Synthesis of heterocycle-attached methylidenebenzenesulfonohydrazones as antifungal agents

Article abstract of DOI:10.1016/j.bmcl.2015.10.017

A series of heterocycle-attached methylidenebenzenesulfonohydrazone derivatives were synthesized and evaluated for their antifungal activities against seven phytopathogenic fungi such as Fusarium graminearum, Alternaria solani, Valsa Mali, Phytophthora ca

Full text of DOI:10.1016/j.bmcl.2015.10.017

Bioorganic & Medicinal Chemistry Letters 25 (2015) 5092–5096
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Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Synthesis of heterocycle-attached
methylidenebenzenesulfonohydrazones as antifungal agents
Zhinan Gao a,y, Min Lv a,y, Qin Li a, Hui Xu a,b,
⇑
a Research Institute of Pesticidal Design & Synthesis, College of Sciences/Plant Protection, Northwest A&F University, Yangling 712100, Shaanxi Province, People’s Republic of China
b State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling 712100, Shaanxi Province, People’s Republic of China
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of heterocycle-attached methylidenebenzenesulfonohydrazone derivatives were synthesized
and evaluated for their antifungal activities against seven phytopathogenic fungi such as Fusarium
graminearum, Alternaria solani, Valsa mali, Phytophthora capsici, Fusarium solani, Botrytis cinerea, and
Glomerella cingulata. Compounds 7b, 8d, 9a, 9b and 9d exhibited a good and broad-spectrum of antifungal
Received 28 May 2015
Revised 2 October 2015
Accepted 7 October 2015
Available online 13 October 2015
activities against at least five phytopathogenic fungi at the concentration of 100 lg/mL. It demonstrated
that addition of one double bond between the phenylsulfonylhydrazone fragment and the furan ring of
6a,b,d could afford more active compounds 9a,b,d; however, introduction of the nitro group on the phe-
nyl ring of 6a–9a gave less potent compounds 6e–9e.
Keywords:
Synthesis
Phenylsulfonylhydrazone
Hybrids
Ó 2015 Elsevier Ltd. All rights reserved.
