Shin W, Kim S J, Shin J M, Kim S H
Department of Chemistry, Seoul National University, Korea.
J Med Chem. 1995 Oct 13;38(21):4325-31. doi: 10.1021/jm00021a022.
The dihydrochalcone derivatives of the bitter flavonoids naringin and neohesperedin are intensely sweet. Phyllodulcin is as sweet as the dihydrochalcones with similar taste properties although its structure apparently resembles that of bitter flavanone or flavone. Multifaceted approaches, including X-ray crystal structure analysis, energy calculation, and structure comparison, have been employed to clarify the structure-taste correlations in these classes of compounds. In the crystal, naringin dihydrochalcone assumes a 'J'-shaped conformation with a fully-extended dihydrochalcone moiety while neohesperidin dihydrochalcone assumes the same overall conformation but with a partially-extended moiety. A 2D conformational energy map of dihydrochalcone obtained using molecular mechanics revealed nine local minima. The pseudoequatorial and pseudoaxial forms of phyllodulcin have the same AM1 energies with a low energy barrier between them. The partially-extended form of dihydrochalcone and the pseudoequatorial form of phyllodulcin which are the maximally superposable conformers are proposed to be the active conformers. The major difference between the structures of flavone and phyllodulcin is not in the overall planarity but in the relative orientation of the pyrone and phenyl ring systems.
苦味类黄酮柚皮苷和新橙皮苷的二氢查耳酮衍生物甜度极高。叶甜素的甜度与二氢查耳酮相当，味道特性相似，尽管其结构明显类似于苦味黄烷酮或黄酮。包括X射线晶体结构分析、能量计算和结构比较在内的多方面方法已被用于阐明这类化合物的结构-味道相关性。在晶体中，柚皮苷二氢查耳酮呈现出一种“J”形构象，二氢查耳酮部分完全伸展，而新橙皮苷二氢查耳酮具有相同的整体构象，但部分伸展。使用分子力学获得的二氢查耳酮二维构象能量图显示有九个局部最小值。叶甜素的假平伏键和假直立键形式具有相同的AM1能量，它们之间的能垒较低。二氢查耳酮的部分伸展形式和叶甜素的假平伏键形式是最大程度可叠加的构象异构体，被认为是活性构象。黄酮和叶甜素结构之间的主要差异不在于整体平面性，而在于吡喃酮和苯环系统的相对取向。
