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A comprehensive phytochemical study of Juniperus turbinata (Cupressaceae) collected from La Maddalena Archipelago (Sardinia, Italy) is reported. Both the essential oil and the ethanolic extract obtained from the aerial parts 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 -terpineol, ent-manoyl oxide, 1,10-di-epi-cubenol as the major constituents. The ethanolic fraction contained mainly diterpenoids. Among these, 15-formyloxyimbricatolic acid (7) is a new natural product since it has hitherto been obtained only by synthetic route. The phenolic fraction contained biflavonoids: cupressuflavone (9), followed by minor amounts of amentoflavone (10) and hinokiflavone (11). The essential oil and six purified compounds (1 - 4, 8 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 higher radical scavenging activity against ABTS(+) radical than the reference Trolox. Noteworthy, compound 8 showed powerful effects towards tumor cell lines, with IC50 values in the range of 0.060 - 0.201 m, which make it a promising anticancer drug candidate.

Eryngium campestre and E. amethystinum are thorny herbs belonging to the Apiaceae family and spontaneously growing in stony pastures and dry meadows, preferentially on calcareous substrates. In the Mediterranean countries, these plants have been used as a food or traditional remedies to treat various ailments. In the present work, we have analysed the chemical composition of the essential oils distilled from the aerial parts by GC-FID and GC-MS, and evaluated their cytotoxic effects on a panel of human cancer cells, namely A375 (human malignant melanoma), MDA-MB 231 cells (human breast adenocarcinoma) and HCT116 cells (human colon carcinoma), by the MTT assay. Furthermore, the Eryngium essential oils were evaluated for antioxidant and acetylcholinesterase (AChE) activities. The two essential oils were rich in sesquiterpene hydrocarbons, with germacrene D as the major compound, accompanied by allo-aromadendrene, β-elemene, spathulenol and ledol. They resulted highly cytotoxic on the tumor cells, with IC50 values (1.65-5.32 and 1.57-2.99 μg/ml for E. amethystinum and E. campestre, respectively) comparable or close to those of the anticancer drug cisplatin. The E. amethystinum essential oil exhibited a moderate antioxidant activity whereas that of E. campestre a weak AChE inhibition. This article is protected by copyright. All rights reserved.

Sideritis montana subsp. montana is a small annual herb occurring in countries bordering the Mediterranean and Balkan regions. The secondary metabolism of this plant has not been fully explored so far. The aim of the present study was to understand the complex mixture of secondary metabolites and the type of secretory structures. The polar constituents were isolated by column chromatography from the ethanolic extract, and their structure was elucidated by NMR and MS. The essential oil was isolated by hydrodistillation and analysed by GC/MS. The plant indumentum was studied by light and scanning electron microscopy. To complete the work, the essential oil antioxidant activity and cytotoxicity on tumor cells were evaluated by DPPH, ABTS, FRAP, and MTT methods. Four different classes of secondary metabolites were isolated, namely flavonoids, caffeoylquinic derivatives, glycosidic hydroquinones and iridoids. The essential oil was mainly characterized by sesquiterpenene hydrocarbons. Peltate and long-capitate hairs were the main sites where terpenes and polar constituents are produced. The secondary metabolites found in S. montana subsp. montana are of chemotaxonomic interest, some of them being typical of the genus Sideritis. The trichomes types observed partially differ from those described in other members of the genus Sideritis. The essential oil showed noteworthy inhibition on tumor cells.

Stachys tymphaea (Lamiaceae) is a perennial herb growing in forest openings and dry meadows of central and southern Italy. It was investigated for the first time here, determining the content of secondary metabolites, the micromorphology of glandular trichomes, the histochemical localization of secretion, and the biological activity of the volatile oil, namely, the cytotoxic, antioxidant, and antimicrobial properties. The plant showed a peculiar molecular pattern, being rich of biophenolic compounds as flavonoids, phenylethanoid glycosides, and caffeoylquinic acid derivatives, but poor of iridoids, which are known as marker compounds of the genus Stachys. The essential oil was characterized by GC-FID and GC/MS analyses, revealing a high percentage of sesquiterpene hydrocarbons (54.6%), with germacrene D (30.0%) and (E)-β-farnesene (12.4%) as the most abundant compounds, while other main components were representatives of the diterpenes (19.2%), represented mainly by (E)-phytol (11.9%). This composition supported the taxonomic relationships in the genus Stachys, which comprises oil-poor species producing essential oils rich in hydrocarbons, with germacrene D as one of the predominant components. The micromorphological study revealed three types of glandular hairs, i.e., Type A peltate trichomes, being the primary sites of essential oil biosynthesis, Type B short-stalked trichomes, typical mucopolysaccharide producers, and Type C long capitate trichomes, secreting a complex mixture of both lipophilic and hydrophilic substances, with a major phenolic fraction. Moreover, the MTT assay revealed the potential of the volatile oil to inhibit A375, HCT116, and MDA-MB 231 tumor cells lines (IC50 values of 23.9-34.4 μg/ml).

a ) b The essential oil obtained from hydrodistillation of flowering aerial parts of Athanasia brownii (Asteraceae) was studied for its chemical composition by GC/FID and GC/MS, and for biological activity, namely, antioxidant, antimicrobial, and chemopreventive potential, by DPPH ( ¼ 2,2-diphenyl-1- picrylhydrazyl), ABTS ( ¼ 2,2'-azinobis(3-ethylbenzothioline-6-sulfonic acid), and FRAP ( ¼ ferric reducing antioxidant power), disk diffusion test, and MTT ( ¼ 3-(4,5-dimethylthiazol-2-yl)-2,5-diphe- nyltetrazolium bromide) assay, respectively. The oil was characterized by a high content of oxygenated sesquiterpenes (71.2%), with selin-11-en-4a-ol (24.6%), caryophyllene oxide (8.7%), humulene epoxide II (5.1%), and (E)-nerolidol (4.9%) as the predominant compounds. The oil showed a moderate activity against streptococci as well as radical-scavenging potential, while the inhibitory effects against human cancer cells examined such as A375 (malignant melanoma) and HCT 116 (colon carcinoma) were significant, with IC50 values of 19.85 and 29.53 mg/ml, respectively.