Antifeedant properties

Sesquiterpenoids possessing the drimane skeleton (22) exhibit an impressive series of biological properties. Recently, all aspects relative to occurrence [76], biological activity [76], insect antifeedant properties [77] and synthesis [78] of these terpenoids have been exhaustively reviewed. 

A more detailed understanding of the biochemical pathways and enzymes involved in saponin biosynthesis will facilitate the development of plants with altered saponin content. In some cases, enhanced levels of saponins or the synthesis of novel saponins may be desirable (for example, for drug production 4 or improved disease resistance3,5,6), while for other plants, reduction in the content of undesirable saponins would be beneficial (for example, for legume saponins that are associated with antifeedant properties in animal feed7). This chapter is concerned with recent progress that has been made in the characterization of the enzymes and genes involved in the synthesis of these complex molecules and focuses on triterpenoid saponins. 

Two chlorine-containing clerodanes, tafricanlns A and B, with similar antifeedant properties, have been isolated from a South African bush, Teucrium africanum (32). Teucjaponln B, from Teucrlum japonlcum, is also inhibitory to the feeding of Spodoptera litura... 

This was demonstrated by Fukumoto and co-workers in a synthesis of (+)-albicanol (251), a sesquiterpene with potent hsh antifeedant properties (272,273). Oxime 248 [prepared from the (+)-Wieland-Miescher ketone 247] was subjected to cycloaddition using sodium hypochlorite and gave isoxazoline 249 in very good yield (Scheme 6.95). Conversion of 249 into (3-hydroxyketone 250 was again accomplished by the reductive hydrolysis sequence using Raney Ni and trimethyl... 

Most acetylenic compounds in plants are derived from meta-bolically altered fatty acids. These often are active in plant-insect relationships. 8-cis-Dihydromatricaria acid is also found in the defensive secretion of the soldier beetle (Chaulioqnathus 1econtei) (125), and has subsequently been shown to have anti-feedant properties against Phidippus spp. (jumping spiders) (126). As previously mentioned matricaria ester has antifeedant properties to the pink bollworm, bollworm and tobacco budworm (115). 

Montanari AM, Fenical W, Lindquist N, Lee AY, Clardy J (1996) Volutamides A-E, Halogenated Alkaloids with Antifeedant Properties from the Atlantic Bryozoan Amathia convoluta. Tetrahedron 52 5371... 

Chicory (Cichorium intybus) is cultivated in cool regions such as Northern Europe. Recently, this vegetable has arisen out of claims that it is able to promote good health since no pesticides are used to cultivate chicory in the field, while the plant remains noticeably free from herbivore and microbial attack. The bitter substances, lactupicrin, 8-deoxylactucin and some phenolics had previously been shown to possess insect antifeedant properties in chicory (Rees and Harbome, 1985). Specifically, sesquiterpenoid lactones from chicory leaves, such as 8-deoxylactucin and lactupicrin (Figure 1), were identified as insect antifeedants against desert locust, Schistocerca gregaria. Similarly, we found some biologically active secondary metabolites in the... 

Mehta, P.K., Sood, A.K., Patial, A. and Lai, R. (2005) Evaluation of toxic and antifeedant properties of some plant extracts against major insect pests of cabbage. Pesticide Research Journal 1 7(2), 30-33. 

Akhdarenol (195), ci-amyrin (196), and the semisynthetic isopimaric acid methyl ester 197 exhibited antifeedant properties against L. decemlineata, with the natural compounds more active than the semisynthetic ones. None of these exhibited any antifeedant activity against S. littoralis. 

Aphidicolin (89) is a diterpenoid tetraol produced by the mold Cephalosporium aphidicola. In 1972, Hesp and co-workers reported its isolation and structure [50]. Aphidicolin (89) displays marked activity against Herpes simplex type I virus in cultures of human embryonic cells, as well as antifeedant properties. Furthermore, aphidicolin (89) exhibits antitumor activity in the C6 mouse colon and B16 mouse melanosarcoma screens and has been shown to inhibit the growth of leukemic T- and B-lymphocytes [51]. Such results have stimulated interest in clinical investigations of the effectiveness of 89 against human tumors. 

During an infestation by larvae of the Egyptian cotton leafworm Spodoptera littoralis (Boisd) in the summer of 1978, it was noticed that shrubs of Physalis peruviana L. (cape gooseberry) were not attacked, whereas other Physalis and Nicandra spp. suffered heavy damage. Asher and co-workers demonstrated that withanolide E (118) and 4(3-hydroxywithanolide E (119), isolated from P. peruviana, as well as several related steroids, had insect antifeedant properties. Further studies on other withanolides showed antifeedant effects and species-specific activity on three insects, S. littoralis (Boisd.) (Lepidoptera), the Mexican bean beetle, Epilachna varivestis Muls. (Coleoptera) and the red flour beetle, Tribolium castaneum (Herbst) [62]. 

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