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Natural products insecticides

Piericidins are the first compounds obtained by the screening search for insecticidal natural products among microbial metabolites.10 They were isolated from Streptomyces mobaraensis in 1963,11 and many piericidin derivatives have been found in microbial metabolites until now.12 Piericidins are not used as insecticides practically, but are important biological reagents because they have specific inhibitory activity toward the mitochondrial electron transport chain protein nicotinamide adenine dinucleotide (NADH)-ubiquinone reductase (complex I).13 Piericidin Ax (1 in Figure 1) is biosynthesized as a polyketide,14 but genes responsible for its biosynthesis are not yet identified. Total synthesis of piericidins A (1) was reported recently.15... [Pg.412]

SATASOOK, C., ISMAN, M.B., WIRIYACHITRA, P., Toxicity of rocaglamide, an insecticidal natural product to the variegated cutworm, Peridroma saucia (Lepidoptera Noctuidae), Pestic. Scl, 1993,36,53-58. [Pg.160]

Researchers at Novartis performed the arylation of aliphatic N-heterocydes with the complex aryl bromide 43 toward the synthesis of analogs 44 of the insecticidal natural product rocaglamide (Scheme 13.48) [103]. CS2CO3 acted as mild base to prevent side reactions and epimerization. [Pg.1024]

These chemorational techniques have generated great interest in, and high expectations for, the acceleration of development of innovative pesticides. However, many purportedly successful appHcations of QSAR procedures have reHed on the quaHtative insights traditionally associated with art-based pesticide development programs. Retrospective QSAR analyses have, however, been helpful in identifying the best compounds for specific uses (17). Chemorational techniques have also found some appHcations in the development of pesticides from natural product lead compounds, the best known examples being the synthetic pyrethroid insecticides (19) modeled on the plant natural product, pyrethmm. [Pg.39]

In 1976 scientists at the Merck Corporation discovered a complex of eight closely related natural products, subsequently named avermectins A through in a culture of Streptomjces avermitilis MA-4680 (NRRL8165) originating from a soil sample collected at Kawana, Ito City, Shizuoka Prefecture, Japan and isolated by the Kitasato Institute. Their stmctures are shown in Figure 1 (1 6). They are among the most potent anthelmintic, insecticidal, and acaricidal compounds known. [Pg.278]

Natural products biosynthesis, 1, 83-109 fused oxirane rings, 7, 192 fused thiirane rings, 7, 192-193 as insecticides, 1, 198 nomenclature, 1, 28-31 oxiranes, 7, 120 as pharmaceuticals, 1, I46-I56 pyridine derivatives... [Pg.709]

Microbial insecticides are very complex materials in their final formulation, because they are produced by fermentation of a variety of natural products. For growth, the bacteria must be provided with a source of carbon, nitrogen, and mineral salts. Sufficient nutrient is provided to take the strain of choice through its life cycle to complete sporulation with concomitant parasporal body formation. Certain crystalliferous bacilli require sources of preformed vitamins and/or amino acids for growth. Media for growing these bacilli may vary from completely soluble, defined formulations, usable for bench scale work, to rich media containing insoluble constituents for production situations (10,27). Complex natural materials such as cottonseed, soybean, and fish meal are commonly used. In fact, one such commercial production method (25) is based on use of a semisolid medium, a bran, which becomes part of the final product. [Pg.70]

Many pesticides are not as novel as they may seem. Some, such as the pyre-throid and neonicotinoid insecticides, are modeled on natural insecticides. Synthetic pyrethroids are related to the natural pyrethrins (see Chapter 12), whereas the neo-nicotinoids share structural features with nicotine. In both cases, the synthetic compounds have the same mode of action as the natural products they resemble. Also, the synthetic pyrethroids are subject to similar mechanisms of metabolic detoxication as natural pyrethrins (Chapter 12). More widely, many detoxication mechanisms are relatively nonspecific, operating against a wide range of compounds that... [Pg.3]

The chemical and biological properties of carbamate insecticides (CBs) are described in some detail in the texts of Kuhr and Borough (1976) and Ballantyne and Marrs (1992). An early model for their development was physostigmine, a natural product found in Calabar beans. Many CBs came into use during the 1960s, sometimes as substitutes for banned OC insecticides. [Pg.212]

Bioassay with mosquito larvae for the detection of insecticide residues in fresh and processed fruits and vegetables is feasible, subject to the limitation that the untreated natural product is in itself nontoxic to the larvae at the dilutions tested. [Pg.99]