Antifungal activity
Phytopathogenic fungi
The hydrazone skeleton occurs in many biologically active com-
pounds, which display a variety of interesting activities such as
anti-inflammatory activity,1 anticancer activity,2,3 antibacterial
activity,4,5 cytotoxic activity,6 antioxidant activity,7 and antischis-
tosomal activity.8 More recently, we have found that introduction
of phenylsulfonylhydrazone fragments into podophyllotoxin or
piperine could result in more potent compounds, that is, podophyl-
lotoxin-based phenylsulfonylhydrazones (I, Fig. 1),9 and piperine-
based phenylsulfonylhydrazones (II, Fig. 1).10
Additionally, some phytopathogenic fungi (e.g., Fusarium
graminearum, Alternaria solani, Valsa mali, Phytophthora capsici,
Fusarium solani, Botrytis cinerea, and Glomerella cingulata) could
easily and quickly infect many crops and cause significant yield
reductions.11 Especially some Fusarium species also produce terri-
ble mycotoxins such as fumonisins, trichothecenes and zear-
alenone in cereal crops that are hazardous for human and animal
health if they enter the food chain.12 Obviously, development of
bioactive compounds to efficiently control these agricultural fungi
is still highly desirable. Consequently, in continuation of our pro-
gram aimed at the discovery and development of novel antifungal
agents, in this Letter we synthesized a series of heterocycle-
attached methylidenebenzenesulfonohydrazone derivatives (III,
Fig. 1). Their antifungal activities were tested against seven
phytopathogenic fungi, such as F. graminearum, A. solani, V. mali,
P. capsici, F. solani, B. cinerea, and G. cingulata.
As shown in Scheme 1, a series of heterocycle-attached methyli-
denebenzenesulfonohydrazone derivatives (6a–e, 7a–e, 8a–e and
9a–e) were smoothly obtained by reaction of four heterocyclic
aldehydes (1–4) with different phenylsulfonyl hydrazides (5a–e)
in 51–99% yields. All compounds were well characterized by 1H
NMR, HRMS and mp (see the Supplementary data).13 To obtain
the precise three-dimensional structural information, the steric
structure of compound 6d was well determined by single-crystal
X-ray diffraction (Fig. 2).14
As described in Table 1, first, a series of compounds 6a–e, 7a–e,
8a–e and 9a–e were screened in vitro for their antifungal activities
at 100 lg/mL against seven phytopathogenic fungi (e.g., F. gramin-
earum, A. solani, V. mali, P. capsici, F. solani, B. cinerea, and G. cingu-
lata).15 Hymexazol, a commercial agricultural fungicide, was used
as a positive control. Among all derivatives, compounds 6d, 7a,b,
8a,b,d, and 9a,b,d showed good antifungal activity against V. mali
with the inhibition rates greater than 50%; compounds 7b, 8a,b,
d, and 9d displayed good antifungal activity against A. solani; com-
pounds 6b,c,d, and 9a,b,d showed good antifungal activity against
F. graminearum; compound 9a exhibited good antifungal activity
against P. capsici; compounds 7b, 8a,b,d, and 9a,b,d showed good
antifungal activity against F. solani; compounds 6b,c,d, 7b, 8d
and 9a,b,d exhibited good antifungal activity against G. cingulata;
compounds 7b and 8d displayed good antifungal activity against
B. cinerea. Two pictures of some compounds inhibiting the growth
⇑
Corresponding author. Tel./fax: +86 (0)29 87091952.
E-mail address: orgxuhui@nwsuaf.edu.cn (H. Xu).
