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Tetranortriterpenoid
The tetranortriterpenoid class of chemical compounds most noted for the chemical azadirachtin, extracted from the neem tree (''Azadirachta indica'') that displays insecticidal properties. Azadirachtin mimics insect hormones called ecdysones that regulate pupation of insects; application of azadirachtin interrupts the development and pupation of insects, which eventually kills them. The name indicates that the basic skeleton of such compounds contains 26 carbon atoms (4 fewer than triterpenes). Azadirachtin is a tetranortriterpenoid and a limonoid Limonoids are phytochemicals of the triterpenoid class which are abundant in sweet or sour-scented citrus fruit and other plants of the families Cucurbitaceae, Rutaceae, and Meliaceae. Certain limonoids are antifeedants such as azadirachtin fro .... References {{insecticides Plant toxin insecticides Triterpenes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Azadirachtin
Azadirachtin, a chemical compound belonging to the limonoid group, is a secondary metabolite present in neem seeds. It is a highly oxidized tetranortriterpenoid which boasts a plethora of oxygen-bearing functional groups, including an enol ether, acetal, hemiacetal, tetra-substituted epoxide and a variety of carboxylic esters. Chemical synthesis Azadirachtin has a complex molecular structure; it presents both secondary and tertiary hydroxyl groups and a tetrahydrofuran ether in its molecular structure, alongside 16 stereogenic centres, 7 of which are tetrasubstituted. These characteristics explain the great difficulty encountered when trying to prepare this compound from simple precursors, using methods of synthetic organic chemistry. Hence, the first total synthesis was published over 22 years after the compound's discovery: this first synthesis was completed by the research group of Steven Ley at the University of Cambridge in 2007. The described synthesis was a relay approach ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limonoid
Limonoids are phytochemicals of the triterpenoid class which are abundant in sweet or sour-scented citrus fruit and other plants of the families Cucurbitaceae, Rutaceae, and Meliaceae. Certain limonoids are antifeedants such as azadirachtin from the neem tree.{{cite journal, title=Biological activity of limonoids from the rutales, journal=Phytochemistry, volume=31, pages=377–394, authors=Donald E.Champagne, Opender Koul, Murray B. Isman, Geoffrey G. E.Scudder, G. H. Neil Towers, year=1992, issue=2, doi=10.1016/0031-9422(92)90003-9 Chemically, the limonoids consist of variations of the furanolactone core structure. The prototypical structure consists of four six-membered rings and a furan Furan is a heterocyclic organic compound, consisting of a five-membered aromatic ring with four carbon atoms and one oxygen atom. Chemical compounds containing such rings are also referred to as furans. Furan is a colorless, flammable, highly ... ring. Limonoids are classed as tetra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neem
''Azadirachta indica'', commonly known as neem, nimtree or Indian lilac, is a tree in the mahogany family Meliaceae. It is one of two species in the genus '' Azadirachta'', and is native to the Indian subcontinent and most of the countries in Africa. It is typically grown in tropical and semi-tropical regions. Neem trees also grow on islands in southern Iran. Its fruits and seeds are the source of neem oil. Description Neem is a fast-growing tree that can reach a height of , and rarely . It is deciduous, shedding many of its leaves during the dry winter months. The branches are wide and spreading. The fairly dense crown is roundish and may reach a diameter of . The neem tree is similar in appearance to its relative, the chinaberry ('' Melia azedarach''). The opposite, pinnate leaves are long, with 20 to 30 medium to dark green leaflets about long. The terminal leaflet often is missing. The petioles are short. White and fragrant flowers are arranged in more-or-less drooping ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Insecticide
Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed to be a major factor behind the increase in the 20th-century's agricultural productivity. Nearly all insecticides have the potential to significantly alter ecosystems; many are toxic to humans and/or animals; some become concentrated as they spread along the food chain. Insecticides can be classified into two major groups: systemic insecticides, which have residual or long term activity; and contact insecticides, which have no residual activity. The mode of action describes how the pesticide kills or inactivates a pest. It provides another way of classifying insecticides. Mode of action can be important in understanding whether an insecticide will be toxic to unrelated species, such as fish, birds and mammals. Insecticides may be repe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecdysone
Ecdysone is a prohormone of the major insect molting hormone 20-hydroxyecdysone, which is secreted from the prothoracic glands. It is of steroidal structure. Insect molting hormones (ecdysone and its homologues) are generally called ecdysteroids. Ecdysteroids act as moulting hormones of arthropods but also occur in other related phyla where they can play different roles. In '' Drosophila melanogaster'', an increase in ecdysone concentration induces the expression of genes coding for proteins that the larva requires, and it causes chromosome puffs (sites of high expression) to form in polytene chromosomes. Recent findings in the laboratory of Chris Q. Doe have found a novel role of this hormone in regulating temporal gene transitions within neural stem cells of the fruit fly. Ecdysone and other ecdysteroids also appear in many plants mostly as a protection agent (toxins or antifeedants) against herbivorous insects. These phytoecdysteroids have been reputed to have medici ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nor-
In chemical nomenclature, nor- is a prefix to name a structural analog that can be derived from a parent compound by the removal of one carbon atom along with the accompanying hydrogen atoms. The nor-compound can be derived by removal of a , , or CH group, or of a C atom. The "nor-" prefix also includes the elimination of a methylene bridge in a cyclic parent compound, followed by ring contraction. (The prefix "homo-" which indicates the next higher member in a homologous series, is usually limited to noncyclic carbons). ''"Since that time the meaning of the prefix has been generalized to denote the replacement of one or more methyl groups by H, or the disappearance of CH2 from a carbon chain"''. At present, the meaning is restricted to denote the removal of only one group from the parent structure, rather than the completely demethylated form of the parent compound. In literature, "nor" is sometimes called the "next lower homologue", although in this context Homology (chemis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triterpene
Triterpenes are a class of chemical compounds composed of three terpene units with the molecular formula C30H48; they may also be thought of as consisting of six isoprene units. Animals, plants and fungi all produce triterpenes, including squalene, the precursor to all steroids. Structures Triterpenes exist in a great variety of structures. Nearly 200 different skeletons have been identified. These skeletons may be broadly divided according to the number of rings present. In general pentacyclic structures (5 rings) tend to dominate. Squalene is biosynthesized through the head-to-head condensation of two farnesyl pyrophosphate units. This coupling converts a pair of C15 components into a C30 product. Squalene serves as precursor for the formation of many triterpenoids, including bacterial hopanoids and eukaryotic sterols. Triterpenoids By definition triterpenoids are triterpenes that possess heteroatoms, usually oxygen. The terms ''triterpene'' and ''triterpenoid'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant Toxin Insecticides
Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclude the fungi and some algae, as well as the prokaryotes (the archaea and bacteria). By one definition, plants form the clade Viridiplantae (Latin name for "green plants") which is sister of the Glaucophyta, and consists of the green algae and Embryophyta (land plants). The latter includes the flowering plants, conifers and other gymnosperms, ferns and their allies, hornworts, liverworts, and mosses. Most plants are multicellular organisms. Green plants obtain most of their energy from sunlight via photosynthesis by primary chloroplasts that are derived from endosymbiosis with cyanobacteria. Their chloroplasts contain chlorophylls a and b, which gives them their green color. Some plants are parasitic or mycotrophic and have lost the abili ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
