δC 172.1). The configurations of the olefinic double bonds
223
were also established by its
224
deduced to be jambone F.
13
C NMR spectrum.23 Accordingly, compound 6 was
225
Compound 7 was also isolated as red gum. Its molecular formula was determined
226
as C26H36O4 according to the HRESIMS (m/z 413.2683 [M+H]+, calcd for C26H37O4,
227
413.2692). The 1H and 13C NMR data of 7 were similar to those of 5 (Tables 1 and 2).
228
The most notable difference was that a double bond at C-14′, 15′ (δC 128.2, 132.7) in
229
5 was replaced by two methylenes (δC 30.4, C-14′; δC 32.6, C-15′) in 7, which was
230
confirmed by the HMBC correlation of H-17′ (δH 0.87)/C-15′. The structure of 7 was
231
confirmed by analysis of the HSQC, 1H-1H COSY and HMBC spectra, and all the 1H 12
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232
and 13C NMR data of 7 were assigned and shown in Tables 1 and 2. So compound 7
233
was identified as jambone G.
234
The cytotoxic activities on melanoma cells of the isolates. All the isolates were
235
tested for their cytotoxic effects on melanoma SK-MEL-28 and SK-MEL-110 cells,
236
as well as normal Vero cells using the MTT assay. As shown in Table 3, compound
237
1 possessed moderate to weak activity against SK-MEL-110 cells, and compounds 3,
238
8 and 9 exhibited moderate inhibitory effects on melanoma SK-MEL-28 and
239
SK-MEL-110 cells. It is noteworthy that compounds 10 and 11, lupane-type
240
triterpenes with coumaroyl moiety at the C-3 position, displayed more potent effects
241
on these two melanoma cells. Our result was consistent with a previous study which
242
indicated that coumaroyl moiety significantly influenced the cytotoxicity of
243
lupane-type triterpene.25
244
The antioxidant activities of the isolates. In a previous study, the extract of
245
leaves of S. jambos showed potent antioxidant capacity, which was mainly caused by
246
gallic and chlorogenic acids, rutin, quercetin, caffeic acid as well as kaempferol.12 In
247
our work, the antioxidant activities of compounds 1‒13 were also tested by FRAP and
248
DPPH radical scavenging capacity assays, however only 1‒2, 4‒7 and 12‒13
249
exhibited weak antioxidant activities (Table 4), suggesting these thirteen compounds
250
were not the major antioxidant constituents of the plant.
13
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■ ASSOCIATED CONTENT Supporting Information
The HRESIMS and NMR spectra of compounds 1–7. This material is available free of charge via the Internet at http://pubs.acs.org.
■ AUTHOR INFORMATION Corresponding Author * (G. C. Wang) E-mail:
[email protected]. * (Y.L. Li) E-mail:
[email protected]. Author Contributions §
These authors contributed equally to this study.
Funding This work was supported financially by the Natural Science Foundations of China (81202429, 81273390 and 81473116), the Fundamental Research Funds for the Central Universities (11615305), the Natural Science Foundation of Guangdong Province (No. S2013020012864) and 111 Project (NO. B13038). Notes The authors declare no competing financial interest.
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Peña, N.; Quintero, L.; Suárez-Roca, H. Antinociceptive activity of Syzygium
jambos leaves extract on rats. J. Ethnopharmacol. 2007, 112, 380–385. (2)
Warrier, P. K.; Nambiar, V. P.; Ramankutty, C. Indian medicinal plants. A
compendium of 500 species. Chennai: Orient Longman Ltd 1996, 5, 229–231. (3)
Sharma, R.; Kishore, N.; Hussein, A.; Lall, N. Antibacterial and
anti-inflammatory effects of Syzygium jambos L. (Alston) and isolated compounds on acne vulgaris. BMC Complementary Altern. Med. 2013, 13, 292. (4)
Simões-Pires, C. A.; Vargas, S.; Marston, A.; Ioset, J. R.; Paulo, M. Q.;
Matheeussen, A.; Maes, L. Ellagic acid derivatives from Syzygium cumini stem bark: investigation of their antiplasmodial activity. Nat. Prod. Commun. 2009, 4, 1371–1376. (5)
Sharma, B.; Viswanath, G.; Salunke, R.; Roy, P. Effects of flavonoid-rich
extract from seeds of Eugenia jambolana (L.) on carbohydrate and lipid metabolism in diabetic mice. Food Chem. 2008, 110, 697–705. (6)
Jayasinghe, U. L.; Ratnayake, R. M.; Medawala, M. M.; Fujimoto, Y.
