Insecticidal Activity Of Compounds Research Articles

Design, Synthesis of Dienthiazole Derivatives, and Evaluation of Aphicidal Activity.

Nitrogen-containing heterocycles have attracted attention for the development of chemicals because of their many types, high physiological activities, and ease of synthesis. Aphids are severe pests found worldwide that cause serious losses in crop yield and quality every year. In this study, a series of novel dienolone thiazole derivatives were synthesized using dienolone acetate as the parent molecule. The synthesis involved bromination, Hantzsch reaction, esterification, deprotection, and other reactions. The structure of the compounds was determined using proton and carbon-13 nuclear magnetic resonance, high-resolution mass spectrometry, and single-crystal diffraction. The synthesized compounds exhibited excellent insecticidal activities against five species of aphids, including Schizaphis graminum, Brevicoryne brassicae, Aphis gossypii, Aphis citricola Van der, and Myzus persicae. The median lethal concentration values of the compound H-13 for S. graminum, B. brassicae, A. gossypii, A. citricola Van der, and M. persicae were 8.72, 13.77, 14.17, 12.96, and 12.35 μg/mL, respectively. The mode of action test results indicated that compound H-13 had superior contact and systemic activity against M. persicae, similar to the positive control flonicamid. Furthermore, a field trial showed that the control effect of compound H-13 at 100 μg/mL concentration was comparable to that of flonicamid against M. persicae. The mortality was 85.6% and 90.3% after 7 and 14 days, respectively. Finally, to further explore the action mechanism of these compounds, the insecticidal activity of compounds H-13 (strong) and H-24 (weak) on aphid protease was determined. Compound H-13 was found to have a significant inhibitory effect on the strong alkaline tryptase activity. Compound H-13 might cause aphid poisoning and death by inhibiting the trypsin activity. This study provided important insights for the discovery and development of new insecticides.

The Insecticidal Activity of Secondary Metabolites Produced by Streptomyces sp. SA61 against Trialeurodes vaporariorum (Hemiptera: Aleyrodidae).

Trialeurodes vaporariorum Westwood poses a significant threat to vegetable and ornamental crops in temperate zones, resulting in notable reductions in yield and substantial economic burdens. In order to find compounds with high insecticidal activity against T. vaporariorum, five compounds were isolated and identified from the crude extract of Streptomyces sp. SA61. These include three new polyketides, named strekingmycins F-H (1-3); one new diterpenoid, named phenalinolactone CD8 (4); and one known compound, strekingmycin A (5). Their structures were analyzed using high-resolution electrospray ionization mass spectrometry and one-dimensional and two-dimensional nuclear magnetic resonance spectroscopy data and by comparing them with previously reported data. The insecticidal activities of compounds 1-5 against T. vaporariorum were evaluated. Among them, compound 5 exhibited the highest insecticidal activity, with an LC50 of 6.949 mg/L against T. vaporariorum at 72 h using the leaf-dip method. Lower insecticidal activities were found in compounds 1-4, with LC50 values of 22.817, 19.150, 16.981 and 41.501 mg/L, respectively. These data indicate that strekingmycin could be a potential candidate for a novel insecticide to control T. vaporariorum.

In-Depth Structural Simplification of Celangulin V: Design, Synthesis, and Biological Activity.

Celangulin V is a novel botanical insecticide with significant bioactivity and a unique molecular target, but its complex polyol ester structure hinders its broader application in agriculture. To discover new analogues of celangulin V with a simpler structure and enhanced biological activities, we initiated a research project aimed at simplifying its structure and assessing insecticidal efficacy. In this study, a series of novel 1-tetralone derivatives were designed via a structure-based rational design approach and synthesized by a facile method. The biological activities of the target compounds were determined against Mythimna separata (M. separata), Plutella xylostella, and Rhopalosiphum padi. The results revealed that most of the synthesized compounds exhibited superior activities compared to celangulin V. Remarkably, the insecticidal activity of compound 6.16 demonstrated 102-fold greater stomach toxicity than celangulin V against M. separata. In addition, certain compounds showed significant contact toxicity against M. separata, a finding not reported previously in the structural optimization studies of celangulin V. Molecular docking analysis illustrated that the binding pocket of compound 6.16 with the H subunit of V-ATPase was the same as celangulin V. This study presents novel insights into the structural optimization of botanical pesticides.

