Dihydrostilbene glycosides from Camellia sinensis var. assamica and their cytotoxic activity

Article abstract of DOI:10.1080/14786419.2021.1900844

Three undescribed dihydrostilbene glycosides, 3,5-dihydroxyldihydrostilbene 4′-O-[6′′-O-(4′′′-hydroxylbenzoyl)]-β-D-glucopyranoside (1), 3,5-dihydroxyldihydrostilbene 4′-O-(6′′-O-galloyl)-β-D-glucopyranoside (2), and 3,5-dihydroxyldihydrostilbene 4′-O-[6′

Full text of DOI:10.1080/14786419.2021.1900844

Natural Product Research
Formerly Natural Product Letters
ISSN: (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/gnpl20
Dihydrostilbene glycosides from Camellia sinensis
var. assamica and their cytotoxic activity
Nguyen Thi Cuc, Duong Thi Hai Yen, Pham Hai Yen, Dan Thi Thuy Hang, Bui
Huu Tai, Yohan Seo, Wan Namkung, Seung Hyun Kim, Pham Van Cuong,
Phan Van Kiem, Nguyen Xuan Nhiem & Tran Minh Ngoc
To cite this article: Nguyen Thi Cuc, Duong Thi Hai Yen, Pham Hai Yen, Dan Thi Thuy
Hang, Bui Huu Tai, Yohan Seo, Wan Namkung, Seung Hyun Kim, Pham Van Cuong, Phan
Van Kiem, Nguyen Xuan Nhiem & Tran Minh Ngoc (2021): Dihydrostilbene glycosides from
Camelliaꢀsinensis var. assamica and their cytotoxic activity, Natural Product Research, DOI:
10.1080/14786419.2021.1900844
To link to this article: https://doi.org/10.1080/14786419.2021.1900844
View supplementary material
Published online: 22 Mar 2021.
Submit your article to this journal
Article views: 56
View related articles
View Crossmark data
Full Terms & Conditions of access and use can be found at
https://www.tandfonline.com/action/journalInformation?journalCode=gnpl20

NATURAL PRODUCT RESEARCH
https://doi.org/10.1080/14786419.2021.1900844
Dihydrostilbene glycosides from Camellia sinensis var.
assamica and their cytotoxic activity
Nguyen Thi Cuca,c, Duong Thi Hai Yena, Pham Hai Yena, Dan Thi Thuy Hanga,
Bui Huu Taia,c, Yohan Seod,e, Wan Namkungd, Seung Hyun Kimd , Pham Van
Cuonga,c, Phan Van Kiema,c, Nguyen Xuan Nhiema,c and Tran Minh Ngocb
aInstitute of Marine Biochemistry, Vietnam Academy of Science and Technology (VAST), Hanoi,
b
c
Vietnam; Traditional Medicine Administration, Ministry of Health, Hanoi, Vietnam; Graduate
d
University of Sciences and Technology, VAST, Hanoi, Vietnam; College of Pharmacy and Yonsei
Institute of Pharmaceutical Sciences, Yonsei University, Incheon, Republic of Korea; New Drug
e
Development Center, Daegu-Gyeonbuk Medical Innovation Foundation, Daegu, Republic of Korea
ABSTRACT
ARTICLE HISTORY
Received 23 December 2020
Accepted 4 March 2021
Three undescribed dihydrostilbene glycosides, 3,5-dihydroxyldihy-
drostilbene 40-O-[600-O-(4000-hydroxylbenzoyl)]-b-D-glucopyranoside
(1), 3,5-dihydroxyldihydrostilbene 40-O-(600-O-galloyl)-b-D-glucopyr-
anoside (2), and 3,5-dihydroxyldihydrostilbene 40-O-[600-O-(3000,4000-
dimethoxyl)galloyl]-b-D-glucopyranoside (3), and seven known
compounds, kaempferol 3-O-b-D-glucopyranoside (4), isoquercitrin
(5), kaempferol 3-O-a-L-rhamnoside (6), quercitrin (7), (6S,9R)-
roseoside (8), (-)-epicatechin 3-O-gallate (9), and (-)-epigallocate-
chin 3-O-gallate (10) have been isolated from the methanol
extract of the leaves of Camellia sinensis var. assamica (J.W.Mast.)
