Synthesis and biological evaluation of α-aryl-α-tetralone derivatives as hepatitis C virus inhibitors

Article abstract of DOI:10.1016/j.ejmech.2015.01.057

The synthesis of a novel series of 1-carba-isoflavanones through the α-arylation of α-tetralones is described. Several of these compounds demonstrated potent activity and selectivity in-vitro against HCV replicon reporter cells. Compound 10 (LQB-314) exhibited the best profile being active and selective in both replicon reporter cells (IC₅₀ 1.8 μM, SI > 111 and IC₅₀ 4.3 μM, SI > 46 in Huh7/Rep-Feo1b and Huh7.5-FGR-JC1-Rluc2A, respectively). Compound 3 (LQB-307) was the more potent and selective for Huh7.5-FGR-JC1-Rluc2A replicon reporter cells (IC₅₀ 1.5 μM, SI > 101.4).

Full text of DOI:10.1016/j.ejmech.2015.01.057

European Journal of Medicinal Chemistry 93 (2015) 51e54
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Short communication
Synthesis and biological evaluation of
hepatitis C virus inhibitors
a-aryl-a-tetralone derivatives as
Dinesh Manvar a, Talita de A. Fernandes b, Jorge L.O. Domingos c,
,
*
Erdenechimeg Baljinnyam a, Amartya Basu a, Eurides F.T. Junior b, Paulo R.R. Costa b
,
,
*
Neerja Kaushik-Basu a
a Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers-The State University of New Jersey, New Jersey Medical School,
185 South Orange Avenue, New Jersey 07103, USA
b
ꢀ
^
^
Laboratorio de Química Bioorganica, Instituto de Pesquisas de Produtos Naturais, Universidade Federal do Rio de Janeiro, Centro de Ciencias da Saúde,
ꢀ
Bloco H, Ilha da Cidade Universitaria, 21941-590 Rio de Janeiro, RJ, Brazil
c
^
^
~
Departamento de Química Organica, Centro de Tecnologia e Ciencias, Universidade do Estado do Rio de Janeiro, Rua Sao Francisco Xavier 524,
~
Pav. Haroldo Lisboa da Cunha e s 406 e Maracana, 20550-900 Rio de Janeiro, RJ, Brazil
a r t i c l e i n f o
a b s t r a c t
Article history:
The synthesis of a novel series of 1-carba-isoflavanones through the
described. Several of these compounds demonstrated potent activity and selectivity in-vitro against HCV
replicon reporter cells. Compound 10 (LQB-314) exhibited the best profile being active and selective in
a-arylation of a-tetralones is
Received 8 November 2014
Received in revised form
25 January 2015
Accepted 27 January 2015
Available online 28 January 2015
both replicon reporter cells (IC50 1.8
FGR-JC1-Rluc2A, respectively). Compound 3 (LQB-307) was the more potent and selective for Huh7.5-
FGR-JC1-Rluc2A replicon reporter cells (IC50 1.5 M, SI > 101.4).
© 2015 Published by Elsevier Masson SAS.
mM, SI > 111 and IC50 4.3 mM, SI > 46 in Huh7/Rep-Feo1b and Huh7.5-
m
Keywords:
Alpha-aryl-alpha-tetralones
Palladium catalyzed arylation
Microwave irradiation
Hepatitis C virus inhibitors
1. Introduction
addition to lack of SVR, treatment with interferon is associated with
numerous side effects. Nowadays, approved anti-HCV therapies
utilize direct acting antivirals (DAAs) targeting viral proteins such
as HCV NS3-4A protease inhibitors and an NS5B viral polymerase
inhibitor [13e16]. The current therapy is much more effective in
producing a SVR. However, to treat most HCV genotypes DAAs must
Hepatitis C Virus (HCV) belongs to the Flaviviridae family of vi-
ruses and was identified as the causative agent of non-A, non-B
hepatitis [1,2], infecting approximately 3% of the world population
[3,4]. During chronic HCV infections, the virus induces numerous
changes within the host, which increases the risk of developing
more serious conditions such as cirrhosis, steatosis, and hepatoma
cellular carcinoma [3,5e9]. Until recently, HCV was treated with a
combination of pegylated-interferon (PEG-IFN
side analog ribavirin [10e12]. This therapy had limited effective-
ness in maintaining sustained virological response (SVR),
be administered in combination with PEG-IFNa and ribavirin [16].
