Discovery of Cysteine and Its Derivatives as Novel Antiviral and Antifungal Agents

Based on the structure of the natural product cysteine, a series of thiazolidine-4-carboxylic acids were designed and synthesized. All target compounds bearing thiazolidine-4-carboxylic acid were characterized by ¹H-NMR, ¹³C-NMR, and HRMS techniques. The antiviral and antifungal activities of cysteine and its derivatives were evaluated in vitro and in vivo. The results of anti-TMV activity revealed that all compounds exhibited moderate to excellent activities against tobacco mosaic virus (TMV) at the concentration of 500 μg/mL. The compounds cysteine (1), 3–4, 7, 10, 13, 20, 23, and 24 displayed higher anti-TMV activities than the commercial plant virucide ribavirin (inhibitory rate: 40, 40, and 38% at 500 μg/mL for inactivation, curative, and protection activity in vivo, respectively), especially compound 3 (inhibitory rate: 51%, 47%, and 49% at 500 μg/mL for inactivation, curative, and protection activity in vivo, respectively) with excellent antiviral activity emerged as a new antiviral candidate. Antiviral mechanism research by TEM exhibited that compound 3 could inhibit virus assembly by aggregated the 20S protein disk. Molecular docking results revealed that compound 3 with higher antiviral activities than that of compound 24 did show stronger interaction with TMV CP. Further fungicidal activity tests against 14 kinds of phytopathogenic fungi revealed that these cysteine derivatives displayed broad-spectrum fungicidal activities. Compound 16 exhibited higher antifungal activities against Cercospora arachidicola Hori and Alternaria solani than commercial fungicides carbendazim and chlorothalonil, which emerged as a new candidate for fungicidal research.     

Design,Synthesis, and Biological Evaluation of Novel 1,3,4‐Thiadiazolylpyrazolines Compounds Containing Ferrocene

The synthesis of 1,3,4‐thiadiazole skeleton compounds exhibiting high fungicidal activities has been demonstrated. Thirteen novel 1,3,4‐thiadiazolyl‐pyrazolines compounds containing ferrocene were designed and synthesized from the ferrocenylchalcones intermediates 3a – 3m and the 2‐hydrazino‐5‐phenyl‐1,3,4‐thiadiazole intermediate 8 . All compounds were characterized by ¹H NMR, ¹³C NMR, FT‐IR spectra, and HR‐MS, and the structure of one of the new compounds N‐(4‐phenyl‐1,3,4‐thiadiazol‐2‐yl)‐3‐ferrocenyl‐5‐phenyl‐pyrazoline 9a was further determined by X‐ray diffraction analysis. The preliminary results of a biological activity assay indicated that all the title compounds exhibited significant fungicidal activities against Pythium solani, Gibberella saubinetii, and Gibberella nicotiancola. Furthermore, compounds 9e and 9h displayed even higher fungicidal activities against the three fungal species compared with the control drug pyraclostrobin.     

新型含吡唑环的N-甲氧基氨基甲酸甲酯类化合物的设计、合成及生物活性

以苯(吡啶)乙/丙酮类化合物为原料, 经酯化、环化和缩合三步制得新型含吡唑环的N-甲氧基氨基甲酸甲酯类化合物3a~3r, 化合物及其中间体的化学结构经红外光谱、核磁共振谱及元素分析确认. 生物活性结果表明, 化合物3在400 mg/L下分别对水稻稻瘟病、黄瓜霜霉病和小麦白粉病具有很好的防治效果. 对水稻稻瘟病, R₁为甲基或甲氧基取代的苯基时活性最好; 对于黄瓜霜霉病和小麦白粉病, R₁为苯基或甲基取代苯基的化合物杀菌活性优于其它化合物, R₂为甲基的化合物杀菌活性优于R₂为氢的化合物.     