Kitam. (synnonym of Camellia assamica (Mast.) H.T.Chang)
(Theaceae). Their structures were elucidated by spectroscopic
methods (1 D-, 2 D-NMR) and mass spectra. All compounds were
evaluated for cytotoxic activity against human oral cancer (CAL27)
and human breast cancer (MDAMB231) cell lines. Compound 10
showed significant cytotoxic activity against CAL27 and
MDAMB231 cell lines with IC50 values of 9.78 0.25 and
3.27 0.18 lM, respectively, compared to those of positive control,
capecitabine (IC50 values of 8.20 0.75 and 5.20 0.89lM).
KEYWORDS
Camellia sinensis var.
assamica; dihydrostilbene;
cytotoxic activity
CONTACT Nguyen Xuan Nhiem
nxnhiem@yahoo.com; Tran Minh Ngoc
tmngocvkn@yahoo.com
Supplemental data for this article can be accessed at https://doi.org/10.1080/14786419.2021.1900844.
ß 2021 Informa UK Limited, trading as Taylor & Francis Group

2
N. T. CUC ET AL.
1. Introduction
Camellia sinensis var. assamica (J.W.Mast.) Kitam. with synonym of Camellia assamica
(Mast.) H.T.Chang (Theaceae) are evergreen shrubs that are extensively cultivated and
consumed in Vietnam, China, India, and Japan. Their leaves have been used as tea use
daily (green, oolong, and black). In addition, the tea from Camellia genus has become
one of the most popular beverages worldwide because of its biological activities and
health benefits (Zhou et al. 2017). Overview of phytochemical studies on C. sinensis
var. assamica indicated that this plant is rich of phenolics and terpenoids and those
compounds exhibited cytotoxic, a-glucosidase inhibitory, and antioxidant activities
(Murakami et al. 2000; Wang et al. 2014; Zhou et al. 2017). This paper reported three
undescribed dihydrostilbene glycosides and seven known compounds from C. sinensis
var. assamica and their cytotoxic activity.
2. Results and discussion
Compound 1 was obtained as a white amorphous powder. Its molecular formula was
determined as C27H28O10 by HR-ESI-MS at m/z 547.1364 [M þ Cl]– (Calcd. for
1
[C27H28O10Cl]–, 547.1371). The H-NMR spectrum of 1 showed signals of two p-substi-
tuted aromatic rings at dH 6.87 (2H, d, J ¼ 9.0 Hz)/7.93 (2H, d, J ¼ 9.0 Hz) and 6.95 (4H,
overlapped signals), one 1,3,5-trisubstituted aromatic ring at dH 6.11 (1H, t, J ¼ 2.5 Hz)
and 6.14 (2H, d, J ¼ 2.5 Hz), two methylene groups at dH 2.69 (2H, m) and 2.77 (2H, m),
and one anomeric proton at dH 4.87 (1H, d, J ¼ 7.5 Hz). The 13C-NMR and HSQC spectra
of 1 showed the signals of 27 carbons, including 8 non-protonateds (dC 122.2, 137.2,
145.4, 157.1, 159.3 ꢀ 2, 163.6, and 167.9), 16 methines (dC 72.1, 74.9, 75.6, 78.0, 101.2,
102.5, 108.1 ꢀ 2, 116.2 ꢀ 2, 117.7 ꢀ 2, 130.3 ꢀ 2, and 133.0 ꢀ 2), and 3 methylenes (dC
1
38.0, 39.2, and 65.0). Analysis of the H- and 13C-NMR data suggested the structure of
1 was dihydrostilbene (Vitalini et al. 2018), similar to 3,5-dihydroxyldihydrostilbene 40-
O-b-D-glucopyranoside, a compound previously reported from Camellia oleifera Abel
(Chen et al. 2011) except for the addition of a 4000-hydroxylbenzoyl group at C-600. The
HMBC correlations between H-2 (dH 6.14) and C-3 (dC 159.3)/C-4 (dC 101.2)/C-6 (dC
108.1) and between H-6 (dH 6.14) and C-2 (dC 108.1)/C-4 (dC 101.2)/C-5 (dC 159.3) con-
firmed the positions of hydroxyl groups at C-3 and C-5 (Figure S2). The monosacchar-
ide was identified as D-glucose after acid hydrolysis, as a trimethylsilyl by GC (Nhiem
et al. 2011). The coupling constant of H-100 and H-200, J ¼ 7.5 Hz and the 13C-NMR data
of sugar moiety at dC 102.5, 74.9, 78.0, 72.1, 75.6, and 65.0 and in combination of simi-
lar compounds from Camellia genus (Cuc et al. 2020) indicated sugar moiety as b-D-
glucopyranosyl. The HMBC correlation from H-100 (dH 4.87) to C-40 (dC 157.1) confirmed
the position of the b-D-glucopyranosyl at C-40. The position of 4000-hydroxylbenzoyl
group at C-600 was confirmed by HMBC correlation between H-600 (dH 4.42 and 4.67)
and C-7000 (dC 167.9). Based on the above data, the structure of 1 was determined as
3,5-dihydroxyldihydrostilbene 40-O-[600-O-(4000-hydroxylbenzoyl)]-b-D-glucopyranoside.
