Endothelin-binding inhibitors, BE-18257A and BE-18257B II. Structure determination.

The structures of novel endothelin-binding inhibitors, BE-18257A and BE-18257B, were elucidated by spectral analyses and chemical studies. Both inhibitors were found to have a cyclic pentapeptide structure containing three D-form amino acid residues, namely, the structures of BE-18257A and BE-18257B were elucidated to be cyclo(-D-Glu-L-Ala-D-Val-L-Leu-D-Trp-) and cyclo(-D-Glu-L-Ala-allo-D-Ile-L-Leu-D-Trp-), respectively.