Synthesis of aglycon analogues of sarmentosin and their bioactivity of lymphocyte proliferation.

Article abstract of DOI:10.1016/S0960-894X(02)00801-6

A number of aglycon analogues of sarmentosin were prepared and their bioactivities on the proliferation of T-lymphocytes and B-lymphocytes were assayed.

Full text of DOI:10.1016/S0960-894X(02)00801-6

Bioorganic & Medicinal Chemistry Letters 12 (2002) 3543–3545
Synthesis of Aglycon Analogues of Sarmentosin and Their
Bioactivity of Lymphocyte Proliferation
Hong Zhang, Rui Xu, Zhongliang Hu, Xuchang He, Donglu Bai,*
Xiaoyu Li and Xiaofeng Wang
Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences,
Chinese Academy of Sciences, 294 Tai-yuan Road, Shanghai 200031, China
Received 7 May 2002; accepted 17 September 2002
Abstract—A number of aglycon analogues of sarmentosin were prepared and their bioactivities on the proliferation of T-lympho-
cytes and B-lymphocytes were assayed.
# 2002 Elsevier Science Ltd. All rights reserved.
Sarmentosin (1), a cyano-ethylene glucoside isolated
from the folk medicine Sedum sarmetosum Bunge, is an
active principle for treatment of hepatitis B in China.1,2
Clinical trials of sarmentosin showed a good effect in
lowering serum glutamate-pyruvate transaminase.3 The
content of sarmentosin in plant varies greatly with the
growing region and the collecting season. It is known
that cyanogenic glycosides are readily hydrolyzed in
aqueous media, so sarmentosin is chemically rather
unstable. Our group accomplished the first total synth-
esis of sarmentosin,4 and is interested in searching new
potential analogues for treatment of hepatitis B. In this
paper, we would like to report the preparation and
bioassay of eight analogues of sarmentosin aglycon.
butane-1,2,4-triol-1,2-acetonide (2) was converted into
iodide 3, which was treated with phenols in the presence
of potassium carbonate to afford aryl ethers 4a. Esters
4b were obtained by the reaction of 2 with aromatic
acids in the presence of DCC and DMAP. Subse-
quently, analogues 5, 6, 7 and 8 were obtained from
ethers 4a or esters 4b via a reaction sequence similar to
the construction of aglycon in the synthesis of sarmen-
tosin itself 4,7 (Scheme 1).
Meantime, a more convenient and convergent route to
the aglycon analogues of sarmentosin has been devel-
oped too (Scheme 2). The protected aglycon 12 was first
synthesized as the common intermediate, then it was
esterified respectively with various acids to yield ester
analogues 15, 16 and 17. For preparation of inter-
mediate 12, the starting material 2 was first protected as
p-methoxy benzyl(PMB) ether 9. Hydrolysis of acet-
onide 9 and the selective protection of the primary
alcohol with t-butyldiphenylsilyl chloride (TPSCl)
afforded 10, which was oxidized by Dess–Martin
method to give ketone 11. Ketone 11 was further con-
verted into the corresponding cyanohydrin by treatment
with acetone cyanohydrin in the presence of Et3N fol-
lowed by dehydration with thionyl chloride in pyridine,
giving the desired E-olefin, the protected aglycon 12 as
the only product. Selective cleavage of PMB group in 12
by DDQ afforded alcohol 13. Esterification of alcohol
13 with the corresponding acids and removal of TPS
group of the esters with TBAF furnished analogues 15,
16 and 17, respectively.7 This approach proved to be
more facile for peparation of various analogues of
We supposed that the aglycon, an unsaturated cyano-
containing moiety of sarmentosin was the pharmaco-
phoric group, and the simplified analogues were thus
designed, in which the acetal group in sarmentosin was
changed into more stable ether and ester groups.
Therefore, b-d-glucopyranosyl in sarmentosin was
replaced by aryl (5, 6), alkyl (14) and acyl (7, 8, 15, 16,
17), respectively. The synthetic approach to these ana-
logues is depicted in Scheme 1. The starting material
*Corresponding author. Tel.: +86-21-64311833; fax:+86-21-
64370269; e-mail: dlbai@mail.shcnc.ac.cn
0960-894X/02/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved.
PII: S0960-894X(02)00801-6

