Design, Synthesis, Nematicidal Evaluation, and Molecular Docking Study of Pyrano[3,2-c]pyridones against Meloidogyne incognita.

Root-knot nematodes pose a serious threat to crops by affecting production and quality. Over a period of time, substantial work has been done toward the development of effective and environmentally benign nematicidal compounds. However, due to the inefficiencies of previously reported synthetics in achieving the target of safe, selective, and effective treatment, it is necessary to develop new efficacious and safer nematicidal agents considering human health and environment on top priority. This work aims to highlight the efficient and convenient l-proline catalyzed synthesis of pyrano[3,2-c]pyridone and their use as potential nematicidal agents. In vitro results of larval mortality and egg hatching inhibition revealed maximum nematicidal activity against Meloidogyne incognita from compounds 15b, 15m, and 15w with LC50 values of 28.8, 46.8, and 49.18 µg/mL at 48 h, respectively. Under similar conditions, pyrano[3,2-c]pyridones derivatives 15b (LC50 = 28.8 µg/mL) was found at par with LC50 (26.92 µg/mL) of commercial nematicide carbofuran. The in vitro results were further validated with in silico studies with the most active compound 15b nematicidal within the binding to the pocket of acetylcholine esterase (AChE). In docking, binding free energy values for compound 15b were found to be -6.90 kcal/mol. Results indicated that pyrano[3,2-c]pyridone derivatives have the potential to control M. incognita.

Synthesis, in vitro antiurease, in vivo antinematodal activity of quinoline analogs and their in-silico study.

Synthesis of quinoline analogs and their urease inhibitory activities with reference to the standard drug, thiourea (IC50 = 21.86 ± 0.40 µM) are presented in this study. The inhibitory activity range is (IC50 = 0.60 ± 0.01 to 24.10 ± 0.70 µM) which displayed that it is most potent class of urease inhibitor. Analog 1-9, and 11-13 emerged with many times greater antiurease potential than thiourea, in which analog 1, 2, 3, 4, 8, 9, and 11 (IC50 = 3.50 ± 0.10, 7.20 ± 0.20, 1.30 ± 0.10, 2.30 ± 0.10, 0.60 ± 0.01, 1.05 ± 0.10 and 2.60 ± 0.10 µM respectively) were appeared the most potent ones among the series. In this context, most potent analogs such as 1, 3, 4, 8, and 9 were further subjected for their in vitro antinematodal study against C. elegans to examine its cytotoxicity under positive control of standard drug, Levamisole. Consequently, the cytotoxicity profile displayed that analogs 3, 8, and 9 were found with minimum cytotoxic outline at higher concentration (500 µg/mL). All analogs were characterized through 1H NMR, 13C NMR and HR-EIMS. The protein-ligand binding interaction for most potent analogs was confirmed via molecular docking study.

Design, synthesis and nematicidal activitives of trifluorobutene amide derivatives against Meloidogyne incognita.

Plant parasitic nematodes have always been a pressing problem in the field of plant protection. Well-established chemical nematicides, especially organophosphorus and carbamates are the most used products for nematode control worldwide. Due to long-term overuse, they have developed serious resistance and new innovative solutions are urgently required. In this study, thirty-one novel trifluorobutene amide derivatives were designed and synthesized, and their nematicidal activities were determined. Three different synthetic methods have been developed for the final amidation reaction enabling the successfully syntheses of the target compounds independently from the nucleophilicities of the substrate amino group. Most target compounds showed good nematicidal activity in our in vitro test. Among all the compounds, compounds A8 and A23 exhibited excellent nematicidal activity against Meloidogyne incognita, their LC50 values are 2.02 mg L-1 and 0.76 mg L-1, respectively. In particular, compound A23 has found to be almost as active as the commercial nematicide fluensulfone. Furthermore, most compounds gave full control (100% inhibition) of M. incognita at 40 mg L-1 in the in vivo tests in sandy soil, the best compounds were further investigated for in vivo activity in matrix soil. Among the compound tested, compound A8 showed excellent in vivo nematicidal activity. At a concentration of 5 mg L-1 still 56% inhibition was observed. The results of our study indicate that compound A8 possesses excellent in vitro and in vivo nematicidal activity, and can be considered as promising lead molecule for further modification.

Microwave assisted synthesis, characterization and biological activities of ferrocenyl chalcones and their QSAR analysis: Part II.

