Correlations between appearance traits and internal quality of Bupleurum scorzonerifolium roots based on theory of "quality evaluation through morphological identification"

Abstract

It is generally believed that high-quality Bupleurum scorzonerifolium roots possess specific morphological characteristics, being red, robust, and long with strong odor. However, the scientific connotation of these characteristics has not been elucidated. According to the theory of "quality evaluation through morphological identification", we studied the correlations between appearance traits(the RGB value of root surface, root length, root diameter, dry weight, and ratio of phloem to xylem) and content of main chemical components(volatile oils, total saponins, total flavonoids, total polysaccharides, and seven saikosaponins) of B. scorzonerifolium roots. Epson Scanner and ImageJ were used to scan the root samples and measure the appearance traits. Ultraviolet spectrophotometry and HPLC were employed to determine the content of chemical components. The correlation, regression, and cluster analyses were performed to study the correlations between the appearance traits and the content of chemical components. The results showed that the content of volatile oils and saikosaponins were significantly correlated with RGB value, root length, and root diameter, indicating that within a certain range, the roots being redder, longer, and thicker had higher content of volatile oils and saikosaponins. According to the appearance traits and chemical component content, the 14 samples from different producing areas were classified into four grades, and the differences in morphological traits and chemical component content were consistent among different grades. The findings in this study demonstrate that appearance traits(RGB value, root length, and root diameter) can be used to evaluate the quality of B. scorzonerifolium roots. Meanwhile, this study lays a foundation for establishing an objective quality evaluation method for B. scorzonerifolium roots.