These authors contributed equally to this work.
y
http://dx.doi.org/10.1016/j.bmcl.2015.10.017
0960-894X/Ó 2015 Elsevier Ltd. All rights reserved.

Z. Gao et al. / Bioorg. Med. Chem. Lett. 25 (2015) 5092–5096
5093
Table 1
Antifungal activities of compounds 6a–e, 7a–e, 8a–e and 9a–e against seven phytopathogenic fungi at 100
l
g/mLa
Compd
Antifungal activities (inhibition %)
V. mali
A. solani
F. graminearum
P. capsici
F. solani
G. cingulata
B. cinerea
6a
6b
6c
6d
6e
7a
7b
7c
7d
7e
8a
8b
8c
8d
8e
9a
9b
9c
18.3 ( 0.3)
41.4 ( 1.9)
33.9 ( 0.6)
52.2 ( 0.7)
4.1 ( 0.3)
51.9 ( 0.3)
62.5 ( 0.7)
27.0 ( 0.9)
28.4 ( 1.5)
22.7 ( 0.3)
54.9 ( 1.1)
68.4 ( 2.1)
49.4 ( 1.4)
68.6 ( 0.4)
8.0 ( 0.8)
4.4 ( 0.8)
36.9 ( 0.6)
59.5 ( 3.3)
56.0 ( 1.8)
55.4 ( 0.9)
3.0 ( 1.0)
23.8 ( 0.3)
12.5 ( 6.3)
6.7 ( 1.7)
3.8 ( 0.4)
1.4 ( 0.3)
24.4 ( 1.8)
41.1 ( 1.8)
8.5 ( 0.6)
30.6 ( 1.4)
3.8 ( 0.4)
86.1 ( 5.5)
68.8 ( 0.4)
45.2 ( 0)
12.6 ( 1.9)
28.5 ( 0.4)
35.2 ( 0.7)
32.3 ( 1.0)
7.3 ( 1.5)
37.6 ( 0.7)
46.5 ( 0.4)
36.3 ( 0.5)
29.6 ( 1.8)
24.5 ( 1.5)
44.6 ( 0.6)
46.8 ( 2.0)
40.1 ( 0.8)
48.1 ( 0.4)
23.4 ( 0)
0 ( 0.8)
26.5 ( 0)
7.3 ( 0.2)
33.8 ( 0.6)
45.7 ( 0.2)
50.6 ( 0)
16.6 ( 0.8)
25.3 ( 2.5)
17.4 ( 1.5)
8.2 ( 0.6)
17.4 ( 0.5)
46.0 ( 4.5)
22.3 ( 1.3)
16.1 ( 0.6)
8.2 ( 0.6)
53.4 ( 0.8)
58.9 ( 1.0)
27.5 ( 2.5)
64.6 ( 1.4)
9.0 ( 0.9)
15.8 ( 0.6)
28.3 ( 2.2)
16.6 ( 0.5)
41.7 ( 4.8)
4.9 ( 1.4)
27.8 ( 1.5)
19.2 ( 1.0)
16.8 ( 0.2)
36.8 ( 2.0)
0 ( 0.6)
63.5 ( 0.2)
64.5 ( 0.2)
86.5 ( 0)
17.1 ( 0.8)
42.0 ( 0.9)
63.3 ( 0.6)
42.9 ( 0.6)
34.3 ( 1.2)
40.8 ( 0.4)
42.9 ( 0.3)
40.4 ( 0.3)
19.2 ( 0.3)
53.5 ( 0.8)
3.3 ( 0)
54.7 ( 0.3)
66.9 ( 0.2)
40.8 ( 0.4)
63.0 ( 0.2)
21.2 ( 0.4)
22.4 ( 0.3)
8.5 ( 0.3)
43.6 ( 0.2)
60.1 ( 0.9)
34.8 ( 0.3)
28.7 ( 2.0)
36.3 ( 0.6)
48.2 ( 0.6)
50.3 ( 0.4)
25.9 ( 0.3)
61.6 ( 0.3)
5.8 ( 0.5)
23.8 ( 0.7)
37.5 ( 0.4)
18.0 ( 0.3)
56.4 ( 1.2)
19.5 ( 0)
43.7 ( 1.2)
53.0 ( 1.4)
15.9 ( 0.8)
27.5 ( 1.9)
15.9 ( 0.8)
65.7 ( 0.4)
73.7 ( 0.2)
38.3 ( 0.2)
74.6 ( 0.7)
10.8 ( 1.7)
76.0 ( 0.4)
69.2 ( 0.4)
39.8 ( 0.3)
58.1 ( 1.5)
0 ( 0.4)
76.0 ( 1.3)
63.4 ( 2.7)
41.6 ( 0.3)
83.3 ( 0.9)
5.7 ( 0.4)
62.4 ( 1.3)
50.3 ( 1.7)
37.4 ( 0.4)
45.2 ( 1.0)
13.2 ( 0.6)
71.0 ( 0.3)
9d
9e
Hymb
71.8 ( 0.2)
2.0 ( 1.0)
48.8 ( 1.8)
37.8 ( 1.3)
43.7 ( 0.2)
76.2 ( 2.5)
a
Values are means S.D. of three replicate.
Hymexazol was used as a positive control.
b
Figure 1. Chemical structures of podophyllotoxin-based phenylsulfonylhydrazones (I), piperine-based phenylsulfonylhydrazones (II), and the target compounds III.
of F. solani and V. mali were depicted in Figures 3 and 4, respec-
tively. Generally, compounds 7b, 8d, 9a, 9b and 9d exhibited a
good and broad-spectrum of antifungal activities against at least
five phytopathogenic fungi at the concentration of 100 lg/mL.
Interestingly, introduction of the ethyl group on the phenyl ring
of 7a–9a afforded more potent compounds than those containing
the methyl group on the phenyl ring (e.g., 7e–9e). However, intro-
duction of the nitro group on the phenyl ring of 6a–9a afforded the
less potent compounds 6e–9e. On the other hand, addition of one
double bond between the phenylsulfonylhydrazone fragment and
the furan ring of 6a,b,d could usually give more active compounds
9a,b,d against six phytopathogenic fungi such as F. graminearum, A.
solani, V. mali, P. capsici, F. solani, and B. cinerea.
