Synthesis and evaluation of novel 1,4-naphthoquinone derivatives as antiviral, antifungal and anticancer agents

Article abstract of DOI:10.1016/j.bmcl.2004.03.047

The synthesis and evaluation of some 2-substituted-1,4-naphthoquinones 2, S-(1,4-naphthoquinon-2-yl)-mercaptoalkanoic acid amides 4, related benzoquinone and naphthoquinone derivatives 6-9 and 2,3-disubstituted 1,4-naphthoquinones 10-11 were carried out.

Full text of DOI:10.1016/j.bmcl.2004.03.047

Bioorganic & Medicinal Chemistry Letters 14 (2004) 2901–2904
Synthesis and evaluation of novel 1,4-naphthoquinone derivatives as
antiviral, antifungal and anticancer agents
Vishnu K. Tandon,a,* Ravindra V. Singhb and Dharmendra B. Yadava
aDepartment of Chemistry, Lucknow University, Lucknow 226007, India
bGEITC, Corporation, Bangalore 37, India
Received 4 February 2004;accepted 12 March 2004
Abstract—The synthesis and evaluation of some 2-substituted-1,4-naphthoquinones 2, S-(1,4-naphthoquinon-2-yl)-mercaptoalka-
noic acid amides 4, related benzoquinone and naphthoquinone derivatives 6–9 and 2,3-disubstituted 1,4-naphthoquinones 10–11
were carried out. The antifungal, antibacterial, antiviral and anticancer activities were determined by using the standard assay. The
results show that compounds 2b and 10a showed in vitro antiviral activity against Inflenza-A Virus and Herpes Simplex Virus and
possess pronounced antifungal profile whereas 4a showed anticancer activites against Lymphoid Leukaemia P 388.
Ó 2004 Elsevier Ltd. All rights reserved.
The 1,4-naphthoquinone structure is common in
numerous natural products associated with antifungal,
active and compared with standard drugs referred to
above and summarized in Table 1. Comparison of
activity of compounds with the antifungal drug Mico-
nazole showed that compound 2b had better activity
against fungi C. albicans and C. neoformans. Compound
10a too showed better antifungal activity against
C. albicans and C. neoformans. Compound 10a had
same activity against T. mentagraphytes when compared
with Miconazole. On comparison of antifungal activity
of compounds referred to in Table 1 with Nystatin, the
antifungal drug, the compound 2b showed better activ-
ity against C. albicans and C. neoformans. Compound
10a also showed better activity when compared with
Nystatin against C. neoformans. On comparison of
antifungal activity of 10a with Amphotericin B, the most
active antifungal drug, it was observed that compound
10a had better antifungal activity against T. mentagra-
phytes and M. cannis. Compounds 2a, 2c, 6, 8c, 9b, 10a
(R2 ¼ OH) and 11c exhibited moderate antifungal
activity. Other compounds whose MIC was >75 lg/mL
are not reported in Table 1 as these were considered
inactive compounds.
antibacterial, antiviral and antitumour activities.1
A
number of 1,4-naphthoquinones having sulfur atom
present in them have been shown to possess antifungal
activity.2–5 1,4-naphthoquinone pharmacophore is
known to impart cytotoxity in a number of drugs, for
example, streptonigrin,6 actinomycins,7 mitomycins,8
alkannins,9 2-hydroxynaphthoquinone derivatives10
and 1,4-furanonaphthoquinones.11 In addition to
imparting antifungal and cytotoxic activity, 1,4-naph-
thoquinones have also exhibited significant antimicro-
bial activity.12
The antifungal, antitumour and antimicrobial profile of
compounds mentioned above prompted us to synthesize
1,4-naphthoquinones 2–11 possessing sulfur atom in
them.
The evaluation of antifungal properties of 2–11 against
various strains of pathogenic fungi, for example,
C. albicans, C. neoformans, T. mentagraphytes, A. fu-
migatus and M. cannis was carried out according to the
method of Dhar et al.13 The antifungal activity was
compared with Miconazole, Nystatin and Amphotericin
B. The compounds having minimum inhibitory con-
centration (MIC) of 50 lg/mL or less were considered
Antibacterial activities of naphthoquinone derivatives
2(a–b), 6, 8c, 10a and 11a were evaluated and the results
are reported in Table 2. Table 2 shows MIC values of
2(a–b), 6, 8c, 10a and 11a against four strains of the
bacteria, S. aureus methicillin resistance, T. tumefaciens,
P. aueruginosa and K. pneumoniae. Gentamycin was
used as a positive control in all the tests and its MIC
value is expressed in lg/mL.
* Corresponding author. Tel.: +91-522-2322283;fax: +91-522-23266-
65;e-mail: vishnutandon@yahoo.co.in
0960-894X/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2004.03.047