Therefore, IFN-related side effects remain and the complicated
dosing regimens of current treatment may further limit patient
compliance [13e16]. Further, selection of HCV drug resistant vari-
ants remains a major concern associated with current anti-HCV
therapies [17,18]. Thus, identification of additional anti-HCV
agents remains a priority.
a) and the nucleo-
a
especially when treating patients infected with HCV genotype 1. In
In this letter we report, for the first time, the anti-HCV activity of
a-aryl-a-tetralones (1-carba-isoflavanones). These compounds
(Fig. 1) are isosters of isoflavanones, a group of naturally occurring
isoflavonoids and synthetic derivatives which comprise com-
pounds bearing antineoplasic and antiviral properties [19e22].
* Corresponding authors.
E-mail addresses: prrcosta2011@gmail.com (P.R.R. Costa), kaushik@njms.
rutgers.edu (N. Kaushik-Basu).
http://dx.doi.org/10.1016/j.ejmech.2015.01.057
0223-5234/© 2015 Published by Elsevier Masson SAS.

52
D. Manvar et al. / European Journal of Medicinal Chemistry 93 (2015) 51e54
a-arylation of a-tetralones 16 with 17a and 17b was accomplished
under the same reaction conditions [26], leading to 18a and 18b in
good yields. We tried to remove the MOM-protecting group in 18a
in acidic medium, but a complex mixture of products was obtained.
We also tried the hydrogenolysis of the benzyl group in 18b with H2
and Pd/C, but a complex mixture of products was also observed,
due to the partial reduction of the carbonyl group and the hydro-
genolysis of the resulting alcohol. However, 13 (LQB-393) could be
prepared from 18b by hydrogenolysis using Pd/C in the presence of
ammonium formate, in acetoneemethanol at 50 ꢀC. Interestingly,
compounds 14 (LQB-394) and 15 (LQB-395), bearing a phenol
Fig. 1. Isoflavanones and 1-carba-isoflavanones.
2. Results
group at the A-ring, were obtained by a-arylation of a-tetralone 19
with bromoarenes 17c and 17b, respectively, without protection of
the phenol group (Scheme 1).
2.1. Synthesis of a-aryl-a-tetralones
The structures of 1-carba-isoflavanones studied in this work are
shown in Fig. 2 and can be divided in three groups. In the first, the
A-ring is unsubstituted (LQB-305, LQB-306); in the second, both A-
and C-rings are substituted by methoxy groups (LQB-307 to LQB-
316), while in the third, a hydroxy group is present in one of the
aromatic rings (LQB-393 to LQB-395).
2.2. Screening of the antiviral activity
The antiviral activity of the target a-aryl-a-tetralones shown in
Fig. 1 was investigated in Huh7/Rep-Feo1b and Huh7.5-FGR-JC1-
Rluc2A replicon reporter cells, bearing the autonomously repli-
cating HCV RNA of genotype 1b and 2a in the firefly and Renilla
luciferase reporters, respectively, as described previously (Table 1)
[29e31]. The levels of luciferase activities in these reporter systems,
thus serves as a measure of HCV RNA replication. The effect of the
compounds on cellular toxicity was determined in non-infected
Huh7.5 parental cells (Table 1) [27].
