This review provides a detailed account on the biological activities of structurally diverse secondary metabolites from marine sponges having 2-aminoimidazole, glycociamidine and/or 2-thiohydantoin ring functions. This review will complement two previous short reviews which did however not address the potential of these natural products for drug discovery. We will discuss the naturally occurring alkaloids and give an account on their structure activity relationships.
Keywords: 2-Aminoimidazole alkaloids, anticancer, antihistaminic, antimicrobial, Glycociamidine, 2-Thiohydantoin, drug discovery, Nagelamides, bioactive agents