Salinamides, Antiinflammatory Depsipeptides from a Marine Streptomycete Bradley S. Moore,* ,† Jacqueline A. Trischman, ‡ Dieter Seng, † David Kho, † Paul R. Jensen, ‡ and William Fenical* ,‡ Department of Chemistry, Box 351700, University of Washington, Seattle, Washington 98195-1700, and Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093-0228 Received July 22, 1998 (Revised Manuscript Received December 8, 1998) In addition to the previously reported antiinflammatory agents salinamides A and B from the marine isolate Streptomyces sp. CNB-091, three minor peptides are described. Their total structures were established using a combination of spectral and chemical techniques. Revised structures are presented for the bicyclic depsipeptides salinamides A and B on the basis of the analysis of the dansylated salinamide A hydrolysate by chiral capillary electrophoresis. The fermentation yield of salinamide D, which contains a D-valine residue in place of the D-isoleucine moiety in salinamide A, can be dramatically increased 30-fold by supplementing the growth media with L-valine. Salinamides C and E are monocyclic depsipeptides that are likely methylated byproducts of salinamide A biosynthetic intermediates. Introduction Actinomycetes are a proven source of structurally diverse secondary metabolites possessing broad ranges of biological activities. Examples include antibiotic (erythromycin and tetracycline), anticancer (mitomycin and daunomycin), immunosuppressant (rapamycin and FK506), and veterinary (thiostrepton and monensin) agents. As the frequency of novel bioactive compounds discovered from terrestrial actinomycetes decreases with time, however, academic and industrial programs are increasingly screening actinomycetes from diverse envi- ronments for their ability to generate new metabolites. Streptomycetes isolated from the marine environment have been largely ignored until recently. Early reports suggested that marine actinomycetes were derived from terrestrial sources and that they existed as metabolically inactive spores. 1 Consequently, the examination of ma- rine actinomycetes was predicted to lead to a high isolation rate of known compounds. Although known compounds are frequently encountered, novel compounds are being reported at a high frequency, 2,3 indicating that marine actinomycetes have the ability to produce novel metabolites that have the potential for development into useful commercial products. 4,5 Recent studies have shown that actinomycetes isolated from the marine environment are metabolically active 6 and that certain taxonomic groups have adapted to life in the sea. 7,8 In a preliminary communication, we reported on the structures of the major depsipeptides, salinamides A and B, isolated from Streptomyces sp. CNB-091, an actino- mycete isolated from the surface of the jellyfish Cassio- peia xamachana collected from the Florida Keys. 9 Salin- amides A and B exhibit moderate antibiotic activity against Gram-positive bacteria and show potent topical antiinflammatory activity in the phorbol ester-induced mouse ear edema assay. 9 Recently, salinamide A was found in an edaphic Streptomyces strain (NRRL 21611), where it was shown to exhibit strong inhibitory activity against bacterial RNA polymerases. 10 In this paper, we describe the entire spectrum of salinamides isolated from Streptomyces sp. CNB-091 and amend the absolute configurations of salinamides A and B. Results and Discussion Fermentation of Streptomyces sp. CNB-091 in seawater- based media followed by double EtOAc extraction of the whole-broth suspension, vacuum-flash chromatography, and reversed-phase HPLC afforded predominantly salin- amide A (1) in approximately 9% yield based on the dry extract. Additional fermentations yielded salinamides B (2), D (3), C (4), and E (5) in addition to the major 1. Salinamide A (1, Figure 1) is a pale yellow noncrystal- line solid having the molecular formula C 51 H 69 N 7 O 15 based on high-resolution fast atom bombardment mass spectrometry (HRFABMS). Analyses by 1 H (Table 1) and 13 C (Table 2) NMR indicated that 1 is a depsipeptide composed of seven amino acids and two non-amino acid residues. The structures of all of the amino acids (glycine, † University of Washington. ‡ Scripps Institution of Oceanography. (1) Goodfellow, M.; Haynes, J. A. In Biological, Biochemical, and Biomedical Aspects of Actinomycetes; Ortiz-Ortiz, L., Bojalil, L. F., Yakoleff, V., Eds.; Academic Press: Orlando, 1984; pp 453-472. (2) Fenical, W.; Jensen, P. R. In Marine Biotechnology, Volume 1: Pharmaceutical and Bioactive Natural Products; Attaway, D. H., Zaborsky, O. R., Eds.; Plenum Press: New York, 1993; pp 419-457. (3) Davidson, B. S. Curr. Opin. Biotechnol. 1995, 6, 284-291. (4) Fenical, W. Chem. Rev. 1993, 93, 1673-1683. (5) Jensen, P. R.; Fenical, W. J. Indust. Microbiol. 1996, 17, 346- 351. (6) Morgan, M. A.; Rutherford, L. T.; Hodson, R. E. Appl. Environ. Microbiol. 1995, 61, 3695-3700. (7) Helmke, E.; Weyland, H. Int. J. Syst. Bacteriol. 1984, 34, 127- 138. (8) Jensen, P. R.; Dwight, R.; Fenical, W. Appl. Environ. Microbiol. 1991, 57, 1102-1108. (9) Trischman, J. A.; Tapiolas, D. M.; Jensen, P. R.; Fenical, W.; McKee, T. C.; Ireland, C. M.; Stout, T. J.; Clardy, J. J. Am. Chem. Soc. 1994, 116, 757-758. (10) Miao, S.; Anstee, M. R.; LaMarco, K.; Matthew, J.; Huang, L. H. T.; Brasseur, M. M. J. Nat. Prod. 1997, 60, 858-861. 1145 J. Org. Chem. 1999, 64, 1145-1150 10.1021/jo9814391 CCC: $18.00 © 1999 American Chemical Society Published on Web 01/22/1999