Spectrophotometric, spectropolarimetric, viscometric and spectrofluorimetric analysis of the binding of the alkaloid nitidine to double- and triple-helical forms of RNA have served to highlight the ability of this drug to produce changes in the structure of RNA. The experimental data collected here confirm that nitidine is able to intercalate into the base pairs of poly(A).poly(U) and poly(U).poly(A)*poly(U) under specified conditions and the strength of interaction was of the order of 106 M−1, as calculated from UV absorption study. The binding constants showed that NIT binds more strongly to the triple-helical form of RNA than the corresponding parent duplex.