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V. K. Tandon et al. / Bioorg. Med. Chem. Lett. 14 (2004) 2901–2904
Table 1. Structure and in vitro antifungal activity for compounds 2, 6, 8 and (9–11)
Compds
n
R
R1
R2
Ar
MIC (lg/mL)
C. albicans C. neoformans
T. mentagraphytes A. fumigatus M. cannis
2a
2b
3
3
2
b
b
b
b
b
b
b
H
H
OH
OH
OH
b
b
>50
3.125
>50
>50
>50
>50
12.5
25
>50
1.56
>50
50
25
3.125
25
>50
>50
>50
>50
>50
>50
25
>50
3.125
>50
>50
>50
>50
<0.98
25
OH
OH
b
OH
CI
b
b
2c
b
6
8c
b
>50
25
OH
OH
H
CI
OH
H
H
b
>50
>50
1.56
>50
>50
>50
12.5
3.5–3.9
0.78
9b
10a
H
b
25
H
Ph
Ph
Ph
Np
<0.78
6.25
>50
50
10a
11c
H
H
OH
b
>50
50
OH
OH
Cl
CI
>50
50
50
11c
b
>50
12.5
a
>50
<0.78
a
Miconazole
Nystatin
Amphotericin-B
25
7.8–7.9
0.39
<0.78
a
1.56
a
1.56
a: Activity not reported;b: not required;Np ¼ naphthyl;Ph ¼ phenyl.
Table 2. Structure and in vitro antibacterial activity for compounds 2, 6, 8, 10 and 11
Compds
n
R
R1
R2
Ar
MIC (lg/mL)
S. aureus
T. tumefaciens
P. aeruginosa
K. pneumoniae
2a
2a
2
3
3
b
b
b
b
H
H
OH
OH
OH
b
b
12.5
12.5
>50
>50
>50
25
25.0
12.5
12.5
>50
>50
>50
>50
a
12.5
50
50
25
H
H
b
2b
OH
b
OH
b
b
>50
25
50
25
6
8c
b
OH
H
Cl
H
H
b
50
25
10a
11a
H
Ph
Np
>50
>50
0.78
>50
>50
0.39
H
H
b
50
Gentamycin
0.78
a: Activity not reported;b: not required;Np ¼ naphthyl;Ph ¼ phenyl.
Compound 2a (n ¼ 2 and 3) showed significant activity
against S. aureus, T. tumefaciens, P. aueruginosa and
K. pneumoniae. Compound 2b showed significant activity
against T. tumefaciens and had no antibacterial activity
against other strains of bacteria tested. The series of 1,4-
naphthoquinones having mercaptobenzoic acid moiety
present in them viz. Compounds 6 and 8c analogues
showed significant activity against P. aueruginosa and K.
pneumoniae and had no antibacterial activity against
other strains of bacteria referred in Table 2. Arylthio
substituted 1,4-naphthoquinones 10a and 11a showed
significant activity against S. aureus only. However the
compounds referred in Table 2 and discussed above were
less active than the standard drug Gentamycin.
Only compounds 2b and 10a showed significant activity
against Influenza-A virus and Herpes Simplex Virus
(HSV-1).
The anticancer activity was carried out against Lym-
phoid Leukaemia P 388 and L 1210. The anticancer
activities of 4a are shown in Table 4. Compound 4a
(n ¼ 2, N<¼ NH2) exhibited marked anticancer activity
having T/C 49% whereas 4a (n ¼ 2, N<¼ piperidino)
exhibited better anticancer activity having T/C 30%.
Compound 2a on evaluation of anticancer activity
against Lymphoid Leukaemia L 1210 was found to be
inactive. The results are shown in Table 5.
The synthesis of S-(1,4-naphthoquinon-2-yl)-mercapto-
alkanoic acid amides 4(a–c) is shown in Scheme 1.
Compound 4 were synthesized by condensation of 1,4-
naphthoquinone 1 with mercaptoalkanoic acid to form
The antiviral activity of compounds 2b and 10a against
Influenza-A virus are given in Table 3. The antiviral
assay was done according to Sidwell and Hoffman.14
Table 3. In vitro antiviral activity of compounds against Influenza-A
and Herpes Simplex Virus-1
Table 4. Anticancer activity against Lymphoid Leukaemia P 388 in
rats
Compds
Influenza-A
inhibition (%)
Herpes Simplex Virus
(HSV) protection (%)
Compds n ¼ 2
Dose
(mg/kg)
Survivors T/C (%) Remark
10a (R2 ¼ OH,
Ar ¼ Ph)
50
20
4a N<¼ NH2 10
4a N<¼ piperidino 10
4/4
4/4
49
30
Active
Active
2b (n ¼ 2)
52
18

