DST Unit of Nanoscience and Thematic Unit of Excellence, Department of Chemistry , Indian Institute of Technology Madras , Chennai - 600036 , India.
Chemical Laboratory , CSIR-Central Leather Research Institute , Adyar, Chennai 600020 , India.
Anal Chem. 2018 Aug 7;90(15):8776-8784. doi: 10.1021/acs.analchem.7b05231. Epub 2018 Jul 24.
A detailed examination of collision cross sections (CCSs) coupled with computational methods has revealed new insights into some of the key questions centered around curcumin, one of the most intensively studied natural therapeutic agents. In this study, we have distinguished the structures and conformers of the well-known enol and the far more elusive keto form of curcumin by using ion mobility mass spectrometry (IM MS). The values of the theoretically predicted isomers were compared with the experimental CCS values to confirm their structures. We have identified a bent structure for the keto form and the degree of bending was estimated. Using IM MS, we have also shown that ESI MS reflects the solution phase structures and their relative populations, in this case. Piperine, a naturally occurring heterocyclic compound, is known to increase the bioavailability of curcumin. However, it is still not clearly understood which tautomeric form of curcumin is better stabilized by it. We have identified preferential stabilization of the enol form in the presence of piperine using IM MS. Cyclodextrins (CDs) are used as well-known carriers in the pharmaceutical industry for increasing the stability, solubility, bioavailability, and tolerability of curcumin. However, the crystal structures of supramolecular complexes of curcumin∩CD are unknown. We have determined the structures of different isomers of curcumin∩CD (α- and β-CD) complexes by comparing the CCSs of theoretically predicted structures with the experimentally obtained CCSs, which will further help in understanding the specific role of the structures involved in different biological activities.
详细研究碰撞截面（CCS）与计算方法相结合，揭示了有关姜黄素的一些关键问题的新见解，姜黄素是研究最多的天然治疗剂之一。在这项研究中，我们使用离子淌度质谱（IM MS）区分了广为人知的烯醇和更难以捉摸的姜黄素酮形式的结构和构象。将理论预测异构体的值与实验 CCS 值进行比较，以确认其结构。我们已经确定了酮形式的弯曲结构，并估计了弯曲程度。使用 IM MS，我们还表明，在这种情况下，ESI MS 反映了溶液相结构及其相对丰度。胡椒碱是一种天然存在的杂环化合物，已知可提高姜黄素的生物利用度。然而，它仍然不清楚哪种姜黄素互变异构形式被它更好地稳定。我们已经确定，在胡椒碱存在下，烯醇形式得到优先稳定。环糊精（CD）在制药行业中用作众所周知的载体，以提高姜黄素的稳定性、溶解度、生物利用度和耐受性。然而，姜黄素∩CD 的超分子配合物的晶体结构尚不清楚。我们通过将理论预测结构的 CCS 与实验获得的 CCS 进行比较，确定了不同姜黄素∩CD（α-和β-CD）配合物的异构体结构，这将有助于进一步了解不同生物活性中涉及的结构的特定作用。
