Bioorganic & Medicinal Chemistry Letters 25 (2015) 5092–5096
Contents lists available at ScienceDirect
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 b
Research Institute of Pesticidal Design & Synthesis, College of Sciences/Plant Protection, Northwest A&F University, Yangling 712100, Shaanxi Province, People’s Republic of China 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
Article history: Received 28 May 2015 Revised 2 October 2015 Accepted 7 October 2015 Available online 13 October 2015 Keywords: Synthesis Phenylsulfonylhydrazone Hybrids Antifungal activity Phytopathogenic fungi
a b s t r a c t 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 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 phenyl ring of 6a–9a gave less potent compounds 6e–9e. Ó 2015 Elsevier Ltd. All rights reserved.
The hydrazone skeleton occurs in many biologically active compounds, 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 antischistosomal activity.8 More recently, we have found that introduction of phenylsulfonylhydrazone fragments into podophyllotoxin or piperine could result in more potent compounds, that is, podophyllotoxin-based phenylsulfonylhydrazones (I, Fig. 1),9 and piperinebased 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 terrible mycotoxins such as fumonisins, trichothecenes and zearalenone 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 program aimed at the discovery and development of novel antifungal agents, in this Letter we synthesized a series of heterocycleattached methylidenebenzenesulfonohydrazone derivatives (III, Fig. 1). Their antifungal activities were tested against seven ⇑ Corresponding author. Tel./fax: +86 (0)29 87091952. y
E-mail address: [email protected] (H. Xu). These authors contributed equally to this work.
http://dx.doi.org/10.1016/j.bmcl.2015.10.017 0960-894X/Ó 2015 Elsevier Ltd. All rights reserved.
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 methylidenebenzenesulfonohydrazone 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. graminearum, A. solani, V. mali, P. capsici, F. solani, B. cinerea, and G. cingulata).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; compounds 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
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Z. Gao et al. / Bioorg. Med. Chem. Lett. 25 (2015) 5092–5096 Table 1 Antifungal activities of compounds 6a–e, 7a–e, 8a–e and 9a–e against seven phytopathogenic fungi at 100 lg/mLa Compd
6a 6b 6c 6d 6e 7a 7b 7c 7d 7e 8a 8b 8c 8d 8e 9a 9b 9c 9d 9e Hymb a b
Antifungal activities (inhibition %) V. mali
A. solani
F. graminearum
P. capsici
F. solani
G. cingulata
B. cinerea
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) 76.0 (±1.3) 63.4 (±2.7) 41.6 (±0.3) 83.3 (±0.9) 5.7 (±0.4) 37.8 (±1.3)
4.4 (±0.8) 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)
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) 71.8 (±0.2) 2.0 (±1.0) 48.8 (±1.8)
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) 62.4 (±1.3) 50.3 (±1.7) 37.4 (±0.4) 45.2 (±1.0) 13.2 (±0.6) 71.0 (±0.3)
0 (±0.8) 19.2 (±1.0) 16.8 (±0.2) 36.8 (±2.0) 0 (±0.6) 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) 43.7 (±0.2)
26.5 (±0) 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)
7.3 (±0.2) 33.8 (±0.6) 45.7 (±0.2) 50.6 (±0) 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) 76.2 (±2.5)
Values are means ± S.D. of three replicate. Hymexazol was used as a positive control.
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, respectively. Generally, compounds 7b, 8d, 9a, 9b and 9d exhibited a good and broad-spectrum of antifungal activities against at least
Figure 2. The X-ray crystal structure of compound 6d.
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, introduction 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 compounds 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 lmol/mL, respectively; whereas the EC50 value of hymexazol against F. solani was 1.152 lmol/mL. The EC50 values of 8b, 8d, 9a, 9b and 9d against V. mali were 0.113, 0.0838, 0.0904, 0.0833 and
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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 lg/ mL (CK: blank control group).
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 lg/mL (CK: blank control group).
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O O N S H 6a-e
O
N
O CHO 1 R S 2
O O N S H 7a-e
S
SO 2NHNH 2
CHO
R
N
5a-e CHO
R
CH3 CH 2OH/r.t./1-3 h
3 O 4
N H
51-99% yields
N N H
O O N S H
R
8a-e
CHO O 9a-e
R= a H; b 4-CH 3;
N
c 4-CH2 CH3 ;
d
4-Br;
O O N S H
R
e 3-NO2
Scheme 1. The synthetic route for the preparation of compounds 6a–e, 7a–e, 8a–e and 9a–e.