–
The HR-ESI-MS of compound 2 exhibited a molecular ion at m/z 543.1502 [M-H]
(Calcd. for [C27H27O12]–, 543.1503), giving the molecular formula of C27H28O12. The H-
1
NMR spectrum of 2 showed the following proton signals: one p-substituted aromatic
ring at dH 6.95 (2H, d, J ¼ 8.5 Hz) and 6.99 (2H, d, J ¼ 8.5 Hz), one 1,3,5-trisubstituted

NATURAL PRODUCT RESEARCH
3
aromatic ring at dH 6.10 (1H, t, J ¼ 2.0 Hz), and 6.17 (2H, dd, J ¼ 2.0 Hz), one 1,3,4,5-tet-
rasubstituted aromatic ring at dH 7.14 (2H, s), two methylene groups at dH 2.68 (2H,
m) and 2.76 (2H, m), and one anomeric proton at dH 4.82 (1H, d, J ¼ 8.0 Hz). The 13C-
NMR and HSQC spectra of 2 showed signals of 27 carbons, of which 14 were assigned
to a dihydrostilbene, 7 to a galloyl, and 6 to a b-D-glucopyranosyl unit. Analysis of the
1H- and 13C-NMR data suggested the structure of 2 was similar to sasastilboside C
(Cuc et al. 2020), a compound was previously reported by us from Camellia sasanqua
Thunb. except for the exchange position of (600-O-galloyl)-b-D-glucopyranosyl group
from C-3 of sasastilboside C to C-40. The position of (600-O-galloyl)-b-D-glucopyranosyl
group at C-40 was confirmed by the HMBC correlations between H-600 (dH 4.45 and
4.60) and C-7000 (dC 168.2) and between H-100 (dH 4.82) and C-40 (dC 157.1). The loca-
tions of the hydroxyl groups at C-3 and C-5 were indicated by the HMBC correlations
between H-2/H-6 (dH 6.17) and C-3/C-5 (dC 159.3)/C-4 (dC 101.2)/C-a (dC 39.3).
Consequently, the structure of 2 was determined as 3,5-dihydroxyldihydrostilbene 40-
O-(600-O-galloyl)-b-D-glucopyranoside.
Compound 3 was assigned the molecular formula of C29H32O12 by HR-ESI-MS at m/
–
1
z 607.1574 [M þ Cl]– (Calcd. for [C29H32O12Cl] , 607.1582). The H- and 13C-NMR spec-
tra of compound 3 exhibited a dihydrostilbene glycoside, similar to those of assamo-
side B (2) except for an addition of two methoxyl groups at C-3000 and C-4000 of galloyl
1
moiety. The H-NMR spectrum of 3 showed signals of one dihydrostilbene, one dime-
thoxylgalloyl group, and one sugar unit. The 13C-NMR and HSQC spectra of 3 showed
signals of 29 carbons, of which, 14 carbons were assigned to a dihydrostilbene, 9 to a
dimethoxylgalloyl moiety, and 6 carbons to a b-D-glucopyranosyl unit. The position of
methoxyl groups at C-3000 and C-4000 were confirmed by HMBC correlations between H-
2000 (dH 7.21) and C-1000 (dC 126.5)/C-3000 (dC 154.4)/C-4000 (dC 142.4)/C-6000 (dC 112.3),
between H-6000 (dH 7.29) and C-2000 (dC 106.4)/C-4000 (dC 142.4)/C-5000 (dC 151.7), and
between methoxyl groups (dH 3.85 and 3.89) and C-3000 (dC 154.4)/C-4000 (dC 142.4).
