Monoterpenes and diterpenes are the major metabolites of S. rosmarinus
To investigate the variation in metabolites among different organs ofS. rosmarinus , we collected and analyzed plant samples from roots, stems and leaves using HPLC-MS and GC-MS. Our analysis identified a total of 85 metabolites, including terpenoids, phenolic acids and flavonoids (Tables S11, S12). As expected, the essential oil extracted from rosemary leaves, which is widely used as a spice, has a distinctive aroma and was found to be rich in monoterpenes (Figure 3a). GC-MS analysis showed that 28 monoterpenes were identified in rosemary leaves, accounting for 99.43% of the volatile components (Table S11). These monoterpnenes included 1,8-cineole (16.66%), camphor (10.20%), limonene (7.57%) and α-pinene (7.55%), which dominated the volatile components in S. rosmarinus . Furthermore, LC-MS analysis revealed a high concentration of the diterpenoid carnosol, which accounted for 20.79% of the diterpenes and was found to be the main antioxidant component of S. rosmarinus (Table S12). Interestingly, the metabolites extracted from stems were similar to those from leaves in terms of chemical species and relative contents.
In constract, the metabolites identified in roots of S. rosmarinus were rather limited, with only 25 terpenoids and 6 phenolic acids (Figure S13). The main components extracted from roots were α-Cubebene (41.16%), camphene (11.13%), γ-muurolene (9.39%), as identified by GC-MS analysis. However, the quantity of monoterpenes and diterpenes extracted from roots was significantly lower compared to that extracted from leaves. For instance, 1,8-cineole, which had a high content in leaves, was present only in a low concentration of 3.04% in roots, and carnosol accounted for only 16.32% of the root components (Figure S13, Tables S11, S12).