Quality evaluation of commercial extracts of Scutellaria baicalensis

Botanical products have been widely used for various illnesses and general well-being. However, quality control of botanical products is often not performed due to lack of standardization, resulting in inconsistent efficacies and sometimes serious toxicity. The goals of this study were to determine the correlation between chemical composition and biological activities and to establish a method to measure authenticity, chemical consistency, and biological potency of botanical products. A high-performance liquid chromatography method was used to analyze the authenticity and chemical composition of 10 different commercial extracts. The cell viability assay and prostaglandin E2 (PGE2) enzyme immunoassay were used to analyze biological potency and consistency. Our results showed all extracts contained marker components (baicalein and/or baicalin), confirming their authenticity. However, significant product-to-product and batch-to-batch variation of these marker components was observed with 4 products containing no baicalin at all and baicalein concentration ranging from 0 to 52.3 g/mg. The 50% growth inhibition concentration of the extracts ranged from 0.18 to 2.0 mg/ml, more than an 11-fold variation. PGE2 levels varied from 19.5 to 111.1 pg/106 cells, more than a 5.7-fold difference. These results demonstrated significant variation in chemical composition and biological activities of the commercial extracts and that the amount of marker components may not reflect biological activity levels. Therefore, chemical analysis alone is inadequate for quality control, and biological assays must be included for botanical products to ensure chemical authenticity as well as pharmacological/biological potency and consistency.