Sponges ircinal-related alkaloids

Ircinal B (70) and Ircinol B (71). The tetracyclic precursors of 65-69, ircinal B (70) [65] and ircinol B (71) [68], were isolated from two different Okinawan sponges, Ircinia sp. and Amphimedon sp., respectively. Surprisingly, the alcohol congener possessed the opposite absolute configuration to that of ircinal B and the aforementioned manzamine related alkaloids. Halicyclamines A (72) and B (73), halyclonacyclamines A... 

Nakadomarin A (4) (Fig. 8) was first isolated from the Okinawan marine sponge Amphimedon sp. (SS-264) by Kobayashi and coworkers in 1997 [105,106]. Nakadomarin A is considered to be a novel manzamine-related alkaloid which contains a unique 6/5/5/5/8/15 ring system involving a furan ring. The biological transformation of ircinal A to nakadomarin A was proposed (Scheme 19) [106]. 

Rao KV, Donia MS, Peng J, Garcia-Palomero E, Alonso D, Martinez A, Medina M, Franzblau SG, Tekwani BL, Khan SI, Wahyuono S, Willett KL, Hamann MT. Manzamine B and E and ircinal A related alkaloids from an Indonesian Acanthostrongylophora sponge and their activity against infectious, tropical parasitic and Alzheimer s diseases. J. Nat. Prod. 2006 69(7) 1034-1040. 

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