Quality assessment and differentiation of Aucklandiae Radix and Vladimiriae Radix based on GC-MS fingerprint and chemometrics analysis: basis for clinical application

Vladimiriae Radix, a geo-authentic medicinal herb found in Sichuan Province in China, is highly similar in chemical composition and pharmacological activity to Aucklandiae Radix. It is often used in local practice and as a substitute for Aucklandiae Radix in the treatment of gastrointestinal tract diseases. However, Vladimiriae Radix is preferred to Aucklandiae Radix in traditional Chinese medicine in Sichuan. In order to compare the difference in quality between the two species and differentiate them according to their chemical profiles, and further to explain the rationality of using Vladimiriae Radix as a substitute and explore the reason for the medication preference in Sichuan, similarity was evaluated using gas chromatography-mass spectrometry (GC-MS) fingerprinting and chemometric analysis. Volatile compounds were identified by comparing mass spectra with spectral data from the National Institute of Standards and Technology library 14.L (NIST 14.L) and the linear retention indices (RI) with those previously reported. The results showed that the similarity between the samples from Aucklandiae Radix (>96%) was greater than that of Vladimiriae Radix (>80%). In addition, 41 and 38 compounds were identified in 10 batches of Vladimiriae Radix and Aucklandiae Radix, respectively, and 21 compounds were common to both species, of which dehydrocostus lactone and aplotaxene were abundant in both. However, gamma-patchoulene, longicyclene, beta-gurjunene, humulene1,2-epoxide, and beta-patchoulene were unique to Vladimiriae Radix, while 4-terpineol, alpha-ionone, trans-alpha-bergamotene, gamma-selinene, and camphene were characteristic compounds of Aucklandiae Radix. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) suggested that the two species were well differentiated with regard to the level of essential oils. Orthogonal partial least squares discriminant analysis (OPLS-DA) further showed that compounds including costol, aplotaxene, caryophyllene, humulene, and beta-eudesmol, together with the characteristic compounds of the two species, could be regarded as potential markers for differentiation, among which beta-eudesmol, which is richer in Vladimiriae Radix, and beta-patchoulene, which is unique to Vladimiriae Radix, have potential therapeutic effects on gastrointestinal diseases. The results obtained in this study distinguished Vladimiriae Radix and Aucklandiae Radix on a chemical level, and the similarity in chemical constituents may provide a basis for the rationality of Vladimiriae Radix as a substitute, while beta-patchoulene and beta-eudesmol existing in Vladimiriae Radix provide a theoretical basis for its preferential use in Sichuan. The analysis method established here has important implications for the quality control and differentiation of Vladimiriae Radix and Aucklandiae Radix, which can also serve as a reference for the identification of similar species. Graphical abstract