Candidaspongiolides, distinctive analogues of tedanolide from sponges of the genus Candidaspongia.

Fractionation of cytotoxic extracts of specimens of a newly described sponge genus, Candidaspongia, has yielded the candidaspongiolides (3), a complex mixture of acyl esters of a macrolide related to tedanolide. The general structure of the candidaspongiolides was determined by analyses of various 2D NMR and MS data sets. The acyl ester components were identified by GC-MS analysis of the derived fatty acid methyl esters. The mixture could be selectively converted to the deacylated macrolide core (4) by enzymolysis with immobilized porcine lipase, with the structure of the candidaspongiolide core then secured by NMR and MS analysis. The candidaspongiolide mixture was potently cytotoxic, exhibiting a mean panel 50% growth inhibition (GI50) of 14 ng/mL in the National Cancer Institute's 60-cell-line in vitro antitumor screen.

Natural products as sources of new drugs over the period 1981-2002.

This review is an updated and expanded version of a paper that was published in this journal in 1997. The time frame has been extended in both directions to include the 22 years from 1981 to 2002, and a new secondary subdivision related to the natural product source but applied to formally synthetic compounds has been introduced, using the concept of a "natural product mimic" or "NM" to join the original primary divisions. From the data presented, the utility of natural products as sources of novel structures, but not necessarily the final drug entity, is still alive and well. Thus, in the area of cancer, the percentage of small molecule, new chemical entities that are nonsynthetic has remained at 62% averaged over the whole time frame. In other areas, the influence of natural product structures is quite marked, particularly in the antihypertensive area, where of the 74 formally synthetic drugs, 48 can be traced to natural product structures/mimics. Similarly, with the 10 antimigraine drugs, seven are based on the serotonin molecule or derivatives thereof. Finally, although combinatorial techniques have succeeded as methods of optimizing structures and have, in fact, been used in the optimization of a number of recently approved agents, we have not been able to identify a de novo combinatorial compound approved as a drug in this time frame.