Novel hydrazone derivatives containing pyridine amide moiety: Design, synthesis, and insecticidal activity

Modulation of Distribution and Diffusion through the Lipophilic Membrane with Cyclodextrins Exemplified by a Model Pyridinecarboxamide Derivative

The main aims of the study were to disclose the influence of the structure on the solubility, distribution and permeability of the parent substances, iproniazid (IPN), isoniazid (INZ) and isonicotinamide (iNCT), at 310.2 K and to evaluate how the presence of cyclodextrins (2-hydroxypropyl-β-cyclodextrin (HP-β-CD) and methylated β-cyclodextrin (M-β-CD)) affects the distribution behavior and diffusion properties of a model pyridinecarboxamide derivative, iproniazid (IPN). The following order of decreasing the distribution and permeability coefficients was estimated: IPN > INZ > iNAM. A slight reduction of the distribution coefficients in the 1-octanol/buffer pH 7.4 and n-hexane/buffer pH 7.4 systems (more pronounced in the first system) was revealed. The extremely weak IPN/cyclodextrins complexes were estimated from the distribution experiments: K_C(IPN/HP-β-CD) > K_C(IPN/M-β-CD). The permeability coefficients of IPN through the lipophilic membrane-the PermeaPad barrier-were also measured with and without cyclodextrins in buffer solution. Permeability of iproniazid was increased in the presence of M-β-CD and reduced by HP-β-CD.

Comprehensive Overview of Diamide Derivatives Acting as Ryanodine Receptor Activators

The world's hunger is continuously rising due to conflicts, climate change, pandemics (such as the recent COVID-19), and crop pests and diseases. It is widely accepted that zero hunger is impossible without using agrochemicals to control crop pests and diseases. Diamide insecticides are one of the widely used green insecticides developed in recent years and play important roles in controlling lepidopteran pests. Currently, eight diamine insecticides have been commercialized, which target the insect ryanodine receptors. This review summarizes the development and optimization processes of diamide derivatives acting as ryanodine receptor activators. The review also discusses pest resistance to diamide derivatives and possible solutions to overcome the limitations posed by the resistance. Thus, with reference to structural biology, this study provides an impetus for designing and developing diamide insecticides with improved insecticidal activities.

Design, Synthesis, and Bioactivity Evaluation of Novel Isoxazole-Amide Derivatives Containing an Acylhydrazone Moiety as New Active Antiviral Agents

As a continuation of our efforts to discover and develop "me-better" active molecules, in this study, a series of novel isoxazole-amide derivatives containing an acylhydrazone moiety were synthesized and evaluated for their antiviral activities against tobacco mosaic virus (TMV) and cucumber mosaic virus (CMV). Antiviral bioassays indicated that some of the target compounds exhibited better in vivo antiviral activities against TMV and CMV than those of Ningnanmycin (NNM). Especially, the compound 7t exhibited the best curative, protection, and inactivation activities against TMV and CMV which were superior to those of NNM. Meanwhile, our present work also revealed that compound 7t could enhance the defense-related enzyme activity and increase the chlorophyll content in tobacco leaves to induce resistance and enhance plant tolerance to TMV infection.

Abdel-Raheem SA. Design, Synthesis, Characterization, and Insecticidal Bioefficacy Screening of Some New Pyridine Derivatives

A lot of insecticides are found nowadays, but neonicotinoids are considered the most famous. So, a series of pyridine derivatives neonicotinoids analogues, namely, 3-cyano-4,6-dimethylpyridine-2(1H)-one (1), 2-chloro-3-cyano-4,6-dimethylpyridine (2), 3-cyano-4,6-dimethylpyridine-2(1H)-thione (3), 3-cyano-4,6-distyrylpyridine-2(1H)-thione (4), 2-((3-cyano-4,6-distyrylpyridin-2-yl)thio)-N-phenylacetamide (5), 3-amino-N-phenyl-4,6-distyrylthieno[2,3-b]pyridine-2-carboxamide (6), 2-((3-cyano-4,6-distyrylpyridin-2-yl)thio)-N-(p-tolyl)acetamide (7), 3-amino-4,6-distyryl-N-(p-tolyl)thieno[2,3-b]pyridine-2-carboxamide (8), 2-((3-cyano-4,6-distyrylpyridin-2-yl)thio)-N-(4-methoxyphenyl)acetamide (9), and 3-amino-N-(4-methoxyphenyl)-4,6-distyrylthieno[2,3-b]pyridine-2-carboxamide (10), have been designed and synthesized in pure state, and their agricultural bioefficacy as insecticides against cowpea aphid Aphis craccivora Koch was screened. The structures of the synthesized compounds were verified by means of spectroscopic and elemental analyses. Insecticidal bioefficacy data illustrated that some compounds are excellent against cowpea aphid, and the bioefficacy of the rest of the tested compounds ranged from good to moderate against the same insects.

