title: An unusual side chain C-C cleavage at the MeBmt amino acid in cyclosporin A.
abstract: The mixture of products obtained by alkaline treatment of cyclosporin A was analyzed by HPLC-continuous-flow-FAB/MS. The changes involve the atypical amino acid (4R)-4-((E)-2-butenyl)-4,N-dimethyl-L-threonine (MeBmt) without affecting the cyclic structure. The main degradation pathway is dehydration producing all four possible anhydro-MeBmt containing cyclosporins. A new cyclosporin, [Sar(1)]CS, resulting from the side chain cleavage of MeBmt has been isolated and characterized.
authors.affiliation: Galena Co., Research Unit, Branišovská 31, CZ-370 05, České Budějovice, Czech Republic.
authors.forename: A
authors.initials: A
authors.lastname: Jegorov
authors.forename: V
authors.initials: V
authors.lastname: Havlíček
authors.forename: P
authors.initials: P
authors.lastname: Sedmera