Design, Synthesis and Insecticidal Activity of Novel meta-Diamide Compounds Containing Pyridine Rings.

In order to discover new meta-diamide compounds with good activity and novel structure, 15 related compounds were designed and synthesized by the bioisosterism principle with cyproflanilide as the lead compound. The insecticidal activities of these compounds against Plutella xylostella and Tetranychus cinnabarinus were tested, and the results of biological activity test showed that some compounds had more than 90 % insecticidal activity against Plutella xylostella at 1 mg/L and Tetranychus cinnabarinus at 100 mg/L. Especially, N-(2-bromo-6-(difluoromethoxy)-4-(perfluoro propan-2-yl)phenyl)-6-(isonicotinamido)picolinamide against Tetranychus cinnabarinus at 10 mg/L was 100 %, which was better than that of cyproflanilide. Molecular docking studies suggested that N-(2-bromo-6-(difluoromethoxy)-4-(perfluoropropan-2-yl)phenyl)-6-(4-cyano-2-methylbenzamido)picolinamide had a closely combined with the Plutella xylostella 3RHW (a glutamate-gated chloride channel). This study provides an avenue for designing and synthesizing a new generation of more effective pesticides.

Phytotoxic, cytogenotoxic, and insecticidal activities of compounds from extracts of freshwater Lyngbya sp

ABSTRACT The development of agroecology has promoted the discovery of new bioactive compounds that might act as biocides to control infections and microbial contamination. Algae belonging to Lyngbya genus produce several allelochemicals, which are compounds with crop protection potential. The present study aimed to examine primary and secondary compounds derived from Lyngbya sp. extracts (aqueous and hydroethanolic) on phytotoxic, cytogenotoxic, and insecticidal activities. Determination of compounds indicated the presence predominantly of proteins and flavonoids. The extracts presented physicochemical characteristics that produced (1) 89% germination inhibition using hydroethanolic extract and (2) diminished development of seedlings of L. sativa by hydroethanolic extract as evidenced by reduced radicles length in 83.54%. Aqueous and hydroethanolic Lyngbya sp. extracts significantly interfered with meristematic cells of A. cepa, as evidenced by chromosomal alterations and aberrant mitotic phases in cells. Extracts also exhibited pro-oxidative activity and a potent insecticidal potential on S. zeamais, indicating that the hydroethanolic extract produced 100% insect mortality at 75 mg/ml after 48 hr while the aqueous extract initiated 90% mortality at the same concentration after 82 hr. Therefore, data demonstrate that Lyngbya genus provides basic information for new environmental and ecotoxicological studies to seek a possible source of proteins and flavonoids to be used in agroecological management.

Insecticidal Activity and Free Radical Scavenging Properties of Isolated Phytoconstituents from the Saudi Plant Nuxia oppositifolia (Hochst.).

Chromatographic purification of the alcoholic extract from the aerial parts of the Saudi plant Nuxia oppositifolia (Hochst.), Benth., resulted in five isolated phenolic compounds. Two flavones, hispidulin (1) and jaceosidin (2), and the phenylethanoid glycosides, verbascoside (3), isoverbascoside (4), and conandroside (5), were identified and their chemical structures were determined by spectroscopic analyses. The insecticidal activity of compounds 1 and 2, in addition to 11 compounds isolated in a previous research (6–16), was evaluated against the Yellow Fever mosquito, Aedes aegypti. Four compounds displayed adulticidal activity with LD50 values of 2–2.3 μg/mosquito. Free radical scavenging properties of the plant extracts and compounds (1–5) were evaluated by measuring the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonate radical cation (ABTS•+) scavenging activity. All compounds exhibited notable activity, compared with the positive control, l-Ascorbic acid. This study suggests that N. oppositifolia could be a promising source of secondary metabolites, some with lethal adulticidal effect against Ae. aegypti.

Insecticidal Activities of Chloramphenicol Derivatives Isolated from a Marine Alga-Derived Endophytic Fungus, Acremonium vitellinum, against the Cotton Bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae).

