The Electrochemical Study Of Anticancer Herbal Drug And The Interaction With DNA

With the study of the anticancer drug, the scientist discovers many medicines synthesized by chemistry damage the normal cell and show the different degree mutation heredity toxicity, however, the toxicity of the herbal drug is not obvious. That indicates that the anticancer herbal drugs have special advantages and broadly applied foreground. 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. The paper investigates the electrochemical characters of idinonine and indirubin and establishes the novel electroanalytical methods for them. Moreover, the interactions of indirubin and methotrexate (MTX) with DNA are then investigated by the electrochemistry and spectrum. The result indicates the drug can intercalate into the double helical structure of DNA or form adducts to inhibit the synthesis of DNA. The main works and results are summarized as following:1. The electrochemical behavior of idinonine (IDN) at the hanging mercury electrode has been investigated. In the acetic acid buffer solution(pH7.8),a adsorption-driven reduce peak of idinonine is obtained with the peak potentials of -1.150V(vs.SCE), the peak currents are linear relationship with IDN concentrations in the range of 7.25 ×10~-7 mol/L~1.01×10~-5mol/L with the detection limit of 1.45×10~-7 mol/L. Based on this method, the idinonine content of rabdosia rubescens tablet was determined with satisfactory.2. The electrochemical behavior of the antitumor herbal drug indirubin was studied in 0.1mol/L KH2PO4 (50% acetone, pH 4.6) by means of cyclic voltammetry (CV) and differential pulse voltammetry (DPV) on the glassy carbon electrode (GCE). The electrode reactions of indirubin in our experiment conditions are very complex. The cyclic voltammetry shows two pair of redox ( I red and Ⅱox Ⅳax and Ⅴred) peaks and one irreversible cathodic peak (Ⅲred). The peak currents are linearly related to the scan rates indicating the electrode reactions controlled by adsorption. Their dynamics parameters were obtained by some electrochemistry methods. The DPV peak currents at 0.920V are linear relationship with indirubin concentrations in the range of 7.643×10~-7 mol/L~1.146 × 10~-5 mol/L with the detection limit of 3.822×10~-7 mol/L, which has been used in sample analysis with satisfactory result.3. The electrochemical characters of the antitumor agent methotrexate (MTX) and the interaction with DNA at the graphite electrode have been investigated in KH2PO4 (pH4.60). The cyclic voltammetry shows one irreversible cathodic peak at 0.914V and a pair of redox (Epc=-0.552V; Epa=-0.453V). The peak potentials shift and currents decrease markedly. Furthermore, the dynamics parameters of MTX and DNA-mMTX are studied in the range of 0V-0.7V. With the interaction of them, the apparent rate constant obviously decreases from 0.662s"1 to 0.325s"1. At the same time, the interaction was studied further by the spectrum and the biosensor. MTX and DNA Parameter such as intrinsic binding constant (K); binding numbers (n) were obtained. The all results indicate that MTX appears to be the interference of DNA.4. The interaction of indirubin with DNA was studied by differential pulse voltammetry (DPV) and linear sweep voltammetry (LSV) at the bare or DNA-modified electrode and UV-vis or IR spectra. As a result of intercalating of this drug into the double helical structure of DNA, the DPV of indirubin shows that peakpotentials shift and peak currents decrease with the addition of DNA. UV-vis spectra exhibits that the absorption intensity of indirubin at 538.7nm decreases, which indicates that the anticancer herbal drug indirubin binds DNA. In addition, IR-spectra of DNA and DNA-indirubin adduct imply indirubin interacts with the phosphate groups of DNA by hydrogen bond or electrostatic interaction. 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 indirubin can interfere with the DNA by intercalating into the double helix of DNA and interacting with the phosphate groups of DNA.