Samsonowicz Mariola, Kalinowska Monika, Gryko Kamila
Department of Chemistry, Biology and Biotechnology, Institute of Civil Engineering and Energetics, Faculty of Civil Engineering and Environmental Science, Bialystok University of Technology, Wiejska 45E Street, 15-351 Bialystok, Poland.
Materials (Basel). 2021 Jan 7;14(2):264. doi: 10.3390/ma14020264.
The copper (II) complex of ursolic acid (Cu(II) UA) was synthesized and discussed in terms of its infrared, UV-visible spectra, quantum-chemical calculations at B3LYP/6-31G(d) level and antioxidant capacity. The copper (II) complex was stable in methanolic solution with the molar ratio metal:ligand 1:1. The data obtained by FT-IR confirmed the metal ion coordination through the carboxylate anion. The antioxidant properties of ursolic acid and its complex with Cu were discussed on the basis of energy of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and values of chemical reactivity parameters. The antiradical properties of ursolic acid and the Cu (II) complex were examined against DPPH and HO radicals, and the ferric reducing antioxidant power (FRAP) was examined. The Cu(II) complex showed higher antioxidant activity than ursolic acid, i.e., in DPPH assay, the EC for UA was 47.0 mM, whereas, for Cu(II), UA EC = 19.5 mM; the FRAP value for UA was 20.8 µM, and 35.4 µM for Cu(II) UA (compound concentration 3 mM). Although there was no distinct difference in the antioxidant activity against HO between these two chemicals, they were both better HO scavengers than DPPH and showed different kinetics in the reaction with DPPH.
合成了熊果酸的铜（II）配合物（Cu（II）UA），并从其红外光谱、紫外可见光谱、B3LYP/6-31G（d）水平的量子化学计算以及抗氧化能力方面进行了讨论。该铜（II）配合物在甲醇溶液中以金属：配体摩尔比1:1稳定存在。傅里叶变换红外光谱（FT-IR）获得的数据证实了通过羧酸根阴离子进行的金属离子配位。基于最高占据分子轨道（HOMO）和最低未占据分子轨道（LUMO）的能量以及化学反应性参数值，讨论了熊果酸及其与铜的配合物的抗氧化性能。考察了熊果酸和Cu（II）配合物对DPPH和HO自由基的抗自由基性能，并检测了铁还原抗氧化能力（FRAP）。Cu（II）配合物表现出比熊果酸更高的抗氧化活性，即在DPPH测定中，UA的EC为47.0 mM，而对于Cu（II）UA，EC = 19.5 mM；UA的FRAP值为20.8 μM，Cu（II）UA为35.4 μM（化合物浓度3 mM）。尽管这两种化合物对HO的抗氧化活性没有明显差异，但它们都是比DPPH更好的HO清除剂，并且在与DPPH的反应中表现出不同的动力学。