Dihydrochalcones with radical scavenging properties from the leaves of Syzygium jambos. Nat. Prod. Res. 2007, 21, 551–554. (7)
Slowing, K.; Söllhuber, M.; Carretero, E.; Villar, A. Flavonoid glycosides
from Eugenia jambos. Phytochemistry 1994, 37, 255–258. (8)
Gupta, G. S.; Sharma, D. P. Triterpenoid and other constituents of Eugenia
jambolana leaves. Phytochemistry 1974, 13, 2013–2014.
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Kuiate, J. R.; Mouokeu, S.; Wabo, H. K.; Tane, P. Antidermatophytic
triterpenoids from Syzygium jambos (L.) Alston (Myrtaceae). Phytother. Res. 2007, 21, 149–152. (10) Djipa, C. D., Delmee, M.; Quetin-Leclercq, J. Antimicrobial activity of bark extracts of Syzygium jambos (L.) alston (Myrtaceae). J. Ethnopharmacol. 2000, 71, 307–313. (11) Slowing, K.; Carretero, E.; Villar, A. Anti-inflammatory activity of leaf extracts of Eugenia jambos in rats. J. Ethnopharmacol. 1994, 43, 9–11. (12) Bonfanti, G., Bitencourt, P. R.; Bona, K. S.; Silva, P. S.; Jantsch, L. B.; Pigatto, A. S.; Boligon, A.; Athayde, M. L.; Gonçalves, T. L.; Moretto, M. B. Syzygium jambos and Solanum guaraniticum show similar antioxidant properties but induce different enzymatic activities in the brain of rats. Molecules 2013, 18, 9179–9194. (13) Islam, M. R.; Parvin, M. S.; Islam, M. E. Antioxidant and hepatoprotective activity of an ethanol extract of Syzygium jambos (L.) leaves. Drug Discov. Ther. 2012, 6, 205–211. (14) Mosmann, T. Rapid colorimetric assay for cellular growth and survival: application to proliferation and cytotoxicity assays. J. Immunol. Methods 1983, 65, 55–63. (15) Zhang, X. L.; Guo, Y. S.; Wang, C. H.; Li, G. Q.; Xu, J. J.; Chung, H. Y.; Ye, W. C.; Li, Y. L.; Wang, G. C. Phenolic compounds from Origanum vulgare and their antioxidant and antiviral activities. Food Chem. 2014, 152, 300–306. 16
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(16) Xu, J. J.; Wu, X.; Li, M. M.; Li, G. Q.; Yang, Y. T.; Luo, H. J.; Huang, W. H.; Chung, H. Y.; Ye, W. C.; Wang, G. C.; Li, Y. L. Antiviral activity of polymethoxylated flavones from “Guangchenpi”, the edible and medicinal pericarps of Citrus reticulata ‘Chachi’. J. Agric. Food Chem. 2014, 62, 2182–2189. (17) Guo, F.; Lin, S.; Li, Y. Isolation and identification of triterpenoids from Schefflera arboricola. Chin. J. Med. Chem. 2005, 15, 294–296. (18) Ma, Z. Z.; Hano, Y.; Nomura, T.; Chen, Y. J. Three new triterpenoids from Peganum nigellastrum. J. Nat. Prod. 2000, 63, 390–392. (19) Yagi, A.; Koda, A.; Inagaki, N.; Haraguchi, Y.; Noda, K.; Okamura, N.; Nishioka, I. Studies on the constituents of Zizyphi fructus. I. Structure of three new para-coumarates of alphitolic acid. Chem. Pharm. Bull. 1978, 26, 1798–1802. (20) Nazreen, S.; Kaur, G.; Alam, M. M.; Shafi, S.; Hamid, H.; Ali, M.; Alam, M. S. New flavones with antidiabetic activity from Callistemon lanceolatus DC. Fitoterapia 2012, 83, 1623–1627. (21) Tu, P. F.; Tao, J.; Hu, Y. Q.; Zhao, M. B. Flavones from the wood Dracaena cochinchinensis. Chin. J. Nat. Med. 2003, 1, 27–29. (22) Kazlauskas, R.; King, L.; Murphy, P. T.; Warren, R. G.; Wells, R. J. New metabolites from the brown algal genus Cystophora. Aust. J. Chem. 1981, 34, 439–447. (23) Tringali, C.; Piattelli, M. Two chromone derivatives from the brown alga Zonaria tournefortii. Tetrahedron Lett. 1982, 23, 1509–1512. (24) Buske, A.; Schmidt, J.; Porzel, A.; Adam, G. Benzopyranones and ferulic 17
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acid derivatives from Antidesma membranaceum. Phytochemistry 1997, 46, 1385–1388. (25)
Lee, S. M.; Min, B. S.; Lee, C. G.; Kim, K. S.; Kho, Y. H. Cytotoxic
triterpenoids from the fruits of Zizyphus jujuba. Planta Med. 2003, 69, 1051–1054.
