we have two part in this thesis, at first: the interaction of native calf thymus dna (ct-dna) with two anthraquinones including quinizarin (1,4- dihydroxy anthraquinone) and danthron (1,8- dihydroxy anthraquinone) in a mixture of 0.04 m brittone-robinson buffer and 50% of ethanol were studied at physiological ph by uv-vis absorption, florescence, circular dichroism spectroscopic methods, viscosity measurements and cyclic voltammetry techniques. the pca and indices methods were used for the prediction the number of light absorbing components. the equispec software and nonlinear least squares analysis were applied for binding constant determinations. thermodynamic study indicated that the reactions of both anthraquinone–dna systems are predominantly entropically driven. furthermore, the binding mechanisms on the reaction of the two anthraquinones with dna and effect of ionic strength on the fluorescence and uv-vis property of the system have also been investigated. the effect of ph on the behavior of the above system and also the interaction of anthraquinones with ds and ss-dna were used to confirm the mentioned binding modes. the results of the assay indicated that the binding modes of quinizarin and danthron with dna were evaluated to be groove binding. moreover, the cytotoxic activity of both compounds against human chronic myelogenous leukemia k562 cell line and dna cleavage were investigated. the results indicated that these compounds cleavage puc18 plasmid dna slightly and showed minor antitumor activity against k562 (human chronic myeloid leukemia) cell line. in second part, fluorescence spectroscopy, uv–visible absorption spectroscopy, circular dichroism spectroscopy (cd), viscometry, cyclic (cv) and differential pulse voltammetry (dpv) were applied to investigate the competitive interaction of dna with nine ?-aminobisphosphonate and spectroscopic probe, neutral red dye (nr) and hoechest (ho), in a tris–hydrogen chloride buffer (ph 7.4). the principal component analysis (pca), was applied to determine the number of chemical components presented in complexation equilibrium of dna with ?-aminobisphosphonates. the spectroscopic and voltammetric studies showed that the groove binding mode of interaction is predominant in the solution containing dna and ?-aminobisphosphonates. furthermore, the results indicated that ?-aminobisphosphonate with the lengthy n alkyl chains had a stronger interaction.

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