A great deal of attention has been focused on the secondary metabolites produced by marine endophytic fungi, which can be better alternatives to chemicals, such as biopesticides, for control of polyphagous pests. On the basis of its novel biocontrol attributes, chemical investigation of a marine alga-derived endophytic fungus, Acremonium vitellinum, resulted in the isolation of three chloramphenicol derivatives (compounds 1–3). Their chemical structures were elucidated by detailed analysis of their nuclear magnetic resonance spectra, high-resolution electrospray ionization mass spectrometry, and by comparison with the data available in the literature. In this paper, compound 2 was firstly reported as the natural origin of these fungal secondary metabolites. The insecticidal activities of compounds 1–3 against the cotton bollworm, Helicoverpa armigera, were evaluated. The natural compound 2 presented considerable activity against H. armigera, with an LC50 value of 0.56 ± 0.03 mg/mL (compared to matrine with an LC50 value of 0.24 ± 0.01 mg/mL). Transcriptome sequencing was used to evaluate the molecular mechanism of the insecticidal activities. The results presented in this study should be useful for developing compound 2 as a novel, ecofriendly and safe biopesticide.

Thioether-bridged arylalkyl-linked N-phenylpyrazole derivatives: Design, synthesis, insecticidal activities, structure-activity relationship and molecular-modeling studies

Owing to thioether diverse physicochemical properties by non-covalent interactions with bio-macromolecules, thioether derivatives containing heterocyclic moiety are known for their interesting insecticidal bioactivities and attracting considerable attention as neuroactive insecticides. Here we synthesis a series of novel thioether bridged N-phenylpyrazole derivatives incorporating various (hetero)aromatic substituents into 4-position of the pyrazole ring. Structure-activity relationship (SAR) studies resulted in compounds 6d and 7d with the most potent insecticidal activity among the series containing various substituted benzene substituents (LC50 = 13.70–25.47 μg/g). Further optimization to increase the lipophilicity and charge density of aromatic substituents of compounds 6d and 7d resulted in compounds 12d, 14d and 16d with sulfur-containing heterocycle substituents possessing good insecticidal activity against Musca domestica L. among the series (LC50 = 0.67–1.30 μg/g). The thioether bridge N-phenylpyrazole derivatives, which exhibit different length of the spacer arm introduced between N-phenylpyrazole moiety and the (hetero)aromatic substituents, were also prepared and evaluated. By contrast, the insecticidal activities of compounds containing the short thioether bridge, 1,2-bis((hetero)aromatic thio) ethane, are higher than that containing the long thioether bridge, 1,3-bis((hetero)aromatic thio) propane. The results of molecular docking and pharmacophore analyses indicated A299, T303, and L306 of a subunit were essential to form non-covalent interactions contacts with the ligands. Specially, the sulfur-containing heterocycle substituent derivatives 12d and 14d as the sterically favored areas could form the important hydrophobic interactions with the deeper residue P295.

Design, synthesis and biological activities of novel 4,5-disubstituted-3-S-(β-D-acetylglycosyl)-1,2,4-triazole derivatives

A series of novel 4,5-disubstituted-3-S-(β-D-acetylglycosyl)-1,2,4-triazole derivatives was designed and synthesized via the strategy of introducing S-β-D-acetylglycosyl fragments into 1,2,4-triazole ring. The structures of 17 target compounds were characterized by means of 1H NMR, 13C NMR and high-resolution mass spectrometer (HRMS). The results of insecticidal activity indicated that compound 5a displayed 60% lethality rate at 100 mg/L concentration. More importantly, the introduction of the carbohydrate fragment to the 1,2,4-triazole core could improve the insecticidal activities since the insecticidal activities of compounds 5 were better than those of compounds 4 and this result was also supported by calcium imaging technique. The antifungal activity of the target compounds showed that some novel compounds displayed moderate to good inhibition rate against Sclerotinia sclerotiorum and Botrytis cinerea, in which compound 5p exhibited 78.8% inhibition rate against Sclerotinia sclerotiorum and 68.6% inhibition rate against Botrytis cinerea. The herbicidal activities of compounds 5 against Brassica campestris indicated that most of the target compounds showed moderate to good activities, especially compound 5g which showed 52.9% herbicidal activity at the concentration of 200 mg/L.