Table 2 EC50 values of compounds 6d, 8b, 8d, 9a, 9b and 9d against some phytopathogenic fungi EC50a (lmol/mL)
Compounds
Hymexazol 6d 8b 8d 9a 9b 9d
F. solani
V. mali
G. cingulata
F. graminearum
1.152 — 0.0979 0.0702 0.142 — —
1.791 — 0.113 0.0838 0.0904 0.0833 0.0475
1.669 0.112 — — — — —
0.660 — — — 0.0636 — 0.0774
a 50% effective concentration: concentration of compound that inhibits the fungi growth by 50%.
0.0475 lmol/mL, respectively; whereas the EC50 value of hymexazol against V. mali was 1.791 lmol/mL. Compound 6d, the EC50 value of which against G. cingulata was 0.112 lmol/mL, was nearly 15-fold more potent than hymexazol (EC50 value: 1.669 lmol/mL). Against F. graminearum, compounds 9a and 9d exhibited 10 and 8.5-fold more potent antifungal activity than hymexazol (EC50 value: 0.66 lmol/mL). In conclusion, a series of heterocycle-attached methylidenebenzenesulfonohydrazone 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 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 afforded more active compounds 9a,b,d; whereas introduction 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 methylidenebenzenesulfonohydrazone 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).
Supplementary data 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. 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. 2. Kaplanek, R.; Havlik, M.; Dolensky, B.; Rak, J.; Dzubak, P.; Konecny, P.; Hajduch, M.; Kralova, J.; Kral, V. Bioorg. Med. Chem. Lett. 2015, 23, 1651. 3. Cui, J. G.; Liu, L.; Zhao, D. D.; Gan, C. F.; Huang, X.; Xiao, Q.; Qi, B. B.; Yang, L.; Huang, Y. M. Steroids 2015, 95, 32. 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. 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 C11H11N2O3S ([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,
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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– 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: [email protected]]. 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 the medium was fixed at 100 lg/mL. The medium was then poured into
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, 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.
Contents lists available at ScienceDirect
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 b
Research Institute of Pesticidal Design & Synthesis, College of Sciences/Plant Protection, Northwest A&F University, Yangling 712100, Shaanxi Province, People’s Republic of China 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
Article history: Received 28 May 2015 Revised 2 October 2015 Accepted 7 October 2015 Available online 13 October 2015 Keywords: Synthesis Phenylsulfonylhydrazone Hybrids Antifungal activity Phytopathogenic fungi
a b s t r a c t 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 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 phenyl ring of 6a–9a gave less potent compounds 6e–9e. Ó 2015 Elsevier Ltd. All rights reserved.
The hydrazone skeleton occurs in many biologically active compounds, 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 antischistosomal activity.8 More recently, we have found that introduction of phenylsulfonylhydrazone fragments into podophyllotoxin or piperine could result in more potent compounds, that is, podophyllotoxin-based phenylsulfonylhydrazones (I, Fig. 1),9 and piperinebased 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 terrible mycotoxins such as fumonisins, trichothecenes and zearalenone 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 program aimed at the discovery and development of novel antifungal agents, in this Letter we synthesized a series of heterocycleattached methylidenebenzenesulfonohydrazone derivatives (III, Fig. 1). Their antifungal activities were tested against seven ⇑ Corresponding author. Tel./fax: +86 (0)29 87091952. y
E-mail address: [email protected] (H. Xu). These authors contributed equally to this work.
http://dx.doi.org/10.1016/j.bmcl.2015.10.017 0960-894X/Ó 2015 Elsevier Ltd. All rights reserved.
