Polycyclic Oroidin Derivatives

This class of bromopyrrole alkaloids includes all those molecules whose cyclized skeleton can be formally derived through the formation of one (or more) C-C or C-N bonds within the oroidin framework. Consequently, we have found it very useful to classify these molecules according to the oroidin atoms involved in the formal cyclization. More than 40 molecules have been thus classified into six different groups. 

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This class of compounds is extensively described in Chapter 10. Oroidin (64) is considered the precursor in the elaboration of polycyclic CjjNs oroidin derivatives isolated from sponges belonging to the Axinellidae and Agelasidae families. These include the antiangiogenic compounds agelastatin A (65) and ageladine A (70). 

The excellent reviews of Berlinck [1-5] have surveyed a great number of guanidine-type natural products. In addition, some guanidine-derived marine alkaloids have been reviewed by Kobayashi and Ishibashi [6,7]. Also, a recent book gave accounts of marine alkaloids including the phakellins, palau amines and oroidin-like dimers derived from bromopyrroles and polyketide-derived polycyclic guanidine alkaloids [8]. 

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