Design,synthesis, and antifungal evaluation of novel coumarin-pyrrole hybrids

A series of coumarin derivatives bearing a pyrrole scaffold were designed, prepared, and assessed for their in vitro antifungal activities against six phytopathogenic fungi. The antifungal activity screening results suggest that some synthesized hybrids exhibited potential fungicidal activities against the tested fungi. In particular, compounds 6j , 6k , 6o , 6p , and 6r displayed significant antifungal effects against Rhizoctorzia solani, and possessed EC₅₀ values of 3.94, 7.75, 6.38, 6.25, and 7.67 μg/ mL, respectively. The above activities are more potent than the commercialized fungicide Boscalid (11.52 μg/mL) and Osthole (9.79 μg/mL). These results provide a significant reference for further rational design of coumarin-based fungicides.     

Design,Synthesis, and Fungicidal Activity of Novel Imidazo[4,5‐b]pyridine Derivatives

A series of novel imidazo[4,5‐b]pyridine derivatives were designed and synthesized. The structures of all the newly synthesized compounds were identified by spectroscopic data NMR, MS, and elemental analysis. Bioassay showed that the compounds exhibited potent fungicidal activities against Erysiphe graminis, Puccinia polysora, and so forth. Particularly, 2‐chloro‐5‐((5‐methoxy‐2‐(2‐(trifluoromethyl)phenyl)‐3H‐imidazo[4,5‐b]pyridin‐3‐yl)methyl)thiazole ( 9b ) displayed fungicidal potency against P. polysora. Its EC₅₀ value: 4.00 mg/L is comparable with that of tebuconazole. The structure–activity relationship for the target compounds is discussed.     

Synthesis and Biological Activities of 3‐Substituted Analogues of Tenuazonic Acid

A series of tenuazonic acid analogues in which the acetyl group was replaced with electron‐withdrawing substituents have been synthesized with the aim of obtaining molecules with various bioactivities. Substituents such as cyano, sulfonyl, and amido were introduced at the 3‐position of the pyrrolidine‐2,4‐dione nucleus of tenuazonic acid. 3‐Cyano and sulfonyl pyrrolidine‐2,4‐dione compounds ( 2 and 6 ) were prepared via a Dieckmann cyclization as key step. 3‐Amido pyrrolidine‐2,4‐dione compounds ( 9 ) were prepared by a microwave‐assisted amidation reaction from corresponding 3‐carboxylate derivative. The target compounds were evaluated; their herbicidal, fungicidal, and insecticidal activities, and the preliminary bioassay data showed that some 3‐cyanopyrrolidine‐2,4‐diones 2 gave good insecticidal activity, whereas some 3‐amido compounds 9 exhibited moderate to strong fungicidal activity against Pythium dissimile at 20 mg/L.     

新型不对称草酰二胺类化合物的设计、合成及生物活性

以氯虫酰胺和氟虫腈骨架结构为基础, 依据生物合理设计思想引入酰胺键活性基团, 设计合成了一系列新型不对称草酰二胺类化合物, 通过核磁共振氢谱和高分辨质谱对合成的化合物进行了结构表征. 初步生物活性测试结果表明, 在浓度为200 mg/L时, 目标化合物未表现出良好的杀粘虫活性, 但具有一定的抑菌活性; 在浓度为50 mg/L时, 化合物6e和6f对番茄早疫病菌的抑菌率为45.0%, 高于其它化合物, 表明含有2,4,6-三氯苯环的该系列化合物对番茄早疫病菌具有良好的抑菌活性; 化合物6g对苹果轮纹病菌的抑菌率为51.9%, 高于其它化合物, 表明含有较大空间位阻的该系列化合物对苹果轮纹病菌具有良好的抑菌活性.     

