Diarylpyrimidine-dihydrobenzyloxopyrimidine hybrids: New, wide-spectrum anti-HIV-1 agents active at (Sub)-nanomolar level

Article abstract of DOI:10.1021/jm101626c

Here, we describe a novel small series of non-nucleoside reverse transcriptase inhibitors (NNRTIs) that combine peculiar structural features of diarylpyrimidines (DAPYs) and dihydro-alkoxy-benzyl-oxopyrimidines (DABOs). These DAPY-DABO hybrids (1-4) showe

Full text of DOI:10.1021/jm101626c

BRIEF ARTICLE
pubs.acs.org/jmc
DiarylpyrimidineꢀDihydrobenzyloxopyrimidine Hybrids: New,
Wide-Spectrum Anti-HIV-1 Agents Active at (Sub)-Nanomolar Level
Dante Rotili,† Domenico Tarantino,† Marino Artico,† Maxim B. Nawrozkij,‡ Emmanuel Gonzalez-Ortega,§
Bonaventura Clotet,§ Alberta Samuele,|| Josꢀe A. Estꢀe,*,§ Giovanni Maga,*,|| and Antonello Mai*,†
†Istituto Pasteur—Fondazione Cenci Bolognetti, Dipartimento di Chimica e Tecnologie del Farmaco, Universitꢁa degli Studi di Roma
“La Sapienza”, P.le A. Moro 5, 00185 Roma, Italy
‡Volgograd State Technical University, prospekt Lenina, 28, 400131 Volgograd, Russia
§Retrovirology Laboratory IrsiCaixa, Hospital Universitari Germans Trias i Pujol, Universitat Autꢁonoma de Barcelona,
08916 Badalona, Spain
Istituto di Genetica Molecolare IGM—CNR, via Abbiategrasso 207, 27100 Pavia, Italy
S Supporting Information
b
ABSTRACT: Here, we describe a novel small series of non-
nucleoside reverse transcriptase inhibitors (NNRTIs) that com-
bine peculiar structural features of diarylpyrimidines (DAPYs)
and dihydro-alkoxy-benzyl-oxopyrimidines (DABOs). These
DAPYꢀDABO hybrids (1ꢀ4) showed a characteristic SAR
profile and a nanomolar anti-HIV-1 activity at both enzymatic
and cellular level. In particular, the two compounds 4d and 2d,
with a (sub)nanomolar activity against wild-type and clinically
relevant HIV-1 mutant strains, were selected as lead compounds
for next optimization studies.
’ INTRODUCTION
of anti-AIDS drugs induces the selection of drug-resistant viral
mutants and the emergence of undesired metabolic side effects.
Moreover and unfortunately, when individuals develop resistance
to one antiretroviral agent within a class there is often, but not
always, development of cross-resistance to other agents of the
same class.
Despite their chemical diversity, NNRTIs bind to a common
allosteric site of HIV-1 reverse transcriptase (RT) and noncom-
petitively inhibit DNA polymerization. NNRTIs currently used
in HAART include nevirapine, delavirdine, efavirenz, and etra-
virine (TMC125), which has been approved by FDA on January
2008.10,11
Since 1992, our research group has been working to develop
effective anti-HIV drugs and our efforts have resulted in the
discovery of the dihydro-alkyloxy-benzyl-oxopyrimidine (DABO)
family of NNRTIs.12 Since the first DABO derivatives, many
structural modifications have been introduced in order to obtain
more potent and selective compounds, which led to the discovery
of some series of excellent DABO compounds such as F2-S-
DABOs13ꢀ16 and F2-N,N-DABOs17ꢀ21 (Chart 1) that are
The worldwide spread of AIDS (acquired immunodeficiency
syndrome), an epidemic disease in continuous development, has
required and still requires potent antiretroviral chemotherapeutic
agents for reducing the number of deaths caused by HIV-1
(human immunodeficiency virus type 1), the etiological agent of
AIDS. Global estimates of WHO/UNAIDS showed 33.4 million