Subsequently, as shown in Table 2, the EC50 values of com-
pounds 6d, 8b, 8d, 9a, 9b and 9d against some phytopathogenic
fungi were further calculated. Among them, the EC50 values of
8b, 8d, and 9a against F. solani were 0.0979, 0.0702, and
0.142
against F. solani was 1.152
9b and 9d against V. mali were 0.113, 0.0838, 0.0904, 0.0833 and
l
mol/mL, respectively; whereas the EC50 value of hymexazol
l
mol/mL. The EC50 values of 8b, 8d, 9a,
Figure 2. The X-ray crystal structure of compound 6d.

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Z. Gao et al. / Bioorg. Med. Chem. Lett. 25 (2015) 5092–5096
Figure 3. Effects of compounds 6c (GZN-27), 7d (GZN-126), 8b (GZN-131), 9b (GZN-43), and hymexazol (HY, a positive control) on the growth of Fusarium solani at 100
mL (CK: blank control group).
lg/
Figure 4. Effects of compounds 6d (GZN-25), 7a (GZN-123), 8d (GZN-133), and 9a (GZN-41), and hymexazol (HY, a positive control) on the growth of Valsa mali at 100
(CK: blank control group).
lg/mL

Z. Gao et al. / Bioorg. Med. Chem. Lett. 25 (2015) 5092–5096
5095
O
O
O
N
S
N
R
O
S
H
CHO
CHO
1
6a-e
R
O
S
SO2NHNH2
O
N
S
N
R
5a-e
2
H
CHO
7a-e
CH3CH2OH/r.t./1-3 h
51-99% yields
N
H
O
O
N
S
3
N
N
H
R
H
8a-e
O
CHO
4
O
O
O
N
S
N
R
H
9a-e
R=
a
b
c
d
e
3-NO2
H;
4-CH3;
4-CH2CH3;
4-Br;
Scheme 1. The synthetic route for the preparation of compounds 6a–e, 7a–e, 8a–e and 9a–e.
Table 2
Supplementary data
EC50 values of compounds 6d, 8b, 8d, 9a, 9b and 9d against some phytopathogenic
fungi
Supplementary data (experimental procedures and spectral
data for all products) associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.bmcl.2015.10.
017.
a
Compounds
EC50
(
l
mol/mL)
F. solani
V. mali
G. cingulata
F. graminearum
Hymexazol
1.152
—
0.0979
0.0702
0.142
—
1.791
—
1.669
0.112
—
—
—
0.660
—
—
—
0.0636
—
6d
8b
8d
9a
9b
9d
0.113
0.0838
0.0904
0.0833
0.0475
References and notes
1. Kumar, V.; Basavarajaswamy, G.; Rai, M. V.; Poojary, B.; Pai, V. R.; Shruthi, N.;
Bhat, M. Bioorg. Med. Chem. Lett. 2015, 25, 1420.
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M.; Kralova, J.; Kral, V. Bioorg. Med. Chem. Lett. 2015, 23, 1651.
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Huang, Y. M. Steroids 2015, 95, 32.
—
—
—
0.0774
a
50% effective concentration: concentration of compound that inhibits the fungi
growth by 50%.
4. Loginova, N. V.; Koval’chuk, T. V.; Gres, A. T.; Osipovich, N. P.; Polozov, G. I.;
Halauko, Y. S.; Faletrov, Y. V.; Harbatsevich, H. I.; Hlushko, A. V.; Azarko, I. I.
Polyhedron 2015, 88, 125.
5. Cukurovali, A.; Yilmaz, E. J. Mol. Struct. 2014, 1075, 566.
6. Abd-Elzaher, M. M.; Labib, A. A.; Mousa, H. A.; Moustafa, S. A.; Abdallah, M. M.
Res. Chem. Intermed. 2014, 40, 1923.
7. El-Tombary, A. A.; El-Hawash, S. A. M. Med. Chem. 2014, 10, 521.
8. Rawi, S.; Youssef, O. A. G.; Metwally, A.; Badawy, M.; Al-Hazmi, M. Parasitol.
Res. 2014, 113, 437.
