Quantitative multicomponent analysis of a single marker–based simultaneous determination and quality assessment of nucleoside analogs from Qi Zhi capsules

Abstract

Qi Zhi capsule (QZC) is approved by the State Drug Administration of China. The QZC consists of nine crude drugs, including astragalus, leeches, ground beetles, curcuma zedoary, hawthorn, semen cassiae, rhizoma sparganii, polygonum multiflorum, and peach kernel, of which leeches and ground beetles are Traditional Chinese Medicine of animal origin. Nucleosides are animal substances with pharmacological effects that are easy to extract and quantify. Different nucleoside analogs in distinct animal‐based formulations can be used to characterize animal‐based medicines. However, the quality control of a single indicator does not reflect the overall quality of Chinese medicine. Here, we developed a method to simultaneously determine the nucleoside analogs uracil, xanthine, hypoxanthine, uridine, guanine, and uric acid in QZCs using high‐performance liquid chromatography. Hypoxanthine was used as an internal reference to determine relative correction factors for the other five components. The six components were determined in ten different batches of QZCs. There was no significant difference between the quantitative multicomponent analysis of a single marker and the external standard method. The relative standard deviation of total nucleosides analogs of 10 batches of samples was 7%. This method can be applied to simultaneously determine multiple active components in QZCs and other nucleoside analog drugs, enabling multi‐indicator quality control.

Simultaneous electrochemical determination of uric acid and hypoxanthine at a TiO2/graphene quantum dot-modified electrode

“…URI is a weak diprotic acid with p K a1 = 5.4 and p K a2 = 9.8 [ 30 ]. HYP contains an ionizable group with p K a = 8.7 [ 31 ]. The improved reversibility and sensitivity of the modified electrode may be due to the electrostatic interaction between positively charged URI and HYP and negatively charged GQD at remaining COO − groups, the complexation of titanium to nitrogen or oxygen, or π–π interactions between the phenyl structure of purine and the planar hexagonal carbon structure of graphene.…”