The concomitant development of metal-catalyzed
enolizable compounds with haloarenes, by Buchwald, Myura and
Hartwig, made the -aryl- -tetralones readily accessible by syn-
a-arylation of
a
a
thesis [23e25]. Compounds 1 (LQB-305) to 12 (LQB-316) were
synthesized in reasonable to excellent chemical yields as previously
described, by palladium catalyzed
methoxylated derivatives with o-bromoarenes [26].
The removal of the methoxy groups in these -aryl-
a
-arylation of
a
-tetralone and
For non-phenolic compounds (1e12) their potency was found to
be strongly dependent on the pattern of substitution at both aro-
matic rings and the HCV genotype. In context of the Huh7/Rep-
a
a
-tetralones
requires the use of boron tribromide (BBr3) and under these con-
ditions only tetracyclic 5-carba-pterocarpens are obtained [26]. We
Feo1b replicon reporter cells, unsubstituted compounds at the a-
tried to prepare
a
-aryltetralone 13 (LQB-393), bearing a phenol
-arylation of tetralone 1
tetralone moiety 1 and 2 displayed weak activity and poor selective
index (entries 1 and 2). The introduction of a methoxy group at 6-
position as in 3 and 4 resulted in higher antiviral activity (entries 3
and 4). The presence of the methoxy group at 7-position in 5 and 6
(entries 5 and 6) led to products with increased potency when
group at the -aryl moiety, through the
a
a
with o-bromo-arenes in which the oxygen at the o-position is
substituted by more easily removable groups, such as methox-
ymethyl ether (MOM) or Bn groups (17a,b, Scheme 1a) [27,28]. The
Fig. 2.
a-Aryltetralones synthesized and studied in this work.

D. Manvar et al. / European Journal of Medicinal Chemistry 93 (2015) 51e54
53
compared to unsubstituted derivatives at the
a-aryl-tetralone
moiety (entries 1 and 2), but less potent than 5-methoxy de-
rivatives 3 and 4 (entries 3 and 4). The presence of methoxy group
at 5-position in compounds 7 and 8 (entries 7 and 8) also resulted
in products with diminished activity compared to 3 and 4. How-
ever, in all these case low to moderated SI were observed. The
presence of two methoxy groups at the
a-tetralone moiety in 9
decreased the potency (entry 9), but 10, bearing two methoxy
groups at both aromatic rings, was the most potent compound in
this series, showing an excellent SI > 111 (entry 10).
Non-phenolic compounds (1e12) were, in general, more potent
on Huh7.5-FGR-JC1-Rluc2A replicon reporter cells. For example, 5
and 6 were 4e5-fold more potent when compared to their activity
on Huh7/Rep-Feo1b replicon reporter cells (entries 1 and 2). Except
for 6 (entry 6) and 12 (entry 12), the activity increased by the
addition of methoxy groups at the A-ring, while the introduction of
a second methoxy group at the C ring led to a decrease in their
activity, except for 8 (entry 8). The more interesting compound was
3 (EC50 1.5 mM, SI 101.4).
Furthermore, the presence of hydroxy groups at the aromatic
rings, as in 13, 14 and 15 showed to be detrimental for compound
potency on Huh7/Rep-Feo1b replicon reporter cells (entries
13e15). However, these compounds present a higher potency on
Huh7.5-FGR-JC1-Rluc2A replicon reporter cells, but low SI.
3. Conclusions
In conclusion, this letter describes the synthesis and anti-HCV
activity evaluations of
which are amenable for further structural optimization. Overall, 4
compounds displayed EC50 values ꢁ8 M against HCV genotype 1b
while 7 compounds exhibited EC50 values below 5 M against HCV
a-aryl-a-tetralones (1-carba-isoflavanones),
m
m
genotype 2a. Considering the selective index, 3 (LQB-307) emerged
as the most promising lead against HCV genotype 2a, displaying
Scheme 1. Synthesis of phenolic a-aryltetralones.
