Synthesis and biological evaluation of 4-methyl-1,2,3- thiadiazole-5-carboxaldehyde benzoyl hydrazone derivatives

To find new lead compounds with high biological activity,a series of novel 4-methyl-1,2,3-thiadiazole-5-carboxaldehyde benzoyl hydrazone derivatives were designed and synthesized.Their structures were confirmed by ~1H NMR,~(13)C NMR,IR spectrum and elemental analysis.Preliminary bioassay indicated that the title compounds exhibited moderate to strong fungicidal activity against six fungi in vitro at50 μg/mL.Moreover,some of the title compounds exhibited good curative activity against TMV in vivo at500 μg/mL.The structure-activity relationship analysis of compounds against Valsa mali showed that compounds containing halogen at the para position on phenyl exhibited the best activity.Especially compound 8k showed broad spectrum fungicidal activities against Valsa mali,Botrytis cinerea,Pythium aphamdermatum,Rhizoctonia solani,Fusarium moniliforme and Altemaria solani with the EC_(50) values of8.20,24.42,15.80,40.53,41.48,and 34.16 μg/mL,respectively.     

Synthesis and structure-activity relationship of rhodomyrtone derivatives as antibacterial agent

To study structure-activity relationship of rhodomyrtone against Gram-positive bacteria,structural modification of rhodo-myrtone was carried out to afford its 10 analogues.All compounds were assayed for their antibacterial potency using broth microdilution method.The results indicated that rhodomyrtone exhibited higher antibacterial activity against all Gram-positive bacteria than its analogues,with the exception of rhodomyrtone 6,8-diacetate(3) and oxime analogues 6 and 7 which demonstrated similar activity as the parent compound against Bacillus subtilis and Staphylococcus epidermidis with minimum inhibitory concentration and minimum bactericidal concentration ranged from 1 to 4μg/mL and 2 to 4μg/mL,respectively.In contrast,all analogues displayed no activity against Acinetobacter baumannii.Hydroxyl and ketone groups of rhodomyrtone were elucidated to be essential for the antibacterial property.     

Synthesis and bioactivities of novel 2-(thioether/sulfone)-5-pyrazolyl-1,3,4-oxadiazole derivatives

By introducing the pyrazole moiety into the 5-position of 1,3,4-oxadiazole,a series of novel 2-(thioether/sulfone)-5-pyrazolyl-l,3,4-oxadiazole derivatives were synthesized.Preliminary bioassays suggested that target compounds exhibited appreciable activity against pathogenic bacteria Xanthomonas oryzae pv.oryzae(Xoo) and five phytopathogenic fungi in vitro.Among them,the half-maximal effective concentration(EC_(50)) values of 6c,7a,7b and 7c against Xoo were within 16.6 μg/mL and 65.7 μg/mL,which were better than those of commercial agricultural antibacterial bismerthiazol(92.6 μg/mL) and thiodiazole copper(121.8 μg/mL).While compounds 7a,7b,and 7c exerted comprehensive antifungal activity toward five plant fungi,which were comparable with that of hymexazol.The results demonstrated that this kind of compounds can be further studied and developed as promising antifungal and antibacterial agents.     

Synthesis and Antiviral Activities of Chiral Thiourea Derivatives

An environmentally benign method has been developed for the synthesis of novel chiral thiourea derivatives in high yields in ionic liquid [Bmim]PF6. The ionic solvent can be recovered and reused without any loss of its activity. The target compounds were characterized by elemental analysis, IR, 1H NMR and 13C NMR spectral data. According to the preliminary bioassay, some of the chiral thiourea analogues exhibited moderate in vivo antiviral activities against TMV at a concentration of 500 mg/L. Title chiral compound 3i was found to possess good in vivo protection, inactivation and curative activities of 57.0%, 96.4% and 55.0%, respectively against TMV with an inhibitory concentration at 500 mg/L. The title chiral compound 3i revealed better inactivation effect on TMV (EC50＝50.8 µg/mL) than Ningnanmycin (EC50＝60.2 µg/mL).     

Novel dihydropyrazole derivatives linked with multi（hetero）aromatic ring： Synthesis and antibacterial activity

Eight novel heterocycle-substituted dihydropyrazole derivatives were synthesized and characterized by ESI-MS,~1H NMR and ~(13)C NMR.All of the compounds have been screened for their antibacterial potential in vitro against Bacillus subtilis, Staphylococcus aureus,Escherichia coli and Pseudomonas aeruginosa.The results show that compounds 9b,9g and 9h displayed significant activity with MIC values in the range of 0.39-1.562μg/mL against B.subtilis.     

