Communications to the Editor
J ournal of Medicinal Chemistry, 1996, Vol. 39, No. 5 1017
Ta ble 1. Anti-HIV, HIV-RT, and Fusion Assay Data for
Betulinic Acid and Dihydrobetulinic Acid Derivatives
fusion. Therefore, compounds 1-6 and 8-10 were also
evaluated for inhibitory activity against HIV-induced
membrane fusion. Compounds 2-5 and 8-10 inhibited
syncytia formation in a concentration range of 33-70
µM, suggesting that an inhibitory effect against HIV-
induced membrane fusion could be involved in their
mechanism(s) of action. However, the anti-HIV activity
of 3 is 7700 times greater than that of 2, although these
compounds inhibited syncytia formation at the same
concentration. This observation indicated that another
mechanism(s) of action other than inhibition of syncytia
formation could be involved in the anti-HIV activity
shown by these compounds. Details of our continuing
mechanism(s) of action study will be reported in a future
paper.
HIV-RT
assay
fusion
assay
IC100
anti-HIV assay
IC50
compd (µM)
EC50
(µM)
IC50
a
b
TIc
9.3
5.9
>20000 >171
d
(µM)e
(µM)
>219
>171
1
2
3
4
5
6
7
8
9
1
1
13.0
15.9
7.0
1.4
2.7
>219
34
34
50
70
-
-
4 f
<3.5 × 10
-
3
4.5
2.3 × 10
1974
1172
14
>167
>175
>218
11.7
12.6
7.7
4.9
5.8
13.1
2.7
1,875 0.15
0.01
0.9
0.56
>218
g
g
13.8
NT
NT
4 f
<3.5 × 10
>14000 >171
34
33
70
-
-
3
5.7 × 10
5.6 × 10
1,017
2344
>167
>174
no inhibition
3
0
2
h
h
h
h
0.03
>90
3
AZT
12500
a
Ack n ow led gm en t . This investigation was sup-
ported by Grant AI-33066 from the National Institute
of Allergies and Infectious Diseases awarded to K. H.
Lee.
Concentration which is toxic to 50% of mock-infected H9 cells.
b
c
Concentration which inhibits viral replication by 50%. IC50
d
value divided by EC50 value. Concentration required to inhibit
5
0% of HIV-1 RT activity. e Concentration required to completely
f
inhibit HIV-1-induced syncytia. These EC50 values are the most
conservative estimations under our experimental conditions due
to an unusual plateau effect. NT ) not tested. Data from ref
Su p p or tin g In for m a tion Ava ila ble: Experimental pro-
cedures for the preparation of compounds 2-5 and 7-10 as
well as for the biological assays (4 pages). Ordering informa-
tion is given on any current masthead page.
g
h
8
.
showed anti-HIV activities with EC50 values of 2.7 and
.56 µM, respectively, and TI values of 5.9 and 13.8,
Refer en ces
0
(
1) Anti-AIDS Agents. 23. For paper 22 in this series, see: Xie,
L.; Crimmins, M. T.; Lee, K. H. Asymmetric Synthesis of 3′,4′-
Di-O-(-)-Camphanoyl-(+)-cis-Khellactone (DCK), A Potent Anti-
HIV Agent. Tetrahedron Lett. 1995, 36, 4529-4532.
respectively, which were significantly lower than those
of 3 and 8. Compounds 4, 5, 9, and 10 also exhibited
potent anti-HIV activities with EC50 values ranging
-
3
(2) Schinazi, R. F.; Mead, J . R.; Feorino, P. M. Insights into HIV
from 0.01 to 2.3 × 10 µM and TI values from 1017 to
Chemotherapy. AIDS Res. Human Retrovir. 1992, 8, 963.
2
344.
(
3) Shirahata, T.; Yarchoan, R.; Obrien, M. C.; Husson, R. N.;
Anderson, B. D.; Kojima, E.; Shimoda, T.; Broder, S.; Mitsuya,
H. Changes in Drug Sensitivity of Human Immunodeficiency
Virus Type-1 During Therapy with Azidothymidine, Dideoxy-
cytidine, and Dideoxyinosine: An In Vitro Comparative Study.