EC50 value of 1.5
potent and selective against Huh7/Rep-Feo1b replicon reporter
cells (IC50 1.8 M, SI > 111), was also potent and selective against
Huh7.5-FGR-JC1-Rluc2A replicon reporter cells (IC50 4.3 M,
mM and SI > 101.4. Notably, 10 (LQB-314), the most
m
m
SI > 46). Work is now in progress to evaluate the anti-HCV activity
of other analogs and to study its mechanism of action.
Table 1
Anti-HCV activity of
a
-aryl-
a
-tetralones.
CC50
M)a
Ent
Comp.
(
m
Huh7/Rep-Feo1b
Huh7.5-FGR-JC1-Rluc2A
M, %)b
EC50
SId
Inhibition (50
m
M, %)b
EC50
SId
c
c
Inhibition (50
m
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
117.4 20.1
63.6 7.1
152.2 18.6
<50
111.2 5.7
<50
48.4 9.6
55.6 2.4
86.4 9.0
89.5 0.4
85.4 3.1
95.2 1.4
51.7 4.2
96.5 1.5
60.2 12.7
89.6 4.0
80.6 5.2
73.8 7.6
26.1 9.1
41.2 10.0
99.1 2.3
50.1 3.2
44.3 5.2
10.6 0.7
7.5 0.5
29.5 1.0
14.3 0.9
48.5 3.9
12.8 1.6
42.5 0.9
1.8 0.5
8.0 0.9
8.2 1.2
ND
2.3
1.4
14.3
<6.6
3.7
<3.5
>4.1
8.2
84.4 6.6
83.9 6.2
88.8 1.7
93.4 3.3
91.8 3.6
97.6 0.4
86.6 5.7
99.5 0.3
79.9 6.1
86.8 1.6
88.8 1.5
86.2 4.4
14.3 1.8
11.0 1.9
1.5 0.8
3.3 0.8
3.6 0.9
15.0 1.6
10.8 1.1
3.2 1.8
4.8 0.8
4.3 1.6
6.8 1.1
21.5 2.8
10.8 0.9
ND
8.2
5.7
101.4
<15.3
30.8
<3.3
>18.5
32.6
>200
104.5 12.1
126.2 18.9
>200
>200
<50
111.1 9.2
>200
<50
9
2.9
26.2
10
11
12
13
14
15
>111.1
>24.9
<6.0
ND
>46.1
>29.5
<2.3
10.2
ND
<11.3
86
44 10
98
6
ND
6.21 0.9
ND
<8.0
1
4.4 0.9
a
CC50 values were evaluated in Huh7.5 parental cells by the MTS assay (CellTiter 96® AQueous One Solution Cell Proliferation kit, Promega). Cells treated with equal
amounts of DMSO served as viability control.
b
Compounds were screened at 50 mM concentrations against Huh7.5/Rep-Feo1b and Huh7.5-FGR-JC1-Rluc2Ab replicon reporter cells. Cells treated with equal amounts of
DMSO served as control.
c
EC50 values were computed from doseeresponse curves using half-log dilutions of the compounds employing CalcuSyn V2 software.
SI: selectivity index represents the ratio of CC50 to EC50. The data represents an average of three independent experiments.
d

54
D. Manvar et al. / European Journal of Medicinal Chemistry 93 (2015) 51e54
963e966.
Acknowledgments
[14] C. Rice, Perspective: miles to go before we sleep, Nature 474 (2011) S8.
[15] C. Sheridan, New Merck and Vertex drugs raise standard of care in hepatitis C,
Nat. Biotechnol. 29 (2011) 553e554.
[16] C. Sheridan, FDA approvals usher in the post-interferon era in HCV, Nat.
Biotechnol. 32 (2014) 3e5.
We thank Drs. Naoya Sakamoto and Hengli Tang for the Huh7/
Rep-Feo1b and Huh7.5-FGR-JC1-Rluc2A replicon reporter cells.
We are grateful to the Brazilian agencies CAPES, CNPq and FAPERJ
for supporting (PRRC) and Fellowships (TAF, JLOD and EFTJ). We
also acknowledge grant support from the New Jersey Health
Foundation to N.K-B.
