Cirratiomycin B

The wide applicability and high sensitivity of a liquid chromatog./atm. pressure ionization mass spectrometer (LC/API-MS) using an interface with direct heating nebulizer and vaporizer are reported.This system can produce mol. ions of many nonvolatile compounds comprising amines, amino acids, peptides, antibiotics, nucleosides, nucleotide, steroids, sugars, lipids, vitamins, and alkaloids, which are difficult or impossible to handle by gas chromatog./mass spectrometry.The detection limit of this system by selected ion detection mode is 5 pg for some compounds such as theophylline and caffeine.In the API method, reduced fragmentation for some types compounds provides insufficient structural information.However, a simple collision induced dissociation method operated at a relatively high pressure proves to be useful for producing fragment ions which give structural information.

The structures of cirratiomycins A (I, R = CH₂CHMe₂) and B (I, R = Me) were determined by chem. degradation and by ¹H and ¹³C NMR anal.