A series of ferrocenyl chalcones using acetylferrocene, with ferrocenyl group at the keto carbonyl group, and different aldehydes were synthesized and their bioefficacy evaluation was done against Sclerotium rolfsii, Alternaria solani and Meloidogyne incognita. In continuation of our quest for potent crop protection products, in the present study, a series of 18 substituted ferrocenyl chalcones were synthesized in which ferrocenyl group was attached to the aldehyde moiety, using ferrocenecarboxyaldehyde and different acetophenones by microwave method (MM) and conventional method (CM) [cf: MM 1 to 5 min; CM 12-40 h] and characterized by various techniques viz. IR, LC-HRMS, 1H-NMR and 13C-NMR. In vitro fungicidal activity showed that compound, (2E)-1-(5-Chloro-2-hydroxyphenyl)-3-ferrocenyl-prop-2-en-1-one (34) (ED50 = 21.50 mg L-1) was found to be most active against S. rolfsii and compound, (2E)-1-(4-Bromophenyl)-3-ferrocenyl-prop-2-en-1-one (21) (ED50 = 31.14 mg L-1) showed highest activity against A. solani. As regards nematicidal activity, compound (2E)-1-(3-Bromophenyl)-3-ferrocenyl-prop-2-en-1-one (29) was more potent with LC50 values of 11.95, 8.07 and 4.34 mg L-1 at 24, 48 and 72 h, respectively. QSAR study revealed that MLR for S. rolfsii (r 2 = 0.9834, q 2= 0.8975) and A. solani (r 2 = 0.9807, q 2= 0.8713) and PLS for M. incognita (r 2 = 0.9023, q 2= 0.7818) were the best models.

Recent advances on synthesis and biological activities of aurones.

Aurones are naturally occurring structural isomerides of flavones that have diverse bioactivities including antiviral, antibacterial, antifungal, anti-inflammatory, antitumor, antimalarial, antioxidant, neuropharmacological activities and so on. They constitute an important class of pharmacologically active scaffolds that exhibit multiple biological activities via diverse mechanisms. This review article provides an update on the recent advances (2013-2020.4) in the synthesis and biological activities of these derivatives. In the cases where sufficient information is available, some important structure-activity relationships (SAR) of their biological activities were presented, and on the strength of our expertise in medicinal chemistry and careful analysis of the recent literature, for the potential of aurones as medicinal drugs is proposed.

Chemical Nematicides: Recent Research Progress and Outlook.

Plant-parasitic nematodes have caused huge economic losses to agriculture worldwide and seriously threaten the sustainable development of modern agriculture. Chemical nematicides are still the most effective means to manage nematodes. However, the long-term use of organophosphorus and carbamate nematicides has led to a lack of field control efficacy and increased nematode resistance. To meet the huge market demand and slow the growth of resistance, new nematicides are needed to enter the market. The rational design and synthesis of new chemical scaffolds to screen for new nematicides is still a difficult task. We reviewed the latest research progress of nematicidal compounds in the past decade, discussed the structure-activity relationship and mechanism of action, and recommended some nematicidal active fragments. It is hoped that this review can update the recent progress on nematicide discoveries and provide new ideas for the design and mechanism of action studies of nematicides.

Synthesis, bioevaluation and docking studies of some 2-phenyl-1H-benzimidazole derivatives as anthelminthic agents against the nematode Teladorsagia circumcincta.

Gastrointestinal nematode infections are the main diseases in herds of small ruminants. Resistance to the main established drugs has become a worldwide problem. The purpose of this study is to obtain and evaluate the in vitro ovicidal and larvicidal activity of some 2-phenylbenzimidazole derivatives on susceptible and resistant strains of Teladorsagia circumcincta. Compounds were prepared by known procedures from substituted o-phenylenediamines and arylaldehydes or intermediate sodium 1-hydroxyphenylmethanesulfonate derivatives. Egg Hatch Test (EHT), Larval Mortality Test (LMT) and Larval Migration Inhibition Test (LMIT) were used in the initial screening of compounds at 50 µM concentration, and EC50 values were determined for the most potent compounds. Cytotoxicity evaluation of compounds was conducted on human Caco-2 and HepG2 cell lines to calculate their Selectivity Indexes (SI). At 50 µM concentration, nine out of twenty-four compounds displayed more than 98% ovicidal activity on a susceptible strain, and four of them showed more than 86% on one resistant strain. The most potent ovicidal benzimidazole (BZ) 3 showed EC50 = 6.30 µM, for the susceptible strain, while BZ 2 showed the lowest EC50 value of 14.5 µM for the resistant strain. Docking studies of most potent compounds in a modelled Teladorsagia tubulin indicated an inverted orientation for BZ 1 in the colchicine binding site, probably due to its fair interaction with glutamic acid at codon 198, which could justify its inactivity against the resistant strain of T. circumcincta.

