Two new tetralone glycosides from the green walnut husks of Juglans mandshurica Maxim

Article abstract of DOI:10.1080/14786419.2018.1510397

Two new tetralone glycosides, 4(S)-5-methoxy juglanoside A (1), 4(S)-5-methoxy juglanoside D (2), together with ten known compounds (3–12) have been isolated from the green walnut husks of Juglans mandshurica Maxim. Their structures were elucidated on the basis of their ESI-MS, 1 D and 2 D NMR spectroscopic data. In addition, all compounds were evaluated for their cytotoxic activities against the cancer BGC-823 (human gastric carcinoma), HCT-15 (human colorectal carcinoma) and K562 (human chronic myeloid leukemia) cell lines. The results showed aglycones of naphthoquinones had stronger cytotoxic activities than glycosides of tetralone.

Full text of DOI:10.1080/14786419.2018.1510397

Natural Product Research
Formerly Natural Product Letters
ISSN: 1478-6419 (Print) 1478-6427 (Online) Journal homepage: http://www.tandfonline.com/loi/gnpl20
Two new tetralone glycosides from the green
walnut husks of Juglans mandshurica Maxim
Yuan-Yuan Zhou, Ying Wang, Shuang Guo, Hong-Juan Song, Xiao-Juan Zhang,
Yan Liu, Bing-You Yang & Hai-Xue Kuang
To cite this article: Yuan-Yuan Zhou, Ying Wang, Shuang Guo, Hong-Juan Song, Xiao-
Juan Zhang, Yan Liu, Bing-You Yang & Hai-Xue Kuang (2018): Two new tetralone glycosides
from the green walnut husks of Juglansꢀmandshurica Maxim, Natural Product Research, DOI:
10.1080/14786419.2018.1510397
To link to this article: https://doi.org/10.1080/14786419.2018.1510397
View supplementary material
Published online: 10 Nov 2018.
Submit your article to this journal
Article views: 11
View Crossmark data
Full Terms & Conditions of access and use can be found at
http://www.tandfonline.com/action/journalInformation?journalCode=gnpl20

NATURAL PRODUCT RESEARCH
https://doi.org/10.1080/14786419.2018.1510397
Two new tetralone glycosides from the green walnut
husks of Juglans mandshurica Maxim
Yuan-Yuan Zhoua, Ying Wanga, Shuang Guoa, Hong-Juan Songa,
Xiao-Juan Zhangb, Yan Liua, Bing-You Yanga and Hai-Xue Kuanga
b
aCollege of Pharmacy, Heilongjiang University of Chinese Medicine, Harbin, China; Academic
Research Department, Heilongjiang University of Chinese Medicine, Harbin, China
ABSTRACT
ARTICLE HISTORY
Received 16 May 2018
Accepted 7 August 2018
Two new tetralone glycosides, 4(S)-5-methoxy juglanoside A (1),
4(S)-5-methoxy juglanoside D (2), together with ten known com-
pounds (3–12) have been isolated from the green walnut husks
of Juglans mandshurica Maxim. Their structures were elucidated
on the basis of their ESI-MS, 1 D and 2 D NMR spectroscopic data.
In addition, all compounds were evaluated for their cytotoxic
activities against the cancer BGC-823 (human gastric carcinoma),
HCT-15 (human colorectal carcinoma) and K562 (human chronic
myeloid leukemia) cell lines. The results showed aglycones of
naphthoquinones had stronger cytotoxic activities than glycosides
of tetralone.
KEYWORDS
Juglans mandshurica Maxim;
tetralone glycosides;
cytotoxicity
1. Introduction
Juglans mandshurica Maxim belongs to the family of Juglandaceae, which is one of
the deciduous trees widely distributed in China and other Asia (Wu and Raven 1999).
As a kind of traditional Chinese medicine, the green walnut husks of Juglans
mandshurica Maxim (Chen et al. 2013; Gawlik-Dziki et al. 2014; Nasiry et al. 2017) have
dramatic effects on analgesia (Erdemoglu et al. 2003) and antitumor (Xin et al. 2014;
Wang et al. 2015; Delaviz et al. 2017). In addition, modern pharmacological studies
have demonstrated that this medicinal part has also antibacterial and antioxidant
effect (Oliveira et al. 2008; Carvalho et al. 2010; Sun et al. 2017). In previous investiga-
tions, a number of naphthoquinones (Chen et al. 2015), triterpenoids (Zhou et al.
CONTACT Hai-Xue Kuang
hxkuang@yahoo.com
Supplemental data for this article can be accessed at https://doi.org/10.1080/14786419.2018.1510397.
ß 2018 Informa UK Limited, trading as Taylor & Francis Group

