Bioactive Constituents of Juniperus turbinata Guss. from La Maddalena Archipelago

In this paper is reported a comprehensive phytochemical study of Juniperus turbinata (Cupressaceae) collected from La Maddalena Archipelago (Sardinia, Italy). Both the essential oil and the ethanolic extract were analyzed. The essential oil appears to belong to a new chemotype compared to other Mediterranean juniper accessions, as it was favored by geographic isolation of the isles. It showed a low content of monoterpene hydrocarbons and α-terpineol, ent-manoyl oxide 1,10-di-epi-cubenol as the major constituents. The ethanolic fraction resulted mainly composed by diterpenoids. Among these 15-formyloxyimbricatolic acid (11) is a new natural product since it has hitherto been obtained only by synthetic route. The phenolic fraction was constituted by biflavonoids: cupressuflavone (3), followed by minor amounts of amentoflavone (4) and hinokiflavone (5). The essential oil and six purified compounds (1, 2, 3, 6, 7 and 9) were assessed for biological activities, namely antioxidant (assessed by DPPH· , ABTS·+ and FRAP methods) and cytotoxic effects towards selected human tumor cell lines (MDA-MB 231, A375 and HCT116 cells). Compound 3 exhibited radical scavenging activity against ABTS·+ radical which was higher than that of the reference Trolox. Noteworthy, compound 9 showed powerful effects on tumor cell lines, with IC50 values in the range of 0.060-0.201 μM, which make it a promising anticancer drug candidate.