芝麻素及其衍生物与DNA相互作用的研究

在pH=7.4的生理条件下，采用紫外吸收光谱法、圆二色(CD)光谱法、DNA热变性法及粘度法对芝麻提取物芝麻酚（SL）、芝麻素（SN）及细辛脂素（AN）与小牛胸腺 DNA(ctDNA)的相互作用机理进行初步探讨。研究结果显示，ctDNA能使三种化合物在290 nm附近处的紫外吸收峰产生减色效应，且伴随轻微的红移现象，ctDNA浓度越大，减色效应越明显，SL、SN及AN与ctDNA的结合常数大小分别为2.65×104、4.91×104、7.33×104 L/mol；三种化合物均能使ctDNA的正CD带(276 nm)增加，负CD带(246 nm)发生轻微的减小，且浓度越大，谱带变化越明显；三种化合物的存在条件下，ctDNA的熔点分别增加了1.75、2.51和6.63 ℃，且ctDNA粘度均有所增加。综合光谱学和粘度实验的结果，推断三种化合物与DNA的作用方式均为经典的嵌插方式，且作用强度大小为：AN>SN>SL。
The mechanism underlying the interaction of calf thymus DNA (ctDNA) with sesamol (SL), sesamin (SN), and asarinin (AN) was investigated by ultraviolet-visible (UV-Vis) and circular dichroism (CD) spectroscopies, DNA melting studies, and viscosity measurement under simulated physiological conditions (pH = 7.4). The results showed that ctDNA could produce the hypochromic effect for the UV absorbance peaks of the three compounds at 290 nm accompanied by a slight redshift; a higher concentration of ctDNA led to a greater hypochromic effect, and the binding constants of SL, SN, and AN to ctDNA were 2.65 × 104, 4.91 × 104, and 7.33 × 104 L/mol, respectively.The intensity of CD positive bands (276 nm) of ctDNA increased with the addition of the three compounds, and the negative bands (246 nm) were slightly reduced in intensity; a higher concentration led to a more significant change in the CD bands. With the presence of the three compounds, the melting temperatures of ctDAN were increased by 1.75, 2.51, and 6.63 ℃, respectively, and the viscosities of ctDNA were all increased to some extent. The results from the spectroscopic and viscosity experiments suggest that the interactions of SL, SN, and AN with DNA involve intercalation binding, and their interaction strengths were in the following order: AN > SN > SL.