Chemical design and toxicity evaluation of new pyrimidothienotetrahydroisoquinolines as potential insecticidal agents

Neonicotinoids are the most widely used from all existing pesticides. So, in purpose to discover new pesticides being more effective against the aphid, twelve heterocyclic compounds neonicotinoid analogs have been prepared in a pure state; pyrimidothienotetrahydroisoquinolines 1-12 and their toxicity as potential insecticidal agents against cowpea Aphid, Aphis craccivora Koch was screened. Their characterizations by using spectroscopic analyses were performed. The toxicity data exhibited that the 8-chloropyrimidine compound 4 is more toxic about 2-fold than a reference insecticide, acetamiprid. The other screened compounds showed weak to strong toxicological activities against cowpea aphid.

Synthesis and biological activities of novel pyrazolomatrine derivatives

In continuation of our program aimed at the development of new natural product-based pesticides, a series of novel pyrazolomatrine derivatives were prepared by structural modifications of matrine, isolated as a quinolizidine alkaloid from the roots of Sophora flave. Their structures were confirmed by ¹H NMR, HRMS, etc. Moreover, the steric structures of three compounds were determined by single-crystal X-ray diffraction. Among all derivatives, 19-(naphthyl-2-oyl)pyrazolomatrine (5y) showed 3.13-fold more potent acaricidal activity than its precusor matrine against Tetranychus cinnabarinus; 19-(4-methylbenzoyl)pyrazolomatrine (5j) and 19-(3,5-dimethylbenzoyl)pyrazolomatrine (5k) displayed the promising aphicidal activity against Aphis citricola van der. Their structure-activity relationships were also observed.

Synthesis of Piperine Analogs Containing Isoxazoline/Pyrazoline Scaffold and Their Pesticidal Bioactivities

In continuation of our program to discover new potential pesticidal agents, thirty-one piperine analogs containing isoxazoline/pyrazoline scaffold were prepared, and confirmed by infrared spectra, proton/carbon-13 nuclear magnetic resonance spectra, and high-resolution mass spectra. The structures of compounds VIIb and VIIIc were further determined by ¹H-¹H COSY spectra. Especially the configuration of compound VIIIc was unambiguously confirmed by single-crystal X-ray diffraction. Their pesticidal activities were evaluated against three serious and typically crop-threatening agricultural pests, Tetranychus cinnabarinus Boisduval (spider mite), Mythimna separata Walker (Oriental armyworm), and Plutella xylostella Linnaeus (diamondback moth). Compounds VIIIb and VIIIc exhibited greater than 40-fold more potent acaricidal activity than the lead compound piperine against T. cinnabarinus. Notably, compounds VIa-c exhibited more pronounced oral toxicity against P. xylostella than toosendanin; compounds VIb and VIc displayed more promising growth inhibitory activity against M. separata than toosendanin. It demonstrated that the methylenedioxy and isoxazoline scaffolds were important for the oral toxicity and growth inhibitory activity against P. xylostella and M. separata, respectively; the ethylenedioxy and isoxazoline scaffolds were vital for the acaricidal activity against T. cinnabarinus. Moreover, compounds VIb, VIIf, and VIIIc showed very low toxicity against NRK-52E cells.

Novel Pyrazole-Hydrazone Derivatives Containing an Isoxazole Moiety: Design, Synthesis, and Antiviral Activity

In this study, a series of novel pyrazole-hydrazone derivatives containing an isoxazole moiety were synthesized. Antiviral bioassays indicated that some of the title compounds exhibited better in vivo antiviral activities against tobacco mosaic virus (TMV). In particular, compounds 6a, 6c and 6q exhibited the best curative activity, protection activity, and inactivation activity against TMV, respectively, which were superior to those of Ningnanmycin. This study demonstrated that this series of novel pyrazole-hydrazone derivatives containing an isoxazole amide moiety could effectively control TMV.

Design and synthesis of novel 3-(thiophen-2-yl)-1,5-dihydro-2H-pyrrol-2-one derivatives bearing a hydrazone moiety as potential fungicides

BACKGROUND

Tetramic acid, thiophene and hydrazone derivatives were found to exhibit favorable antifungal activity. Aiming to discover novel template molecules with potent antifungal activity, a series of novel 3-(thiophen-2-yl)-1,5-dihydro-2H-pyrrol-2-one derivatives containing a hydrazone group were designed, synthesized, and evaluated for their antifungal activity.

