Chemodiversity and bioactivity of Chrysanthemum, Opisthopappus, Ajania, and Crossostephium: Intergeneric differences revealed by GC–MS and multivariate analysis in Anthemideae

This study examined the intergeneric chemodiversity and bioactivities of essential oils (EOs) from 50 accessions of four Anthemideae genera ( Chrysanthemum, Opisthopappus, Ajania , and Crossostephium ). Hydrodistilled EOs from 25 representative accessions were predominantly terpenoids. Multivariate analyses—principal component analysis (PCA) and orthogonal partial least-squares discriminant analysis (OPLS-DA)—clearly discriminated the four genera and revealed a correspondence between chemical profiles and original geographic provenance. This finding suggests that essential oil chemotypes in Anthemideae largely reflect genetically fixed chemotypic differentiation rather than plastic responses to local environments. Characteristic marker compounds were identified for each genus, including caryophyllene oxide in Opisthopappus and 1,8-cineole with camphene in Ajania and Crossostephium . Bioactivity assays revealed significant intergeneric variation in antioxidant and antibacterial activities. Chemometric analysis linked these activities to specific compounds: antioxidant capacity was associated with myrcene, eugenol, and γ-elemene, while antibacterial effects correlated with guaiol, spathulenol, and bisabolol. Scanning electron microscopy (SEM) confirmed that the antibacterial mechanism involves concentration-dependent bacterial membrane disruption. Collectively, this work provides a chemotaxonomic framework for Anthemideae, elucidates key structure-activity relationships, and offers valuable insights for germplasm screening and natural product development.