Antifibrotic activities of Scutellariae Radix extracts and flavonoids: Comparative proteomics reveals distinct and shared mechanisms

Background:Scutellariae Radix (SR), the root of Scutellaria baicalensis Georgi, and SR flavonoids have antifibrotic activities. It remains obscure, however, amongst SR aqueous extract (SRA), SR methanolic extract (SRM) and five major SR flavonoids (baicalein, baicalin, wogonoside, wogonin and oroxyloside), which ones are the most promising antifibrotics and what their mechanisms are. Purpose:To compare the antifibrotic activities of SR extracts and flavonoids, and the proteomic signatures of selected SR extract and flavonoid, versus IN1130 phosphate, an antifibrotic positive control (abbreviated as IN1130), in TGF-81-induced in vitro model of fibrosis in NRK-49F renal fibroblasts. Methods:Isobaric labelling-based mass spectrometry was used for proteomic studies. Differentially expressed proteins were further analyzed using Gene Ontology annotation enrichment, protein-protein interaction network analysis and pathway analysis. Selected proteins of interest were validated by enzyme-linked immunosorbent assay (ELISA). Results:Baicalein was the SR flavonoid with the best efficacy-toxicity ratio. SRM contained 8-fold more flavonoids and was more potently antifibrotic than SRA. Proteomic analysis of cells treated by TGF-81, with or without baicalein (40 and 80 mu M), SRM (40 and 80 mu g/ml) and IN1130 (1 mu M) suggested that baicalein, SRM and IN1130 all repressed TGF-81-induced ribosomal proteins in cell lysates, while baicalein and SRM, but not IN1130, regulated the intracellular lysosome pathway; secretomic analysis suggested that 40 and 80 mu g/ml SRM

Automated summary

This study compared the antifibrotic activities of Scutellariae Radix extracts and flavonoids, and conducted proteomic analysis on selected flavonoids. The results showed that baicalein was one of the most promising antifibrotic flavonoids, and SR methanolic extract had stronger antifibrotic effects compared to the aqueous extract.