HYDROLYSIS OF CYCLOSPORINE-A - IDENTIFICATION OF 1,11-SECO-CYCLOSPORINE-A AND 4,5-SECO-ISOCYCLOSPORIN-A BY FAB-MS MS/

We have previously reported that treatment of CsA with aqueous HCl giv es rise to the formation of a number of water-soluble compounds. Two o f these were identified from their FAB-MS/MS spectra as open chain non a- and decapeptides. We describe here the identification of two other main compounds deriving from the same treatment. Identification was re ndered possible from the comparison of their FAB-MS/MS spectra with th ose of methyl and acetyl derivatives. The two compounds are water-solu ble, open-chain undecapeptides corresponding to 1,11 seco-CsA and of 4 ,5 seco-isoCsA, respectively.