Identification of functional biomarkers of Peganum harmala and Hypericum perforatum using PCA-constructed secondary metabolite maps

Abstract

Peganum harmala L. (P. harmala), also known as Espand, Harmel, or Syrian rue, and Hypericum perforatum L. (H. perforatum), commonly known as St. John's wort, are two of the widely cultivated industrial crops and used worldwide in antihepatoma-related products. However, their main functional substances are still not clear, thus impeding the efficacy evaluations and quality controls of relative products around the world. In this work, the anti-hepatoma biomarkers of P. harmala and H. perforatum were clarified through the development of principal components analysis (PCA)-HPLC secondary metabolite mapping models. The chemical fingerprints of plant extracts were profiled by HPLC and then mapped to produce the secondary metabolite models using PCA. The models correlated the chemical information with the anti-hepatoma activities of plant extracts, thus indicating the functional inhibitors of P. harmala and H. perforatum against hepatoma cells. The activities of the identified compounds were validated by cytotoxic and apoptotic assays. The major inhibitors of P. harmala and H. perforatum against human hepatoma were determined to be harmine and quercetin, respectively. The IC50 values and the induced apoptotic rate of harmine on HepG2 cells were 20.7 ± 2.8 μM and 46.7 ± 3.5 %, respectively. The IC50 values and the induced apoptotic rate of quercetin on HepG2 cells were 49.5 ± 6.6 μM and 38.7 ± 2.6 %, respectively. In conclusion, the results significantly expanded the understanding of the biochemical foundations of P. harmala and H. perforatum, thus evidently supporting their current applications around the world. Moreover, harmine and quercetin could be used as biomarkers to evaluate the efficacy and quality of related products of industrial crops in therapeutic and health-improving applications.