2
Y.-Y. ZHOU ET AL.
2015) and other compounds (Yao et al. 2014; Zhou et al. 2017) have been isolated
from the green walnut husks of Juglans mandshurica Maxim. In this study, two new
tetralone glycosides together with ten known compounds have been obtained. We
mainly reported the structural elucidation of them as well as the cytotoxic activities
against three human cancer cell lines.
2. Results and discussion
2.1. Chemistry
Compound 1 was obtained as a red amorphous powder with the molecular formula
C17H22O8, as determined by HR-ESI-MS at m/z 377.3248 ([M þ Na]þ, calcd for
1
C17H22O8Na, 377.3283). The H-NMR spectrum of 1 indicated a set of proton signals of
two methylene protons in the high field at dH 2.48 (1 H, ddd, J ¼ 17.7, 4.1, 2.2 Hz, H-
2a), 3.11-3.20 (1 H, m, H-2b); 2.15 (1 H, tdd, J ¼ 14.0, 4.4, 2.6 Hz, H-3a), 2.58 (1 H, ddt,
J ¼ 14.0, 4.4, 2.6 Hz, H-3b) and a methine proton at dH 5.47 (1 H, t, J ¼ 2.8 Hz, H-4).
DEPT and HSQC experiments showed signals of two methylene carbons at dC 30.3 (C-
3), 33.8 (C-2), a tertiary carbon with hydroxyl group at dC 68.3 (C-4) and a carbonyl car-
bon at dC 200.9 (C-1). All above data further revealed that 1 had an a-tetralone frame-
1
work, similar to the reference (Liu et al. 2004). Meanwhile, the H-NMR spectrum of 1
showed three mutually ortho-coupled aromatic protons at dH 7.57 (1 H, dd, J ¼ 8.0,
0.9 Hz, H-8), 7.44 (1 H, t, J ¼ 8.0 Hz, H-7) and 7.28 (1 H, dd, J ¼ 8.0, 0.9 Hz, H-6) in the
downfield, which were ascribed to an ABC-type aromatic ring substituted with
a methoxy group. The substituent position of the methoxy group was deduced to be
C-5 by observation of the HMBC correlations between dH 3.91 (3 H, s, H-11) and dC
159.0 (C-5) (Figure S6). Moreover, a glucose moiety was showed with the signals of dH
4.47 (1 H, d, J ¼ 7.8 Hz, H-10), 3.30 (1 H, m, H-50), 3.72 (1 H, dd, J ¼ 4.0, 12.0 Hz, H-60a),
3.91 (1 H, m, H-60b), and dC 103.8 (C-10), 78.1 (C-50), 62.9 (C-60). The conjunctive position
of sugar to aglycone was located at C-4, as established by HMBC correlations between
dH 4.47 (1 H, d, J ¼ 7.8 Hz, H-10) and dC 68.3. The coupling constants dH 4.47 of the
anomeric protons suggested that sugar unit was b-configuration. The absolute config-
uration of the glucose was determined as D-form by acid hydrolysis. Furthermore, the
absolute configuration of the chiral center at C-4 of the aglycone was measured by
CD (Figure S14) spectrum. It was identified to be S configuration where a positive
Cotton effect at 240 nm and a negative Cotton effect at 352 nm were observed. These
NMR data were almost similar to those of juglanoside A (Liu et al. 2004). Therefore,
the structure of 1 was determined to be 4(S)-4-hydroxy-5-methoxy-a-tetralone-4-O-
b-D-glucopyranoside, named 4(S)-5-methoxy juglanoside A. The structure was
elucidated as shown (Figure 1).
Compound 2 was obtained as a red amorphous powder, which was assigned the
molecular formula to be C17H22O9 according to HR-ESI-MS data at m/z 393.1162
[M þ Na]þ (calcd for C17H22O9Na, 393.1204). The general features of its NMR spectra
closely resembled those of 1, indicating that 2 was a derivative of 1. There was the
minor difference between 1 and 2 was that an additional hydroxy group at C-8 (dC
157.5) appeared in 2. Thus, the 1H-NMR spectrum showed the AB-type aromatic
proton signals at dH 7.31 (1 H, d, J ¼ 9.2 Hz, H-6) and 6.91 (1 H, d, J ¼ 9.2 Hz, H-7)

