Rapid characterization of non-volatile phenolic compounds reveals the reliable chemical markers for authentication of traditional Chinese medicine Xiang-ru among confusing Elsholtzia species

The aerial parts of Mosla chinensis Maxim. and Mosla chinensis cv. 'Jiangxiangru' (MCJ) are widely utilized in traditional Chinese medicine (TCM), known collectively as Xiang-ru. However, due to clinical effectiveness concerns and frequent misidentification, the original plants have increasingly been substituted by various species within the genera Elsholtzia and Mosla. The challenge in distinguishing between these genera arises from their similar morphological and metabolic profiles. To address this issue, our study introduced a rapid method for metabolic characterization, employing high-resolution mass spectrometry-based metabolomics. Through detailed biosynthetic and chemometric analyses, we pinpointed five phenolic compounds—salviaflaside, cynaroside, scutellarein-7-O-D-glucoside, rutin, and vicenin-2—among 203 identified compounds, as reliable chemical markers for distinguishing Xiang-ru from closely related Elsholtzia species. This methodology holds promise for broad application in the analysis of plant aerial parts, especially in verifying the authenticity of aromatic traditional medicinal plants. Our findings underscore the importance of non-volatile compounds as dependable chemical markers in the authentication process of aromatic traditional medicinal plants.