Simultaneous Quantification of 66 Compounds in Two Tibetan Codonopsis Species Reveals Four Chemical Features by Database-Enabled UHPLC-Q-Orbitrap-MS/MS Analysis

<i>Codonopsis canescens</i> Nannf. (CoC) and <i>Codonopsis nervosa</i> Nannf. (CoN) are two traditional Tibetan medicinal herbs (Zangdangshen), which have been widely used in the treatment of various diseases. In this study, their aerial and underground parts were systematically analyzed using database-enabled UHPLC-Q-Orbitrap-MS/MS technology. This technology introduced three adduct ions, [M - H]^-, [M + H]⁺, and [M + NH₄]⁺, to putatively identify a total of 66 compounds. During the putative identification, at least 16 isomers were successfully differentiated, such as isochlorogenic acid A vs. isochlorogenic acid B vs. isochlorogenic acid C. Thereafter, all these identified compounds were further quantified for their contents based on a linear regression method. Their contents were observed to vary from 0.00 to 39,127.03 µg/g. Through multiple comparisons of these quantification results, the study found the following four chemical features: (1) Four sesquiterpenes (especially atractylenolide III) enriched mainly in CoC and rarely in CoN; (2) four quinic acid derivatives were abundant in the aerial part of two species; (3) sixteen flavonoids (particularly diosmetin and chrysoeriol) showed higher content in CoC than in CoN; and (4) lobetyolin was ubiquitously distributed in four parts of both CoC and CoN. Based on these features and the relevant principles, four compounds (lobetyolin, atractylenolide III, diosmetin, and chrysoeriol) are recommended as the quality markers of two Tibetan <i>Codonopsis</i> species. All these findings can facilitate the sustainable development and quality control of the two traditional Tibetan medicinal herbs.