[17] D.L. Wyles, Beyond telaprevir and boceprevir: resistance and new agents for
hepatitis C virus infection, Top. Antivir. Med. 20 (2012) 139e145.
ꢀ
[18] N. Palanisamy, A. Danielsson, C. Kokkula, H. Yin, K. Bondeson, L. Wesslen,
A.S. Duberg, J. Lennerstrand, Implications of baseline polymorphisms for po-
tential resistance to NS3 protease inhibitors in hepatitis C virus genotypes 1a,
2b and 3a, Antivir. Res. 99 (2013) 12e17.
Appendix A. Supplementary data
[19] Q.-F. Hu, D.-Y. Niu, B. Zhou, Y.-Q. Ye, G. Du, C.-Y. Meng, X.-M. Gao, Iso-
flavanones from the stem of Cassia siamea and their anti-tobacco mosaic virus
activities, Bull. Korean Chem. Soc. 34 (2013) 3013e3016.
[20] P. Mashava. Isolation of naturally occurring isoflavanone and some clinical
uses thereof. PCT Int. Appl. (1996) WO 9641800 A1 19961227.
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.ejmech.2015.01.057.
[21] M. Luo, X. Liu, Y. Zu, Y. Fu, S. Zhang, L. Yao, T. Efferth, Cajanol, a novel anti-
cancer agent from Pigeonpea [Cajanuscajan (L.) Millsp.] roots, induces
References
ꢀ
apoptosis in human breast cancer cells through a ROS-mediated mitocondrial
pathway, Chem.-Biol. Interact. 188 (2010) 151e160.
[1] Q.L. Choo, G. Kuo, A.J. Weiner, L.R. Overby, D.W. Bradley, M. Houghton,
Isolation of a cDNA clone derived from a blood-borne non-A, non-B viral
hepatitis genome, Science 244 (1989) 359e362.
[2] T.K. Scheel, C.M. Rice, Understanding the hepatitis C virus life cycle paves the
way for highly effective therapies, Nat. Med. 19 (2013) 837e849.
[3] M.J. Alter, Epidemiology of hepatitis C virus infection, World J. Gastroenterol.
13 (2007) 2436e2441.
[4] K. MohdHanafiah, J. Groeger, A.D. Flaxman, S.T. Wiersma, Global epidemiology
of hepatitis C virus infection: new estimates of age-specific antibody to HCV
seroprevalence, Hepatology 57 (2013) 1333e1342.
[22] E. Amato, T. Bankemper, R. Kidney, T. Do, A. Onate, F.S. Thowfeik, E.J. Merino,
S. Paula, L. Ma, Investigation of fluorinated and bifunctionalized 3-
phenylchroman-4-one (isoflavanone) aromatase inhibitors, Bioorg. Med.
Chem. 22 (2014) 126e134.
[23] M. Palucki, S.L. Buchwald, Palladium-catalyzed a-arylation of ketones, J. Am.
Chem. Soc. 119 (1997) 11108e11109.
[24] T. Satoh, Y. Kawamura, M. Miura, M. Nomura, Palladium-catalyzed regiose-
lective mono- and diarylation reactions of 2-phenylphenols and naphthols
with aryl halides, Angew. Chem. Int. Ed. 36 (1997) 1740e1742.
[25] J.F. Hartwig, B.C. Hamann, Palladium-catalyzed direct a-arylation of ketones
[5] M.J. Alter, H.S. Margolis, K. Krawczynski, F.N. Judson, A. Mares, W.J. Alexander,
P.Y. Hu, J.K. Miller, M.A. Gerber, R.E. Sampliner, E.L. Meeks, M.J. Beach, The
natural history of community-acquired hepatitis C in the United States. The
Sentinel Counties Chronic non-A, non-B Hepatitis Study Team, N. Engl. J. Med.