Design,Synthesis and Biological Evaluation of Novel N‐(4‐([2,2′:5′,2′′‐Terthiophen]‐5‐yl)‐2‐methylbut‐3‐yn‐2‐yl) Benzamide Derivatives

On the basis of the principle of combination of active groups, a series of novel N‐(4‐([2,2′:5′,2′′‐terthiophen]‐5‐yl)‐2‐methylbut‐3‐yn‐2‐yl) benzamide derivatives were designed, synthesized and systematically evaluated for their antiviral activity against tobacco mosaic virus (TMV). The bioassay results showed that most of these compounds displayed good anti‐TMV activity, and some of them exhibited higher antiviral activity than commercial Ningnanmycin. Especially, compound 8e with excellent anti‐TMV activity (inactivation activity, 92.3%/500 µg·mL^?1; curative activity, 85.7%/500 µg·mL^?1 and protection activity, 64.7%/500 µg·mL^?1) emerged as a potential inhibitor of plant virus TMV. Quantitative structure‐activity relationship studies proved that the van der Waals volume (V) and electronic parameter (∑(∑σ_o+σ_p) and ∑σ_m) for the substituent R¹ were very important for antiviral activities in this class of compounds.     

Indole-Based Tubulin Inhibitors: Binding Modes and SARs Investigations

Tubulin inhibitors can interfere with normal cell mitosis and inhibit cell proliferation through interfering with the normal structure and function of microtubules, forming spindle filaments. Indole, as a privileged pharmacological skeleton, has been widely used in anti-cancer inhibitors. A variety of alkaloids containing an indole core obtained from natural sources have been proven to inhibit tubulin polymerization, and an ever-increasing number of synthetic indole-based tubulin inhibitors have been reported. Among these, several kinds of indole-based derivatives, such as TMP analogues, aroylindoles, arylthioindoles, fused indole, carbazoles, azacarbolines, alkaloid nortopsentin analogues and bis-indole derivatives, have shown good inhibition activities towards tubulin polymerization. The binding modes and SARs investigations of synthetic indole derivatives, along with a brief mechanism on their anti-tubulin activity, are presented in this review.     

Synthesis and Fungicidal Activity of Strobilurin Analogues Containing 1,2,4‐Triazole Oxime Ether Moiety

Strobilurins are a class of important agricultural fungicides that are used widely in plant protection. To find new strobilurin analogues with high activity against resistant pathogens, a series of new strobilurin derivatives bearing 1,2,4‐triazole oxime ether side chain 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h were designed and synthesized. Their structures were confirmed by IR, ¹H NMR, EIMS, and elemental analyses. Bioassays indicated that some of the compounds showed good fungicidal activities in the concentration of 50 mg/L. For example, compound 3f possessed 100%, 100%, and 95.5% inhibition against Fusarium omysporum, Physalospora piricola Nose, and Gibberella saubinetii at the concentration of 50 mg/L, respectively.     

Synthesis and Biological Activities of Novel 6‐Alkylamino‐11,12‐dihydro‐11‐arylbenzo[c]phenanthridine Derivatives

A series of novel benzo[c]phenanthridine derivatives 2a , 2b , 2c , 2d , 2e , 2f , 2g , 2h , 2i , 2j , 2k , 2l , 2m and 3a , 3b , 3c , 3d , 3e , 3f bearing an alkylamino side chain at their 6‐position were synthesized. All of the target compounds were confirmed by ¹H NMR, ¹³C NMR, and HRMS, and some of them were also characterized by IR and ¹⁹F NMR. The preliminary bioassays showed that the target compounds displayed fungicidal activities; for example, compound 2l showed 60.0% and 70.0% inhibitive activity against Alternaria solani and Cercospora arachidicola at 50 mg/L, respectively, and some compounds also displayed plant growth‐regulating activities.     

含1,2,3-噻二唑的邻甲酰胺基苯甲酰胺类化合物的合成、晶体结构与生物活性

以取代邻氨基苯甲酸为起始原料, 设计并合成了一系列未见文献报道的含1,2,3-噻二唑的邻甲酰胺基苯甲酰胺类化合物. 所有化合物的结构均经元素分析和1H NMR确证, 并且采用X射线单晶衍射分析方法测定了化合物7g的结构. 初步的生物活性试验结果表明, 部分化合物具有一定的杀菌活性.     