V. K. Tandon et al. / Bioorg. Med. Chem. Lett. 14 (2004) 2901–2904
Table 5. Anticancer activity against Lymphoid Leukaemia L-1210
2903
Compds
Dose (mg/kg)
Survivors
Tumour evaluation test control
T/C
Remark
Test
Control
2a (n ¼ 2)
25.0
12.5
6.25
1/6
6/6
6/6
4.0
13.3
13.8
12.0
12.0
12.0
Toxic
110
115
Inactive
Inactive
Inactive
2a (n ¼ 3)
6.25
3.12
1.56
6/6
6/6
6/6
10.8
10.4
9.7
10.8
10.8
10.8
100
96
Inactive
Inactive
Inactive
89
O
O
R
O
R
O
O
S
S
a
(CH )
2 n
2
COR
HO
O
SH
1
O
1
R
O
R
2
6
+
COOH
EtOH
1
b
O
S
O
R
O
R
O
O
S
5
S
(CH )
c
2 n
(CH )
2 n
O
O
C
N
O
COCl
7
1
R
O
1
1
R
O
R
4
S
3
2
(a) R=R =H, R =OH
O
1
1
2
HO
+
R
O
R
R
O
O
SH
(b) R=R = OH,R = OH
2
8
1
2
R
(c) R=OH, R =Cl, R =OH
COOH
EtOH
Scheme 1. Reagents and conditions: (a) HS(CH2)nCOOH, EtOH;(b)
SOCl2, benzene;(c) N <.
R
O
1
S
1
S-(1,4-naphthoquinon-2-yl)-mercaptoalkanoic acid 2,
which in turn were converted to amides 4 by reaction
with SOCl2 and primary or secondary amines.15
1
1
2
(a) R=R =R =H
1
R
O
O
2
(b) R=R =OH, R =H
9
1
2
(c) R=OH, R =Cl, R =H
Scheme 2.
Reaction of 1,4-benzoquinone 5 and 1,4-naphthoqui-
nones 1 with thiosalicylic acid resulted in the formation
of S-(1,4-benzoquinon-2-yl) mercaptobenzoic acid 6 and
7,10-dihydrothioxanthene-6,7,10-trione 7, S-(1,4-naph-
thoquinon-2-yl)-mercaptobenzoic acid 8 and 7,8-di-
hydrobenzo[b]thioxanthene-6,7,12(H)-trione 9 as shown
in Scheme 2.16
R
O
O
R
O
O
S Ar
S Ar
2eq.Ar-SH
EtOH
R2
R1
R1
11
Scheme 3 describes about reactions of 1,4-naphthoqui-
nones 1 with arylthiol leading to the formation of 2-
arylthio-1,4-naphthoquinone 10 and 2,3-bis-(phenyl-
thio)-1,4-naphthoquinone 11.17
1
1
2
Ar-SH
EtOH
(a) R=R =H; R =H, OH, CH
3
1
(b) R=R = OH
R
O
1
(c) R= OH, R =Cl
S Ar
R2
(d) Ar= Phenyl, Naphthyl
In conclusion we have synthesized a series of 2-substi-
tuted 1,4-naphthoquinones containing sulfur atom in
them and carried out their biological activities. Amongst
the promising compounds 4a (N<¼ NH2, piperidino)
has shown significant anticancer activity against Lym-
phoid Leukaemia P 388. Compound 2b (n ¼ 2) and 10b
(R2 ¼ OH, Ar ¼ phenyl) have shown in vitro antiviral
activity against Influenza-A virus and Herpes Simplex
Virus (HSV-1). Compounds 2a, 2b, 6, 8c, 10a and 11a
have shown some antibacterial activity. Compounds 2b
and 10a are lead compounds for antifungal activity.
Further work on compounds 2b and 10a is in progress.
R1
10
O
Scheme 3.
Acknowledgements
We thank Regional Scientific Instrumentation Centre
(RSIC) for spectral data and Pharmacology Division
of Central Drug Research Institute, Lucknow for