NATURAL PRODUCT RESEARCH
3
Figure 1. Structures of new compounds 1 and 2.
in place of ABC-type in the aromatic ring. There were a group of b-D-glucopyranose
carbon signals observed at dC 103.1 (C-10), 75.1 (C-20), 78.1 (C-30), 71.8 (C-40), 78.1 (C-50)
and 62.9 (C-60) in the DEPT and 13C NMR spectrums. The glucopyranosyl unit was also
assigned to C-4 by the key HMBC correlation between dH 4.42 (1 H, d, J ¼ 7.8 Hz, H-10)
and dC 67.8 (C-4) (Figure S12). What’s more, the absolute configuration of the chiral
center at C-4 of the aglycone was identified to be S configuration from the CD (Figure
S14) spectrum with a positive Cotton effect at 249 nm and a negative Cotton effect
at 383 nm. In addition to C-5 as methoxy, the spectroscopic data of 2 were nearly
similar to those of juglanoside D (Liu et al. 2004). Thus, the structure of 2 was eluci-
dated to be 4(S)-4,8-dihydroxy-5-methoxy-a-tetralone-4-O-b-D-glucopyranoside, and
named as 4(S)-5-methoxy juglanoside D. The structure of 2 was shown in Figure 1.
By comparing the spectral data in the literature, the remaining ten known com-
pounds were respectively identified as 4(S)-4-hydroxy-a-tetralone-4-O-b-D-glucopyrano-
side (3) (Zhou et al. 2015), 4(S)-4,5-dihydroxy-a-tetralone-4-O-b-D-glucopyranoside (4)
(Zhou et al. 2015), 1,4,8-trihydroxy-3-naphthalenecarboxylic acid-1-O-b-D-glucopyrano-
side ethyl ester (5) (Zhou et al. 2015), 4(S)-4,5,8-trihydroxy-a-tetralone-5-O-b-D-[6’-O-
(3",4",5"-trihydroxybenzoyl)] glucopyranoside (6) (Zhou et al. 2015), juglone (7) (Luo
et al. 2012), 3-ethoxy juglone (8) (Zhou et al. 2015), 2-hydroxy-1,4-naphthoquinone (9)
(Dong et al. 2011), 2,5-dihydroxy-1,4-naphthoquinone (10) (Dong et al. 2011), 5,8-dihy-
droxy-1,4-naphthoquinone (11) (Zhou et al. 2015) and 3,5-dihydroxy-1,4-naphthoqui-
none (12) (Zhou et al. 2015).
2.2. Anti-tumour activity in vitro
All compounds (1–12) were separated then tested for cytotoxicity against BGC-823
cells, HCT-15 cells and K562 cells by methyl thiazolyl tetrazolium (MTT) assay in vitro.
BGC-823 cells were shown obvious inhibition by compounds 7, 8, 10–12. Compounds
(7–9) were potently against HCT-15 cells. While K562 cells were inhibited by com-
pounds 7 and 10. However, other compounds including two new naphthoquinones
were inactive. All results were shown in Table S3.