people infected with HIV/AIDS at the end of 2008, with 2.7
million newly infected and 2.0 million deaths.1
The current therapy against AIDS is based on seven classes of
anti-HIV drugs: the nucleoside and nucleotide reverse transcrip-
tase inhibitors (indicated as NRTIs and NtRTIs, respectively),2,3
the non-nucleoside reverse transcriptase inhibitors (NNRTIs),4
the protease inhibitors (PIs),5 the integrase inhibitor (INI)
raltegravir,6 the chemokine (CꢀC motif) receptor 5 (CCR5)
inhibitor maraviroc,7,8 and the fusion inhibitor (FI) enfuvirtide.7,8
NRTIs, NtRTIs, NNRTIs, and PIs are actually mixed in the highly
active antiretroviral therapy (HAART), which dramatically re-
duces the incidence of AIDS infection and death. Despite the fact
that HAART combination regimens have significantly decreased
the morbidity and mortality among patients with HIV infections,
slowing the viral replication to very low levels, they are still unable
to eradicate the virus.9 So, the needed long-term or permanent use
Received: December 22, 2010
Published: March 25, 2011
r
2011 American Chemical Society
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|

Journal of Medicinal Chemistry
BRIEF ARTICLE
Chart 1. Chemical Structures of Selected DAPY and DABO
Derivatives
Scheme 1a
a (i) EtONa, dry EtOH, reflux; (ii) POCl3/DMF, dry DMF, rt; (iii) zinc
dust, 33% NH4OH, THF-dioxane, reflux; (iv) 7 N methanolic ammonia,
dry THF, 120 °C, Parr high pressure reactor.
Chart 2. Design of DAPYꢀDABO Hybrid Compounds
’ CHEMISTRY
Condensation of the β-oxoesters 5aꢀd, prepared as reported
previously,14 with the 1-(4-cyanophenyl)guanidine nitrate26 in
the presence of sodium ethoxide in dry ethanol under reflux
conditions, afforded the 2-(4-cyanoanilino)-pyrimidin-4(3H)-
ones 1aꢀd. Further Vilsmeier reaction with phosphorus oxy-
chloride and N,N-dimethylformamide at room temperature in
dry N,N-dimethylformamide performed on 1aꢀd yielded their
4-choropyrimidine analogues 2aꢀd. The 4-unsubstituted-
(3aꢀd) and the 4-aminopyrimidine (4aꢀd) derivatives were
synthesized from the appropriate 2aꢀd by reductive dehalogena-
tion with zinc dust in a mixture of THFꢀdioxane in the presence
of ammonium hydroxide under reflux conditions and by nucleo-
philic substitution with methanolic ammonia in a Parr high
pressure reactor, respectively (Scheme 1).
endowed with inhibitory potencies in the low nanomolar or
subnanomolar range without a significant cytotoxicity at high
concentrations.
’ RESULTS AND DISCUSSION
Diarylpyrimidine (DAPY) derivatives are one of the most
successful family of NNRTIs developed so far, as confirmed by
the recent approval of etravirine for the clinical use.10 The
innate flexibility between their characteristic two aromatic
rings allows these compounds to adopt multiple conforma-
tions within the RT non-nucleosidic binding site, explaining
their potent activity against many clinically relevant resistant
viral mutant strains. SAR studies on the DAPY series had also
found that the para-cyanoaniline substitution at the C-2
pyrimidine ring position is crucial for a significant inhibitory
activity (Chart 1).22ꢀ25
To obtain NNRTIs highly active against wild type and
mutant HIV-1 strains, we prepared four brief series of com-
pounds (1ꢀ4) characterized by the para-cyanoaniline group
typical of DAPYs at the C-2 of the pyrimidine ring and the 2,6-
difluorobenzyl group peculiar of DABOs at the C-6 position.