Synthesis and nematicidal activities of 1,2,3-benzotriazin-4-one derivatives containing benzo[d][1,2,3]thiadiazole against Meloidogyne incognita.

Based on the characteristic of benzo[d][1,2,3]thiadiazole to induce the systemic acquired resistance and improve the immunity of plants, benzo[d][1,2,3]thiadiazole was introduced into 1,2,3-benzotriazin-4-one, thirty-one novel 1,2,3-benzotriazin-4-one derivatives containing benzo[d][1,2,3]thiadiazole were designed and synthesized. Nematicidal activity showed that most of the synthesized compounds exhibited great inhibitory activity in vivo against Meloidogyne incognita at 20 mg/L. Among 31 tested compounds, A2 and A3 showed an excellent nematicidal activity with the inhibition rate of 50.4% and 53.1% at the concentration of 1.0 mg/L, respectively. The influence of substituent type and position was investigated. The relationship between structure and activity was also preliminary analyzed.

Synthesis and Anthelmintic Activity of New Thiosemicarbazide Derivatives-A Preliminary Study.

Parasitic infections caused by different species of intestinal helminths still poses a threat to public health. There is a need to search for new, effective anthelmintic drugs. A series of novel thiosemicarbazides were synthesized and evaluated for their in vitro anthelmintic activity. The preliminary results showed that the most of synthesized compounds were very active. 4-Phenyl-1-[(1-methyl-4-nitroimidazol-2-yl)carbonyl]thiosemicarbazide and 4-(3-chlorophenyl)-1-[(1-methyl-4-nitroimidazol-2-yl)carbonyl]thiosemicarbazide showed a 100% mortality of nematodes and a high anthelmintic activity in both tested concentrations.

Synthesis and Antibacterial Evaluation of N-phenylacetamide Derivatives Containing 4-arylthiazole Moieties.

A series of new N-phenylacetamide derivatives containing 4-arylthiazole moieties was designed and synthesized by introducing the thiazole moiety into the amide scaffold. The structures of the target compounds were confirmed by 1H-NMR, 13C-NMR and HRMS. Their in vitro antibacterial activities were evaluated against three kinds of bacteria-Xanthomonas oryzae pv. Oryzae (Xoo), Xanthomonas axonopodis pv. Citri (Xac) and X.oryzae pv. oryzicola (Xoc)-showing promising results. The minimum 50% effective concentration (EC50) value of N-(4-((4-(4-fluoro-phenyl)thiazol-2-yl)amino)phenyl)acetamide (A1) is 156.7 µM, which is superior to bismerthiazol (230.5 µM) and thiodiazole copper (545.2 µM). A scanning electron microscopy (SEM) investigation has confirmed that compound A1 could cause cell membrane rupture of Xoo. In addition, the nematicidal activity of the compounds against Meloidogyne incognita (M. incognita) was also tested, and compound A23 displayed excellent nematicidal activity, with mortality of 100% and 53.2% at 500 µg/mL and 100 µg/mL after 24 h of treatment, respectively. The preliminary structure-activity relationship (SAR) studies of these compounds are also briefly described. These results demonstrated that phenylacetamide derivatives may be considered as potential leads in the design of antibacterial agents.

Novel amide derivatives containing 1,3,4-thiadiazole moiety: Design, synthesis, nematocidal and antibacterial activities.

A series of novel amide derivatives containing 1,3,4-thiadiazole moiety were synthesized and their bioactivities were evaluated. The compound 34 exhibited good nematocidal activities against Meloidogyne incognita in vitro and in vivo, the LC50 value and control effect were 6.5 mg/L and 83.3%, respectively. Meanwhile, it exhibited exciting antibacterial activities against Xanthomonas oryzae pv. oryzae, Xanthomonas campestris pv. citri, and Ralstonia solanacearum, the EC50 values were 0.4, 6.7 and 5.1 mg/L, respectively, which were better than positive controls. The curative and protection activities under the greenhouse conditions of compound 34 against rice bacterial blight were 47.9 and 55.8%, respectively. The structure-activity relationship were analyzed in detail.