4
Y.-Y. ZHOU ET AL.
3. Experimental
3.1. General experimental procedures
Optical rotations were obtained with a JASCO P2000 digital polarimeter (Jasco, Tokyo,
Japan). High-resolution electrospray ionization (HR-ESI) mass spectra were obtained on
a micromass LCT spectrometer (Waters, Milford, USA). Circular dichroism spectra were
taken on an Applied Photophysics Spectropolarimeter (Agilent, USA). The NMR spectra
were recorded on Bruker DPX 400 spectrometer (Bruker, Rheinstetten, Germany) oper-
1
ating at 400 MHz for H and at 100 MHz for 13C, using TMS as an internal standard. GC
was performed on Agilent 7890 A Gas Chromatograph System (Agilent Technologies,
Santa Clara, CA, USA). Thin-layer chromatography (TLC) was carried out on precoated
silica gel GF254 (Qingdao Haiyang Chemical Co. Ltd., Qingdao, China). Column chroma-
tography (CC) was performed using 200–300 mesh Si gel (HaiYang Co. Ltd, Qingdao,
China). Octadecylsilanized (ODS) silica gel (YMC Ltd., Kyoto, Japan) and Sephadex LH-
20 (Amersham Pharmacia Biotech, Uppsala, Sweden) were used for open column chro-
matography. HPLC chromatograms were obtained with an Agilent Technologies 1260
infinity HPLC system (Agilent Technologies, Germany) and semi-preparative HPLC
(Waters, 515–2414, Milford, USA) was performed using a Hypersil-ODS II column
(300 ꢀ 20 mm i.d., 10 lm, Ylite, Dalian, China).
3.2. Plant material
The green walnut husks of Juglans Mandshurica Maxim were collected from Changbai
Mountain (Jilin, China), which were identified by Prof. B.Y. Yang. The specimen
(No.20170902) has been deposited in College of Pharmacy, Heilongjiang University of
Chinese Medicine.
3.3. Extraction and isolation
The air-dry green walnut husks of Juglans mandshurica Maxim (5.0 kg) were powdered
and extracted with 95% EtOH (40 L ꢀ 7d ꢀ 3) at room temperature. After vacuum con-
centration, we got 95% EtOH extract (330.6 g). Then, the residue was scattered in
water and extracted successively by CH2Cl2, EtOAc and n-BuOH to get these three
parts. The CH2Cl2 part (52.2 g) was subjected to silica gel column chromatography (CC)
with a stepwise gradient of PE-EtOAc (40:1-1:1, v/v) to get ten fractions (Fr.C1-C10).
Compound 7 (61.2 mg) was obtained from the fraction C1 (3.5 g) by recrystallization
from dichloromethane. From the fraction C4 (5.5 g), compounds 8 (10.8 mg) and 9
(9.6 mg) were isolated by using CC with PE-EtOAc (40:1-1:1, v/v). Fraction C5 (69.0 mg)
was subjected to CC with PE-EtOAc (20:1-3:1, v/v) to afford compounds 10 (8.4 mg), 11
(5.0 mg) and 12 (7.2 mg). The n-BuOH part (65.1 g) was subjected to CC using CH2Cl2-
MeOH (15:1-0:1, v/v) to purified eight fractions (Fr.B1-B8). Fraction B1 (13.5 g) was per-
formed repeatedly over the CC with CH2Cl2-MeOH (10:1-0:1, v/v) and the Sephadex
LH-20 chromatography eluting with MeOH-H2O (40:60, v/v) to get compounds 3
(4.3 mg), 1 (6.2 mg) and 4 (7.1 mg). Fraction B2 (3.7 g) was subjected to CC with
CH2Cl2-MeOH (8:1-0:1, v/v) repeatedly to give compound 2 (4.8 mg). Fraction B5 (6.4 g)

NATURAL PRODUCT RESEARCH
5
was purified by the CC with CH2Cl2-MeOH (6:1-0:1, v/v) to get six fractions (Fr.B5a-
Fr.B5f), and then semi-preparative HPLC chromatography (MeOH-H2O 70:30, v/v,
3.0 mL/min) to give 6 (4.2 mg, tR ¼ 26.0 min) and 5 (3.8 mg, tR ¼ 32.0 min) from fraction
B5b (312.2 mg).
3.3.1. 4(S)-5-methoxy juglanoside A (1)
25
Red powder; ½aꢁD -56 (c 0.60, MeOH); CD (c 1.31 ꢀ 10ꢂ5, MeOH) ᭝e (nm): þ7.81 (240),
ꢂ2.48 (352); 1H and 13C-NMR spectral data, see Table S1; HR-ESI-MS m/z 377.3248
[M þ Na]þ (calcd for C17H22O8Na, 377.3283).
3.3.2. 4(S)-5-methoxy juglanoside D (2)
25
Red powder; ½aꢁD -25 (c 0.80, MeOH); CD (c 1.08 ꢀ 10ꢂ5, MeOH) ᭝e (nm): þ8.38 (249),
ꢂ2.10(383); 1 H and 13C-NMR spectral data, see Table S2; HR-ESI-MS m/z 393.1162
[M þ Na]þ (calcd for C17H22O9Na, 393.1204).
3.4. Acid hydrolysis of 1 and 2
Compounds 1 and 2 (each of 1.5 mg) were treated with 1.0 mol/L HCl (5 mL) and
refluxed for 6 h at 90 ꢃC. After cooling to room temperature, these two mixed solutions
were extracted with CH2Cl2:H2O (each 1:1, v/v, 1 mL) thrice. Then, each mixture was
added NaHCO3 to neutralize and concentrated to dryness. The monosaccharide of
compounds 1 and 2 was examined by co-TLC [CH2Cl2-MeOH-HOAc-H2O (25:10:2:2)].
After sprayed with 10% H2SO4 followed by heating, the sugars in compounds 1 and 2
were D-glucose by the same retention factor value (Rf) with authentic sample (Rf value
of D-glucose was 0.24). At the same time, the residue was dissolved in anhydrous pyri-
dine and then added 1.5 mg hydroxylamine hydrochloride The solution was stirred at
90 ꢃC in water bath for 30 min. After cooling to room temperature, the mixture was
added acetic anhydride (150 lL) and kept for another 30 min at 90 ꢃC in water bath
with stirring. After centrifuged off and filtered through 0.45 lm millipore filtration, the
supernatant was ready subjected to GC analysis (Jia et al. 2017, Yang et al. 2018)
under the following conditions: column temperature, 260 ꢃC; injection temperature,
250 ꢃC; flow rate, 1.0 mL/min; carrier gas, N2. Comparing the retentions times (Rt) of
standard D-glucose (Rt at 20.4 min), the absolute configuration of sugar of compounds
1 and 2 was determined as D-glucose.
3.5. Antitumor activity in vitro
Three human cancer cell lines BGC-823, HCT-15 and K562 (Institute of Biochemistry
and Cell Biology, Shanghai, China) maintained in Dulbecco’s Modified Eagle’s Medium
(DMEM) containing 5% fetal bovine serum (Gibco, New York, USA) and 1% antibiotic
mixture comprising penicillin-streptomycin (Sigma, Missouri, USA) were grown in 96-
well microtiter plates with a density of 4 ꢀ 104 cells/mL in an atmosphere containing
at 37 ꢃC with 5% CO2. After 24 h, different concentrations of test samples (10 lL) and
cisplatin which was as a positive control were added and cultivated in the above

