Antifeeding activity

Limonoids (tetranorterpenoids with furan fragments) from Melia toosendan (Meliaceae) and their antifeedant activity 99H(50)595. 

Bruno M, Piozzi F, Rosselli S. Natural and hemisynthetic neoclerodane diterpenoids from Scutellaria and their antifeedant activity. Nat Prod Rep 2002 19 357-78. 

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. 

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). 

Figure 1. Clerodanes with insect antifeedant activity.

Antifeedant activity of kauranes isolated from S. nemoralis... 

However these compounds either singly or in combination do not account for the total lack of feeding activity observed either in the laboratory or in the field. Resistance of S. nemoralis to Insect attack seems to Involve, as is expected, not a single class of compounds but a multichemical response. Other compounds isolated from nemoralis showing antifeedant activity to Trirhabda canadensis are at present under investigation. 

Siciliano, T., De Leo, M., Bader, A., De Tommasi, N., Vrieling, K., Braca, A. and Morelli, 1.2005. Pyrrolizidine alkaloids from Anchusa strigosa and their antifeedant activity. Phytochemistry, 66 1593-1600. 

Faini, F. et al.. Chemistry toxicity and antifeedant activity of the resin of Flourensia thurifera, Biochem. Syst. Ecol, 25, 189, 1997. 

Machocho, A.K. et al.. Three new flavonoids from the root of Tephrosia emoroides and their antifeedant activity against the larvae of the spotted stalk borer Chilo partellus Swinhoe, Int. J. Pharmacogn., 33, 222, 1995. 

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>. 

Several non-volatile iridoid monoterpenes occur as glycosides and have been observed to have biological activity. For example, xylomolin, from the unripe fruits of Xylocarpus moluccensis Roem. (Meliaceae) has antifeedant activity against Spodoptera exempta an African armyworm at 100 ppm ( ) and crotepoxide from Croton macrostachys (Euphorbiaceae) possesses antifeedant activity against Spodoptera exempta (85). 

Furocoumarins such as isopimpinellin, bergapten, and kokusagin have antifeedant activity against Spodoptera litura (54). A number of similar compounds from umbelliferous plants have been demonstrated to be active antifeedants against Spodoptera litura. Periplaneta americana. Musca domestica. Blattela germani ca, and Stylopyga rhombifolia (98). 

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]. 

Samaderin B, (17 ,2A,5R,5a7 ,7a3, 113, lla3, llhR,14.5 )T,7,7tf,ll,ll ,117-hexahydro-l,ll-dihydroxy-8,lltf,14-tri-methyl-277-5tf,2,5-(methanoxymetheno)naphth[l,2-<7]oxepine-4,6,10(577)-trione, and samaderin C, (lR,2S,5R,5aR, 7aS, KXS, 113, 11 3, 1 HR, 14S)-7,7a, 10, ll,ll ,117-hexahydro-l, 10,11 -trihydroxy-8, ll ,14-trimethyl-277-5 , 2,5-(metha-noxymetheno)naphth[l,2- oxepine-4,6(177,577)-dione, were isolated from the seed kernels of Samadera indica and exhibit antifeedant activity against Spodoptera litura third-instar larvae <2003AXC416>. 

Many polyhalogenated monoterpenes have potent biological activity (7). In addition to cytotoxic activity, several compounds display insect repellent and antifeedant activity, and selective insect cell toxicity (480). To acquire sufficient quantities of these and other target metabolites for biological evaluation, the laboratory cultivation of marine algae - bioprocess engineering - is under intense exploration (481 483). 

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). 

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