These series differed each other for the groups at the C-4
pyrimidine ring position which were characteristic either
of DABOs (ꢀOH, 1aꢀd) or of DAPYs (ꢀCl, 2aꢀd; ꢀH,
3aꢀd; ꢀNH2, 4aꢀd). We also studied the effects of the
methyl substitution at the C-5 pyrimidine position and at
the methylene group of the benzylic moiety in C-6 of these
arylamino benzyl pyrimidines that can be considered a sort of
DAPY-DABO hybrid compounds (Chart 2).
The DAPYꢀDABO hybrid compounds 1ꢀ4 were tested in
MT-4 cells to evaluate their cytotoxicity and their capability to
inhibit the HIV-induced cytopathic effect (HIV-1 strain: NL4-3)
by 50%. The compounds were also tested against a panel of
clinically relevant HIV-1 mutant strains (K103N, Y181C, and
Y188L). Nevirapine (NVP), efavirenz (EFV), dapivirine
(TMC120), and MC1220 (the F2-N,N-DABO prototype) were
also tested as reference drugs (Table 1).
The highest inhibitory activity (EC50, concentration
needed to inhibit the HIV-induced cytopathic effect by
50%) against wild type HIV-1 was displayed by the com-
pounds with a free amino group (ꢀNH2) at the C-4 position
of the pyrimidine ring (4aꢀd, values ranging from 0.2 to 0.6
nM), apart from their methyl substitution at the C-5 and/or
C-6 benzylic positions. All of them were more than 10-fold
more potent than efavirenz, and showed against wild type
HIV-1 a potency greater than or comparable to TMC120 and
MC1220, the DAPY and DABO prototypes, respectively. In
addition, 4aꢀd showed CC50 (compound concentration toxic
for 50% cells) values >10- and 2.5-fold higher than TMC120
and MC1220, respectively, exhibiting in such a way up to 45-
fold higher selectivity indexes (SI, CC50/EC50). Similar sub-
nanomolar WT HIV-1 inhibiting activity was displayed by the
pyrimidine C-4 unsubstituted 3a,c,d (3b was about 6 times
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Journal of Medicinal Chemistry
BRIEF ARTICLE
Table 1. Cytotoxicity and Anti-HIV-1 Activity of 1ꢀ4 against WT (NL4-3) and Clinically Relevant HIV-1 Mutant Strainsa
EC50,b nM (fold resistance)c
compd
1a
X
R
R1
NL4-3
K103N
Y181C
Y188L
>2 500
CC50,d nM
SIe
>7.3
OH
OH
OH
OH
Cl
H
H
344
244.1
9.1
290 (0.8)
1 391 (6)
56.8 (6)
344 (1)
>2 500
>2 838
>2 838
1 064
1b
Me
H
H
>2 838
>2 838
>11.6
1c
Me
Me
H
88 (10)
652.8 (72)
230.4 (79)
1 401 (105)
>2 697
>311.9
1d
Me
H
2.9
61.14 (21)
171 (13)
739 (23)
51.24 (34)
2.3 (1)
45.58 (16)
561 (42)
2 535 (80)
153.7 (102)
44 (22)
366.9
2a
13.4
21.6
1.5
>2 803
>2 697
>2 697
>13 000
>77 564
>74 330
37 492
71 354
44 585.9
45 936.7
46 079
40 505.9
3 035.8
>17 000
7 510
>209.2
2b
Cl
Me
H
H
>124.9
2c
Cl
Me
Me
H
836.1 (557)
60 (30)
>1 798
>5 652.2
>155 128
>22 524.3
74 984
2d
Cl
Me
H
2.3
3a
H
0.5
68.2 (136)
88.3 (27)
27.3 (55)
51.9 (86)
14.2 (47)
8.2 (41)
60.2 (120)
357.7 (108)
44.3 (89)
42.5 (71)
71.4 (238)
70.3 (352)
44.7 (149)
39.9 (66)
1.2 (2)
224.9 (450)
1 016.8 (308)
100.2 (200)
31.4 (52)
108.2 (361)
151.1 (756)
66.6 (222)
27.4 (46)
333.9 (556)
50 (167)
3b
H
Me
H
H
3.3
3c
H
Me
Me
H
0.5
3d
H
Me
H
0.6
118 923.3
148 619.7
229 683.5
153 596.7
67 509.8
5 059.7
>56 667
57.15
4a
NH2
NH2
NH2
NH2
0.3
4b
Me
H
H
0.2
4c
Me
Me
0.3
8.2 (27)
4d
Me
0.6
34.7 (58)
1.2 (2)
TMC120
MC1220
NVP
EFV
0.6
0.3
50 (167)
6 121 (47)
343.4 (327)
14 (47)
131.4
>7 510
>7 510
7.3
10.1 (1.4)
1 615 (221)
3 167.8
433.9
a Values are means determined from at least two experiments. b Effective concentration 50, concentration needed to inhibit 50% HIV-induced strain.
