Antioxidant activity and components of a traditional chinese medicine formula consisting of Crataegus pinnatifida and Salvia miltiorrhiza

Background: The aims of this study were to evaluate the antioxidant activity and to identify the antioxidant components of a traditional Chinese medicine formula consisting of a combination of Shanzha (the fruit of Crataegus pinnatifida Bge. var. major N.E.Br., SZ) and Danshen (the root of Salvia miltiorrhiza Bge., DS). This medicine is extensively used to treat cardiovascular disease. Methods: Twelve samples extracted and fractionated from SZ, DS and the formula (SZ+DS) were analyzed. The concentrations of eight phenolic compounds were determined by high performance liquid chromatography. Oxygen radical absorbance capacity (ORAC) assay and 1,1-diphenyl-2-picrylhydrazyl assay were conducted to explore the antioxidant activities of the samples and of the 15 phenolic compounds detected. Correlation analysis of the antioxidant activity of herb samples and their phenolic components was performed. Results: The main phenolic component in all SZ+DS samples was salvianolic acid B, which exhibited strong antioxidant activity (ORAC value: 16.73 +/- 2.53, IC50 value: 8.80 +/- 0.06 mu M) compared with the other phenolic compounds. For all samples, there was a positive relationship between their total phenolic components and their antioxidant activities. Conclusions: Phenolic compounds were the bioactive components of the herb samples, and salvianolic acid B was identified as the main bioactive compound in the SZ+DS formula.