Insecticidal Activity of Compounds from the South China Sea Invertebrate Scapharca Subcrenata

Insecticidal Activity of Compounds from the South China Sea Invertebrate Scapharca Subcrenata

Pyridine Derivatives as Insecticides. Part 1: Synthesis and Toxicity of Some Pyridine Derivatives Against Cowpea Aphid, Aphis craccivora Koch (Homoptera: Aphididae)

Five pyridine derivatives, namely, N-morpholinium 7,7-dimethyl-3-cyano-4-(4'-nitrophenyl)-5-oxo-1,4,5,6,7,8-hexahydroquinoline-2-thiolate (1), sodium 5-acetyl-3-amino-4-(4'-methoxyphenyl)-6-methylthieno[2,3-b] pyridine-2-carboxylate (2), piperidinium 3,5-dicyano-2-oxo-4-spirocyclopentane-1,2,3,4-tetrahydropyridine-6-thiolate (3), piperidinium 5-acetyl-3-cyano-4-(4'-methoxyphenyl)-6-methylpyridine-2-thiolate (4), and piperidinium 5-acetyl-4-(4'-chlorophenyl)-3-cyano-6-methyl-pyridine-2-thiolate (5) were prepared in pure state and subjected to the title study. The bioassay results indicated that the insecticidal activity of compound 1 is about 4-fold that of acetamiprid insecticide. The rest of the tested compounds possess moderate to strong aphidicidal activities.

Tabulvelutin A, the first 19-nor limonoid with unprecedented ring system from Chukrasia tabularis var. velutina

Tabulvelutin A ( 1), the first 19-nor limonoid incorporating a unique 7,10-γ-lactone, together with a biosynthetically related limonoid tabulvelutin B ( 2) was isolated from the stem bark of Chukrasia tabularis var. velutina. Their structures were elucidated by extensive spectroscopic analysis and chemical computation. The insecticidal activity of compounds 1 and 2 was also assessed.

Khayasin and 2'S-methylbutanoylproceranolide: Promising candidate insecticides for the control of the coconut leaf beetle, Brontispa longissima

Brontispa longissima (Gestro) is a serious pest of coconut palms in tropical areas. In our continuing search for potential pesticides from tropical mangrove plants, khayasin (1) and 2′S-methylbutanoylproceranolide (2), two mexicanolides with a Δ8,14 double bond, were isolated from seeds of an Indian mangrove, Xylocarpus moluccensis. The structures of these compounds were established by comparison with data in the literature. Compound 1 was found to exhibit potent insecticidal activities against second- to fifth-instar larvae of B. longissima at a concentration of 50 μg/ml, and compound 2 displayed marked insecticidal activity against fifth-instar larvae of the same pest at the same concentration. LC50 (concentration of 50% mortality) values for compound 1 against fifth-instar larvae of B. longissima at exposure times of 24 and 48 h are 7.27 and 3.39 μg/ml, respectively, and those for compound 2 are 10.57 and 4.03 μg/mL, respectively. The insecticidal activities of compounds 1 and 2 against fifth-instar larvae of B. longissima are more potent than those of azadirachtin and toosendanin, and are similar to those of rotenone; however, compounds 1 and 2 only exhibited moderate antifeedant activities against third-instar larvae of Prodenia litura (Fabricius). These results suggested that compounds 1 and 2 had selectively insecticidal activities against the larvae of B. longissima. They are promising candidate insecticides for the control of B. longissima.

A New Insecticidal Sesquiterpene Ester from Celastrus Angulatus

A new sesquiterpene polyol ester with a β-dihydroagarofuran skeleton, NW37 (1), and three known compounds NW13 (2), NW16 (3) and NW35 (4) were isolated by bioassay-guided fractionation from the highly polar MeOH extracts of the root bark of Celastrus angulatus. Their chemical structures were elucidated mainly by analyses of MS and NMR spectral data. The insecticidal activity of compound 1 against 4th instar Mythimna separata larvae with a KD50 value of 252.3 μg·g-1 was demonstrated.