Synthesis and Antileishmanial Activities of Some New Azasterols

A series of novel azasterols 8a―8h and 10a―10c were synthesized from the key intermediate 6 by acylation and deprotection.Compound 6 was obtained through a series of reactions including Wittig reaction,etherification,ene reaction,oxidation,oximation and reduction.Structures of the synthesized compounds were confirmed by IR,MS and 1H NMR.Furthermore,all of these compounds were screened for in vitro antiparasitic activity against L.donovani.Among them,compounds 8h,10a and 10b showed a fair inhibition of leishmania promastigotes growth at 25 μg/mL,with potencies close to that of the reference drug,amphotericin B.The results provide a starting point for the development of novel drugs to treat leishmaniasis.     

Synthesis and antibacterial activity of C-2(S)-substituted pleuromutilin derivatives

<正>In order to probe the effect of C-2(S)-substituted groups in the antibacterial activity,a series of novel C-2(S)-substituted pleuromutilin analogues of SB-225586 were synthesized and evaluated for their in vitro antibacterial activity.The results of antibacterial activities indicated that C-2(S)-substituted pleuromutilin derivatives retained appreciable antibacterial activity,and the 2-fluorination compounds 6a and 6b are more potent than the corresponding 2-hydroxylation analogues 7a and 7b.     

Synthesis and biological evaluation of novel 1,2,4-triazole containing 1,2,3-thiadiazole derivatives

A series of novel 1,2,4-triazoles containing 1,2,3-thiadiazole derivatives were designed and synthesized. Their structures were confirmed by melting points, IR, 1H NMR, and elemental analysis and ESI-MS or HRMS. Preliminary bioassays indicated that these compounds exhibited very good insecticidal activity against Aphis laburni at 100 μg/mL, with mortality no less than 95%. Compounds 6a, 6c, 6f, 61 showed higher curative activity against TMV and compound 6h showed a higher induction effects against TMV in vivo at 100 μg/mL. Collectively, our data demonstrate a new strategy for control of insects and viruses.     

Synthesis and fungicidal activity study of novel daphneolone analogs with 2,6-dimethylmorpholine

A series of novel daphneolone analogs was designed and synthesized on the basis of natural product 1,5-diphenyl-2-penten-1-one(I) from Stellera chamaejasme L. as lead compound, whereby 2,6-dimethylmorpholine moiety was introduced to replace 1-phenyl group. Their structures were confirmed by IR,1H NMR, and HRMS(ESI) or elemental analysis,13 C NMR for some representative compounds. The two isomers of target compounds were separated and identified by NOESY technique and chemical method.All of the synthesized compounds have been evaluated for anti-plant pathogenic fungi activities. The results showed that some compounds exhibited moderate to good antifungal activities against tested fungi at the concentration of 50 mg/L. Among them, compound 7d, with a 4-bromine-substituted phenyl group and cis-2,6-dimethylmorpholine moiety, displayed best activity with an EC50 of 23.87 mmol/L against Valsa mali, superior to lead compound I. In addition, preliminary structure–activity relationship analysis indicated that, between two isomers of target compounds, the antifungal activities of the isomer with cis-2,6-dimethylmorpholine were better than the trans-isomer.     

Antifungal and cytotoxic substances from the stem barks of Desmos chinensis

Isounonal-7-methyl ether（1） and chinendihydrochalcone（2） together with 8 known compounds were isolated from the stem barks of Desmos chinensis.Their structures were determined on the basis of spectroscopic data.Compound 2 exhibited cytotoxic activity against MOLT-3 cancer cell line(IC₅₀ 7.16μg/mL) and antifungal activity against Pyricularia oryzae and Rhizoctonia solani with MIC values of 15.6 and 31.2μg/mL,respectively.     

Synthesis and biological activities of novel 2-amino-1,3-thiazole-4-carboxylic acid derivatives

A series of novel 2-amino-1, 3-thiazole-4-carboxylic acid derivatives were designed and synthesized. Their structures were confirmed by melting points, IR, ¹H NMR, ¹³C NMR, and HRMS or elemental analysis. Biological activities of all title compounds including fungicidal activity and antivirus activity were evaluated systematically. Preliminary bioassays indicated that these compounds exhibited good fungicidal activity at 50 μg/mL, compounds 4b and 4i exhibited over 50% activity against six fungi tested. Most compounds showed good activity against TMV with different models in vivo at 100 μg/mL. Compounds 4c and 4e stood out with high effects against TMV in vivo in all models tested, including protective, inactivative, curative, and inductive activities. These data demonstrate a new strategy for fungi and virus control.     