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 methylidenebenzenesulfonohydrazone 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. graminearum, A. solani, V. mali, P. capsici, F. solani, B. cinerea, and G. cingulata).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; compounds 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
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Z. Gao et al. / Bioorg. Med. Chem. Lett. 25 (2015) 5092–5096 Table 1 Antifungal activities of compounds 6a–e, 7a–e, 8a–e and 9a–e against seven phytopathogenic fungi at 100 lg/mLa Compd
6a 6b 6c 6d 6e 7a 7b 7c 7d 7e 8a 8b 8c 8d 8e 9a 9b 9c 9d 9e Hymb a b
Antifungal activities (inhibition %) V. mali
A. solani
F. graminearum
P. capsici
F. solani
G. cingulata
B. cinerea
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) 76.0 (±1.3) 63.4 (±2.7) 41.6 (±0.3) 83.3 (±0.9) 5.7 (±0.4) 37.8 (±1.3)
4.4 (±0.8) 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)
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) 71.8 (±0.2) 2.0 (±1.0) 48.8 (±1.8)
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) 62.4 (±1.3) 50.3 (±1.7) 37.4 (±0.4) 45.2 (±1.0) 13.2 (±0.6) 71.0 (±0.3)
0 (±0.8) 19.2 (±1.0) 16.8 (±0.2) 36.8 (±2.0) 0 (±0.6) 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) 43.7 (±0.2)
26.5 (±0) 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)
7.3 (±0.2) 33.8 (±0.6) 45.7 (±0.2) 50.6 (±0) 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) 76.2 (±2.5)
Values are means ± S.D. of three replicate. Hymexazol was used as a positive control.
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, respectively. Generally, compounds 7b, 8d, 9a, 9b and 9d exhibited a good and broad-spectrum of antifungal activities against at least
Figure 2. The X-ray crystal structure of compound 6d.
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, introduction 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 compounds 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 lmol/mL, respectively; whereas the EC50 value of hymexazol against F. solani was 1.152 lmol/mL. The EC50 values of 8b, 8d, 9a, 9b and 9d against V. mali were 0.113, 0.0838, 0.0904, 0.0833 and
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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 lg/ mL (CK: blank control group).
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 lg/mL (CK: blank control group).
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O O N S H 6a-e
O
N
O CHO 1 R S 2
O O N S H 7a-e
S
SO 2NHNH 2
CHO
R
N
5a-e CHO
R
CH3 CH 2OH/r.t./1-3 h
3 O 4
N H
51-99% yields
N N H
O O N S H
R
8a-e
CHO O 9a-e
R= a H; b 4-CH 3;
N
c 4-CH2 CH3 ;
d
4-Br;
O O N S H
R
e 3-NO2
Scheme 1. The synthetic route for the preparation of compounds 6a–e, 7a–e, 8a–e and 9a–e.
Table 2 EC50 values of compounds 6d, 8b, 8d, 9a, 9b and 9d against some phytopathogenic fungi EC50a (lmol/mL)
Compounds
Hymexazol 6d 8b 8d 9a 9b 9d
F. solani
V. mali
G. cingulata
F. graminearum
1.152 — 0.0979 0.0702 0.142 — —
1.791 — 0.113 0.0838 0.0904 0.0833 0.0475
1.669 0.112 — — — — —
0.660 — — — 0.0636 — 0.0774
a 50% effective concentration: concentration of compound that inhibits the fungi growth by 50%.
0.0475 lmol/mL, respectively; whereas the EC50 value of hymexazol against V. mali was 1.791 lmol/mL. Compound 6d, the EC50 value of which against G. cingulata was 0.112 lmol/mL, was nearly 15-fold more potent than hymexazol (EC50 value: 1.669 lmol/mL). Against F. graminearum, compounds 9a and 9d exhibited 10 and 8.5-fold more potent antifungal activity than hymexazol (EC50 value: 0.66 lmol/mL). In conclusion, a series of heterocycle-attached methylidenebenzenesulfonohydrazone 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 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 afforded more active compounds 9a,b,d; whereas introduction 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 methylidenebenzenesulfonohydrazone 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).
Supplementary data 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. 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. 2. Kaplanek, R.; Havlik, M.; Dolensky, B.; Rak, J.; Dzubak, P.; Konecny, P.; Hajduch, M.; Kralova, J.; Kral, V. Bioorg. Med. Chem. Lett. 2015, 23, 1651. 3. Cui, J. G.; Liu, L.; Zhao, D. D.; Gan, C. F.; Huang, X.; Xiao, Q.; Qi, B. B.; Yang, L.; Huang, Y. M. Steroids 2015, 95, 32. 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. 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 C11H11N2O3S ([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,
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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– 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: [email protected]]. 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 the medium was fixed at 100 lg/mL. The medium was then poured into
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, 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.
