Determination of trace metal ions in Gentiana rigescens by inductively coupled plasma-optical emission spectrometry after deep eutectic solvent-based digestion and related pharmacodynamic evaluation

A fast, simple and environmentally friendly method for the digestion of solid samples of Gentiana rigescens Franch. ex Hemsl. (G. rigescens) based on deep eutectic solvent (DES) was established, and inductively coupled plasma-optical emission spectrometry (ICP-OES) was used to quantify Ni, Zn, Co, Cr and Cu in DES digestion solution. Under optimized conditions, limits of detection (LOD) and limits of quantification (LOQ) ranged from 0.4 to 2.5 and 1.2–8.2 μg g-1, respectively. The intra-day and inter-day precision were carried out by relative standard deviation (RSD) ranged from 0.8% to 4.9% and 0.6%–1.4%, and the spiked recoveries ranged from 90.6% to 111.9%, respectively. The results of quantitative analysis by the developed method were in good agreement with those of microwave digestion. At the same time, the contents of the metal ions in the G. rigescens decoction liquid and freeze-dried powder solution of the decoction liquid of G. rigescens (crude extract) were determined by ICP-OES. The results showed that the contents of Ni, Zn, Co and Cu in the decoction liquid and crude extract were significantly lower than the contents in DES digestion liquid, and Cr was not detected. Then, the oxidative damage model of LO2 cells induced by H2O2 was established. The protective effect of crude extract of G. rigescens on damaged liver cells and the effect of metal ions with the same contents of decoction liquid on liver protection of G. rigescens were investigated for the first time. The results show that H2O2 could induce the decrease of LO2 cell viability and damage the cell morphology. GPS and crude extract could inhibit H2O2-induced liver injury by adjusting the antioxidant enzyme system. Metal ions corresponding to the content of the decoction liquid may weaken the hepatoprotective effect of GPS or crude extract by regulating the antioxidant enzyme system.