Synthesis and anti-inflammatory activity of gold-nanoparticle bearing a dermatan sulfate disaccharide analog

Article abstract of DOI:10.1016/j.cclet.2017.06.010

A dermatan sulfate (DS) repeating disaccharide analog, α-L-idopyranosiduronate-(1 → 3)-2-amino-2-deoxy-4,6-di-O-sulfo-β-D-galactopyranoside, has been convergently synthesized and successfully applied to prepare the GAG-functionalized gold glyconanoparticle. This new material exhibited good anti-inflammatory activity which was comparable to that of the drug ibuprofen incarrageenan-induced paw edema in a rat model.

Full text of DOI:10.1016/j.cclet.2017.06.010

Accepted Manuscript
Title: Synthesis and anti-inflammatory activity of
gold-nanoparticle bearing a dermatan sulfate disaccharide
analog
Authors: Chengxiang Shang, Chao Cai, Cuixia Zhao, Yuguo
Du
PII:
S1001-8417(17)30214-0
DOI:
Reference:
http://dx.doi.org/doi:10.1016/j.cclet.2017.06.010
CCLET 4104
To appear in:
Chinese Chemical Letters
Received date:
Revised date:
Accepted date:
27-3-2017
23-4-2017
2-6-2017
Please cite this article as: Chengxiang Shang, Chao Cai, Cuixia Zhao,
Yuguo Du, Synthesis and anti-inflammatory activity of gold-nanoparticle
bearing
a
dermatan sulfate disaccharide analog, Chinese Chemical
Lettershttp://dx.doi.org/10.1016/j.cclet.2017.06.010
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Communication
Synthesis and anti-inflammatory activity of gold-nanoparticle bearing a dermatan
sulfate disaccharide analog
Chengxiang Shang a,b, Chao Cai a,c, Cuixia Zhao a,b, Yuguo Du a,b,*
aState Key Laboratory of Environmental Chemistry and Eco-toxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences,
Beijing 100085, China,
bSchool of Chemistry and Chemical Engineering, Graduate University of Chinese Academy of Sciences, Beijing 100049, China,
cKey Lab of Marine Drugs, Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
* Corresponding author.
E-mail address: duyuguo@rcees.ac.cn (Y. Du).
Graphical abstarct
A novel gold glyconanoparticle coating with DS disaccharide analog has been synthesized, and the potential anti-
inflammatory activity was studied using carrageenan-induced paw edema model.
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
A dermatan sulfate (DS) repeating disaccharide analog, α-L-idopyranosiduronate-(1→3)-2-
amino-2-deoxy-4,6-di-O-sulfo-β-D-galactopyranoside, has been convergently synthesized
and successfully applied to prepare the GAG-functionalized gold glyconanoparticle. This
new material exhibited good anti-inflammatory activity which was comparable to that of the
drug ibuprofen incarrageenan-induced paw edema in a rat model.
Available online
Keywords:
L-Iduronic acid
Gold glyconanoparticles
Dermatan sulfate disaccharide
Anti-inflammatory
Carbohydrates
Gold nanoparticles [1] have many potential applications in the fields of chemistry and medicine development, and their affinity
for binding many biological carbohydrate molecules can readily generate glyconanoparticles (GNPs) [2], which are atmospheric
stable, water-soluble and carbohydrate-functionalized nanoclusters [3-5]. A novel Neu5Ac-Gal-containing neoglycoside for the
exploration of anticancer antigen has been accomplished using modified gold glyco-nanotechnology in our laboratory [6].
Dermatan sulfate (DS), the linear and sulfated polysaccharides belonging to the family of glycosaminoglycans (GAGs) [7], is
mainly composed of a repeating disaccharide motif of uronic acid such as D-glucuronate (GlcA) or L-iduronate (IdoA)] and N-
acetylgalactosamine (GalNAc) residues, which play the important roles in a diverse set of biological processes including cellular
proliferation and differentiation, wound healing, anticoagulant, antithrombotic, and anti-inflammatory activities [8]. GAGs-
containing nanoparticles bound to Au and Ag still retain their original biological activities and can be localized to prevent rapid
diffusion into body like other drugs [9-11]. Moreover, chemical synthesis may avoid the potential crisis caused by impurities that
———