Insecticidal activity of daphnane diterpenes fromLasiosiphon kraussianus (Meisn) (Thymelaeaceae) roots

A methanol extract of roots of Lasiosiphon kraussianus (Meisn) (Thymelaeaceae) showed potent insecticidal activity against Aphis gossypii (Glov) and Drosophila melanogaster (Meig). Bioassay-driven fractionation of this extract led to the isolation and characterisation of two known daphnane diterpenoids: Excoecaria toxin (1) and wikstrotoxin D (2). The two natural products were inferior to methomyl in activity against A gossypii and Myzus persicae (Sulz) in contact assays but were superior in ingestion assays against D melanogaster. This is the first report on insecticidal activities of compounds 1 and 2. AChE was insensitive to the two natural products. © 1999 Society of Chemical Industry

Insecticidal activity of daphnane diterpenes fromLasiosiphon kraussianus(Meisn) (Thymelaeaceae) roots

A methanol extract of roots of Lasiosiphon kraussianus (Meisn) (Thymelaeaceae) showed potent insecticidal activity against Aphis gossypii (Glov) and Drosophila melanogaster (Meig). Bioassay-driven fractionation of this extract led to the isolation and characterisation of two known daphnane diterpenoids: Excoecaria toxin (1) and wikstrotoxin D (2). The two natural products were inferior to methomyl in activity against A gossypii and Myzus persicae (Sulz) in contact assays but were superior in ingestion assays against D melanogaster. This is the first report on insecticidal activities of compounds 1 and 2. AChE was insensitive to the two natural products.

Insecticidal activity of daphnane diterpenes from Lasiosiphon kraussianus (Meisn) (Thymelaeaceae) roots

A methanol extract of roots of Lasiosiphon kraussianus (Meisn) (Thymelaeaceae) showed potent insecticidal activity against Aphis gossypii (Glov) and Drosophila melanogaster (Meig). Bioassay-driven fractionation of this extract led to the isolation and characterisation of two known daphnane diterpenoids: Excoecaria toxin (1) and wikstrotoxin D (2). The two natural products were inferior to methomyl in activity against A gossypii and Myzus persicae (Sulz) in contact assays but were superior in ingestion assays against D melanogaster. This is the first report on insecticidal activities of compounds 1 and 2. AChE was insensitive to the two natural products. © 1999 Society of Chemical Industry

Quantitative Structure-Activity Relationships of DDT-Type Compounds in a Sodium Tail-Current in Crayfish Giant Axons

Effects of DDT-type compounds including 1,1-bis(para-substituted phenyl)-2,2-dichlorocyclopropanes (DCC-series compounds) on sodium currents in crayfish giant axons were measured under voltage-clamp conditions. Variations in the activity to prolong the tail-current that was observed upon step repolarization of the membrane were quantitatively analysed by use of physicochemical parameters of aromatic substituents and regression analysis. Introduction of lengthy and narrow substituents was favourable to the activity. Variations in the activity were parabolically related to the hydrophobicity, optimum value being around that of H. DDT- and prolan-series compounds were 2–3 times more active than DCC-series compounds when other structural factors were the same. Insecticidal activity of the compounds was linearly correlated with the tail-current activity when the hydrophobic factor was separately considered. The insecticidal activity of DDT-series compounds was 2·5 times higher than that of others when the other factors were the same. © 1997 SCI.

Effects of the α-cyano group in the benzyl alcohol moiety on insecticidal and neurophysiological activities of pyrethroid esters

This work was undertaken to clarify the criteria for classifying pyrethroids into Types I and II on the basis of their structure-activity pattern. Thus, effects on the membrane potential in crayfish giant axons of substituted benzyl esters of chrysanthemic, α-substituted iso-valeric, and related carboxylic acids with and without the cyano group at the α-position of the alcohol moiety were examined by an intracellular recording technique. Some α-cyano-benzyl alcohol esters caused a remarkable depolarizing afterpotential in response to a single stimulus similar to that induced by esters without the cyano group. Their effects on sodium currents were examined with an internally perfused crayfish axon under voltage clamp conditions using the sucrose gap method. Irrespective of the presence of the α-cyano group in the alcohol moiety, these compounds induced a tail current upon a step repolarization of the membrane, although the α-cyano compounds decreased the rate of fall of the tail current much more slowly than that of the corresponding compounds without the cyano group. Insecticidal activity of compounds was measured against the American cockroaches under synergistic conditions with metabolic inhibitors. The activity of compounds with the α-cyano group was much higher than that of the corresponding compounds without the cyano group. The higher the tail current activity, the higher was the insecticidal activity, although contributions of such structural effects as hydrophobicity may differ between the two activities. The results suggest that the presence of the cyano group at the α-position of the benzyl alcohol moiety of synthetic pyrethroids enhances both the sodium current and insecticidal activities but is by no means a sufficient structural requirement to differentiate the types of each of the biological activities.