| Currently, herbal medicines especially anticancer herbal drugs are gaining more attention from modern pharmaceutical institutes, as scientists become aware that herbal medicine is an almost infinite resource for drug development. Furthermore, the toxicity of the herbal drug is very low and most of them have no side-effect. The exploitation of the natural source makes the difference in the field of the medicine. As are known, the study of herbal drugs mainly embody the methods of purification and separation, it is not enough to study the characters and the anticancer mechanism of them. This dissertation have investigated the electrochemical characters of emodin and apigenin and established the novel electroanalytical methods for them. Moreover, the interactions of emodin and apigenin with DNA are then investigated by the electrochemistry and spectrum. The result indicates emodin can intercalate into the double helical structure of DNA to inhibit the synthesis of DNA. Apigenin doesn't interact with DNA under the conditions, This simultaneously exhibits the low toxic effect of apigenin to a certain extent. The main works and results are summarized as following:1.The electrochemical behavior of emodin at the glassy carbon electrode has been investigated. In 0.05 M NH3-NH4Cl (50 % ethanol, pH 7.2) buffer solution, a pair of quasi-reversible redox peaks at potentials of EP1 = -0.688V and Ep2 = -0.628V and one irreversible anodic peak at Ep3= -0.235V were appeared. They are all adsorption-driven peaks. The peak currents of P3 are linear relationship with apigenin concentrations in the range of 8.9×10-8 mol/L～7.8×10-6mol/L with the detection limit of 7.8×10-9mol/L. Based on this method, the apigenin content of Sanhuang tablets was determined with satisfactory. There is no need to separate other 9, 10-anthraquinone derivative ingredients contained in herbal drug.2. The electrochemical behavior of the antitumor herbal drug apigenin was studied in 0.1 M B-R buffer solution (50% ethanol, pH 9.0) by means of some electrochemistry methods on the glassy carbon electrode (GCE). The cyclic voltammetry shows one irreversible anodic peak. The plot of ip vs.υ1/2 gives a straight line. The result shows that the irreversible oxidation reaction is a diffusion-driven process. Their dynamics parameters were obtained by some electrochemistry methods. The differential pulse voltammetry (DPV) peak currents are linear relationship with apigenin concentrations in the range of 5.0×10-6 mol/L9.0×10-5 mol/L with the detection limit of 1.5×10-6 mol/L, which has been used in sample analysis with satisfactory result. We also study the interaction of apigenin with DNA by DPV and Ultraviolet-Visible (UV) spectra. The results show apigenin doesn't interact with DNA under the conditions.3. The interaction of apigenin with DNA was studied by DPV at the bare or DNA-modified electrode and UV-vis spectra. As a result of intercalating of this drug into the double helical structure of DNA, the DPV of apigenin shows that peak potentials shift and peak currents decrease with the addition of DNA. UV-vis spectra exhibits that a decrease in the absorbance of emodin at about 440 nm with red shift and two isobestic points at about 400 and 475 nm. Under our experiment conditions, the decrease of peak current is proportional to DNA concentration, which can be applied to estimate DNA concentration. The results indicate that the herbal drug emodin can interfere with the DNA by intercalating into the double helix of DNA.
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