Thus, the structure of 3 was elucidated to be 3,5-dihydroxyldihydrostilbene 40-O-[600-O-
(3000,4000-dimethoxyl)galloyl]-b-D-glucopyranoside.
The structures of known compounds were identified as kaempferol 3-O-b-D-gluco-
pyranoside (4) (Jayasinghe et al. 2004), isoquercitrin (5) (Kanegae et al. 2013), kaemp-
ferol 3-O-a-L-rhamnoside (6) (Fukunaga et al. 1988), quercitrin (7) (Markham et al.
1978), (6S,9R)-roseoside (8) (Vu et al. 2019), ()-epicatechin 3-O-gallate (9) (Davis et al.
1996), and ()-epigallocatechin 3-O-gallate (10) (Davis et al. 1996) (Figure 1) by analyz-
ing the NMR and MS methods and in comparison with the reported values in
the literature.
All compounds from C. sinensis var. assamica were screened for cytotoxic activity
against human oral cancer (CAL27) and human breast cancer (MDAMB231) cell lines at
the concentration of 30 lM (Table S1). As the results, compound 10 showed cell viabil-
ity <50%. Thus, this compound was evaluated at various concentrations (30, 10, 5,
and 1 lM) to get IC50 values. Capecitabine, an anticancer agent was used as positive
control exhibited cytotoxic activity with IC50 values of (IC50 values of 8.20 0.75
(CAL27) and 5.20 0.89 lM (MDAMB231). Compound 10 showed significant cytotoxic
activity against CAL27 and MDAMB231 cell lines with IC50 value of 9.78 0.25, and
3.27 0.18 lM, respectively.

4
N. T. CUC ET AL.
Figure 1. The chemical structures of compounds 1–10.
3. Experimental
3.1. General: see supporting information
3.2. Plant materials
The leaves of Camellia sinensis var. assamica (J.W.Mast.) Kitam. (Theaceae) were col-
lected in Nguyen Binh, Cao Bang province, Viet Nam (N22053’82,7" E:105082’83,1") in
April 2019, and identified by Dr. Nguyen The Cuong, Institute of Ecology and
Biological Resources. A voucher specimen (NCCT-P86) was deposited at Institute of
Marine Biochemistry, VAST.
3.3. Extraction and isolation
The dried powder leaves of C. sinensis var. assamica (5.0 kg) were ultrasonically
extracted with methanol for three times (each 15 L, 30 minutes at 45 ꢁC). After removal
of solvent, the MeOH extract (400.0 g) was suspended with water and successively par-
titioned with CH2Cl2, ethyl acetate (EtOAc) to give corresponding CH2Cl2 (CA1A,
100.0 g), EtOAc (CA1B, 70.0 g) residues, and water layer (CA1C).
The CA1B fraction was separated on a silica gel column chromatography (CC), elut-
ing with CH2Cl2/MeOH (50/1, 20/1, 10/1, 2/1, v/v) to give four fractions, CA1B1-CA1B4.
CA1B2 was loaded on an RP-18 CC eluting with MeOH/water (1/1.5, v/v) to give three
fractions, CA1B2A-CA1B2C. CA1B2A was subjected to an HPLC system (J’sphere M-80
column, 150 mm length ꢀ 20 mm ID, eluting with 25% acetonitrile in water, a flow
rate of 3 mL/min) to yield compound 4 (30.0 mg). CA1B2B was chromatographed to an

NATURAL PRODUCT RESEARCH
5
HPLC system (J’sphere M-80 column, 150 mm length ꢀ 20 mm ID, eluting with 28%
acetonitrile in water, a flow rate of 3 mL/min) to yield compounds 1 (9.0 mg), 3
(5.0 mg), 6 (31.0 mg), and 7 (11.0 mg). CA1B4 was loaded on a RP-18 CC eluting with
MeOH/water (1/2.0, v/v) to give three fractions, CA1B4A-CA1B4C. Compounds 9
(20.0 mg) and 10 (500.0 mg) were obtained from the CA1B4A and CA1B4B fractions on
a Sephadex LH-20 CC eluting with MeOH/water (1/1, v/v).
