Antifeedants warburganal

Warburganal Warburgia salutaris (muziga tree) Antifeedant against... 

The potent biological activity (insect antifeedant, antitumour, antifungal) of warburganal (35) has stimulated considerable synthetic interest in this compound. Three total syntheses of this compound have been recorded in the period under review. " The synthesis by Tanis and Nakanishi has additional flexibility since the key intermediate diol (34) can be used in the syntheses of cinnamolide (36), drimenin (37), and polygodial (38). Both norisoambreinolide (39 R = O) and isoambrox (39 R = H2) have been synthesized from (40), the product of the stannic chloride-catalysed cyclization of farnesyl phenyl sulphone. Yahazunol (41), a bicyclofarnesyl hydroquinone, has been identified in the brown seaweed... 

I. Kubo, I. Miura, M. Pettei, Y. W. Lee, F. Pilkiewicz and K. Nakanishi, Muzigadial and warburganal, potent antifungal antiyeast and African armyworm antifeedant agents. 

Warburganal (65, Figure 3.14) was isolated in 1976 as an antifeedant sesquiterpene of African plants, Warburgia stuhlmannii and W. ugandensis, by Kubo, Nakanishi et al. Our 1989 synthesis of (-)-warburganal (65) is shown in Figure 3.14.45... 

Scheme 3 shows the synthesis of (-)-cinnamodial (ugandensidial) (18), the warburganal-related dialdehyde, from the drimenol (2) [25]. Cinnamodial also has a bitter taste [3], and possesses antimicrobial, antifeedant, piscicidal and antihelmintic activities [3, 4]. Cinnamodial (18) has been simultaneously isolated from Cinnamosma fragrans [26] and from Warburgia ugandensis [27], and then from other plants [4],... 

Drimenol (53) can be produced from drimenyl pyrophosphate by fermentation processes, and can then be converted by inexpensive processes to antifeedants such as warburganal (55) and 9-hydroxydrimenal (57) (Scheme 3). The latter is a synthetic drimane which is a potent antifeedant against lepidopteran larvae [92]. 

Warburganal (12) [5], a sesquiterpene dialdehyde, shows a strong antifeedant activity against African armyworms, and exhibits heliocidal... 

Figure 8. Warburganal and azadirachtin, two potent insect antifeedants.

Defensive chemicals also include antifeedants that make the organism unattractive or toxic to would be predators. Examples include Bufotalin (16), which is produced by toads azadirachtin (17), which is produced by Melia azadirachta and also by the Indian neem tree, Azadirachta indica and warburganal (18) is produced by plants of the genus Warburgia. 

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