3544
H. Zhang et al. / Bioorg. Med. Chem. Lett. 12 (2002) 3543–3545
Scheme 1. Reagents and conditions: (a) (i) CH3SO2Cl, Et3N, CH2Cl2; (ii) NaI, K2CO3; (b) ArOH, K2CO3, acetone; (c) RCOOH, DCC, DMAP,
CH2Cl2; (d) (i) p-TsOH, MeOH; (ii) Ph3CCl, Et3N, CH2Cl2; (e) PCC, NaOAc, CH2Cl2; (f) (i) acetone cyanohydrin, NaHCO3, MeOH; (ii) SOCl2,
pyridine; (g) p-TsOH.H2O, CH3OH.
.
Scheme 2. Reagents and conditions: (a) PMBOC(=NH)CCl3, CSA(cat.), CH2Cl2, 91%; (b) (i) TsOH H2O, MeOH; (ii) TPSCl, imidazole, CH2Cl2,
87%; (c) Dess–Martin periodinane, pyridine, CH2Cl2, 89%; (d) (i) acetone cyanohydrin, Et3N, MeOH; (ii) SOCl2, pyridine, 32%; (e) DDQ, CH3Cl,
H2O, 90%; (f) RCOOH, DCC, DMAP, toluene, 88%; (g) TBAF, HOAc, THF, 82%.
Table 1. Effects of sarmentosin aglycon analogues on the proliferation
of T and B lymphocytesa
3H-thymidine incorporation test of mouse splenocytes
in vitro. A brief description of the proliferation test is
provided below.5,6 The results of the proliferation test
are listed in Table 1.
Compd
T cell proliferation
(%) mmol/L
B cell proliferation
(%) mmol/L
20
2
0.2
20
2
0.2
The results indicate that within the concentration range
tested, 14 and 15 showed the distinct suppressive effect
on T cell proliferation while 5 showed the most sig-
nificant effect on B-lymphocytes. Further pharmaco-
logical studies are under way.
5
6
7
8
14
15
16
17
131
80
113
114
68
100
101
97
100
93
45#
79
67
31#
38###
20#
113
73
48###
77
73
51###
81
137
109
169"
96
23###
25##
37##
38#
63
86
71##
54#
62##
98
80
69
29##
131
123
119"
151"
69
151
68
94
Acknowledgements
aCompared to DMSO as control (%): #deceased P<0.05; ##P<0.01;
This work was supported by the National Natural
Science foundation of China.
###P<0.001. Values are means of three experiments.
aglycon and sarmentosin itself as well. Analogue 14
was directly yielded by selective cleavage of TPS group
in 12.7
References and Notes
1. Fang, S. D.; Yan, X. Q.; Li, J. F.; Fan, Z. Y.; Xu, X. Y.;
Xu, R. S. Chinese Science Bulletin 1979, 24, 431.
2. Fang, S. D.; Yan, X. Q.; Li, J. F.; Fan, Z. Y.; Xu, X. Y.;
Xu, R. S. Acta Chim. Sin. 1982, 40, 273.
3. Zhai, S. K.; Shen, M. L.; Xiong, Y. L.; Li, J. F.; Ding,
Y. E.; Gao, Y. S. Chin. J. Microbiol. Immun. 1982, 2, 145.
4. Chu, G.; Zhou, Q.; Bai, D. L. Bioorg. Med. Chem. Lett.
1993, 3, 1343.
It was reported that sarmentosin showed good and
rapid effects in lowering serum transaminase levels and
improved liver function by an immunomodulating
mechanism.3 The analogues mentioned above were tes-
ted for their activities on the proliferation of T lympho-
cytes to show the cell-mediated immunity, and B
lymphocytes to show the antibody formation ability by

