PCA and FA analysis of steady-state fluorescence spectra of camptothecin

Fluorescence spectroscopy methods are widely used in biomedical research. The fluorescence spectra of camptothecin (CPT) - anticancer agent are analyzed in this paper. CPT can exist in two forms: lactone and carboxylate. Only the lactone form is biologically active. Under physiological conditions (pH 7.4) the lactone form hydrolyses and converts into inactive carboxylate form. There are some differences in fluorescence spectra of lactone and carboxylate form of CPT - the emission spectra of carboxylate form is slightly red-shifted and is characterized by lower intensity. Principal components analysis (PCA) fallowed by factor analysis (FA) enable to detect presence of both forms on the basis of series of time dependent set of spectra, to follow changes in their contributions and to determine these contributions.