Syntheses and Insecticidal Activity of Spirocyclic Tetronic Acid Derivatives Containing Oxime Ether Moiety

In order to develop novel spirocyclic tetronic acid lead compounds, a series of new spirocyclic tetronic acid derivatives containing oxime ether moiety was synthesized and bioassayed. The structures of 16 target compounds were characterized by ¹H NMR spectra, ¹³C NMR spectra and high-resolution mass spectrometer(HRMS). Preliminary bioassays indicated that most of the title compounds displayed excellent insecticidal activity against Aphis fabae and Nilaparvata lugens at 100 mg/L. In particular, compound 6k showed the similar activity(LC₅₀=6.87 mg/L) against A. fabae as the spirotetramat(LC₅₀=4.56 mg/L) and had better effects(LC₅₀=1.64 mg/L) against N. lugens in comparison with spirotetramat(LC₅₀=7.90 mg/L). The study showed that compound 6k exhibited more promising and broad-spectrum insecticide activity and may serve as a new insecticidal agent for sucking pests.     

Synthesis and biological evaluation of novel pyrazole carboxamide with diarylamine-modified scaffold as potent antifungal agents

Twenty-seven novel pyrazole carboxamides with diarylamine-modified scaffold were designed, synthesized and characterized in detail via ¹H NMR, ¹³C NMR, IR and ESI-HRMS. Preliminary bioassays showed that some of the target compounds exhibited good antifungal activity against Rhizoctonia solani, Rhizoctonia cerealis and Sclerotinia sclerotiorum. Among them, compound 9c-7 exhibited the highest antifungal activities against R. solani, R. cerealis and S. sclerotiorum in vitro with IC₅₀ values of 0.013, 1.608 and 1.874 μg/mL, respectively. Notably, compound 9c-7 still presented the highest fungicidal activities against R. solani in vivo with an IC₅₀ value of 22.21 μg/mL. Molecular docking simulation results reveal that compound 9c-7 binds well to the hydrophobic pockets of the receptor protein succinate dehydrogenase. This study suggests that compound 9c-7 could act as a potential fungicide to be used for further optimization.     

Synthesis and biological activities of some fluorine-and piperazine-containing 1,2,4-triazole thione derivatives

A series of fluorine-and piperazine-containing 1,2,4-triazole thione derivatives were synthesized by the Mannich reaction of triazole intermediates with various substituted piperazines and formaldehyde in high yields. Structures of title compounds were confirmed by melting points, IR, ¹H NMR, ¹³C NMR and elemental analysis. The preliminary bioassays for 17 novel title compounds showed that several compounds have significant fungicidal activity against Cercospora arachidicola, Physalospora piricola and Rhizoctonia cerealis at 50μg/mL.     

Design,Synthesis and Antifungal Activity of Novel Thioureas Containing 1,3,4-Thiadiazole and Thioether Skeleton

To find new lead compounds with high antifungal activity, a series of new thiourea derivatives containing 1,3,4-thiadiazole and thioether skeleton was designed via linking the active sub-structures. The target compounds were prepared via three steps from the commercially available thiosemicarbazide. Their structures were characterized by means of HRMS, ¹H NMR, ¹³C NMR and IR spectroscopy. The preliminary results indicate that the title compounds show various antifungal activity against the tested fungi. Compounds 4c, 4g, 4h, 4k, 4n, 4o, 4p, 4q and 4r display excellent antifungal activities against one or more tested fungi with inhibitory efficiencies of 90%-100% at 200 μg/mL. Especially, compound 4o shows the best inhibitory effect against Curvularia lunata, Cotton Fusarium Wilt, P. P. var nicotianae and Fusarium spp. with the EC₅₀ values of 28.12, 30.41, 15.2 and 6.22 μg/mL, respectively, which are even superior to those of triadimefon(98.73, 96.58, 105.37 and 102.18 μg/mL). The preliminary structure-activity relationship indicates that allyl and aromatic groups are favorable to their antifungal activities.     

