CYCLIC-PEPTIDES FROM HIGHER-PLANTS .10. CONFORMATIONAL-ANALYSIS OF A TYROSINASE INHIBITORY CYCLIC PENTAPEPTIDE, PSEUDOSTELLARIN-A, FROM PSEUDODELLARIA-HETEROPHYLLA

Conformational studies of pseudostellarin A were performed by a combin ation of high field NMR and computational chemical evidences to elucid ate a relationship between the structures and their tyrosinase inhibit ory activities in a series of cyclic peptides, pseudostellarins, and t o establish a pharmacophore model. The three-dimensional structure of pseudostellarin A was characterized by gamma- and beta-turn structures , fixed by trans-annular hydrogen bonds between Gly and Leu.