Synthesis,molecular modeling,TD-DFT,antimicrobial, and in vitro therapeutic activity of new spherical nano-sized sulfonamide imine ligands and their zinc (II) and copper (II) complexes

A series of nanometer-sized spherical sulfonamide imine ligands HL ¹ -HL ⁵ and their copper and zinc complexes were synthesized and fully characterized based on elemental analyses, spectroscopic (UV/vis, FT-IR, NMR, EPR, SEM) studies, molar conductance and thermal analyses. Furthermore, computational studies of HL ¹ -HL ⁵ were carried out by the DFT/B3LYP method. TD-DFT, HOMO and LUMO energy values, chemical hardness, electronegativity, electrophilic index, softness, and other parameters were calculated. Screening against several pathogenic microorganisms indicated that HL ¹ exhibited high activity against the tested Gram-negative bacteria relative to other analogues and the inhibition activity is greater than the standard Gentamicin. Analogously, HL ² exhibited high potent activity against the tested Gram-positive bacteria. Copper complexes exhibited a higher potent activity than zinc analogues. Noteworthy, inhibition activity of [Cu ( L ³ )(OAc)] complex is higher than that of the standard Ampicillin. [Cu ( L ² )(OAc)] complex displayed a similar activity of the standard bactericides and fungicides in use. The complexes showed appreciated values of MIC against bacterial strains: B. subtilis (MIC = 0.4 μg / mL), E. coli and S. pneumonia (MIC = 1.95 μg / mL) and P. aeruginosa (MIC = 7.81 μg / mL). in vitro cytotoxic activities study proved that [Cu ( L ³ )(OAc)] complex exhibited appreciable activity versus (HEPG-2); IC₅₀ = 4.8 μg/ml, while [Cu( L ² )(OAc)] complex showed a high activity against (MCF-7); IC₅₀ = 6.2 μg/ml. These results could be considered as new findings of promising antitumor candidates for experimental chemotherapy.     

Design,synthesis, and anti-TMV bioactivities of nucleobase phosphonate analogs

A series of novel nucleobase derivatives and their analogues possessing diethoxyphosphoryl scaffolds were synthesized through four-step reactions and screened for their antiviral activity toward tobacco mosaic virus (TMV). Preliminary bioassays suggested that some of these simple structures displayed appreciable anti-TMV activity in vivo. Among them, compound (diethoxyphosphoryl)methyl 4-[2-(1H-benzo[d][1,2,3]triazol-1-yl)acetamido]-benzoate (a-3) exerted the strongest chemotherapeutic and protective effects against TMV with the rates of 52.8 and 72.2% at the dosage of 500 µg/mL, respectively, which were comparable with those of the commercial agricultural antiviral agent ningnanmycin (54.2 and 70.2%). Molecular docking with TMV helicases revealed that compound a-3 had strong interactions with receptor amino acid residues. Given the facile synthetic route and significant chemotherapeutic and protective potentials, compound a-3 could be further studied and exploited as a promising antiviral candidate.     

Synthesis and antiviral evaluation of some carbonucleoside analogues

1,2‐O‐Isopropylidene‐α‐L‐threofuranosyl heterocyclic derivatives were synthesized from 1,2‐O‐iso‐propylidene‐α‐D‐xilopentadialdo‐1,4‐furanose and tested for antiviral activity against herpes simplex virus type 1, dengue virus type 2 and Junin virus. For comparative propose, the antiviral activity of some of their pyranosyl analogues were also tested. The furanosyl derivatives showed to be moderate inhibitors of Junin virus and, in general, proved to be more effective than the pyranosyl analogues.     

