No abstract

Didemnins A, B, and C, cyclic depsipeptides previously reported by our laboratory from the Caribbean tunicate Trididemnum solidum, have now been synthesized and, in the process, their structures have been revised to include the new amino acid (3S,4R,5S)-isostatine,C2H5CH(CH3)CHNH2CHOHCH2COOH. All other isomers of isostatine have also been prepared. Didemnin B is currently in Phase II clinical trials as an anticancer agent, and the antineoplastic activity, as well as the antiviral and immunosuppressive activities, of the didemnins are reviewed. A highly unusual porphynoid has also been isolated from T. solidum. The compound has been named tunichlorin and is apparently the first nickel-containing chlorin (and only the second nickel-containing porphyrin-related compound) identified from a living organism.

Both in-house human genetic and literature data have converged on the identification of leukotriene 4 hydrolase (LTA(4)H) as a key target for the treatment of cardiovascular disease. We combined fragment-based crystallography screening with an iterative medicinal chemistry effort to optimize inhibitors of LTA(4)H. Ligand efficiency was followed throughout our structure-activity studies. As applied within the context of LTA(4)H inhibitor design, the chemistry team was able to design a potent compound 20 (DG-051) (K(d) = 26 nM) with high aqueous solubility (>30 mg/mL) and high oral bioavailability (>80% across species) that is currently undergoing clinical evaluation for the treatment of myocardial infarction and stroke. The structural biology-chemistry interaction described in this paper provides a sound alternative to conventional screening techniques. This is the first example of a gene-to-clinic paradigm enabled by a fragment-based drug discovery effort.

No abstract

DG-051B is a first-in-class small molecule inhibitor of leukotriene A4 hydrolase (LTA4H), currently in Phase II clinical development for the prevention of heart attack. Process optimization led from a linear seven-step synthetic procedure to a convergent four-step manufacturing sequence that has been used to manufacture at 100-kg scale. The entire process can be telescoped due to high conversion reactions, low impurity levels, efficient separations, and a very effective final purification. Two key aspects of the process are: (a) bypassing the isolation of a reactive electrophile by using its aqueous-washed reaction mixture directly into a coupling reaction with a phenoxide nucleophile and (b) modulating the properties of the final product solutions for optimal extraction, purification, and crystallization.