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OH O R
1'
3'
HO
3
5
7
9
1
11
R HO
OH O R
17
OH O
1R=H 2 R = CH3 5
14
OH
5'
15
12
OH
4
10
3R=H 4 R = CH3
2
HO 7
9 O
1'
5R=H 6 R = CH3
OH O
HO
O 7
O
O R1
OH HO
OH
R2 9 R1 = H R2 = OH 10 R1 = OH R2 = trans-p-counaroyl 11 R1 = OH R2 = cis-p-counaroyl
8
O HO
O
OH O
OH O
O
OH O
12
13
Fig. 1 Structures of compounds 1–13
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Fig.2 Key 1H-1H COSY and HMBC correlations of 1 and 5
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Table 1. 1H and 13C NMR data for 1–4 (500 and 125 MHz, CD3OD, J in Hz)a No.
1 δH 3.01 t (7.3) 1.63 m 1.22-1.40 1.22-1.40 1.22-1.40 1.22-1.40 2.03 5.23-5.37 5.23-5.37 2.77 5.23-5.37 5.23-5.37 2.77 5.23-5.37 5.23-5.37 2.04 0.93 t (7.5)
2 δC 207.3 44.8 26.1 30.2b 30.4b 30.6b 30.6b 28.1 131.0 128.7 c 26.4 129.1 129.1 26.3 128.1 c 132.6 21.4 14.6 105.3 165.7 95.7 165.9 95.7 165.7
δH 2.96 t (7.5) 1.63 m 1.23-1.33 1.23-1.33 1.23-1.33 1.23-1.33 2.00 5.15-5.38 5.15-5.38 2.74 5.15-5.38 5.15-5.38 2.74 5.15-5.38 5.15-5.38 2.01 0.89 t (7.5)
δC 1 207.5 2 44.9 3 26.3 4 30.2 5 30.4b 6 30.6b 7 30.7b 8 28.1 9 131.1 128.8c 10 11 26.5 12 129.1d 13 129.2d 26.4 14 128.2c 15 16 132.7 17 21.4 14.6 18 105.1 1′ 163.7 2′ 5.80 d (2.0) 103.5 3′ 164.9 4′ 5.80 d (2.0) 5.83 s 94.8 5′ 161.3 6′ 1.85 s 7.3 7′ a Overlapped signals were reported without designating multiplicity. b-d Assignments may be intermixed.
3 δH 3.01 t (7.8) 1.63 m 1.23-1.40 1.23-1.40 1.23-1.40 1.23-1.40 2.03 5.25-5.40 5.25-5.40 2.75 5.25-5.40 5.25-5.40 2.04 1.23-1.40 1.28 1.26 0.87 t (7.5)
5.79 d (2.0) 5.79 d (2.0) -
4 δC 207.3 44.8 26.1 30.2b 30.4b 30.6b 30.7b 28.1 130.8c 129.0 26.5 129.0 130.8c 28.1 30.4 32.6 23.6 14.4 105.3 165.8 95.7 166.0 95.7 165.8
δH 3.02 t (7.5) 1.65 m 1.23-1.40 1.23-1.40 1.23-1.40 1.23-1.40 2.03 5.25-5.40 5.25-5.40 2.76 5.25-5.40 5.25-5.40 2.04 1.23-1.40 1.28 1.26 0.88 t (7.5)
5.89 s 1.90 s
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δC 207.5 44.9 26.3 30.2b 30.4b 30.6b 30.7b 28.1 130.9 129.0 26.5 129.0 130.9 28.1 30.4 32.6 23.6 14.4 105.1 163.8 103.5 164.9 94.8 161.3 7.3
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Table 2. 1H and 13C NMR data for 5–7 (500 and 125 MHz, CD3OD, J in Hz)a No.