Proc. Natl. Acad. Sci. U.S.A. 1993, 91, 562.
The C3 acyl groups of the more active compounds
have dimethyl groups or oxygen at the C3′ position.
Since the lone pairs of the oxygen in the diglycoyl group
might correspond to the dimethyl groups at C3′ in the
dimethylsuccinyl or dimethylglutaryl groups, these
three acyl groups are structurally similar to one an-
other. This observation suggested that this type of acyl
group might be important to the enhanced anti-HIV
activity.
The inhibitory activities of 8 and 9 against HIV-1
replication in PHA-stimulated peripheral blood mono-
nuclear cells (PBMCs) were also evaluated. Preliminary
results demonstrate that these two agents also display
potent inhibitory activity but their therapeutic indexes
are 4-6-fold lower than those found in acute HIV-1
infection of H9 cells (data not provided). Studies are
planned to evaluate these two agents with other HIV-
infected target cells.
(
4) Lee, T. T.-Y.; Kashiwada, Y.; Huang, L.; Snider, J .; Cosentino,
M.; Lee, K. H. Suksdorfin: an Anti-HIV Principle from Loma-
tium suksdorfii, Its Structure-Activity Correlation with Related
Coumarins, and Synergistic Effects with Anti-AIDS Nucleosides.
Bioorg. Med. Chem. 1994, 2, 1051-1056.
(
5) Huang, L.; Kashiwada, Y.; Cosentino, L. M.; Fan, S.; Lee, K. H.
3′,4′-Di-O-Camphanoyl-(+)-cis-Khellactone and Related Com-
pounds: A New Class of Potent Anti-HIV Agents. Bioorg. Med.
Chem. Lett. 1994, 4, 593-598.
(6) Huang, L.; Kashiwada, Y.; Cosentino, L. M.; Fan, S.; Chen, C.-
H.; McPhail, A. T.; Fujioka, T.; Mihashi, K.; Lee, K. H. Anti-
AIDS Agents. 15. Synthesis and Anti-HIV Activity of Dihy-
droseselins and Related Analogs. J . Med. Chem. 1994, 37,
3947-3955.
(
7) Fujioka, T.; Kashiwada, Y.; Kilkuskie, R. E.; Cosentino, L. M.;
Ballas, L. M.; J iang, J . B.; J anzen, W. P.; Chen, I. S.; Lee, K. H.
Anti-AIDS Agents, 11. Betulinic Acid and Platanic Acid as Anti-
HIV Principles from Syzygium claviflorum, and the Anti-HIV
Activity of Structurally Related Triterpenoids. J . Nat. Prod.
1
994, 57, 243-247.
As a mechanism(s) of action study, the inhibitory
activity of compounds 1-6 and 8-10 against HIV-1 RT
was investigated. The tested compounds did not inhibit
HIV-RT activity in a concentration range of 167-219
µM. In the same experiment, ddCTP, a known HIV-
RT inhibitor, inhibited RT activity by 50% at 18 µM.
Recently, other betulinic acid derivatives, such as
(8) Mayaux, J .; Bousseau, A.; Pauwels, R.; Huet, T.; Henin, Y.;
Dereu, N.; Evers, M.; Solder, F.; Poujade, C.; DeClercq, E.;
LePecq, J . B. Triterpene Derivatives That Block Entry of Human
Immunodeficiency Virus Type 1 Into Cells. Proc. Natl. Acad.
Sci. U.S.A. 1994, 91, 3564-3568.
9) Matthews, T. J .; Winhold, K. J .; Lyerly, H. K.; Langlois, A. J .;
Wigzell, H.; Bolognesi, D. P. Interaction Between the Human
T-cell Lymphotropic Virus Type III Envelope Glycoprotein gp120
and the Surface Antigen CD4: Role of Carbohydrate in Binding
and Cell Fusion. Proc. Natl. Sci. U.S.A. 1987, 84, 5424-5428.
(
8
RPR103611 (12), were reported as anti-HIV agents.
They were shown to inhibit HIV-induced membrane
J M950922Q