title: neo-Clerodane diterpenoids from Ajuga bracteosa.
abstract: Different neo-clerodane diterpenoids were isolated from a dichloromethane extract of Ajuga bracteosa depending on the isolation procedure used, owing to the labile nature of these tetrahydrofurofuran derivatives. Under "hydroxyl-free" purification conditions, both clerodin- and dihydroclerodin-type diterpenes were obtained [four new compounds, ajubractins A-D (1-4), along with clerodin (5), 3-epi-caryoptin (6), ajugapitin (7), 14,15-dihydroclerodin (8), 3-epi-14,15-dihydrocaryoptin (9), ivain II (10), and 14,15-dihydroajugapitin (11)]. When methanol-water mixtures were used for a C18 reversed-phase prepurification procedure and for semipreparative HPLC, the new ajubractin E (12) was also isolated along with 3 and 8-11, as previously, but 7 was the only tetrahydrofurofuran derivative obtained. Epimeric (15R and 15S) mixtures were obtained instead of 14-hydro-15-hydroxyclerodin derivatives [15-hydroxyajubractin C (13), 14-hydro-15-hydroxyajugachin A (14), and 14-hydro-15-hydroxyajugapitin (15)], along with 15-epi-lupulin B (16). The structures of the new compounds were elucidated by NMR and MS data analysis and by comparison with values previously reported. Antifeedant activity against Spodoptera littoralis larvae was evaluated for the compounds obtained.
authors.affiliation: Departament de Química Biològica i Modelització Molecular, Institut de Química Avançada de Catalunya, Consejo Superior de Investigaciones Científicas, Jordi Girona 18-26, 08034 Barcelona, Spain.
authors.forename: Amaya
authors.initials: A
authors.lastname: Castro
authors.forename: Josep
authors.initials: J
authors.lastname: Coll
authors.forename: Mohammad
authors.initials: M
authors.lastname: Arfan
mesh_terms: D031328:Ajuga / Q000737:chemistry*; D000818:Animals; D045785:Diterpenes, Clerodane / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D005247:Feeding Behavior / Q000187:drug effects; D007814:Larva / Q000187:drug effects; D015394:Molecular Structure; D010154:Pakistan; D018411:Spodoptera / Q000187:drug effects*
chemical_list: D045785:Diterpenes, Clerodane