Olga Tzakou

Two highly oxygenated eudesmanes and 10 lignans from Achillea holosericea

Two new highly oxygenated eudesmanes and 10 known lignans were isolated from the aerial parts of Achillea holosericea. Their structures were elucidated by extensive application of one- and two-dimensional 1H and 13C NMR spectroscopy.

Chemical Composition and Biological Activity of Nepeta parnassica Oils and Isolated Nepetalactones

Abstract Essential oils of Nepeta parnassica, collected at different developmental stages, were analyzed by means of GC/MS. From the fifty-five identified constituents in samples A and B, representing 94.8% and 98.7% of the oils respectively, 4aα,7α,7aβ-nepetalactone (22.0%), 1,8-cineole (21.1%), α-pinene (9.5%) and 4aα,7β,7aβ-nepetalactone (7.9%) were the major components of sample A (vegetative stage), whereas in sample B (flowering stage) the main contributors were 1,8-cineole (34.6%), 4aα,7α,7aα-nepetalactone (17.3%), α-pinene (11.4%) and 4aα,7α,7aβ-nepetalactone (8.9%). The oils were tested on human health important insects such as the Pogonomyrmex sp. ants and the Culex pipiens molestus mosquitoes with promising results on insect repellency/toxicity.

Effects of Teucrium divaricatum Heldr. ssp. divaricatum decoction on experimental ulcer in rats.

The effects of chronic intragastric administration of the aerial parts decoction of Teucrium divaricatum Heldr. ssp. divaricatum (Labiateae) on experimental acetylsalicylic acid (ASA)-induced ulcer were studied in rats. The ulcer index and histological mucosa regeneration were evaluated. The ulcer index significantly decreased (U.I. 1.7+/-1.5; P<0.05) after treatment with a lyophilized decoction of T. divaricatum (500 mg/kg os), once daily for 7 days, compared to the control (U.I. 11.4+/-2.3). The ultrastructure modifications of gastric mucosa were observed by transmission electronic microscopy (TEM) confirming the antisecretory effect exercised by administration of the T. divaricatum decoction. Treatment with T. divaricatum seems to block up parietal cell acid secretion and to stimulate in the chief cells the formation of zymogen granules.

ESSENTIAL OIL COMPOSITION OF NEPETA ARGOLICA BORY ET CHAUB. SUBSP. ARGOLICA

The chemical composition of the essential oils obtained from the herbal parts and different plant parts of Nepeta argolica Bory et Chaub. subsp. argolica was examined by GC and GC–MS. Sixty-two con-ystituents were identified. The major constituents were found to be stereoisomers of nepetalactones (94.5–68.0%). 4aα,7α,7aβ-nepetalactone was isolated and identified by 1H- and 13C-NMR. Copyright

Composition and Antifungal Activity of the Essential Oil of Salvia pomifera subsp. calycina Growing Wild in Greece

Abstract The hydrodistilled essential oil of the aerial parts of Salvia pomifera subsp. calycina was analyzed by GC/MS. Fifty compounds representing 98% of the oil were identified. The main components of the oil were α-thujone (20.3%), β-thujone (36.3%) and myrcene (5.9%). The biostatic activity of the oil was evaluated in vitro against seven fungal strains.

Ligustolide A and B, two novel sesquiterpenes with rare skeletons and three 1,10-seco-guaianolide derivatives from Achillea ligustica

Achillea ligustica afforded two novel sesquiterpene lactones with rare 5/6/5 skeletons, three 1,10-seco-guaianolides and a chlorine-containing sesquiterpene lactone as well as six known compounds, including two monoterpenes, two guaianolides, one eudesmane and one secocaryophyllene derivative. The structures of the compounds were elucidated by extensive application of one- and two-dimensional NMR spectroscopy.

Chemical Composition and Antibacterial Properties of Thymus longicaulis subsp. chaoubardii Oils: Three Chemotypes in the Same Population

Abstract Three chemotypes of Thymus longicaulis C. Presl subsp. chaoubardii (Reichenb. fil.) Jalas were collected from the same population growing in one m2 area. Their oils were examined by GC and GC/MS. Limonene (18.7%) and thymol (19–4%); geraniol (56.8%) and geranyl acetate (7.6%); linalool (63.1%) and α-terpinyl acetate (20.4%) were the predominant components in each of the three different chemotypes, respectively. The oils also exhibited moderate to strong antimicrobial activity against the six Gram (±) tested bacteria

β-Orcinol Metabolites from the Lichen Hypotrachyna revoluta

Four new β-orcinol metabolites, hypotrachynic acid (1), deoxystictic acid (2), cryptostictinolide (3) and 8 -methylconstictic acid (4) along with the metabolites 8 -methylstictic acid (5), 8 -methylmenegazziaic acid (6), stictic acid (7), 8 -ethylstictic acid (8) and atranorin (9), that have been previously described, were isolated for the first time from the tissue extracts of the lichen Hypotrachyna revoluta (Florke) Hale. The structures of the new metabolites were elucidated on the basis of extensive spectroscopic analyses. Radical scavenging activity (RSA) of the metabolites isolated in adequate amounts, was evaluated using luminol chemiluminescence and comparison with Trolox®.

Essential oil and its systematic significance in species of Micromeria Bentham from Serbia & Montenegro

The composition and quantity of the essential oil of Micromeria allowed us to clearly distinguish between sections Pseudomelissa and Eumicromeria. According to our results the species of section Pseudomelissa (M. thymifolia, M. albanica, M. dalmatica and M. pulegium) contained a large quantity of oil (>0.5%) dominated by oxygenated monoterpenes of the menthane type, while the species of section Eumicromeria (M. croatica, M. juliana, M. cristata and M. parviflora) had a small quantity of essential oil (<0.5%) dominated by various terpene compounds. 0.5% of essential oil is defined like boundary value on the basis of the lowest quantity of essential oil measured in populations of species of section Pseudomelissa.

Nepeta sibthorpii Bentham (Lamiaceae): micromorphological analysis of leaves and flowers.

Nepeta sibthorpii Bentham (Lamiaceae) is an herbaceous aromatic plant, growing in dry, usually rocky areas of Southern Greece. In this paper, we report the study of micromorphological features of the flowers and leaves of Nepeta sibthorpii Bentham. The analysis by means of scanning electron microscopy has permitted to characterize both the covering trichomatous garment, abundantly present on the calyx and on the leaves, and the glandular hairs, distributed on the adaxial leaf surface and on the outer surfaces of calyx and corolla, showing also the peculiar features of the epidermal cells, all useful diagnostic elements for the identification of this medicinal plant.