9. Wang, Y.; Yu, X.; Zhi, X. Y.; Xiao, X.; Yang, C.; Xu, H. Bioorg. Med. Chem. Lett.
2014, 24, 2621.
0.0475
zol against V. mali was 1.791
value of which against G. cingulata was 0.112
15-fold more potent than hymexazol (EC50 value: 1.669
Against F. graminearum, compounds 9a and 9d exhibited 10 and
8.5-fold more potent antifungal activity than hymexazol (EC50
l
mol/mL, respectively; whereas the EC50 value of hymexa-
mol/mL. Compound 6d, the EC50
mol/mL, was nearly
mol/mL).
l
l
l
value: 0.66 lmol/mL).
In conclusion, a series of heterocycle-attached methylideneben-
zenesulfonohydrazone derivatives (6a–e, 7a–e, 8a–e and 9a–e)
were synthesized and evaluated for their antifungal activities
against seven phytopathogenic fungi. Compounds 7b, 8d, 9a, 9b
and 9d exhibited a good and broad-spectrum of antifungal activi-
ties against at least five phytopathogenic fungi at the concentration
10. Qu, H.; Lv, M.; Yu, X.; Lian, X. H.; Xu, H. Sci. Rep. 2015, 5, 13077.
11. Ke, Y.; Zhi, X.; Yu, X.; Ding, G.; Xu, H. Comb. Chem. High Throughput Screening
2014, 17, 89.
12. Yazar, S.; Omurtag, G. Z. Int. J. Mol. Sci. 2008, 9, 2062.
13. Representative spectral data for6a–e: Data for 6a: Brown solid, 67% yield, mp
128–130 °C; 1H NMR (500 MHz, DMSO-d6) d: 11.52 (s, 0.4H), 7.85 (s, 1H), 7.83
(d, J = 1.5 Hz, 1H), 7.79 (s, 1H), 7.75 (d, J = 1.5 Hz, 1H), 7.64–7.67 (m, 1H), 7.59–
7.62 (m, 2H), 6.80 (d, J = 3.5 Hz, 1H), 6.55–6.56 (m, 1H); HRMS (ESI): Calcd for
of 100 lg/mL. It demonstrated that addition of one double bond
C
11H11N2O3S ([M+H]+), 251.0485; found, 251.0484. Data for 6b (E/Z = 2/1):
Brown solid, 61% yield, mp 116–118 °C; 1H NMR (500 MHz, CDCl3) d: 9.57 (s,
0.6H), 8.05 (s, 0.3H), 7.84–7.88 (m, 2H), 7.73 (s, 0.3H), 7.60 (d, J = 1.5 Hz, 0.6H),
7.45 (d, J = 1.5 Hz, 0.3H), 7.29–7.32 (m, 2H), 7.15 (s, 0.6H), 6.67 (d, J = 3.5 Hz,
1H), 6.52 (dd, J = 1.5, 3.5 Hz, 0.6H), 6.42 (dd, J = 1.5, 3.5 Hz, 0.3H), 2.41 (s, 2H),
2.40 (s, 1H); HRMS (ESI): Calcd for C12H13N2O3S ([M+H]+), 265.0641; found,
265.0639. Data for 6c: Light yellow solid, 52% yield, mp 136–138 °C; 1H NMR
(500 MHz, DMSO-d6) d: 11.45 (s, 1H), 7.74–7.78 (m, 4H), 7.43 (d, J = 8.0 Hz, 2H),
6.80 (d, J = 3.5 Hz, 1H), 6.55–6.56 (m, 1H), 2.63 (q, J = 7.5 Hz, 2H), 1.15 (t,
J = 7.5 Hz, 3H); HRMS (ESI): Calcd for C13H15N2O3S ([M+H]+), 279.0798; found,
279.0797. Data for 6d: Maroon solid, 69% yield, mp 146–148 °C; 1H NMR
(500 MHz, DMSO-d6) d: 11.58 (s, 0.3H), 7.84 (s, 1H), 7.83 (s, 1H), 7.80 (s, 1H),
7.75–7.76 (m, 3H), 6.82 (d, J = 3.5 Hz, 1H), 6.56–6.57 (m, 1H); HRMS (ESI):
Calcd for C11H10BrN2O3S ([M+H]+), 328.9590; found, 328.9588. Data for 6e:
Brown solid, 70% yield, mp 153–154 °C; 1H NMR (500 MHz, DMSO-d6) d: 11.80
(s, 1H), 8.55 (t, J = 2.0 Hz, 1H), 8.48–8.50 (m, 1H), 8.25–8.27 (m, 1H), 7.91 (t,
between the phenylsulfonylhydrazone fragment and the furan ring
of 6a,b,d afforded more active compounds 9a,b,d; whereas intro-
duction of the nitro group on the phenyl ring of 6a–9a gave less
potent compounds 6e–9e; It will pave the way for further design
and synthesis of heterocycle-attached methylidenebenzenesul-
fonohydrazone derivatives as antifungal agents.