a
5
6
7
2
δH -
δC 172.2
δH -
δC 172.1
δH -
δC 172.3
3
5.95 s
108.1
5.97 s
108.2
5.99 s
108.3
4
-
183.7
-
184.0
-
183.8
5
-
163.1
-
160.0
-
163.2
6
6.21 d (2.0)
100.7
-
108.8
6.15 s
100.0
7
-
168.0
-
163.8
-
165.8
8
6.09 d (2.0)
9
-
160.0
-
157.5
-
159.7
10
-
104.6
-
104.8
-
105.2
11
-
-
7.3
-
-
1′
2.55 t (7.6)
34.9
2.55 t (7.5)
34.9
2.57 t (7.3)
34.9
2′
1.66 m
27.8
1.65 m
27.8
1.68 m
27.8
95.4
b
6.30 s
1.97 s
93.8
6.27 s
94.9
1.24-1.38
29.9
b
1.22-1.40
30.0b
3′
1.22-1.38
30.0
4′
1.22-1.38
30.1b
1.24-1.38
30.0b
1.22-1.40
30.1b
5′
1.22-1.38
30.1b
1.24-1.38
30.0b
1.22-1.40
30.2b
6′
1.22-1.38
30.6b
1.24-1.38
30.5b
1.22-1.40
30.6b
7′
2.02
8′
5.22-5.35
131.0c
5.22-5.35
131.0
5.24-5.37
130.8c
9′
5.22-5.35
128.8c
5.22-5.35
128.2c
5.24-5.37
129.0d
10′
2.75
11′
5.22-5.35
129.1d
5.22-5.35
129.1
5.24-5.37
129.1d
12′
5.22-5.35
129.2d
5.22-5.35
129.1
5.24-5.37
130.9c
13′
2.75
14′
5.22-5.35
128.2c
5.22-5.35
128.8c
15′
5.22-5.35
132.7
5.22-5.35
16′
2.01
21.4
17′
0.89 t (7.5)
14.6
28.1
26.5
26.4
2.02
2.73
2.73
28.0
26.5
26.3
2.02
28.1
2.74 t (6.2)
26.5
2.01
28.1
1.22-1.40
30.4
132.7
1.26
32.6
2.01
21.4
1.25
23.6
0.89 t (7.5)
14.6
0.87 t (6.8)
14.4
Overlapped signals were reported without designating multiplicity. Assignments may be intermixed.
b-d
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Table 3. Cytotoxic activities of the active compounds a IC50 (µM) b
Compounds SK-MEL-28 1 3 8 9 10 11 Cisplatin
c
>100 39.6 ± 0.6 30.8 ± 1.5 53.1 ± 2.3 19.3 ± 0.9 27.5 ± 1.0 11.5 ± 0.5
SK-MEL-110
Vero
75.6 ± 3.6 50.4 ± 1.3 31.5 ± 2.1 43.5 ± 1.7 18.3 ± 0.4 25.9 ± 0.5 26.5 ± 1.3
82.9 ± 6.7 63.7 ± 5.2 >100 >100 26.2 ± 2.1 81.5 ± 5.9 11.3 ± 0.4
a
Data represented as the mean value ± SD. The test concentrations ranged from 0 to 100 µM, and the IC50 value was tested by MTT assay after incubation for 72 hours. c The IC50 value of sample was higher than 100 µM.
b
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Table 4. Antioxidant activities of compounds 1–13 a Compounds
DPPH SC50
(µM) b
411.8 ± 15.7 1 377.9 ± 8.3 2 d 3 >500 4 487.0 ± 5.7 350.4 ± 6.3 5 316.0 ± 2.1 6 387.1 ± 13.6 7 >500 8 9 >500 >500 10 >500 11 427.2 ± 12.7 12 439.6 ± 8.0 13 Ascorbic acid 18.2 ± 0.4 a Data are represented as mean ± SD. b The test concentrations ranged from 0 to 200 µM. c The test concentrations was 100 µM. d The SC50 value of sample is higher than 500 µM. e n.d. Not detectable.
FRAP value (µM) c 30.1 ± 0.7 38.8 ± 4.9 n.d. e n.d. 43.4 ± 3.6 50.5 ± 1.5 29.2 ± 0.7 n.d. n.d. n.d. n.d. 36.6 ± 3.1 28.3 ± 4.4 457.8 ± 5.8
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Graphic for table of contents
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