Pseudoanisatin-type sesquiterpene

Fig. (4). Ketone and acetal equilibrium of pseudoanisatin-type sesquiterpenes 12 and 25 - 26, and acetal sesquiterpenes 27 - 29...

Our own work on structure-activity relationships of convulsant sesquiterpene lactones was initiated after isolation of a variety of seco-prczizaanc type compounds from Illicium floridanum and I. parviflorum, both endemic to the southern United States [157, 179-181]. A study on the in-vivo toxicity of several of these compounds [182] showed that anisatin, major constituent in leaves and fruits of I. floridanum (as in those of other previously studied toxic Illicium (=star anise) species, review see [3]), was apparently the only derivative in the tested series which was toxic to mammals, although further compounds, such as pseudoanisatin (PSA, structure 4 in Fig. (27)) were accumulated in the plant in similarly high amounts [179, 180]. In the light of reports that indicated an identical mechanism of action and -possibly- the existence of a common binding site for anisatin and picrotoxinin [156-161] the question arose which structural features in these compounds were similar enough to warrant an identical mode of molecular recognition at the channel protein. 

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