plague the natural products chemistry [12]. We plan to investigate the feasibility of synthesizing stable GAGs-containing
nanoparticles, which may serve as a useful technique for biological activity research [13-14]. Herein, we report a synthesis of
dermatan sulfate disaccharide analog coated gold nanoparticle, as well as a preliminary study in anti-inflammatory activities.
The synthesis of gold nanoparticle began with the construction of DS repeating disaccharide containing IdoA and GalNAc. All
compounds were prepared under standard reaction conditions unless mentioned specifically. Optical rotations were determined at
25 oC with a Perkin Elmer Model 241-Mc automatic polarimeter. 1H NMR, 13C NMR and spectra were recorded with Bruker ARX
400 spectrometers for solutions in CDCl3 or D2O. Chemical shifts are given in ppm downfield from internal Me4Si. Mass spectra
were measured using MALDI-TOF-MS with CCA as matrix or recorded with a VG PLATFORM mass spectrometer using the
ESI technique to introduce the sample. Thin-layer chromatography (TLC) was performed on silica gel HF254 with detection by
charring with 30% (v/v) H2SO4 in MeOH or in some cases by a UV detector. Column chromatography was conducted by elution
of silica gel (100~200 mesh) with EtOAc-petroleum ether (60 - 90 oC) as the eluent. Solutions were concentrated at <50 oC under
reduced pressure. Experimental details and the key spectra are presented in the Supporting information.
Commercially available diacetone D-glucose 1 was converted into L-iduronate analog 2 in nine steps and 36% overall yield
(Scheme 1), employing a similar procedure of Seeberger’s group [15]. Then, compound 2 was treated with levulinic acid in the
presence of DCC and DMAP furnishing the desired compound 3 in a yield of 92%, and benzyl was removed with sodium
hyposulfite and NaBrO3 under two phase conditions (EtOAc : H2O = 1:1) [16]. After cleavage of the 1, 2-O-isopropylidene with
90% CF3COOH at room temperature, selective silylation with tert-butyldimethylsilyl chloride (TBDMSCl) and imidazole at -25
oC to protect the C-1 hydroxyl, and subsequent acetylation with acetic anhydride in pyridine, compound 5 was obtained in 68%
yield over three steps. Desilylation of 5 with HF·pyridine in THF obtained the lactol, which was converted to the corresponding
trichloroacetimidate 6 in a yield of 77% in two steps. The structure of 6 was confirmed by its physical and spectral data and
further identified through its X-ray crystallography [17].
The acceptor 10 was prepared from galactosamine hydrochloride (7, Scheme 2), which was treated with
trichloroethoxycarbonyl chloride (TrocCl) and NaHCO3 in water, and followed by acetylation with acetic anhydride in pyridine
[18]. For activation of C-1, a thiophenyl group was introduced through a BF3·Et2O catalyzed reaction between galactosaminyl
tetra-acetates and thiophenol in CH2Cl2. Subsequent deacetylation with NaOMe ( 9), followed by benzylidenation with ,-
dimethoxytoluene in DMF in the presence of camphorsulfonic acid furnishing 10 in 83% yield over two steps.
Glycosylation of donor 6 and acceptor 10 with the catalyst of trimethylsilyl trifluoromethanesulfonate (TMSOTf) in anhydrous
CH2Cl2 obtained disaccharide in a low yield, and the similar results were obtained using AgOTf or TBSOTf. To our delight,
BF3·Et2O in toluene successfully promoted this coupling reaction in a yield of 82% (Scheme 3). N-iodosuccinimide
(NIS)/TMSOTf-mediated coupling of disaccharide donor 11 with 11-bromoundecanol at -25 oC in CH2Cl2 gave 12 in 90% yield.
Replacement of the primary bromide 12 by thioacetate could be carried out with KSAc and t-Bu4NI in acetone, affording the
o
corresponding 13 quantitatively [19]. The benzaldehyde acetal was cleaved in HOAc/H2O (v/v, 4:1) at 80 C smoothly, and the
free hydroxyls of compound 14 was sulfated with SO3·pyridine at room temperature for 24 h, which was purified through a
Sephadex LH-20 column immediately. Removal of the acyls and methyl ester with 2 mol/L NaOH in THF (v/v, 1:1) at room
temperature, followed by in situ O2 oxidation, neutralization with Amberlite IR-120 (H+), and purification through a Sephadex G-
25 column, afforded compound 16 in 81% yield. Gold glyconanoparticle 17 was prepared by treatment of 16 with HAuCl4·4H2O
and NaBH4 in water according to our previous report [6], and the formed glyconanoparticle (GNP) was collected by centrifugal
filtration and characterized by transmission electron microscopy (see Supporting information). The mean diameter of the
generated glyconanoparticles was 4.4 nm, bearing approximately 0.1 mg/mg (disaccharide/glyconanoparticle) based on
thermogravimetric analysis.
With GNP in hand, we next investigated the anti-inflammatory activity using carrageenan induced rat paw edema model [20].
Rats were divided into seven groups with five animals each. Acute inflammation was induced by subplantar injection of 0.1%
freshly prepared carrageenan suspension into the paw of each rat. The paw volume was measured plethysmometrically at 0 and 3
h after carrageenan injection. The difference between the two volumes represented the edema value and thus calculated the anti-
inflammatory activity. The dermatan disaccharide coated gold-nanoparticles were administered orally to three groups of rats with
concentrations of 25, 50, and 100 mg/kg, respectively. The other groups of rats were used as controls. All compounds were given
1 h before carrageenan injection. As seen in Table 1, disaccharide-coated Au-NPs (entry 7) presented much stronger edema
suppression activities comparing to its disaccharide unit (entry 3) in a concentration-dependent manner (entries 5 and 6). The
current result implies that the cluster effect may be important for carbohydrates to show their biological activities although more
evidences are needed to support this theory.

