Antifeedant activity against insects

Several neolignans, found in Piper futokazura Sieb. et Zucc., are quite interesting because of their antifeedant activity against insects. 4-Substituted 2-allyl-5-methoxyphenol 92 was submitted to constant current electrolysis (10 mA -1-900-1090 V3. SCE) to afford isodihydrofutoquinol A (93) in 51% yield, together with dienone 94 (15%) and a spiro... 

Certain limonoids also possess an antifeedant activity against insect pests such as fall armyworm, cotton bollworm and spruce budworm (29, 30). Limonoids do not directly kill the pests, but gradually lower their growth rates. 

Shanmugham and White used an intramolecular base-catalyzed cyclization reaction to construct the tricyclic framework of 6-P-hydroxyeuryopsin, a compound with strong antifeedant activity against insects of the genera Leptinotarsa and Myzus Treatment of a chiral aldehyde precursor with TMSOTf in the presence of 2,6-lutidine gave the desired tetrasubstituted furan in quantitative yield. Two additional steps were required to access the target compound, 6p-hydroxyeuryopsin. 

Among some other quinoline alkaloids, N-methylflindersine was isolated firom rutaceous plants such as O. japonica and Fagara chalybea and showed antifeedant activity against insects Spodoptera exempta) [10]. Eduli-nine, on the other hand, isolated from Zanthoxylum simulans (Rutaceae), was shown to possess analgesic and anticonvulsive activities [11]. 

Limonoid aglycones have been shown to possess certain biological activities such as the inhibition of cancerous tumour growth in laboratory animals (Lam et al. 1989 a,b Miller et al. 1989) and antifeedant activities against insects (Alford and Bentley 1986 Liu et al. 1990). Recently, the glucoside of limonin, limonin 17-P-d-glucopyranoside, was found to possess anticancer activities as well (Miller et al. 1992). 

A SN reaction-based domino route to clerodane diterpenoid tanabalin (2-488) [258] has been described by Watanabe s group (Scheme 2.111) [259]. This natural product is interesting as it exhibits potent insect antifeedant activity against the pink bollworm, Pectinophora gossypiella, a severe pest of the cotton plant The domino sequence towards the substituted trans-decalin 2-487 as the key scaffold is induced by an intermolecular alkylation of the (5-ke toes ter 2-484 with the iodoalkane 2-483 followed by an intramolecular Michael addition/aldol condensation (Robin-... 

Diterpenoids have a wide range of biological activities. Their role in plant-insect interactions, both as antifeedants and growth inhibitors, is reviewed. Four ent-kauranes, kaur-16-en-19-oic acid, (-)-kauran-l > -ol, 15 t-hydroxy-(-)-kaur-16-en-19-oic acid, and 17-hydroxy-(-)-kaur-15-en-19-oic acid, have recently been isolated from the leaves of Solidago nemoralis.These compounds were found to have antifeedant activity against Trirhabda canadensis. 

A number of diterpenes are known to have pronounced antifeedant activity against herbivores (Mabry and Gill, 1979 Munakata, 1977). Abietic (52), dehydroabietic, 12-methoxyabietic, sandaracopimaric (32), and isopimaric (69) acid serve as feeding deterrents for the larch sawfly, Pristi-phora erichsonii in single needles from new shoots of tamarack (Larix laricina) (Ohigashi et al, 1981). The larvae of this insect do eat tufted needles on short shoots of the same trees. 

USE Antifeedant activity against granary pests [7910] and insect [7904],... 

Nephthea chahmiii Terpenoid Hydroxycolorenone Antifeedant activity against the pest insect Spodoptera littoralis [54]... 

Bicyclic diterpenes-clerodanes. An important group of Insect antifeedants are the clerodane diterpenoids, which have been isolated from several different plant families (13)(Figure 1). Particularly well studied are the antifeedant activities of caryoptln and clerodin, and their derivatives, from Clerodendron and Caryopteris, Verbenaceae, against the tobacco cutworm Spodoptera litura L. (25-27). 

Twenty two new limonoids have been isolated from a Meliaceae plant Metia toosendan. Their antifeeding activity was tested against the larvae of Spodoptera insects <99H(50)595>. Noelaquinone 7, a new hexacyclic triazine quinone, has been isolated from the Indonesian spongt Xestospongia sp. <98H(49)355>. 

Plant parts other than seeds have been less well studied and little attention has been placed on insecticidal modes of action of the defenses of the neotropical Meliaceae. Our study of the insect growth-reducing activity of 50 extracts of bark, leaf and wood of Central American Meliaceae showed the potent effect of these extracts against lepidopteran larvae and the potential for isolation of bioactive compounds from alarge number of these species. Extracts from the genera Trichilia and Cedrela (Xie etal., 1994 Ewete etal., 1996a Wheeler etal., 2001) show exceptional activity. Trichilia americana extracts have strong antifeedant activity to Spodoptera... 

These natural substances are of great interest due to both their unusual structures and the potent wide-ranging spectrum of biological activities that they possess antitumor activity [10] in vitro and/or in vivo, antiinflammatory activity [7], fungicidal activity [11], herbivorous mammalian antifeedant activity [12], insecticide activity against house-fly larvae and other insects [13] and, lastly, a potent plant growth regulatory activity, both as inhibitors and as stimulants [14-15]. 

During the course of screening plants for insect antifeedants, the extract of the bulbs of Lycoris radiata Herb, was found to exhibit antifeeding activity when tested against the larvae of the yellow butterfly Eurema hecabe mandarina (61). 

Nutmeg oil has strong antifeedant activity, fumigant toxicity and contact toxicity against the stored product insects, Tribolium castaneum and Sitophilus zeamis. The... 

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