CA1C was loaded on a diaion HP-20 CC, washed with water, and then eluted step-
wise with methanol in water (25, 50, 75, and 100% MeOH, each 1 L) to give four frac-
tions, CA1C1-CA1C4, respectively. The CA1C4 fraction was subjected on a silica gel CC
eluting with gradient solvent of CH2Cl2/MeOH (20/1, 10/1, 5/1, and 2/1, v/v) to give
four fractions, CA1C4A-CA1C4D. CA1C4B was chromatographed on an RP-18 column
eluting with MeOH/water (1/1, v/v) to give three fractions, CA1C4B1-CA1C4B3.
Compound 2 (3.0 mg) was obtained from the CA1C4B2 fraction using an HPLC system
(J’sphere M-80 column, 150 mm length ꢀ 20 mm ID, eluting with 30% acetonitrile in
water, a flow rate of 3 mL/min). The CA1C4D fraction was loaded on an RP-18 column
eluting with MeOH/water (1/1.5, v/v) to give three fractions, CA1C4D1-CA1C4D3.
CA1C4D2 was subjected to an HPLC (J’sphere M-80 column, 150 mm length ꢀ 20 mm
ID, eluting with 25% acetonitrile in water, a flow rate of 3 mL/min) to yield compound
8 (18.0 mg). Compound 5 (60.0 mg) was obtained from CA1C4D3 on a sephadex LH-
20 CC eluting with MeOH/water (1/1, v/v).
3.3.1. 3,5-Dihydroxyldihydrostilbene 40-O-[600-O-(4000-hydroxylbenzoyl)]-b-D-
glucopyranoside (1)
White amorphous powder; [a]D25: ꢂ39.1 (c 0.1, MeOH); C27H28O10; HR-ESI-MS m/z:
–
1
547.1364 [M þ Cl]– (Calcd. for [C27H28O10Cl] , 547.1371); H-NMR (CD3OD, 500 MHz) dH:
6.14 (d, J ¼ 2.5 Hz, H-2, H-6), 6.11 (t, J ¼ 2.5 Hz, H-4), 2.69 (m, H-a), 2.77 (m, H-a0), 6.95
(overlapped, H-20, H-30, H-50, H-60), 4.87 (d, J ¼ 7.5 Hz, H-100), 3.49 (dd, J ¼ 7.5, 8.0 Hz, H-
200), 3.51 (m, H-300), 3.45 (dd, J ¼ 8.5, 9.5 Hz, H-400), 3.78 (ddd, J ¼ 2.0, 7.5, 9.5 Hz, H-500),
4.42 (dd, J ¼ 7.5, 11.5 Hz, Ha-600), 4.67 (dd, J ¼ 2.0, 11.5 Hz, Hb-600), and 7.93 (d,
J ¼ 9.0 Hz, H-2000, H-6000), 6.87 (d, J ¼ 9.0 Hz, H-3000, H-5000); 13C-NMR (CD3OD, 125 MHz) dC:
145.4 (C-1), 108.1 (C-2), 159.3 (C-3), 101.2 (C-4), 159.3 (C-5), 108.1 (C-6), 39.2 (C-a), 38.0
(C-a0), 137.2 (C-10), 130.3 (C-20), 117.7 (C-30), 157.1 (C-40), 117.7 (C-50), 130.3 (C-60), 102.5
(C-100), 74.9 (C-200), 78.0 (C-300), 72.1 (C-400), 75.6 (C-500), 65.0 (C-600), 122.2 (C-1000), 133.0
(C-2000), 116.2 (C-3000), 163.6 (C-4000), 116.2 (C-5000), 133.0 (C-6000), and 167.9 (C-7000).