Acknowledgments
The present research was supported by the Special Funds of
Central Colleges Basic Scientific Research Operating Expenses
(Nos. 2452015096, YQ2013008).

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Z. Gao et al. / Bioorg. Med. Chem. Lett. 25 (2015) 5092–5096
J = 8.0 Hz, 1H), 7.83 (s, 1H), 7.77 (d, J = 1.0 Hz, 1H), 6.84 (d, J = 3.5 Hz, 1H), 6.56–
sterilized Petri dishes. All types of fungi were incubated in PDA at 28 1 °C for
5 days to get new mycelium for the antifungal assays, and a mycelia disk of
approximately 5 mm diameter cut from culture medium was picked up with a
sterilized inoculation needle and inoculated in the center of the PDA Petri
dishes. The inoculated Petri dishes were incubated at 28 1 °C for 4 days.
Acetone without any compounds mixed with PDA was served as a blank
control (CK); while hymexazol, a commercial agricultural fungicide, was used
as a positive control. For each treatment, three replicates were conducted. The
radial growths of the fungal colonies were measured and the data were
statistically analyzed. The inhibitory effects of the test compounds on these
fungi in vitro were calculated by the formula: Inhibition rate (%) = (C ꢀ T) ꢁ
100/(C ꢀ 4 mm), where C represents the diameter of fungi growth on untreated
PDA, and T represents the diameter of fungi on treated PDA. Subsequently,
6.57 (m, 1H); HRMS (ESI): Calcd for C11H10N3O5S ([M+H]+), 296.0336; found,
296.0334.
14. Crystallographic data (excluding structure factors) for the structure of 6d have
been deposited with the Cambridge Crystallographic Data Centre as
supplementary publication number CCDC 1062007. Copies of the data can be
obtained, free of charge, on application to CCDC, 12 Union Road, Cambridge
CB2 1EZ, UK [fax: +44 (0)1223 336033 or e-mail: deposit@ccdc.cam.ac.uk].
15. Antifungal
activities
assay:
A
series
of
heterocycle-attached
methylidenebenzenesulfonohydrazone derivatives (6a–e, 7a–e, 8a–e and 9a–
e) were screened in vitro for their antifungal activities against seven
phytopathogenic fungi by poisoned food technique. Seven phytopathogenic
fungi such as Fusarium graminearum, Alternaria solani, Valsa mali, Botrytis
cinerea, Phytophthora capsici, Fusarium solani and Glomerella cingulata, were
used for the assays. Potato dextrose agar (PDA) medium was prepared in the
flasks and sterilized. Compounds 6a–e, 7a–e, 8a–e and 9a–e were dissolved in
acetone before mixing with PDA, and the concentration of test compounds in
seven concentrations (10, 20, 40, 60, 80, 100 and 120 lg/mL) of the selective
compounds 6d, 8b, 8d, 9a, 9b and 9d were set, and the linear regressions of
inhibition rates (%) versus seven concentrations of 6d, 8b, 8d, 9a, 9b and 9d
against some phytopathogenic fungi were obtained. Finally, the EC50 values
were calculated.
the medium was fixed at 100 lg/mL. The medium was then poured into