RESULTS

The structures of 3-(thiophen-2-yl)-1,5-dihydro-2H-pyrrol-2-one derivatives bearing a hydrazone group were confirmed by FT-IR, 1H NMR, 13C NMR, 1H-1H NOESY, EI-MS and elemental analysis. Antifungal assays indicated that some title compounds exhibited antifungal activity against Fusarium graminearum (Fg), Rhizoctorzia solani (Rs), Botrytis cinerea (Bc) and Colletotrichum capsici (Cc) in vitro. Strikingly, the EC50 value of 5e against Rs was 1.26 µg/mL, which is better than that of drazoxolon (1.77 µg/mL). Meanwhile, title compounds 5b, 5d, 5e-5g, 5n-5q and 5t exhibited remarkable anti-Cc activity, with corresponding EC50 values of 7.65, 9.97, 6.04, 6.66, 7.84, 7.59, 9.47, 5.52, 6.41 and 7.53 µg/mL, respectively, which are better than that of drazoxolon (19.46 µg/mL).

CONCLUSIONS

A series of 3-(thiophen-2-yl)-1,5-dihydro-2H-pyrrol-2-one derivatives bearing a hydrazone group were designed, synthesized and evaluated for their antifungal activity against Fg, Rs, Bc and Cc. Bioassays indicated that some target compounds exhibited obvious antifungal activity against the above tested fungi. These results provide a significant basis for the further structural optimization of tetramic acid derivatives as potential fungicides.

Synthesis and fungicidal activity of phenylhydrazone derivatives containing two carbonic acid ester groups

Substituted phenylhydrazone moieties and two carbonate groups were merged in one molecule scaffold to obtain 48 novel compounds. ¹H and ¹³C NMR, MS, elemental analysis, and X-ray single-crystal diffraction were used to confirm their structures. Bioassay results revealed that some of the compounds have strong antifungal activities against Botrytis cinerea, Rhizoctonia solani, and Colletotrichum capsici (especially Rhizoctonia solani). Compound 5H₁ is the most promising of the tested compounds against R. solani with an EC₅₀ value of 1.91 mg/L, which is comparable with the positive control fungicide drazoxolon (1.94 mg/L). The structure-activity relationships against R. solani formed three rules: 1) small carbonate groups may improve the antifungal activity of the title compounds; 2) electron-withdrawing groups at the phenyl ring of phenylhydrazone are preferable to their non-substituted counterparts; and 3) halogen at the para position is more beneficial than at the ortho or meta position.

Semisynthesis of Esters of Fraxinellone C4/10-Oxime and Their Pesticidal Activities

A total of 20 esters of fraxinellone C4/10-oxime were synthesized and determined by melting points, optical rotation, infrared spectra, proton nuclear magnetic resonance spectra, and high-resolution mass spectrometry spectra. Two steric configurations of compounds 7i and 8i were unambiguously confirmed by X-ray crystallography. Additionally, their pesticidal activities were assessed on two typical lepidopteran pests, Mythimna separata Walker and Plutella xylostella Linnaeus. Generally, all compounds exhibited less potent oral toxicity than toosendanin against third-instar larvae of P. xylostella. However, all compounds showed the growth inhibitory property against early third-instar larvae of M. separata. Notably, compounds 7m, 8b, 8k, 9, and 11 displayed more potent pesticidal activity than toosendanin. This demonstrated that introducing the C-4 carbonyl or oxime group on fraxinellone resulted in more promising derivatives than those bearing a C-10 carbonyl or oxime substituent.

Synthesis and antitubercular activity of new 1,3,4-oxadiazoles bearing pyridyl and thiazolyl scaffolds

In search of more potent and safe new antitubercular agents, here new 2-pyridinyl substituted thiazolyl-5-aryl-1,3,4-oxadiazoles (6a-o), have been designed and synthesized using thionicotinamide as a starting, following novel multistep synthetic route. An intermediate, pyridinyl substituted thiazolyl acid hydrazide (4) when condensed with benzoic acids/nicotinic acids (5a-o) in the presence of silica supported POCl3 yielded better to excellent yields of the title compounds. All the synthesized compounds (6a-o) and intermediate acid hydrazide (4) have been screened for their in vitro antitubercular activity against Mycobacterium tuberculosis H37Ra (MTB) and Mycobacterium bovis BCG. Amongst them, 6f, 6j, 6l and 6o have revealed promising activity against M. bovis BCG at concentrations less than 3μg/mL. These compounds have shown low cytotoxicity (CC50: >100μg/mL) towards four human cancer cell lines. Molecular docking study has also been performed against mycobacterial enoyl reductase (InhA) enzyme to gain an insight into the binding modes of these molecules and recorded good binding affinity. The ADME properties the title products have also been analyzed.