Synthesis and antiviral evaluation of novel N-6 substituted adenosine analogues

A series of adenosine analogues were synthesized and their biological evaluation was tested against Coxsackie virus B3 (CVB3) and Herpes simplex virus type 1(HSV-1) in HEp-2 cells. The hydrophobic constant, acute toxicity, carcinogenicity and mutagenicity were calculated. Analogues with piperazine derivatives 8b showed promising activities against CVB3 with a lower IC₅₀value and higher selectivity index, their efficacy was better than that of the commercialized medicine, Ribavirin. These described adenosine analogues exhibit potent antiviral activities against several viruses, and offer new leads for further development.     

Experimental, theoretical and biological activity study on 1-(4,5-dihydro-3-arylpyrazol-1-yl)-2-(1H-1,2,4-triazol-1-yl)-ethanone

Four compounds have been synthesized and characterized by¹H NMR spectroscopy and elemental analyses, among which 1-(4,5-dihydro-3-phenyl-pyrazol-1-yl)-2-(1H-1,2,4-triazol-1-yl)ethanone 3a was further confirmed by X-ray crystallographic analysis. The biological activities of these compounds were tested, with the result that they displayed moderate fungicidal activities. In addition, a MO calculations using density functional theory (DFT) at B3LYP/6-31G^* level have also been carried out, and the structure–activity relationships for these compounds are discussed.     

Synthesis and Fungicidal Activity of 2-Acetyl-6-(un)substituted-1 H-benzimidazole Oxime-ethers

Twelve novel compounds of 2‐acetyl‐1H‐benzimidazole oxime‐ethers and 2‐acetyl‐6‐chloro‐1H‐benzimidazole oxime‐ethers were synthesized with o‐phenylenediamine (or 4‐chloro‐o‐phenylenediamine), 2‐hydroxypropyl acid, alkoxy (or benzyloxy) amines hydrochloride as starting materials. The structures of the target compounds were characterized by IR, ¹H NMR spectra and elemental analyses. The in vitro fungicidal activities against Botrytis cinerea Pers and Alternaria alternata were also evaluated by mycelium growth rate method. The results indicate that the compounds 3b , 3c , 3f , 3g and 3h exhibit good activities against Botrytis cinerea Pers, while 3b and 3f possess excellent activities against Alternaria alternate, and their fungicidal activities are all higher than that of carbendazim.     

Synthesis,Crystal Structure,Antifungal Activity,and Docking Study of Difluoromethyl Pyrazole Derivatives

Nine novel difluoromethylpyrazole acyl urea derivatives were synthesized via seven steps conveniently. All the structures were determined by ¹H‐NMR, ¹³C‐NMR, HRMS, and X‐ray diffraction. The in vivo fungicidal activities were determined against Corynespora mazei, Botrytis cinerea, Fusarium oxysporum, and Pseudomonas syringae, respectively. The bioassay results indicated that some of them displayed good control effective (around 50 and 80%) against P. syringae and B. cinerea at 50 mg/L, respectively, which is better than control. It is possible that difluoromethylpyrazole acyl urea derivatives can be a leading compound for the development of new fungicides against the two fungi with further structure optimization. Furthermore, docking model was studied to establish structure–activity relationship of difluoromethylpyrazole acyl urea derivatives.     

Synthesis and fungicidal activity of 1,3,4-oxadiazol-2-yl thioether derivatives containing a phenazine-1-carboxylic acid scaffold

To find new higher fungicidal activities lead compounds and develop new eco-friendly agrochemicals, natural product phenazine-1-carboxylic acid (PCA) as scaffold, a series of 1,3,4-oxadiazol-2-yl thioether derivatives was synthesized and bio-assayed. The results reveal that most target compounds possessed moderate to good fungicidal activities against R. solani, S. sclerotioru and P. oryzac Cavgra. Compounds 6n and 6o exhibit more than 90% bioactivity against S. sclerotioru. The EC₅₀ value of compounds 6n and 6o are 11.16 and 30.47?μM respectively, in particular, compound 6n show equal activity against S. sclerotioru to PCA (10.49?μM). This result provides a valuable lead compound for further studies.