Design, synthesis, and insecticidal activity evaluation of novel 4-(N, N-diarylmethylamines)furan-2(5H)-one derivatives as potential acetylcholine receptor insecticides.

BACKGROUND: Flupyradifurone is a member of a novel class of insecticides that possess excellent insecticidal activities. Halogen-containing phenyl groups are important and indispensable structural components of many pesticides. However, replacement of the difluoromethyl group of flupyradifurone with halogen-containing phenyl groups has not been reported. Hence, a series of novel butenolide derivatives containing phenyl groups were synthesized and bioassayed to discover novel compounds with excellent insecticidal activities. RESULTS: Some target molecules exhibited good insecticidal activities against Aphis craccivora. Among the title compounds, 4cc showed the best insecticidal activities with an 50% lethal concentration (LC50 ) value of 1.72 µg mL-1 , which is superior to that of pymetrozine (LC50  = 6.86 µg mL-1 ). Molecular docking indicated that 4cc lacks oxidative metabolism by CYP6CM1 and metabolic resistance with imidacloprid. Furthermore, label-free quantitative proteomic analysis indicated that 4cc may be a potential acetylcholine receptor insecticide that acts on the nicotinic acetylcholine receptor. Compound 4cc also decreased the capability for oxidative metabolism, which further supported the molecular docking results. CONCLUSION: This work can be used to further investigate the mechanism underlying the insecticidal activity of butenolide derivatives and develop potential novel butenolide insecticides. © 2018 Society of Chemical Industry.

Synthesis, characterization and SAR of novel Bezimidazole derivatives as Nematicidal agents.

Six novel analogues were prepared by reacting benzimidazole molecules (BM and CMB) propiophenone and benzoyl chlorides respectively. The structures of newly synthesized compounds were determined with the help of spectroscopic techniques. The compounds were subjected to in-vitro screening for their activity against nematodes. It was observed that the benzimidazole (BM) derivatives possessed more nematicidal activity as compared to that of cyanomethyl-benzimidazole (CMB) for Meloidogyne incognita. Among them, the propiophenone substituted benzimidazole derivative B3 was found to be the most active compound and can be further studied as lead molecule for development of anthelmintic drugs.

Novel bisthioether derivatives containing a 1,3,4-oxadiazole moiety: design, synthesis, antibacterial and nematocidal activities.

BACKGROUND: The literature shows that bisthioether and 1,3,4-oxadiazole derivatives exhibit a wide variety of biological activities. In this study, a series of novel bisthioether derivatives containing a 1,3,4-oxadiazole moiety were synthesized and their antibacterial and nematocidal activities investigated. RESULTS: Among the title compounds evaluated, compound 4f demonstrated the best antibacterial activities against rice bacterial leaf blight, rice bacterial leaf streak and citrus canker caused by Xanthomonas oryzae pv. oryzae (Xoo), Xanthomonas oryzae pv. oryzicola (Xoc) and Xanthomonas axonopodis pv. citri (Xac), with EC50 values of 4.82, 11.15 and 16.57 µg mL-1 , respectively, which were even better than those of thiodiazole copper and bismerthiazol. Meanwhile, compound 4f had better in vitro nematocidal activity against Caenorhabditis elegans at 48 h, with an LC50 value of 2.89 µg mL-1 , which was superior to those of ethoprophos and fosthiazate. In addition, greenhouse trials indicated that compound 4f was effective in reducing rice bacterial leaf blight relative to thiodiazole copper and bismerthiazol. CONCLUSION: A series of novel bisthioether derivatives containing a 1,3,4-oxadiazole moiety were synthesized and bioassay results showed that compound 4f exhibited the best antibacterial and nematocidal activities. © 2017 Society of Chemical Industry.

Synthesis and nematicidal activities of 1,2,3-benzotriazin-4-one derivatives containing thiourea and acylthiourea against Meloidogyne incognita.

Two series of novel 1,2,3-benzotriazin-4-one derivatives containing thiourea and acylthiourea were designed and synthesized. The bioassay results showed that most of the test compounds showed good nematicidal activity against M. incognita at the concentration of 10.0mgL-1in vivo. The compounds A13, A17 and B3 showed excellent nematicidal activity on the second stage juveniles of the root-knot nematode with the inhibition rate of 51.3%, 58.3% and 51.3% at the concentration of 1.0mgL-1 respectively. It suggested that the structure of 1,2,3-benzotriazin-4-one derivatives containing thiourea and acylthiourea could be optimized further.

