Ponasterone A activity

Ecdysone Itself and the phytoecdysones, inokosterone and maklsterone A, were much less effective as abortifacients than 20-0HE (Table I). Cyasterone and ponasterone A were inactive the implication being that the hydroxyl group on C25 is required for activity (10). 

Ponasterones A, B, and C, and related biologically active compounds have been reviewed. The configuration of the 2a,3a-diol system of ponasterone B has been confirmed and mass spectral studies have revealed the presence of an extra hydroxy-group in ponasterone C which, on n.m.r. and c.d. evidence must be SP thereby leading to the revised structure (138). 

Several active, related derivatives of ecdysterone (81) can be isolated from insects as well as from several plants and from the marine crab, Callinectes sapidus. Most of them differ with respect to the side chain. Characteristic examples of this type are ponasterone A (92), inokosterone (93), pterosterone (94), makisterone A (95) and cyasterone (96) (Scheme 1.28). 

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