De Ranjit, Jo Kyung Won, Kim Kyong-Tai
Laboratory of Molecular Neurophysiology, Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea.
Biomedicines. 2022 May 28;10(6):1265. doi: 10.3390/biomedicines10061265.
Flavonoids are being increasingly applied for the treatment of various diseases due to their anti-cancer, anti-oxidant, anti-inflammatory, and anti-viral properties. However, it is often challenging to detect their presence in cells and tissues through bioimaging, as most of them are not fluorescent or are too weak to visualize. Here, fluorescence possibilities of nine naturally occurring analogous flavonoids have been investigated through UV/visible spectroscopy, molecular structure examination, fluorescent images in mammalian cells and their statistical analysis employing aluminum chloride and diphenylboric acid 2-aminoethyl ester as fluorescence enhancers. It is found that, in order to form a stable fluorescent complex with an enhancer, flavonoids should have a keto group at C4 position and at least one -OH group at C3 or C5 position. Additionally, the presence of a double bond at C2-C3 can stabilize extended quinonoid structure at the cinnamoyl moiety, which thereby enhances the complex stability. A possible restriction to the free rotation of ring B around C1'-C2 single bond can contribute to the further enhancement of fluorescence. Thus, these findings can act as a guide for distinguishing flavonoids capable of exhibiting fluorescence from thousands of their analogues. Finally, using this technique, flavonoids are detected in neuroblastoma cells and their time course assay is conducted via fluorescence imaging. Their cellular uptake efficiency is found to be high and differential in nature and their distribution throughout the cytoplasm is clearly detected.
黄酮类化合物因其抗癌、抗氧化、抗炎和抗病毒特性而越来越多地应用于各种疾病的治疗。然而，通过生物成像检测它们在细胞和组织中的存在往往具有挑战性，因为它们中的大多数不是荧光的，或者荧光太弱而无法可视化。在这里，通过紫外/可见光谱、分子结构检查、哺乳动物细胞中的荧光图像以及使用氯化铝和二苯基硼酸2-氨基乙酯作为荧光增强剂的统计分析，研究了九种天然存在的类似黄酮类化合物的荧光可能性。研究发现，为了与增强剂形成稳定的荧光复合物，黄酮类化合物应在C4位置具有一个酮基，并且在C3或C5位置至少有一个-OH基团。此外，C2-C3处的双键可以稳定肉桂酰部分的扩展醌类结构，从而提高复合物的稳定性。环B围绕C1'-C2单键的自由旋转可能受到的限制有助于进一步增强荧光。因此，这些发现可以作为从数千种类似物中区分能够发出荧光的黄酮类化合物的指南。最后，使用该技术在神经母细胞瘤细胞中检测到黄酮类化合物，并通过荧光成像进行了它们的时间进程分析。发现它们的细胞摄取效率很高且具有差异性，并且清楚地检测到它们在整个细胞质中的分布。
