ACS Medicinal Chemistry Letters
Letter
Biological assays, synthetic methods, solubility determi-
1
nation, chemical characterization of final products, H
1
3
Compounds 8a−c, 9a−c, and 10a−c were evaluated in an
and C NMR spectra, and HRMS spectra (PDF)
22
anti-HIV (wild-type) replication assay, and the in vitro anti-
HIV activity results are listed in Table 1. Cytotoxicity was
Corresponding Authors
22
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evaluated using the MTT assay.
Yanli Wang − National Health Commission Key Laboratory of
Table 1. Anti-HIV Activities of Compounds 8a−10c
a
b
c
compound
IC50 (μM)
CC50 (MT4 cells, μM)
SI
Kuo-Hsiung Lee − Natural Products Research Laboratories,
UNC Eshelman School of Pharmacy, University of North
Carolina, Chapel Hill, North Carolina 27599-7568, United
States; Chinese Medicine Research and Development Center,
8
8
8
9
9
9
1
1
1
3
a
b
c
a
b
c
0a
0b
0c
0.097 ± 0.028
>25.2
>260
−
−
>525
−
d
d
−
−
−
−
d
d
0.048 ± 0.018
>25.2
d
d
−
−
>1.3
>1.3
−
0.0078 ± 0.0020
0.020 ± 0.005
>1.3
0.021 ± 0.007
0.000262 ± 0.000084
0.219 ± 0.060
0.018 ± 0.006
9.6 ± 0.82
23.8 ± 1.79
>1.3
>6.84
0.09957 ± 0.00863
>3.48
1231
1190
−
>326
380
>16
>20.6
Authors
Qiang Wang − High & New Technology Research Center of
Henan Academy of Sciences, Zhengzhou 450002, China;
National Health Commission Key Laboratory of Birth Defect
Prevention, Zhengzhou 450002, China; Institute of Medical and
Pharmaceutical Sciences, Zhengzhou University, Zhengzhou
Yujiang Li − High & New Technology Research Center of
Henan Academy of Sciences, Zhengzhou 450002, China
Liyun Zheng − Institute of Medical and Pharmaceutical
Sciences, Zhengzhou University, Zhengzhou 450052, China
Sciences, Zhengzhou University, Zhengzhou 450052, China
Chin-Ho Chen − Surgical Science, Department of Surgery, Duke
University Medical Center, Durham, North Carolina 27710,
United States
Yung-Yi Cheng − Natural Products Research Laboratories,
UNC Eshelman School of Pharmacy, University of North
Carolina, Chapel Hill, North Carolina 27599-7568, United
Susan L. Morris-Natschke − Natural Products Research
Laboratories, UNC Eshelman School of Pharmacy, University of
North Carolina, Chapel Hill, North Carolina 27599-7568,
United States
AFC
AFU
AZT
>0.37
a
IC50 is the 50% HIV inhibitory concentration. The results are
presented as mean ± standard deviation (SD) of triplicate
experiments. CC50 is the 50% cytotoxic concentration. The results
are presented as mean ± SD of triplicate experiments. Selectivity
index, defined as SI = CC /IC . No selective anti-HIV activity (SI
5).
b
c
d
5
0
50
<
As shown in Table 1, none of the three hybrids conjugated
with AZT (8c, 9c, 10c) displayed significant anti-HIV activity,
one of the three hybrids conjugated with AFU (10b) showed
anti-HIV activity, and all three hybrids conjugated with AFC
(
8a, 9a, 10a) exerted potent anti-HIV activity. Compared with
the positive controls AZT and 3, compounds 10a and 10b
showed greater and comparable potency, respectively, as well
as lower cytotoxicity. Although compound 10b (the hybrid of
1
and AFU) was less potent than 10a (the hybrid of 1 and
AFC), it was also less cytotoxic, resulting in similar selectivity
index (SI) values (10a, 1231; 10b, 1190). These values were
higher than the SI of 380 for AFC, the most potent compound,
which exhibits nanomolar anti-HIV activity. Moreover, the
three triterpenoid−AFC hybrids had the following order of
potency: 10a (3β-OH, 17-COOH) > 9a (3β-OH, 17-
COOMe) > 8a (3-oxo, 17-COOMe). Also, comparison of
the structural differences between 9a−c and 10a−c shows that
the betulinic acid scaffold with a 17-COOH is preferred over
its methyl ester analogues.
In summary, we synthesized a novel class of betulinic/
betulonic acid−nucleoside hybrids. From this class, we
identified two analogues, 10a and 10b, with highly potent
anti-HIV activity. Although the hybrid compounds were less
potent than the nucleoside (AFC) itself, they were also less
cytotoxic and perhaps would be safer therapeutic agents.
Mechanism studies, further optimization of activity, and
determination of efficacy in animal models will be reported
in the future.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
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This work was supported by the Science and Technology
Research Project of Henan Province (192102310407), the
Basal Research Fund of Henan Academy of Sciences
(
200602007), and the Medical Science and Technology
Research Project of Henan Province (LHGJ20190829).
Grant support from the National Institute of Allergy and
Infectious Diseases, U.S. National Institutes of Health
(
AI033066 to K.-H.L.) is also acknowledged.
ABBREVIATIONS
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ASSOCIATED CONTENT
AFC, 4′-azido-2′-deoxy-2′-fluoro-β-D-arabinocytidine; AFU,
4′-azido-2′-deoxy-2′-fluoro-β-D-arabinouridine; CC , 50% cy-
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*
sı Supporting Information
5
0
totoxic concentration; DBU, 1,8-diazabicyclo[5.4.0]undec-7-
ene; DMC, dimethyl carbonate; IC , 50% HIV inhibitory
5
0
C
ACS Med. Chem. Lett. XXXX, XXX, XXX−XXX