DISCRIMINATION BETWEEN TUMOR AND NORMAL-CELLS BY STAINING WITH YCARBONYL)-19-ALPHA-METHYL-20-ALPHA-OXAYOHIMBANIUM - THE URACIL RING AS A TARGET FOR THE SPECIFIC INTERACTION BETWEEN RNA(S) AND THE FLUORESCENT-PROBE

3,4,5,6,16,17-Hexadehydro-16-(methoxycarbonyl)-19 alpha-methyl-20 alph a-oxayohimbanium (Alstonine) is a fluorescent alcaloid which has been known to stain tumour cells more efficiently than normal ones. In this paper the spectral properties of Alstonine were first investigated an d its capability for preferential staining of tumour cells verified in culture using SK-OV-3 cells as tumour cells and Mouse 3T3 fibroblasts as controls. Then interactions between Alstonine and biological macro molecules were investigated to provide the rationale for preferential labelling. Molecular filtration techniques have demonstrated that bind ing occurs only with RNA molecules. Similar experiments were performed with different isopolynucleotides to find an explanation for that spe cificity. They provide evidence that binding occurs only in the presen ce of a uridyl ring. This is consistent with the specificity of the li nkage to RNA. As the linkage of Alstonine with RNA did not induce any shift or obvious change in the intensity of its fluoroescence spectrum , it is concluded that the binding might involve the side chain of the fluorescent compound.