327 (1992) 1899e1905.
[6] M. Houghton, A. Weiner, J. Han, G. Kuo, Q.L. Choo, Molecular biology of the
hepatitis C viruses: implications for diagnosis, development and control of
viral disease, Hepatology 14 (1991) 381e388.
rate acceleration by sterically hindered chelating ligands and reductive
elimination from a transition metal enolate complex, J. Am. Chem. Soc. 119
(1997) 12382e12383.
ꢀ
[26] T. de A. Fernandes, J.L.O. Domingos, L.I.A. da Rocha, S. de Medeiros, C. Najera,
P.R.R. Costa, Synthesis of 5-carbapterocarpens by
a-arylation of tetralones
followed by one-pot demethylation/cyclization with BBr3, Eur. J. Org. Chem.
(2014) 1314e1320.
[27] U. Lüning, F. Fahrenkrug, Synthesis of concave 1,10-phenanthrolines by a
combination of Suzuki coupling, ring closing metathesis and hydrogenation,
Eur. J. Org. Chem. (2004) 3119e3127.
[7] G.M. Lauer, B.D. Walker, Hepatitis C virus infection, N. Engl. J. Med. 345 (2001)
41e52.
[8] I. Saito, T. Miyamura, A. Ohbayashi, H. Harada, T. Katayama, S. Kikuchi,
Y. Watanabe, S. Koi, M. Onji, Y. Ohta, Q.-L. Choo, M. Houghton, G. Kuo, Hep-
atitis C virus infection is associated with the development of hepatocellular
carcinoma, Proc. Natl. Acad. Sci. U. S. A. 87 (1990) 6547e6549.
[9] R. Williams, Global challenges in liver disease, Hepatology 44 (2006)
521e526.
[10] R. Arjal, J.F. Trotter, International normalized ratio of prothrombin time in the
model for end-stage liver disease score: an unreliable measure, Clin. Liver Dis.
13 (2009) 67e71.
[11] J. Ruiz, B. Sangro, J.I. Cuende, O. Beloqui, J.I. Riezu-Boj, J.I. Herrero, J. Prieto,
Hepatitis B and C viral infections in patients with hepatocellular carcinoma,
Hepatology 16 (1992) 637e641.
[12] J.M. Pawlotsky, Therapy of hepatitis C: from empiricism to eradication, Hep-
atology 43 (2006) S207eS220.
[28] R.S. Khupse, P.W. Erhardt, Practical synthesis of Lespedezol A1, J. Nat. Prod. 71
(2) (2008) 275e277.
[29] K. Kim, K.H. Kim, H.Y. Kim, H.K. Cho, N. Sakamoto, J. Cheong, Curcumin in-
hibits hepatitis C virus replication via suppressing the Akt-SREBP-1 pathway,
FEBS Lett. 584 (2010) 707e712.
[30] Y. Sekine-Osajima, N. Sakamoto, M. Nakagawa, Y. Itsui, M. Tasaka,
Y. Nishimura-Sakurai, C.H. Chen, G. Suda, K. Mishima, Y. Onuki, M. Yamamoto,
S. Maekawa, N. Enomoto, T. Kanai, K. Tsuchiya, M. Watanabe, Two flavonoids
extracts from glycyrrhizaeradix inhibit in vitro hepatitis C virus replication,
Hepatol. Res. Off. J. Jpn. Soc. Hepatol. 39 (2009) 60e69.
[31] I. Kucukguzel, G. Satilmis, K.R. Gurukumar, A. Basu, E. Tatar, D.B. Nichols,
T.T. Talele, N. Kaushik-Basu, 2-Heteroarylimino-5-arylidene-4-thiazolidinones
as a new class of non-nucleoside inhibitors of HCV NS5B polymerase, Eur. J.
Med. Chem. 69 (2013) 931e941.
[13] K. Garber, Hepatitis C: move over interferon, Nat. Biotechnol. 29 (2011)