Insecticidal sesquiterpenes

Fig. (16). Insecticidal sesquiterpenes alkaloids from Celastraceae species...

Effects of Sesquiterpene Lactones on Seed Germination. Sesquiterpene lactones are common constituents of the Asteraceae but are also found in other angiosperm families and in certain liverworts (31,32). These highly bitter substances exhibit a wide spectrum of biological activities (J 3) which include cytotoxicity, anti-tumor, anti-microbial, insecticidal (34) and molluscicidal (35) properties. Furthermore, they are known causes for livestock poisoning and contact dermatitis in humans (33). Structure-activity relationship studies on sesquiterpene lactones have demonstrated that biological activity frequently depend on the presence of the cr... 

The sesquiterpene pyridine alkaloids have antifeedant and insecticidal activ-ihes. Some alkaloids, such as triptonine B, hypoglaunine B, hyponine B and wilfortrine, have antivirus activity potential. Others, such as emarginatines A-B, E-G and emarginatine, have cytotoxic activity. Ebenifoline and cangorinine have immunosuppressive activity. 

In combination with sesquiterpene lactones, the chromenes and benzofurans are another group of defensive compounds that desert Invertebrates have to detoxify. Indeed, the success of many desert sunflower species Is In part due to their diverse secondary chemistry. Prenylated qulnones, on the other hand seem to be restricted to the Hydrophyllaceae and tropical trees. The qulnones are extremely active chemicals that exhibit Insecticidal activity at concentrations lower than many chromenes. The prenylated qulnones of Phacella are also potent cytotoxlns and allergens. 

N.A. Pyrethrins, cinerins, palmitic, linoleic acid, sesquiterpene lactones.100 107 118 Externally used as a contact insecticide. 

The dichloromethane extract of Hyptis verticillata (Lamiaceae) yielded the sesquiterpene cadina-4,10(15)-dien-3-one, Fig. (2) [142]. Besides its insecticidal activity against Cylas formicarius, this chemical inhibited the... 

Pyridine was first isolated, like pyrrole, from bone pyrolysates. Its name is derived from the Greek for fire (pyr) and the suffix idine used to designate aromatic bases. Pyridine can also be formed from the breakdown of many natural materials in the environment. Pyridine is used as a solvent, in addition to many other uses including products such as pharmaceuticals, vitamins, food flavorings, paints, dyes, rubber products, adhesives, insecticides, and herbicides. Structurally, pyridine derivatives can range in complexity from the relatively simple monosubstituted pyridine, nicotine (1), to the highly elaborated sesquiterpene pyridine alkaloids, chuchuhuanines [1] (2). 

In the course of these research programmes, cytotoxic quinones, polyester sesquiterpenes and pyridine-sesquiterpene alkaloids with antifeedant and/or insecticidal properties have been isolated from Latin American species, in particular those of the Maytenus genus which is extensively used by rural communities and tribes in the Andes and the Amazon basin. Recently some sesquiterpene alkaloids with immunosuppressive activity and sesquiterpenes with antitumoral activity have also been described [3]. 

The interest generated by polyester sesquiterpenes from the Celastraceae has increased in line with die complexity of the substances isolated and the possibility of their being applied to combat insect plagues instead of synthetic insecticides. The complexity and increasing numbers of these sesquiterpenes makes it difficult to arrange them systematically. They can however, be treated as derivatives of a basic polyhydroxy skeleton and thereafter organized in simpler series. 

Products isolated from plants of the Celastraceae family have showed insecticidal and antifeedant activities, as discussed earlier. The compounds reported belong to the agarofuran sesquiterpene-type and sesquiterpene pyridine-type alkaloids. Nevertheless, the only description of insecticidal activity of quinone methides found is from Avilla et al [102], Despite the fact that the compounds assayed were known the... 

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