6
Y.-Y. ZHOU ET AL.
environment for 48 h. Before the end of cultivation, MTT (10 lL, 5 mg/mL) was added
into each well and continuously incubated for 4 h. Then, the DMSO (100 lL) was
added to each well to suspended. And the absorbance at 490 nm of each well was
detected and inhibition rate was counted on a multiscan microplate reader (Thermo
Labsystems, Helsinki, Finland). The results were expressed as the 50% inhibitory con-
centration (IC50 value). Data was represented as mean SD of three independent
experiments.
4. Conclusions
In summary, this work separated seven naphthoquinones and five tetralone from the
green walnut husks of Juglans mandshurica Maxim including two new tetralone glyco-
sides (compounds 1 and 2) together with ten known compounds. All compounds
were tested against BGC-823 cells, HCT-15 cells and K562 cells to survey their cytotoxic
activities. Compounds 7, 8, 10–12 exhibited obvious anticancer activities against BGC-
823 cells with the IC50 value ranges of 9.6 2.35 to 33.8 2.06 lM. Compounds 7–9
showed IC50 value of 27.8 2.66 to 37.4 5.10 lM on HCT-15 cells. In addition, com-
pounds 7 and 10 inhibited significant toxicities with the IC50 value ranges of
35.5 5.11 and 39.7 1.21 lM on K562 cells. Obviously, aglycones of naphthoquinones
had stronger cytotoxic activities than tetralone including aglycones and glycosides.
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding
This work was supported by the National Science Foundation of China [grant number
81202890]; China Postdoctoral Science Foundation funded project [grant number 2013M530164
and 2014T70374]; Heilongjiang Postdoctoral Fund [grant number LBH-Z13195 and LBH-Q16207];
and Harbin city youth science and technology innovation talents [grant number 2013RFQXJ052].
References
ꢀ
Carvalho M, Ferreira PJ, Mendes VS, Silva R, Pereira JA, Jeronimo C, Silva BM. 2010. Human
cancer cell antiproliferative and antioxidant activities of Juglans regia L. Food Chem Toxicol.
48(1):441–447. doi:10.1016/j.fct.2009.10.043
Chen CM, Han SJ, Yuan SS, Wang CJ, Yu JH. 2013. Isolation and characterization of 20
polymorphic microsatellite markers for Juglans mandshurica (Juglandaceae). Appl Plant Sci.
1(7):1200009.
Chen G, Pi XM, Yu CY. 2015. A new naphthalenone isolated from the green walnut husks of
Juglans mandshurica Maxim. Nat Prod Res. 29(2):174–179.
Delaviz H, Mohammadi J, Ghalamfarsa G, Mohammadi B, Farhadi N. 2017. A review study on
phytochemistry and pharmacology applications of Juglans regia Plant. Pharmacogn Rev.
11(22):145–152.
Dong M, Yuan R, Qi FQ, Li TL. 2011. Chemical constituents of pericarpium Juglantis. Nat Prod
Res Dev. 23:805–808.