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V. K. Tandon et al. / Bioorg. Med. Chem. Lett. 14 (2004) 2901–2904
without purification. To a stirred solution of 4(a–c)
(10 mmol) in benzene (20 mL) was added 5 mL of concen-
trated solution of NH4OH and the mixture was stirred at
0 °C for 3 h. The solid thus obtained were filtered and
crystallized from methanol. Compound 4a (n ¼ 2,
and 1630 (quinone –C@O) cmÀ1;MS;M þ (m=e) 261. Anal.
Calcd for C13H11NO3S (261): C, 59.77;H, 4.21;N, 5.36;S,
12.26. Found: C, 60.12;H, 4.30;N, 5.48;S, 12.42.
biological data reported in the manuscript. R. V. Singh
acknowledges University Grants Commission, New
Delhi, India for financial assistance.
N<¼ NH2);78% yield;mp 168 °C;IR: 3258 (NH ), 1658
2
References and notes
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Med. Chem. 2002, 10, 1947.
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Soc. 1949, 71, 1124.
6. McBride, T. J.;Oleson, J. J.;Woolf, D. Cancer Res. 1966,
26A, 727.
7. Reich, E.;Goldbreg, I. H.;Rabinowitz, M. Nature 1962,
196, 743.
8. Keyes, S. R.;Loomis, R.;DiGiovanna, M. P.;Pritsos,
C. A.;Rockwell, S.;Sartorelli, A. C. Cancer Commun.
1991, 3, 351.
9. Papageorgiou, V. P.;Assimopoulou, A. N.;Couladou-
rous, E. A.;Hepworth, D.;Nicolaou, K. C. Angew. Chem.,
Int. Ed. 1999, 38, 270.
10. Hatzigrigoriou, E.;Papadopoulou, M. V.;Shields, D.;
Bloomer, W. D. Oncol. Res. 1993, 5, 29.
11. Itoigawa, M.;Ito, C.;Tan, H. T. W.;Okuda, M.;Tokuda,
H.;Nishino, H.;Furukawa, H. Cancer Lett. 2001, 174,
135.
16. General procedure for the synthesis of S-(1,4-naphthoqui-
none-2-yl)-mercaptobenzoic acid 8a and 7,8-dihydrobenzo
[b] thioxanthene-6,7,12 (H)-trione 9a. Thiosalicylic acid
(1.54 g, 10 mmol) was added to a solution of 1,4-naphtho-
quinone 1 (1.58 g, 10 mmol) in absolute alcohol and stirred
at room temperature for 4 h. The dark red solution was
concentrated in vacuo. The residue was dissolved in ether
and extracted with aqueous NaHCO3. The NaHCO3
extract was acidified with 3 N HCl, when the mixture of 8a
and 9a was obtained as an orange solid. It was washed
with water. Compound 8a was obtained after two
crystallizations with CHCl3–hexane;orange crystals, yield
2.78 g (90%);mp 205–207 °C;IR (KBr): 1700 ( >C@O of
acid), 1650 (>C@O of quinone carbonyl); 1H NMR
þ
(CDCl3): d 7.5–8.1 (m, 8H, aromatic protons);MS: M
(m=e) 310. Anal. Calcd for C17H10O4S (310): C, 65.80;H,
3.32;S, 10.32. Found: C, 66.08;H, 3.34;S, 10.54.
Compound 9a: Mother liquor on crystallization yielded
9a as orange needles;116 mg (4%), mp 190–192 °C;IRþ
(KBr): 1665 (>C@O of keto carbonyl) cmÀ1;MS: M
(m=e) 292. Anal. Calcd for C17H8O3S (292): C, 69.84;H,
2.73;S, 10.95. Found: C, 69.98;H, 2.86;S, 11.12.
12. Ball, M. D.;Bartlett, M. S.;Shaw, M.;Smith, J. W.;Nasr,
M.;Meshnick, S. R. Antimicrob. Agents Chemother. 2001,
45, 1473.
13. Dhar, M. L.;Dhar, M. M.;Dhawan, B. N.;Ray, C. Indian
J. Exp. Biol. 1968, 6, 232.
17. General procedure for the prepration of 2-arylthio-1,4-
naphthoquinones 10(a–c). Arylthiol (10 mmol) was added
to a solution of 1,4-naphthoquinone 1 (10 mmol) in
anhydrous ethanol (40 mL). The reaction mixture was
refluxed for 10 h on steam bath. The dark coloured
mixture was cooled and poured in ice cooled water. The
solid product was filtered and crystallized with methanol.
Compound 10a (R2 ¼ H) was obtained in 83% yield;mp
142–143 °C;IR: 1656 and 1568 cm À1; 1H NMR (CDCl3): d
6.12 (s, 1H, C3H), 7.52 (s, 5H, thiophenyl protons), 7.77
14. Sidwell, R. A.;Hoffman, T. H. Appl. Microbiol. 1971, 22,
797.
15. General procedure for the preparation of S-(1,4-naphtho-
quinone-2-yl)-mercaptoalkanoic acid amides 4(a–c). Thion-
yl chloride (1.42 g, 12 mmol) was added to a stirred solution
of 1,4-naphthoquinone derivatives 2(a–c) (10 mmol) in
benzene (20 mL). The reaction mixture was refluxed for 4 h
and concentrated in vacuo. Compounds 4(a–c) were
obtained as oil in quantitative yield and was further used
(m, 2H, C6–H and C7–H), 8.05 (m, 1H, C8–H), 8.15 (m,
þ
1H, C5–H);MS:
M
(m=e) 266. Anal. Calcd for
C16H10O2S (266): C, 72.18;H, 3.78;S, 12.03. Found: C,
72.30;H, 3.82;S, 12.28.