Abstract: Fluorescence spectrometry with two kinds of fluorescence probe and resonance light scattering spectroscopy were applied to study the interaction between lawsone and DNA.The DNA saturation binding value was adopted to evaluate the toxicity of the lawsone and its toxicity mechanism was inferred.Results showed that the DNA saturation binding value of lawsone was 0.33.In case the binding effect of six kinds of environmentally co-existing material,sodium chloride,calcium chloride,glucose,isoleucine,histidine and vitamin C achieving the highest value,the DNA saturation binding values of lawsone is 0.40,0.50,0.29,0.33,0.25 and 0.29 respectively.The lawsone can eliminate the fluorescence intensity of ethidium bromide-DNA abruptly and can eliminate that of SYBR Green-DNA slightly.Intensity of resonance light scattering of lawsone-single stranded DNA was weaker than that of lawsone-double stranded DNA.The conclusion is that the lawsone has certain toxicity.It can cause embedded binding with the DNA base pairs,and weakly bind into the minor groove of DNA.

Key words: lawsone, DNA toxicity, saturation binding value, toxicity mechanism