c Fold change of the corresponding EC50 and the EC50 value of the WT NL4-3 strain. d Cytotoxic concentration 50, concentration to induce 50% death of
noninfected cells, evaluated with the MTT method in MT-4 cells. e Selectivity index, CC50/EC50(NL4-3).
Table 2. Cytotoxicity and Anti-HIV-1 Activity of Selected
Compounds 2d and 4d against WT HIV-1 (NL4-3) and
Multidrug Resistant (MDR) HIV-1 Strain IRLL98 Bearing
K101Q, Y181C, and G190A Mutationsa
less potent), also in these cases joined to very low cytotoxicity
and high SI. The C-4 chloro- and hydroxy-substituted com-
pounds were still active in the single digit nanomolar range
against the wild type HIV-1 when substituted with a methyl
group in the C-6 benzylic position (2c,d and 1c,d), while
showing a decrease of potency in its absence.
EC50,b nM (fold resistance)c
The C-4 chlorosubstituted 2d showed very promising single
digit nanomolar inhibiting activity against the K103N mutant
strain [EC50K103N (nM)/fold resistance: 2.3/1], which was >170-
and 22-fold higher than efavirenz and MC1220, respectively, and
comparable to TMC120. For this activity, it seems important the
presence of two methyl groups both at the C-5 and at the C-6
benzylic positions of the pyrimidine ring. In fact, the removal of
one or both of these groups is responsible of a decrease of
inhibition against this mutant. Also, the C-4 aminosubstituted
4aꢀd showed K103N mutant inhibiting activity in the low
nanomolar range (with the exception of 4d), while the unsub-
stituted (3aꢀd) and the hydroxysubstituted (1aꢀd) derivatives
inhibited the K103N mutantathigh nanomolar orlow micromolar
(1b) level.
compd
2d
NL4-3
IRLL98
7.8 (3)
CC50,d nM
2.6
0.08
0.03
3.41
226.1
3.17
>13 000
>13 700
1 821.5
>17 000
>18 850
3 167.8
4d
0.82 (10)
TMC120
MC1220
NVP
0.3 (10)
204.6 (60)
>18 850 (>83)
633.5 (200)
EFV
a Values are means determined from at least two experiments. b Effective
concentration 50, concentration needed to inhibit 50% HIV-induced
strains. c Fold change of the corresponding EC50 and the EC50 value of
the WT NL4-3 strain. d Cytotoxic concentration 50, concentration to
induce 50% death of noninfected cells, evaluated with the MTT method
in MT-4 cells.
Among the tested derivatives, the C-4 unsubstituted 3d and
the C-4 amino analogue 4d, containing two methyl groups at
both the C-5 and C-6 benzylic positions of the pyrimidine ring,
were the most efficient agents against the Y181C and Y188L
HIV-1 mutants. Indeed, they displayed nanomolar inhibitory
potencies against the two HIV-1 variants, and when compared to
TMC120 and MC1220, they were less potent against the Y181C
and more effective against the Y188L mutant strain. The order of
potency of the four different series (1ꢀ4) against the Y181C and
Y188L mutants resembled the activity against the wild type HIV-
1: C4ꢀNH2 > ꢀH > ꢀCl > ꢀOH.
