Abstract:

Solanum nigrum L. contains a variety of active ingredients. It has been applied broadly in clinical practice. However, the compositions of Solanum nigrum L. from different cultivated areas are quite different. Therefore, it is necessary to set up a standard fingerprint. In this work, a series of Solanum nigrum L. samples were collected from different habitats. A high performance liquid chromatography with evaporative light-scattering detection (HPLC-ELSD) method was developed to study the differences in quality of these samples. The method was optimized by comparing different columns, gradient or isocratic elution and temperatures of evaporating tube. A Phenomenex C₁₈ column was finally selected for separation with gradient elution. The mobile phases were acetonitrile-20% (v/v) methanol aqueous solution containing 0.03% (v/v) triethylamine. The temperature of evaporating tube was set at 40 ℃. The validation was performed and the results showed that the method had good precision, repeatability and stability. The validated method was applied to detect Solanum nigrum L. from different habitats. The similarities of the acquired chromatograms were analyzed by using the similarity evaluation system for chromatographic fingerprint of traditional Chinese medicine (TCM). The chromatograms with a similarity between 0.9 and 1.0 were normalized and fitted to form a standard fingerprint of Solanum nigrum L. Thirteen common peaks were found and eleven peaks were identified with authentic standards. The results showed that remarkable differences were found among Solanum nigrum L. from different habitats. These herbs could be distinguished based on the compositions detected by HPLC-ELSD. This method provided a technology to evaluate the homogeneity and stability of Solanum nigrum L with wide application prospects and practical value.

Key words: Solanum nigrum L., evaporative light-scattering detection (ELSD), fingerprints, high performance liquid chromatography (HPLC)