NATURAL PRODUCT RESEARCH
7
€
Erdemoglu N, Kupeli E, Yes¸ilada E. 2003. Anti-inflammatory and antinociceptive activity
assessment of plants used as remedy in Turkish folk medicine. J Ethnopharmacol. 89(1):
123–129.
Gawlik-Dziki U, Durak A, Pecio L, Kowalska I. 2014. Nutraceutical potential of tinctures from
fruits, green husks, and leaves of Juglans regia L. Sci World J. 2014:501392.
Jia W, Mao SM, Jin J, Yan GL, Li J, Liu YH. 2017. Study on monosaccharide components of
polysaccharide from Lonicera japonica thumb by thin layer chromatography combined with
gas chromatography. Shandong J Trad Chin Med. 36:326–328.
Liu LJ, Li W, Koike K, Zhang SJ, Nikaido T. 2004. New a-tetralonyl glucosides from the fruit of
Juglans mandshurica. Chem Pharm Bull. 52(5):566–569.
Luo JJ, Yang B, Zeng Y, Li C. 2012. Chemical constituents from the flower of Juglans regia. J
Chin Med Mater. 35:1614–1616.
Nasiry D, Khalatbary AR, Ahmadvand H, Talebpour Amiri F, Akbari E. 2017. Protective effects
of methanolic extract of Juglans regia L. leaf on streptozotocin-induced diabetic peripheral
neuropathy in rats. BMC Complement Altern Med. 17(1):476.
Oliveira I, Sousa A, Ferreira IC, Bento A, Estevinho L, Pereira JA. 2008. Total phenols, antioxidant
potential and antimicrobial activity of walnut (Juglans regia L.) green husks. Food Chem
Toxicol. 46(7):2326–2331.
Sun ZL, Dong JL, Wu J. 2017. Juglanin induces apoptosis and autophagy in human breast cancer
progression via ROS/JNK promotion. Biomed Pharmacother. 85:303–312.
Wang RJ, Wang S, Xia YJ, Tu MWLJ, Zhang LJ, Wang YM. 2015. Antitumor effects and immune
regulation activities of a purified polysaccharide extracted from Juglan regia. Int J Biol
Macromol. 72:771–775.
Wu ZY, Raven PH. 1999. Flora of China. Vol. 4. Peking: Science Press. 282.
Xin N, Hasan M, Li W, Li Y. 2014. Juglans mandshurica Maxim extracts exhibit antitumor activity
on HeLa cells in vitro. Mol Med Rep. 9(4):1313–1318.
Yang BY, Chen ZL, Liu Y, Guo JT, Kuang HX. 2018. New lignan from the rattan stems
of Schisandra chinensis. Nat Prod Res. 2018:1–7.
Yao D, Jin M, Zhang C, Luo J, Li R, Zheng M, Cui J, Li G. 2014. A new phenolic glycoside
from Juglans mandshurica. Nat Prod Res. 28(13):998–1002.
Zhou YY, Liu YX, Jiang YA, Liu ZX, Niu F, Yang BY, Xiao HB, Zhao H. 2015. Chemical constituents
from pericarp of Juglans mandshurica Maxim. Chin Trad Patent Med. 37:2669–2673.
Zhou YY, Liu QY, Yang BY, Jiang YQ, Liu YX, Wang Y, Guo S, Kuang HX. 2017. Two new cytotoxic
glycosides isolated from the green walnut husks of Juglans mandshurica Maxim. Nat Prod Res.
31(11):1237–1244.
Zhou YY, Yang BY, Jiang YQ, Liu ZX, Liu YX, Wang XL, Kuang HX. 2015. Studies on cytotoxic
activity against HepG-2 Cells of naphthoquinones from green walnut husks of Juglans
mandshurica Maxim. Molecules. 20(9):15572–15588.
Zhou YY, Yang BY, Liu ZX, Jiang YQ, Liu YX, Fu L, Wang XL, Kuang HX. 2015. Cytotoxicity
of triterpenes from green walnut husks of Juglans mandshurica Maxim in HepG-2 cancer cells.
Molecules. 20(10):19252–19262.