Front Cover: Preparative isolation of antioxidative gallic acid derivatives from Saxifraga tangutica using a class separation method based on medium‐pressure liquid chromatography and reversed‐phase liquid chromatography

Abstract

DOI: 10.1002/jssc.202100361 The cover picture shows the discovery of antioxidative natural products from traditional Chineses medicines (TCMs) or traditional Tibetan medicines (TTMs). Firstly, the TCMs or TTMs extract underwent the sample pretreatment process with medium pressure liquid chromatography (part A, red labeled Part A). Second, the preprocessed fractions should be screened the DPPH inhibitors using the on-line RPLC-DPPH system and the active chromatographic peaks (DPPH inhibitors) can be recognized (part B, red labeled Part B). Then, the active compounds (DPPH inhibitors or antioxidative natural products) contained in the active chromatographic peaks were separated by the off-line two-dimensional (RPLC×HILIC in this manuscript) preparative liquid chromatography (part C, red labeled Part C). Lastly, through analysis of MS and NMR spectra, the structures of antioxidative natural products (part D, red labeled Part D) were identified.