Roush and coworkers developed a new one-pot sequence consisting of an intramolecular Diels-Alder- and an intramolecular vinylogous Morita-Baylis-Hillman-cyclization for the synthesis of spinosyns [31]. These compounds are poly-ketide natural products possessing extraordinary insecticidal activity. [Pg.292]

Avermectins are a series of eight related natural products with potent anthelmintic and insecticidal activities produced by Gram-positive, filamentous soil bacteria Streptomyces avermitlis [30]. All of these molecules share a 16-membered macrocyclic PK aglycon with the attachment of a dimeric o-methyl-a-L-oleandrose to C-13 (Figure 13.6). Avermectins differ in three substituents R1 R2 and R3. Rj can be either a hydroxyl or hydrogen, in which case there is a double bond between the C-22 and C-23. R2 can be either methyl or ethyl, and R3 can be either hydrogen or methyl. [Pg.296]

Meanwhile, this ingredient of pyrethrins has been re-evaluated as a safe raw material for insecticides, reflecting the recent trend of reverting to natural products. [Pg.5]

Natural product screening may capture a compound, such as an antibiotic, insecticide, or HMG-CoA reductase inhibitor, designed for the... [Pg.201]

Cyclopropanation of 2,5-dimethyl-2,4-hexadiene provides chiysanthemic acid, a natural product of the group of pyrethroic acids, used as an insecticide, see Figure 17.3 [3]. The appropriate esters of the 1R stereomers are the active compounds, which are obtained industrially by resolution of the racemates. [Pg.360]

Uses Manufacture of fluorocarbon refrigerants, fluorocarbon plastics, and propellants solvent for natural products analytical chemistry cleansing agent soil fumigant insecticides preparation of chlorodifluoromethane, methyl fluoride, salicylaldehyde cleaning electronic circuit boards in fire extinguishers. [Pg.296]

Four isobutylamide analogs of the natural products were synthesized in order to compare their insecticidal efficacy with that of the natural products. The synthetic scheme for the preparation of cis-fagaramide ( ) is shown in Figure 1. The syntheses of the cis (9) and trans (8) isomers of N -isobutyl-cinnamamide were accomplished by procedures similar to those utilized in the preparation of the cis (7) and trans (1 ) isomers of fagaramide, with the exception that benzaldehyde was used as starting material in the former case, piperonal in the latter. Isobutylbenzamide (10) was synthesized from benzoyl chloride and isobutylamine. [Pg.164]

The peer-reviewed literature is full of reports on natural products possessing insecticidal activity and references therein] therefore, the focus of this section will be on both recent and well investigated natural products. Of those well investigated natural products, at least three natural product derived products (neem, spinosyn, and pyrethrum) seem to be used more than all the others. [Pg.218]

Fig. 9. Natural products that are used commercially as insecticides. Fig. 9. Natural products that are used commercially as insecticides.
Early insecticides also included organic natural products such as nicotine, rotenone, and pyrethrin. Rotenone is used today as a method of killing rough fish when a lake has been taken over completely by them. A couple of weeks after treatment the lake is then planted with fresh game fish. The... [Pg.365]

Mention was made of the natural product pyrethrins and the structure of pyrethrin I was given in this chapter, Section 3.1. Because of the unique structures of these cyclopropane-containing natural products and their high insecticidal properties, syntheses of analogs have been studied. The isobutenyldimethylcyclopropanecarboxylic acid moiety, called chrysan-themic acid, has been modified by using different ester groups. As a result a number of synthetic pyrethroids are available for certain specific uses. [Pg.377]

The most economically important group of natural plant insecticides are the pyrethrins, a group of six closely related esters extracted from pyrethrum (Chrysanthemum clnerariaefollum) flower heads (Figure 1). Pyrethrum has been used as an insecticide since at least the early 1800 s in Persia and Yugoslavia. By 1828 pyrethrum was being processed for commercial Insect control, and by 1939 imports of pyrethrum into the United States reached a peak of 13.5 million pounds. Use of the natural product declined in the early 1950 s because of the advent of synthetic pyrethroid analogs (for example, allethrins), which were both more stable and more effective in the field. The present worldwide demand for pyrethrum flowers remains in excess of 25,000 tons annually and is satisfied by the estimated 150 million flowers still hand-harvested daily, predominantly in natural stands and cultivated fields in Kenya, Tanzania, and Ecuador (9 ). [Pg.397]


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See also in sourсe #XX -- [ Pg.63 , Pg.64 , Pg.65 , Pg.66 , Pg.67 ]




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