H. Zhang et al. / Bioorg. Med. Chem. Lett. 12 (2002) 3543–3545
3545
5. Coligan, J. E., Kruisbeek, A. M., Margulies, D. M.,
J=6.4, 1.4 Hz, 2H), 4.32 (d, J=2.8 Hz, 2H); IR (film, cmꢂ1
)
Shevach, E. M., Strober, W., Eds. Current Protocols in Immu-
nology. Greene Publishing Associates & Wiley-Interscience:
New York, 1991.
3456, 2225, 1722, 1600, 1452, 1272, 1116, 713; HRMS (m/z):
calcd for C12H11NO3: 217.0739, found 217.0747; 1H NMR
(CDCl3, 300 MHz) d 8.01(d, J=6.8 Hz, 2H), 6.91(d, J=7.0
Hz, 2H), 6.65 (tt, J=6.3, 1.6 Hz, 1H), 5.08 (dt, J=6.3, 1.2 Hz,
6. T cell and B cell function assay: Fresh spleen cells were
obtained from ICR mice (male, 7–9 weeks old). 5ꢀ105 of
spleen cells were cultured in 96-well flat plates with 200 mL of
RPMI 1640 media containing 10% FBS, 100 U/mL penicillin
and 100 mg/mL streptomycin in a humidified, 37 ꢁC, 5% CO2
incubator for 48 h. The cultures were either unstimulated or
stimulated with 5 mg/mL of concanavalin A (ConA) or 10 mg/
mL of lipopolysaccharide (LPS) to induce T cells or B cells
proliferative responses respectively. The compounds were
added in cultures with indicated concentrations to test their
bioactivities. Proliferation was assessed in terms of uptake of
[3H]-thymidine during 6–12 h pulsing with 20 kBq [3H]-thy-
midine/well, then the cells were harvested by a Basic 96 har-
vester, and counted in a 1540 MicroBeta Trilux (PerkinElmer
Life Sciences).
2H), 4.30 (d, J=1.2 Hz, 2H), 3.85 (s, 3H); IR (film, cmꢂ1
)
3470, 2223, 1716, 1606, 1511, 1259, 1170, 1105, 1027, 769;
HRMS (m/z): calcd for C13H13NO4: 274.0844, found
274.0844; 14: 1H NMR (CDCl3, 300 MHz) d 7.28 (m, 2H),
6.90 (dd, J=6.6, 2.1Hz, 2H), 6.58 (tt, J=6.4, 1.3 Hz, 1H),
4.50 (s, 2H), 4.32 (d, J=6.4 Hz, 2H), 4.24 (d, J=2.8 Hz, 2H),
3.82 (s, 3H); IR (film, cmꢂ1) 3430, 2221, 1612, 1513, 1249,
1176, 1033, 821; HRMS (m/z): calcd for C13H15NO3:
1
233.1052, found 233.1050; 15: H NMR (CDCl3, 300 MHz) d
7.73 (d, J=16.0 Hz, 1H), 7.51 (m, 2H), 7.39 (m, 3H), 6.60 (tt,
J=6.3, 1.6 Hz, 1H), 6.43 (d, J=16.0 Hz, 1H), 4.98 (d, J=6.3
Hz, 2H), 4.29 (d, J=2.9 Hz, 2H); IR (film, cmꢂ1) 3446, 2223,
1714, 1635, 1450, 1311, 1166, 981, 769, 684: calcd for
1
C14H13NO3: 243.0895, found 243.0891; 16: H NMR (CDCl3,
7. Analytical data: Compound 5: 1H NMR (CDCl3,
300 MHz) d 7.31(t, J=7.4 Hz, 2H), 7.00 (t, J=7.4 Hz, 1H),
6.92 (d, J=8.5 Hz, 2H), 6.72 (t, J=6.0 Hz, 1H), 4.85 (d,
J=6.0 Hz, 2H), 4.30 (d, J=1.4 Hz, 2H); 3425, 2223, 1587,
1494, 1238, 1033, 756, 692; HRMS (m/z): calcd for
300 MHz) d 7.95 (m, 1H), 7.20 (m, 1H), 7.03 (m, 1H), 6.65 (tt,
J=6.4, 1.7 Hz, 1H), 5.10 (dt, J=6.4, 1.3 Hz, 2H), 4.30 (d,
J=1.6 Hz, 2H); IR (film, cmꢂ1) 3461, 2225, 1731, 1602, 1490,
1251, 1114, 1043, 910, 769; HRMS (m/z): calcd for
C12H9NFClO3: 269.0255, found 269.0264; 17: 1H NMR
(CDCl3, 300 MHz) d 7.84 (d, J=8.4 Hz, 1H), 7.47 (d, J=1.9
Hz, 1H), 7.30 (dd, J=8.4, 1.9 Hz, 1H), 6.65 (t, J=6.4 Hz, 1H),
5.10 (d, J=6.4 Hz, 2H), 4.28 (d, J=1.2 Hz, 2H); IR (film,
cmꢂ1) 3430, 2231, 1708, 1587, 1376, 1286, 1137, 1026, 765; MS
(m/z): 145 (17), 173 (100), 175 (63), 285 (M+, 26), 287
(M++2, 17).
1
C11H11NO2: 189.0789, found 189.0776; 6: H NMR (CDCl3,
300 MHz) d 6.83 (s, 4H), 6.66 (t, J=6.0 Hz, 1H), 4.77 (d,
J=6.0 Hz, 2H), 4.26 (d, J=2.9 Hz, 2H), 3.75 (s, 3H); IR (film,
cmꢂ1) 3442, 2925, 2223, 1508, 1228, 1035, 825; HRMS (m/z):
1
calcd for C12H13NO3: 219.0896, found 219.0907; 7: H NMR
(CDCl3, 300 MHz) d 8.06 (dd, J=7.3, 1.4 Hz, 2H), 7.59 (m,
1H), 7.45 (dd, J=7.6, 7.3 Hz, 2H), 6.68 (m, 1H), 5.13 (dt,