Selected 4-chloro- and 4-amino hybrids 2d and 4d were then
tested against the HIV-1 IRLL98 strain, bearing the K101Q, Y181C,
and G190A mutations and being resistant to NVP, EFV, and
delavirdine. TMC120, MC1220, NVP, and EFV were also tested
as reference drugs (Table 2). In this assay, 2d displayed nanomolar
activity against both WT and IRLL98 strains, with only 3-fold lower
activity against the triple, multidrug resistant mutant, while 4d was
potent at subnanomolar level against the two tested strains, showing
similar potency and fold-resistance as TMC120. Both 2d and 4d
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Journal of Medicinal Chemistry
BRIEF ARTICLE
Table 3. Inhibitory Activity of 1ꢀ4 against HIV-1 RT Wild Type and NNRTI-Resistant Mutantsa
ID50,b nM (fold resistance)c
compd
1a
X
R
R1
WT
K103N
Y181I
Y188L
L100I
OH
OH
OH
OH
Cl
H
H
0.8
200
28
0.4
59
17
12
8.8
6
2 600 (3 250)
21 440 (107)
347 (12)
125 (312)
4 365 (74)
445 (26)
286 (24)
71 (8.1)
56 000 (70 000)
>80 000
1 238 (1 547)
>80 000
1 600 (2 000)
NDd
1b
Me
H
H
1c
Me
Me
H
12 260 (438)
1 400 (3 500)
>80 000
4 171 (149)
69 (172)
ND
1d
Me
H
1 000 (2 500)
ND
2a
>80 000
2b
Cl
Me
H
H
>40 000
6 300 (371)
2 847 (237)
23 (2.6)
ND
2c
Cl
Me
Me
H
28 550 (2 379)
3 400 (386)
7 474 (1 246)
>80 000
ND
2d
Cl
Me
H
150 (17)
671 (112)
2 957 (329)
664 (74)
128 (19)
1 509 (137)
603 (55)
765 (69)
282 (20)
90 (13)
1 000 (10)
9 000 (17)
ND
3a
H
500 (83)
262 (29)
248 (28)
154 (22)
169 (15)
90 (8)
1 836 (306)
>80 000
3b
H
Me
H
H
9
3c
H
Me
Me
H
9
5 906 (656)
5 000 (725)
17 260 (1 569)
22 070 (2 006)
11 080 (1 007)
1 683 (120)
>1 000 (>143)
4 000 (40)
766 (85)
3d
H
Me
H
6.9
11
11
11
14
7
294 (43)
4a
NH2
NH2
NH2
NH2
3 079 (280)
3 462 (315)
1 623 (147)
146 (10)
4b
Me
H
H
4c
Me
Me
109 (10)
22 (1.6)
4d
Me
TMC120
MC1220
NVP
EFV
100 (14)
500 (5)
380 (54)
100
400
30
500 (5)
7 000 (17)
35 000 (87)
18 000 (45)
3 000 (100)
80 (3)
ND
a Values are means determined from at least three experiments. b Inhibitory dose 50, compound dose required to inhibit the HIV-1 rRT. c Fold change of
the corresponding EC50 and the EC50 value of the WT HIV-1 NL4-3 strain. d ND, not determined.
were much more efficient than MC1220 and than, as expected,
NVP and EFV in inhibiting the HIV-1 IRLL98 strain.
The DAPYꢀDABO hybrid derivatives 1ꢀ4 were also tested
against recombinant WT HIV-1 RT as well as against a panel of
recombinant RTs carrying known NNRTI-resistance mutations
(K103N, Y181I, Y188L, and L100I) (Table 3).