Synthesis,in vitro antibacterial and antifungal evaluation of novel 1,3,4-oxadiazole thioether derivatives bearing the 6-fluoroquinazolinylpiperidinyl moiety

A series of structurally novel 1,3,4-oxadiazole thioether derivatives(6a-6z) containing a 6-fluoroquinazolinylpiperidinyl moiety were designed and synthesized using pharmacophore hybrid approach,and their structures were fully characterized by ^1H NMR,¹³C NMR and HRMS spectra.Among them,the structure of compound 6 d was further corroborated via single-crystal X-ray diffraction analysis.In vitro antibacterial bioassays showed that compounds 6 a,6 g,6 u and 6 v possessed EC₅₀ values of 30.4,30.6,27.5 and 26.0 μg/mL against phytopathogenic bacterium Xanthomonas oryzae pv.oryzae,respectively,which were significantly superior to that of commercially-available bactericide Bismerthiazol(85.1 μg/mL).Moreover,in vitro antifungal bioassays indicated that seven compounds demonstrated broad-spectrum fungicidal acitivties against six types of phytopathogenic fungi at 50 μg/mL.The present work showed the potential of 1,3,4-oxadiazole thioether derivatives carrying a 6-fluoroquinazolinylpiperidinyl moiety as effective antimicrobial agents for crop protection,deserving further investigations in the future.     

Synthesis and structure-insecticidal activity relationship of novel phenylpyrazole carboxylic acid derivatives containing fluorine moiety

A series of novel phenylpyrazole carboxylic acid derivatives containing fluorine moiety,i.e.,diamides 11,simple aryl-bearing amides 12 and acylthioureas 14 were successfully synthesized based on the key fluo ro-containing phe nylpyrazole acid intermediate.The new compounds were identified and confirmed by melting point,1H NMR,13C NMR and elemental analysis or HRMS.The bioassay results indicated that some of the compounds possessed excellent insecticidal activities towards oriental armyworm,diamondback moth and corn borer at low concentrations.For examples,compounds 11a,11e-g and 14b exhibited remarkable larvicidal activities with LC50 values of 0.13-0.39 mg/L and 0.0002-0.0014 mg/L against oriental armyworm and diamondback moth,respectively,were comparable with those of the control chlorantraniliprole.Particularly,lie were found superior to chlorantraniliprole in oriental armyworm tests(LC50:0.23 mg/L vs.0.26 mg/L);11a,lie,11f and 14c in diamondback moth tests with LC50 values of 0.0002 mg/L,0.0002 mg/L,0.0008 mg/L and 0.0005 mg/L,respectively,we re more effective than that of chlorantraniliprole.In addition,12 a also showed a promising insecticidal potential and development/optimization advantage.Compounds 11a,lle-g,12a,14b and 14c could be considered as possible new leading structures for further study.The SAR investigation indicated that the compounds with fluorine motif(e.g.,-F,-CF2H,-CF3)held apparently favorable insecticidal potentials,which provided useful guidance for further design/development of new phenylpyrazole-containing agrochemicals.     

Synthesis and Antifungal Activities of Novel Strobilurin Derivatives Containing Quinolin-2(1H)-one Moiety

To discover novel lead compounds with better antifungal activities, a series of novel strobilurin derivatives containing quinolin-2(1H)-one moiety was designed and synthesized via intermediate derivatization method. Their structures were characterized by means of ¹H nuclear magnetic resonance(¹H NMR), ¹³C NMR and high resolution mass spectrometry(HRMS). The biological assay results indicate that most target compounds exhibit good to excellent fungicidal activities against 10 plant pathogens. Compounds 4d, 5b and 5c possess 94.1%, 83.8% and 80.9% in vitro inhibition respectively against Rhizotonia cereals at the concentration of 50 μg/mL, which are better than that of the control agents. Especially, the inhibition activities of compound 4d against all of the tested fungi approach or exceed those of the controls. The structure-activity relationship was also discussed.     

Synthesis and Biological Evaluation of Novel Saccharin Derivatives Containing 1,2,3-Triazole Moiety

A series of novel saccharin derivatives containing 1,2,3-triazole moiety was synthesized in satisfactory yields. The structures of all the compounds were elucidated and confirmed by Fourier transform infrared(FTIR) spectroscopy, ¹H and ¹³C nuclear magnetic resonance(¹H NMR, ¹³C NMR) spectroscopy, and high resolution mass spectrometry(HRMS). The bioassays indicated that most of the title compounds displayed some extent herbicidal activities at 100 μg/mL.