Simple beta-carboline alkaloids as nucleic acids fluorochromes

Treatment of cell smears (chicken blood, Trypanosoma cruzi epimastigotes, Ehrlich ascites tumor cells and mouse spleen) with simple beta-carboline alkaloids induced a strong bluish white fluorescence emission of condensed chromatin and basophilic cytoplasm under ultraviolet excitation. The compounds used were harmine, harmol, harman, norharman, harmalol and harmaline (25-50 micrograms/ml aqueous solutions for 2-3 min). Spectrofluorometric studies on harmine solutions in vitro (emission peak at 420 nm) showed fluorescence quenching at high concentrations as well as in the presence of DNA. Microscopic fluorescence features of these new fluorochromes and possible binding modes to nucleic acids are discussed.