BackgroundMyricetin and 1,3,4-thiadiazole derivatives were reported to exhibit favorable antiviral and antibacterial activities. Aiming to discover novel myricetin analogues with potent activities, a series of novel myricetin derivatives containing 1,3,4-thiadiazole moiety were synthesized, and their antibacterial and antiviral activities were evaluated.ResultBioassay results indicated that some target compounds exhibited potential antibacterial and antiviral activities. Among them, compounds 2, 3a, 3b, 3d, 3f, 3i, 3m and 3p exhibited excellent antibacterial activities against Xanthomonas oryzae pv. Oryzae (Xoo), with EC50 values of 42.7, 38.6, 20.8, 12.9, 22.7, 27.3, 18.3 and 29.4 μg/mL, respectively, which were better than that of thiadiazole-copper (94.9 μg/mL). Compounds 3b, 3d, 3e, 3f, 3i and 3o showed good antibacterial activities against Ralstonia solanacearum (Rs), with EC50 values of 37.9, 72.6, 43.6, 59.6, 60.6 and 39.6 μg/mL, respectively, which were superior to that of thiadiazole-copper (131.7 μg/mL). In addition, compounds 3d, 3f, 3i and 3m showed better curative activities against tobacco mosaic virus (TMV), with EC50 values of 152.8, 99.7, 127.1, and 167.3 μg/mL, respectively, which were better than that of ningnanmycin (211.1 μg/mL).ConclusionsA series of myricetin derivatives containing 1,3,4-thiadiazole scaffold were synthesized, and their antibacterial activities against Xoo and Rs and their antiviral activity against TMV were evaluated. Bioassays indicated that some target compounds exhibited potential antibacterial and antiviral activities. These results indicated this kind of myricetin analogues could be further studied as potential alternative templates in the search for novel antibacterial and antiviral agents.Electronic supplementary materialThe online version of this article (doi:10.1186/s13065-017-0336-7) contains supplementary material, which is available to authorized users.

A series of quinazolin‐4(3H)‐one derivatives containing a hydrazide moiety were designed, synthesized and characterized in detail via FT‐IR, 1H NMR, 13C NMR and HRMS spectra. The antifungal activities against Rhizoctonia solani (Rs) and Fusarium graminearum (Fg) were evaluated in vitro. The bioassay results indicated that most of the title compounds exhibited significant antifungal activities against Rs and Fg. Strikingly, the EC50 values of some title compounds against Rs are obviously superior to that of the positive control carbendazim. Based on the antifungal bioassay results against Rs, the comparative molecular filed analysis (CoMFA) and comparative molecular similarity index analysis (CoMSIA) models were generated to investigate the structure‐activity relationship of title compounds against Rs. The analytical results indicated that these two models exhibited good predictive accuracies and could provide significant structural insights for the design of bioactive quinazolin‐4(3H)‐one derivatives containing a hydrazide moiety.

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Background penta-1,4-diene-3-one oxime ether and quinazolin-4(3 H )-one derivatives possess favorable agricultural activities. Aiming to discover novel molecules with highly-efficient agricultural activities, a series of penta-1,4-diene-3-one oxime ether derivatives containing a quinazolin-4(3 H )-one scaffold were synthesized and evaluated for their antiviral activities. Result Antiviral bioassays indicated that some title compounds exhibited significant antiviral activity against tobacco mosaic virus (TMV). In particular, compounds 8c , 8j and 8k possessed appreciable curative activities against TMV in vivo, with half-maximal effective concentration (EC 50 ) values of 138.5, 132.9 and 125.6 μg/mL, respectively, which are better than that of ningnanmycin (207.3 μg/mL). Furthermore, the microscale thermophoresis experiments (MST) on the interaction of compound 8k with TMV coat protein (TMV CP) showed 8k bound to TMV CP with a dissociation constant of 0.97 mmol/L. Docking studies provided further insights into the interaction of 8k with the Arg90 of TMV CP. Conclusions Sixteen penta-1,4-diene-3-one oxime ether derivatives containing a quinazolin-4(3 H )-one scaffold were designed, synthesized, and their antiviral activities against TMV were evaluated. Antiviral bioassays indicated that some target compounds exhibited remarkable antiviral activities against TMV. Furthermore, through the MST and docking studies, we can speculate that 8k inhibited the virulence of TMV by binding Arg90 in TMV CP. These results indicated that this kind of penta-1,4-diene-3-one oxime ether derivatives containing a quinazolin-4(3 H )-one scaffold could be further studied as potential alternative templates in the search for novel antiviral agents. Electronic supplementary material The online version of this article (10.1186/s13065-019-0547-1) contains supplementary material, which is available to authorized users.

Aiming to develop novel antifungal agents with a distinctive molecular scaffold targeting succinate dehydrogenase (SDH), 24 N′-phenyl-1H-pyrazole-4-sulfonohydrazide derivatives were first devised, synthesized, and verified by 1 H NMR, 13 C NMR, high-resolution mass spectrometry (HRMS), and single-crystal X-ray diffraction analysis. The bioassays revealed that the target compounds possessed highly efficient and broad-spectrum antifungal activities against four tested plant pathogenic fungi Rhizoctonia solani (R. solani), Botrytis cinerea, Fusarium graminearum, and Alternaria sonali. Strikingly, compound B6 was assessed as the selective inhibitor against R. solani, with an in vitro EC 50 value (0.23 μg/mL) that was similar to that of thifluzamide (0.20 μg/ mL). The in vivo preventative effect of compound B6 (75.76%) at 200 μg/mL against R. solani was roughly comparable to thifluzamide (84.31%) under the same conditions. The exploration of morphological observations indicated that compound B6 could strongly damage the mycelium morphology, obviously increase the permeability of the cell membrane, and dramatically increase the number of mitochondria. Compound B6 also significantly inhibited SDH enzyme activity with an IC 50 value of 0.28 μg/ mL, and its fluorescence quenching dynamic curves were similar to that of thifluzamide. Molecular docking and molecular dynamics simulations demonstrated that compound B6 could strongly interact with similar residues around the SDH active pocket as thifluzamide. The present study revealed that the novel N′-phenyl-1H-pyrazole pyrazole-4-sulfonohydrazide derivatives are worthy of being further investigated as the promising replacements of traditional carboxamide derivatives targeting SDH of fungi.

A series of novel Schiff base derivatives containing 4(3

The ever-increasing resistance of Fusarium graminearum has emerged as a pressing agricultural issue that could be settled by developing novel fungicides owning inimitable action mechanisms. With the aim of discovering novel antifungal leads inhibiting F. graminearum, a tryptanthrin structure was dexterously optimized to generate 30 novel quinazolin-4­(3H)-one derivatives. The aforementioned optimization generated the molecule C 17 that owned exhilarating in vitro anti-F. graminearum effect (EC50 value = 0.76 μg/mL). Whereafter, the in vivo anti-F. graminearum preventative efficacy of the molecule C 17 was measured to be 59.5% at 200 μg/mL, which was approximately comparable with that of carbendazim (64.9%). Furthermore, morphological observations indicated that the molecule C 17 could cause the hypha to become slender and dense, distort the outline of cell walls, induce an increase in liposome numbers, and cause the reduction of mitochondria numbers. The above results have emerged as an obbligato complement for developing novel antifungal leads that could effectively control Fusarium head blight.