抗癌药β—榄香烯分子内部运动的￣（13）C核自旋弛豫研究

THE INVESTIGATION OF MOLECULAR INTERNAL MOTIONS OF ANTICANCER DRUG β-ELEMENE BY^(13)C NMR RELAXATION

首次应用变温实验方法和￣（１３）Ｃ核自旋弛豫方法研究了抗癌药β－榄香烯小分子的内部运动状况。结果表明β－榄香烯分子的六元环在所研究的温度范围（２９８～３１８Ｋ）内几乎是刚性的。该分子的整体滚动自扩散活化能为１４ｋＪ／ｍｏｌ．其六元环外侧链基团ＣＨ＿２＝ＣＣＨ＿３－和ＣＨ＿２＝ＣＨ－的整体内旋转扩散活化能均为１９ｋＪ／ｍｏｌ．而与该六元环直接相连的甲基的内旋转扩散活化能为１８ｋＪ／ｍｏｌ．这个数值大大高于连在六元环上不同位置的两个侧链基团ＣＨ＿２＝ＣＣＨ＿３一中甲基的内旋转扩散活化能（其数值分别为了７ｋＪ／ｍｏｌ和２．８ＫＪ／ｍｏｌ）．３个不同位置的甲基的内旋转扩散活化能有很大差别可能是由它们所处的分子空间环境不同而引起的。

The internal motions of β-Elemene， which is anti-caneer compound， havebeen investigated by using variable temperature ^(13)C NMR relaxation experiments forthe rirst time。The results show that the hexacyclic ring in β-Elemene is almost rigid inexperimental temperature range from 298K to 318K and the self-diffusion activationenergy of overall motion of the moleeule is 14 kJ／mol． All the intemal rotationactivation energies for side Chain molccular groups CH_2=CCH_3- andCH_2= CH- connecting with the hexacyclic ring are 19 kJ／mol．The methyl grouplinking directly the hcxacyclic ring has much higher internal rotation activation energy，which is 18 kJ／mol， than those in two side chain groups CH_2 = CCH_3-which connectwith the hexacyclic ring at different positions and moreo ver， the methyl groups in thetwo side chain groups CH_2 = CCH_3- have different internal rotation activation energieswhich are 7，7 kJ／mol and 2．8 kJ／mol， respectively； This may result from thatthe three methyl groups have different space circumstances in β-Elemene。