In conclusion, in the present paper, we report a novel series of
DAPYꢀDABO hybrids (1ꢀ4) endowed with high, wide-spec-
trum anti-HIV-1 activity both in cellular and enzyme assays. The
new compounds have been obtained by combination of peculiar
chemical features of the two well-known families of pyrimidine-
containing NNRTIs (DAPYs and DABOs) and showed a
distinct, characteristic structureꢀactivity relationship (SAR)
profile. Among these highly potent compounds, all the deriva-
tives carrying the double pyrimidine C-5/C-6 benzylic position
methyl substitution (1d, 2d, 3d, and 4d) displayed the highest
inhibitory activity both in cell and enzyme assays, exhibiting an
inhibition profile in general better than that of TMC120 and
MC1220, the two DAPY and DABO prototypes. Among them,
the pyrimidine C-4 choro- (2d) and C-4 amino (4d) derivatives
showing efficient inhibition at (sub)nanomolar level against the
tested WT/mutant HIV-1 strains and the WT/mutated HIV-1
RTs were selected as lead compounds for next optimization
studies.
In this assay, the majority of the tested derivatives (1a, 1d,
2bꢀd, 3aꢀd, and 4aꢀd) showed ID50 (inhibitory dose 50,
compound dose required to inhibit the HIV-1 rRT activity by
50%) values at low nanomolar level against WT RT, in some
cases also reaching subnanomolar concentration (1a and 1d).
As a rule, the substitution pattern of the hybrids at the C-4
(ꢀOH, ꢀCl, ꢀH, or ꢀNH2), C-5 (ꢀH or ꢀCH3), and C-6
benzylic (ꢀH or ꢀCH3) positions of the pyrimidine ring played
only modulatory effects on the WT RT inhibiting activity of the
derivatives. Nevertheless, in all the 1ꢀ4 series, the double methyl
substitution at both C-5/C-6 benzylic position was crucial in
terms of potency against the mutated HIV-1 RTs. Indeed,
compounds 1d, 2d, 3d, and 4d displayed the highest inhibitory
activity (within the corresponding series) against the K103N,
Y181I, Y188L, and L100I mutated RTs, with a low fold resistance
respect to WT RT. In particular, the C-4 chloro- (2d) and the
C-4 amino- (4d) derivatives were more efficient than TMC120
against the K103N RT, while the C-4 hydroxy- (1d) and the C-4
unsubstituted (3d) compounds were less effective. All the four
pyrimidines (1d, 2d, 3d, and 4d) displayed higher activity than
TMC120 against the Y181I RT, while they were less potent
against the L100I RT. Finally, 1d, 2d, 3d, and 4d inhibited all the
mutated RTs up to 23-fold tighter than MC1220, with 2d and 4d
being again the most effective in the comparison (for example,
they were 22 (2d) or 23 (4d) times more potent than MC1220 in
inhibiting the Y188L or the K103N RT, respectively).
’ EXPERIMENTAL SECTION
Anti-HIV Activity in Lymphoid Cells. Biological activity of the
compounds was tested in the lymphoid MT-4 cell line (received from
the NIH AIDS Reagent Program) against the wt HIV-1 NL4ꢀ3 strain
and three different HIV-1 strains, as described before.27ꢀ29 Briefly, MT-
4 cells were infected with the appropriate HIV-1 strain (or mock-
infected to determine cytotoxicity) in the presence of different drug
concentrations. At day five postinfection, a tetrazolium-based colori-
metric method (MTT method) was used to evaluate the number of
viable cells. The HIV-1 K103N, Y181C, or Y188L mutant were received
from the Medical Research Council Centralised Facility for AIDS
Reagents, Herfordshire, UK.
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Journal of Medicinal Chemistry
BRIEF ARTICLE
Anti-HIV Reverse Transcriptase Assays. RNA-dependent
DNA polymerase activity was assayed as described30 in the presence
of 0.5 μg of poly(rA)/oligo(dT)10:1 (0.3 μM 30-OH ends), 10 μM [3H]-
dTTP (1 Ci/mmol) and 2ꢀ4 nM RT in the presence of 8% final
concentration of DMSO.
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’ ASSOCIATED CONTENT
S
Supporting Information. Chemical and physical data of
b
compounds 1ꢀ4. Experimental chemical procedures. Elemental
analyses of compounds 1ꢀ4. 1H NMR data for compounds 1ꢀ4.
This material is available free of charge via the Internet at http://
pubs.acs.org.
