以核磁共振光譜探討赭麴毒素與環糊精之交互作用

Interaction between Ochratoxin A and Cyclodextrin：Nuclear MagneticResonance Study

林昱誠(Lin Yu-Chin)

指導教授 ： 錢偉鈞

朝陽科技大學/理工學院/應用化學系生化科技碩博士班/碩士(2014年)

摘要

以赭麴毒素A導入三種環糊精(α、β、γ)進行螢光光譜測詴，其中以β-環糊精增加幅度最為明顯，而在圓二色光譜的結果與螢光光譜結果相同，以β-環糊對赭麴毒素A之苯環區段 (波長 220nm ~ 260 nm) 增幅明顯。藉由結果推斷赭麴毒素A的苯環亦會被環糊精之疏水性部位吸引，進入環糊精空腔中形成似凡德瓦爾力等作用力固定於空腔中。 核磁共振光譜技術探討赭麴毒素A與各類環糊精之作用。一維共振光譜滴定實驗結果顯示，當赭麴毒素A與各類環糊莫耳數比(R) 1:1 此濃度條件下，β-、γ-環糊精的 H3、H5共振訊號產生明顯位移。進行TOCSY、NOESY及DOSY實驗，在NOESY光譜顯示赭麴毒素A苯環區(H-Ph)與β-環糊精分子的H3、H5產生明顯的NOE。然而赭麴毒素A與α-、γ-環糊精結合時，在NOESY光譜沒有明顯的NOE，此結果對應螢光光譜及圓二色光譜之結果相符，赭麴毒素A的苯環區被導入β-環糊精的疏水性部位。且於DOSY實驗中，藉由公式推導出結合常數:赭麴毒素A對β-環糊精結合常數為 497.68 M-1，赭麴毒素A對γ-環糊精結合常數198.86 M-1，則α-環糊精因空腔空間較窄，赭麴毒素A無法進入。這個實驗結果可運用於穀物上黴菌毒素檢測的快速篩選及增加偵測極限。

關鍵字

環糊精 ； 赭麴毒素 ； 核磁共振光譜儀 ； 內包複合物

並列摘要

Cyclodextrin (CDs) enhance the fluorescence of hydrophobic fluorophores, which is a useful property in improving the detection limits in the analysis of mycotoxins. The inclusion complex interaction between ochratoxin A with α-CD、β-CD and γ-CD have been investigated by fluorescence, circular dichroism and NMR spectroscopy, respectively. The fluorescence enhancements was most prominent when β-CD was introducing into the aqueous solution of ochratoxin A. The H1-NMR spectra provide direct evidence of interaction between guest and host molecules. The closely related protons in space between ochratoxin A and CD molecules can be identified by the NOEs. The H3、H5、H6 proton are proximate to the aromatic group of toxin molecule. Based on a two-state-model, the association constants of mycotoxin to different CSs are determined by monitoring the change of self-diffusion coefficient (Ds) of ochratoxin A from aqueous solution into CD environment. The Ds values are measured by pulsed-field-gradient NMR techniques. No evident interaction between ochratoxin A with α-CD. For β-CD, the aromatic region of toxin molecule embedded inside the cavity of cyclodextrin with Ka is 497.68 M-1. For γ-CD, the guest molecule almost penetrate the host molecule, and the Ka is 198.86 M-1. The formation of ochratoxin A - CD complex is a spontaneous process. The mycotoxin-CD inclusion complex is simulated using NMR constraints. Hydrophobicity is the major factor in the toxin-CD recognition process which is also triggered by the cavity size of host molecules.

並列關鍵字

inclusion complex ； cyclodextrin ； ochratoxin A ； NMR

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