Recent synthetic and medicinal perspectives of dihydropyrimidinones: A review.

Dihydropyrimidines are the most important heterocyclic ring systems which play an important role in the synthesis of DNA and RNA. Synthetically they were synthesized using Multi-component reactions like Biginelli reaction and Hantzschdihydropyridine. In the past decades, such Biginelli type dihydropyrimidones have received a considerable amount of attention due to the interesting pharmacological properties associated with this heterocyclic scaffold. In this review, we highlight recent developments in this area, with a focus on the DHPMs, recently developed as anti-inflammatory, anti-HIV, anti-tubercular, antifungal anticancer, antibacterial, antifilarial, antihyperglycemic, antihypertensive, analgesic, anti-convulsant, antioxidant, anti-TRPA1, anti-SARS, and anti-cancer activity and α1a binding affinity.

Phytoalexin Phenalenone Derivatives Inactivate Mosquito Larvae and Root-knot Nematode as Type-II Photosensitizer.

Phytoalexins phenalenones (PNs) are phytochemicals biosynthesized inside the plant in responsive to exterior threat. PNs are excellent type-II photosensitizers, which efficiently produce singlet oxygen upon light irradiation. Based on the core functional structure of PNs, novel PN derivatives were synthesized here and their singlet oxygen generating abilities and their phototoxicity were evaluated. At the presence of light, these PNs have photoinduced toxicity towards Aedes albopictus larvae and nematode Meloidogyne incognita, while the activity lost in the dark. The obvious tissue damage was observed on the treated mosquito larvae and nematode due to the generation of singlet oxygen. Our results revealed the potential of phenalenones as photoactivated agents for mosquito and root-knot nematode management together with light.

Synthesis, biological activities and structure-activity relationships for new avermectin analogues.

In an effort to discover new molecules with good insecticidal activities, more than 40 new avermectin derivatives were synthesized and evaluated for their biological activities against three species of arachnids, insects and nematodes, namely, Tetranychus Cinnabarinus, Aphis craccivora and Bursaphelenchus xylophilus. All the tested compounds showed potent inhibitory activities against three insect species. Notably, the majority of compounds exhibited high selectivity against T. cinnabarinus, some of which were much better in comparison with avermectin. Especially compounds 9j (LC50: 0.005 µM) and 16d (LC50: 0.002 µM) were 2.5- and 4.7-fold more active than avermectin (LC50: 0.013 µM), respectively, against T. cinnabarinus. Moreover, compounds 9b, 9d-f, 9h, 9j, 9l, 9n, 9p, 9r, 9v and 17d showed superior activities with LC50 values of 2.959-5.013 µM compared to that of 1 (LC50: 6.746 µM) against B. xylophilus. Meanwhile, the insecticidal activities of compounds 9f, 9g, 9h, and 9m against A. craccivora were 7-8 times better than that of avermectin, with LC50 values of 7.744, 5.634, 6.809, 7.939 and 52.234 µM, respectively. Furthermore, QSAR analysis showed that the molecular shape, size, connectivity degree and electronic distribution of avermectin analogues had substantial effects on insecticidal potency. These preliminary results provided useful insight in guiding further modifications of avermectin in the development of potential new insecticides.

Synthesis, nematocidal activity and docking study of novel chiral 1-(3-chloropyridin-2-yl)-3-(trifluoromethyl)-1H-pyrazole-4-carboxamide derivatives.

A series of novel chiral fluorinated pyrazole carboxamides derivatives were designed and synthesized. All these title compounds were confirmed by NMR and MS. The primarily nematocidal activity results indicated that some of them exhibited good control efficacy against the tomato root-knot nematode disease caused by Meloidogyne incognita. The docking results indicated that compound 5n interact with amino acid residue Tyr 121, Trp 279 of AchE via hydrogen bond.

Synthetic approaches to the 2010-2014 new agrochemicals.

In this review, the synthesis of 30 agrochemicals that received an international standardization organization (ISO) name during the last five years (January 2010 to December 2014) is described. The aim is to showcase the range and scope of chemistries used to discover or produce the latest active ingredients addressing the crop protection industry's needs.