An approach based on antioxidant fingerprint–efficacy relationship and TLC bioautography assay to quality evaluation of Rubia cordifolia from various sources

In this work, an approach based on antioxidant fingerprint–efficacy relationships and TLC bioautography assay was developed for quality evaluation of traditional Chinese medicine (TCM). First, chemical fingerprints of 20 batches of different sources of Rubia cordifolia were established by HPLC. The antioxidant activities of these samples were evaluated by 1,1-diphenyl-2-picrylhydrazyl radical scavenging assay. Then, five active components from fingerprint peaks were determined by both multiple correlation analysis and TLC bioautography assay. Similarity analysis and hierarchical clustering analysis (HCA) based on these active peaks were chosen to evaluate the quality of R. cordifolia from different sources. The samples with similarities below 0.9 had poorer antioxidant activities and those having stronger activities fell into the same cluster in HCA. Finally, five batches of commercial samples were processed in the same way to verify the feasibility of this method. The results suggested that chemical fingerprinting combined with similarity analysis based on fingerprint–efficacy relationship and TLC bioautography could evaluate the antioxidant activity of R. cordifolia from various sources. The established technique would also provide an easy method of evaluating the quality of other TCMs.