3.3.2. 3,5-Dihydroxyldihydrostilbene 40-O-(600-O-galloyl)-b-D-glucopyranoside (2)
White amorphous powder; [a]D25: ꢂ43.4 (c 0.1, MeOH); C27H28O12; HR-ESI-MS m/z:
–
–
543.1502 [M-H] (Calcd. for [C27H27O12] , 543.1503); 1H-NMR (CD3OD, 500 MHz) dH:
6.17 (d, J ¼ 2.0 Hz, H-2, H-6), 6.10 (t, J ¼ 2.0 Hz, H-4), 2.68 (m, H-a), 2.76 (m, H-a0), 6.99
(d, J ¼ 8.5 Hz, H-20, H-60), 6.95 (d, J ¼ 8.5 Hz, H-30, H-50), 4.82 (d, J ¼ 8.0 Hz, H-100), 3.49
(dd, J ¼ 8.0, 8.5 Hz, H-200), 3.50 (m, H-300), 3.45 (m, H-400), 3.77 (m, H-500), 4.45 (dd,
J ¼ 7.5, 11.5 Hz, Ha-600), 4.60 (dd, J ¼ 2.0, 11.5 Hz, Hb-600), and 7.14 (s, H-2000, H-6000); 13C-
NMR (CD3OD, 125 MHz) dC: 145.6 (C-1), 108.1 (C-2), 159.3 (C-3), 101.2 (C-4), 159.3 (C-5),
108.1 (C-6), 39.3 (C-a), 38.1 (C-a0), 137.3 (C-10), 130.3 (C-20), 117.7 (C-30), 157.1 (C-40),
117.7 (C-50), 130.3 (C-60), 102.6 (C-100), 75.0 (C-200), 78.1 (C-300), 72.0 (C-400), 75.6 (C-500),

6
N. T. CUC ET AL.
64.9 (C-600), 121.5 (C-1000), 110.4 (C-2000), 146.6 (C-3000), 140.0 (C-4000), 146.6 (C-5000), 110.4
(C-6000), and 168.2 (C-7000).
3.3.3. 3,5-Dihydroxyldihydrostilbene 40-O-[600-O-(3000,4000-dimethoxyl)galloyl]-b-D-
glucopyranoside (3)
White amorphous powder; [a]D25: ꢂ46.6 (c 0.1, MeOH); C29H32O12; HR-ESI-MS m/z:
–
1
607.1574 [M þ Cl]– (Calcd. for [C29H32O12Cl] , 607.1582); H-NMR (CD3OD, 500 MHz) dH:
6.14 (d, J ¼ 2.0 Hz, H-2, H-6), 6.10 (t, J ¼ 2.0 Hz, H-4), 2.67 (m, H-a), 2.76 (m, H-a0), 6.95
(overlapped, H-20, H-30, H-50, H-60), 4.84 (overlapped, H-100), 3.50 (dd, J ¼ 7.5, 8.5 Hz, H-
200), 3.51 (dd, J ¼ 8.5, 9.0 Hz, H-300), 3.43 (dd, J ¼ 9.0, 9.5 Hz, H-400), 3.79 (ddd, J ¼ 2.0, 8.0,
9.5 Hz, H-500), 4.45 (dd, J ¼ 8.0, 12.0 Hz, Ha-600), 4.69 (dd, J ¼ 2.0, 12.0 Hz, Hb-600), 7.21 (d,
J ¼ 2.0 Hz, H-2000), 7.29 (d, J ¼ 2.0 Hz, H-6000), 3.85 (s, 3000-OMe), and 3.89 (s, 4000-OMe);
13C-NMR (CD3OD, 125 MHz) dC: 145.4 (C-1), 108.1 (C-2), 159.3 (C-3), 101.2 (C-4), 159.3
(C-5), 108.1 (C-6), 39.2 (C-a), 38.0 (C-a0), 137.3 (C-10), 130.3 (C-20), 117.7 (C-30), 157.1 (C-
40), 117.7 (C-50), 130.3 (C-60), 102.5 (C-100), 74.9 (C-200), 78.0 (C-300), 72.1 (C-400), 75.5 (C-
500), 65.4 (C-600), 126.5 (C-1000), 106.4 (C-2000), 154.4 (C-3000), 142.4 (C-4000), 151.7 (C-5000),
112.3 (C-6000), 167.6 (C-7000), 56.6 (3000-OMe), and 61.1 (4000-OMe).