In summary, a novel Au-nanoparticle bearing dermatan sulfate disaccharide analog has been successfully designed and
synthesized. Levulinic group on iduronic acid could hold an opportunity to construct tetra- or even more complex demertan sulfate
oligosaccharides or analogs using the similar building block. Our newly designed GAGs-containing GNPs show potential anti-
inflammatory activity in carrageenan-induced paw edema in a rat model. The current results suggest that these series of
compounds could be used for further biological activity investigations.
Acknowledgments
This work was supported in partial by National Natural Science Foundation of China projects (Nos. 21232002, 21372254,
21621064 and 21672255).
References
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emy of Sciences, 2010.
O
OBn
O
OBn
O
O
NaBrO3, Na2S2O3
EtOAc/H2O, 89%.
OH
O
MeOOC
O
MeOOC
O
O
O
O
OLev
OH
Ref .15
LevOH, DCC, DMAP
O
2
1
3
OAc
OH
O
OTBS
OC(NH)CCl
OAc
O
3
MeOOC
O
MeOOC
O
MeOOC
O
OAc
1) HF-pyridine, THF
2) Cl3CCN, DBU, DCM
77% over two steps
OLev
OLev
1) 90% CF3COOH
2) TBSCl, Im, DMF, -25 o
3) Ac2O, Pyr
OAc
OLev
C
4
5
6
Scheme 1. Synthesis of IdoA unit.
Scheme 2. Synthesis of the GalNH2 building block.

Ph
Ph
OC(NH)CCl3
+
AcO
O
BF3 Et2O, Toluene, 0 o
82%
C
MeOOC
LevO
O
OAc
O
O
O
MeOOC
O
O
O
O
SPh
SPh
HO
OAc
LevO
NHTroc
AcO
NHTroc
6
11
10
KSAc, t-Bu4NI
Acetone
Ph
Ph
11-Bromoundecanol,
NIS, TMSOTf
CH2Cl2, -25 oC, 90%
O
O
O
O
OAc
O
MeOOC
LevO
OAc
O
MeOOC
LevO
quantitative
O
O
O
O
O
O
SAc
Br
5
5
NHTroc
NHTroc
AcO
AcO
12
13
SO3 pyridine
DMF, 69%
HO3SO
OAc
HOAc/H2O (v/v, 4:1)
80 oC, 94%.
OH
OSO3H
O
O
OH
O
OAc
O
MeOOC
LevO
MeOOC
LevO
O
14
O
O
O
5 SAc
5 SAc
NHTroc
NHTroc
AcO
AcO
15
HO3SO
OH
O
OSO3
O
H
HOOC
HO3SO
OSO3
H
DS
O
OH
HOOC
HO
DS
1) THF/2 mol/L NaOH
(v/v, 1:1), 12 h, r.t.
2) O2, 12 h; 81%.
DS
DS
S
O
O
HO
S
S
5
5
O
O
O
HAuCl4
NaBH4
NH2
S
S
HO
S
NH2
S
S
S
HO
HO3SO
OH
DS
Au
S
S
DS
DS
OSO3
O
H
DS
HOOC
HO
O
S
O
S
DS
S
O
DS
DS
HO
NH2
17
DS
16
Scheme 3. Synthesis of Gold glyconanoparticles.
Table 1
Effect of dermatan disaccharide analog coated Au-NPs on Carrageenan-induced rat paw edema.
Entry Treatment
Dose (mg/kg, p.o.)
Edema volume (mL)a
Inhibition (%)
1
2
3
4
5
6
7
Propylene glycol
5 mL/kg
0.45
-
Ibuprofen
100
100
100
25
0.18
0.31
0.46
0.32
0.26
0.21
60.0
Dermatan sulfate disaccharide [21]
Au-NPs
31.0
-
Disaccharide-coated Au-NPs
Disaccharide -coated Au-NPs
Disaccharide -coated Au-NPs
28.8
42.2
53.3
50
100
a Values are mean of the five rats in the same group