’ AUTHOR INFORMATION
Corresponding Author
(14) Mai, A.; Sbardella, G.; Artico, M.; Ragno, R.; Massa, S.;
Novellino, E.; Greco, G.; Lavecchia, A.; Musiu, C.; La Colla, M.;
Murgioni, C.; La Colla, P.; Loddo, R. Structure-Based Design, Synthesis,
and Biological Evaluation of Conformationally Restricted Novel 2-Al-
kylthio-6-[1-(2,6-difluorophenyl)alkyl]-3,4-dihydro-5-alkylpyrimidin-
4(3H)-ones as Non-nucleoside Inhibitors of HIV-1 Reverse Transcrip-
tase. J. Med. Chem. 2001, 44, 2544–2554.
*For J.A.E.: phone, þ34-934656374; fax, þ34-934653968; E-mail,
iaeste@irsicaixa.es. For G.M.: phone, þ39 0382 546354; fax, þ39
0382 422286; E-mail, maga@igm.cnr.it. For A.M.: phone, þ39 06
49913392; fax, þ39 06 49693268; E-mail, antonello.mai@
uniroma1.it.
(15) Mugnaini, C.; Alongi, M.; Togninelli, A.; Gevarija, H.; Brizzi,
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F.; Massa, S.; Maga, G.; Samuele, A.; Facchini, M.; Clotet-Codina, I.;
Armand-Ugꢀon, M.; Estꢀe, J. A.; Botta, M. Dihydro-alkylthio-benzyl-
oxopyrimidines as Inhibitors of Reverse Transcriptase: Synthesis and
Rationalization of the Biological Data on Both Wild-Type Enzyme and
Relevant Clinical Mutants. J. Med. Chem. 2007, 50, 6580–6505and
references therein cited..
’ ACKNOWLEDGMENT
This work was partially supported by grants from the Spanish
Ministry of Science (projects BFU2009-06958 and SAF2010-
21617-C02-00) and by the Italian National AIDS Program ISS
Grant 40H26.
(16) Nawrozkij, M. B.; Rotili, D.; Tarantino, D.; Botta, G.;
EremiychukA. S.; Musmuca, I.; Ragno, R.; Samuele, A.; Zanoli, S.;
Armand-Ugꢀon, M.; Clotet-Codina, I.; Novakov, I. A.; Orlinson, B. S.;
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phenylethylsulfanyl)pyrimidin-4(3H)-ones, a Series of Anti-HIV-1 Agents
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tureꢀActivity Relationship Profile. J. Med. Chem. 2008, 51, 4641–4652.
(17) Ragno, R.; Mai, A.; Sbardella, S.; Artico, M.; Massa, S.;
Musiu, C.; Mura, M.; Marceddu, T.; Cadeddu, A.; La Colla, P.
Computer-aided design, synthesis, and anti-HIV-1 activity in
vitro of 2-alkylamino-6-[1-(2,6-difluorophenyl)alkyl]-3,4-dihydro-
5-alkylpyrimidin-4(3H)-ones as novel potent non-nucleoside reverse
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’ ABBREVIATIONS USED
AIDS, acquired immunodeficiency syndrome; DABOs, dihydro-
alkoxy-benzyl-oxopyrimidines; DAPYs, diarylpyrimidines; EFV, ,
efavirenz; F2-N,N-DABOs, 5-alkyl-2-(N,N-disubstituted)amino-
6-(2,6-difluorophenylalkyl)pyrimidin-4(3H)ones; HIV, human
immunodeficiency virus; MTT, 3-(4,5-dimethylthiazol-2-yl)-
2,5-diphenyltetrazolium bromide; NH-DABOs, dihydro-alkyl-
amino-benzyl-oxopyrimidines; NNRTIs, non-nucleoside reverse
transcriptase inhibitors; NVP, nevirapine; RT, reverse transcrip-
tase; SAR, structureꢀactivity relationship; S-DABOs, dihydro-
alkylthio-benzyl-oxopyrimidines; WT, wild type
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Journal of Medicinal Chemistry
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