3.4. Acid hydrolysis: see supporting information
3.5. Cytotoxic assay: see supporting information
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding
This research is funded by Vietnam National Foundation for Science and Technology
Development (NAFOSTED) under grant number 104.01-2018.09.
ORCID
Seung Hyun Kim
http://orcid.org/0000-0003-2613-0674
References
Chen Y, Tang L, Feng B, Shi L, Wang H, Wang Y. 2011. New bibenzyl glycosides from leaves of
Camellia oleifera Abel. with cytotoxic activities. Fitoterapia. 82(3):481–484.
Cuc NT, Cuong NT, Anh LT, Yen DTH, Tai BH, Thu TD, Yen PH, Kiem PV, Nam NH, Minh CV, et al.
2020. Dihydrostilbene glycosides from Camellia sasanqua and their a-glucosidase and a-amyl-
ase inhibitory activities. Nat Prod Res. :1–7. doi.org/10.1080/14786419.2020.1756802.
1
Davis AL, Cai Y, Davies AP, Lewis JR. 1996. H- and 13C-NMR assignments of some green tea pol-
yphenols. Magn Reson Chem. 34(11):887–890.

NATURAL PRODUCT RESEARCH
7
Fukunaga T, Nishiya K, Kajikawa I, Watanabe Y, Suzuki N, Takeya K, Itokawa H. 1988. Chemical
studies on the constituents of hyphear tanakae hosokawa from different Host trees. Chem
Pharm Bull. 36(3):1180–1184.
Jayasinghe UL, Balasooriya BA, Bandara AG, Fujimoto Y. 2004. Glycosides from Grewia damine
and Filicium decipiens. Nat Prod Res. 18(6):499–502.
Kanegae A, Sakamoto A, Nakayama H, Nakazono Y, Yakashiro I, Matsuo Y, Tanaka T, Ishimaru K.
2013. New phenolic compounds from Camellia sinensis L. fermented leaves. J Nat Med. 67(3):
652–656.
Markham K, Ternai B, Stanley R, Geiger H, Mabry T. 1978. Carbon-13 NMR studies of flavo-
noids—III: Naturally occurring flavonoid glycosides and their acylated derivatives.
Tetrahedron. 34(9):1389–1397.
Murakami T, Nakamura J, Kageura T, Matsuda H, Yoshikawa M. 2000. Bioactive saponins and gly-
cosides. XVII. Inhibitory effect on gastric emptying and accelerating effect on gastrointestinal
transit of tea saponins: Structures of assamsaponins F, G, H, I, and J from the seeds and
leaves of the tea plant. Chem Pharm Bull (Tokyo)). 48(11):1720–1725.
Nhiem NX, Tai BH, Quang TH, Van Kiem P, Van Minh C, Nam NH, Kim JH, Im LR, Lee YM, Kim
YH. 2011. A new ursane-type triterpenoid glycoside from Centella asiatica leaves modulates
the production of nitric oxide and secretion of TNF-a in activated RAW 264.7 cells. Bioorg
Med Chem Lett. 21(6):1777–1781.
Vitalini S, Cicek SS, Granica S, Zidorn C. 2018. Dihydroresveratrol type dihydrostilbenoids: chem-
ical diversity, chemosystematics, and bioactivity. Curr Med Chem. 25(10):1194–1240.
Vu LTN, Anh LT, Cuc NT, Nhiem NX, Tai BH, Van Kiem P, Litaudon M, Thach TD, Van Minh C, Mai
HDT, et al. 2019. Prenylated flavonoids and other constituents from Macaranga indica. Nat
Prod Res.:1–8. doi.org/10.1080/14786419.2019.1662007.
Wang W, Zhang L, Wang S, Shi S, Jiang Y, Li N, Tu P. 2014. 8-C N-ethyl-2-pyrrolidinone substi-
tuted flavan-3-ols as the marker compounds of Chinese dark teas formed in the post-fermen-
tation process provide significant antioxidative activity. Food Chem. 152:539–545.
Zhou H, Li HM, Du YM, Yan RA, Ou SY, Chen TF, Wang Y, Zhou LX, Fu L. 2017. C-geranylated
flavanones from YingDe black tea and their antioxidant and a-glucosidase inhibition activities.
Food Chem. 235:227–233.