Diamanto Lazari

Essential oil analysis and antimicrobial activity of eight Stachys species from Greece.

The volatile composition of eight Stachys species has been studied. The investigated taxa were St. alopecuros (L.) Bentham., St. scardica (Griseb.) Hayek, St. cretica L. ssp. cretica, St. germanica L. ssp. heldreichii (Boiss.) Hayek, St. recta L., St. spinulosa L., St. euboica Rech. and St. menthifolia Vis., growing wild in Greece. The essential oils were obtained by hydrodistillation in a modified Clevenger-type apparatus, and their analyses were performed by GC and GC-MS. Identification of the substances was made by comparison of mass spectra and retention indices with literature records. Sesquiterpene hydrocarbons were shown to be the main group of constituents of all taxa. Furthermore, the obtained essential oils were tested against the following six bacteria: Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 35210), Bacillus subtilis (ATCC 10907), Bacillus cereus (clinical isolates), Micrococcus flavus (ATCC 10240), Staphylococcus epidermidis (ATCC 2228), as well as against the following five fungi: Aspergillus niger (ATCC 6275), Penicillium ochrochloron (ATCC 9112), Epidermophyton floccosum (clinical isolates), Candida albicans (clinical isolates) and Trichophyton mentagrophytes (clinical isolates). The tested essential oils showed better activity against bacterial species than against fungi. Pseudomonas aeruginosa was the most resistant strain, as none of the essential oils was active against this strain. The essential oil of St. scardica has been proven most active against both bacteria and fungi.

Sesquiterpene lactones from Centaurea thessala and Centaurea attica. Antifungal activity.

The aerial parts of Centaurea thessala ssp. drakiensis and C. attica ssp. attica afforded, in addition to several known sesquiterpene lactones, two new eudesmanolides, 4-epi-sonchucarpolide and its 8-(3-hydroxy-4-acetoxy-2-methylene-butanoyloxy) derivative and one new eudesmane derivative, named atticin. The in vitro antifungal activity of most compounds was tested against nine fungal species, using the micro-dilution method. All the compounds tested showed great antifungal activity.

Over-expression of a tomato N-acetyl-L-glutamate synthase gene (SlNAGS1) in Arabidopsis thaliana results in high ornithine levels and increased tolerance in salt and drought stresses

A single copy of the N-acetyl-L-glutamate synthase gene (SlNAGS1) has been isolated from tomato. The deduced amino acid sequence consists of 604 amino acids and shows a high level of similarity to the predicted Arabidopsis NAGS1 and NAGS2 proteins. Furthermore, the N-terminus ArgB domain and the C-terminus ArgA domain found in SlNAGS1 are similar to the structural arrangements that have been reported for other predicted NAGS proteins. SlNAGS1 was expressed at high levels in all aerial organs, and at basic levels in seeds, whereas it was not detected at all in roots. SlNAGS1 transcript accumulation was noticed transiently in tomato fruit at the red-fruit stage. In addition, an increase of SlNAGS1 transcripts was detected in mature green tomato fruit within the first hour of exposure to low oxygen concentrations. Transgenic Arabidopsis plants have been generated expressing the SlNAGS1 gene under the control of the cauliflower mosaic virus (CaMV) 35S promoter. Three homozygous transgenic lines expressing the transgene (lines 1-7, 3-8, and 6-5) were evaluated further. All three transgenic lines showed a significant accumulation of ornithine in the leaves with line 3-8 exhibiting the highest concentration. The same lines demonstrated higher germination ability compared to wild-type (WT) plants when subjected to 250 mM NaCl. Similarly, mature plants of all three transgenic lines displayed a higher tolerance to salt and drought stress compared to WT plants. Under most experimental conditions, transgenic line 3-8 performed best, while the responses obtained from lines 1-7 and 6-5 depended on the applied stimulus. To our knowledge, this is the first plant NAGS gene to be isolated, characterized, and genetically modified.

Volatile constituents of Centaurea pelia DC., C. thessala Hausskn. subsp. drakiensis (Freyn & Sint.) Georg. and C. zuccariniana DC. from Greece.

The volatile constituents of the aerial parts of Centaurea pelia, C. thessala ssp. drakiensis and C. zuccariniana (Asteraceae) were extracted by steam distillation and analysed by gas chromatography–mass spectroscopy (GC–MS). Their components were represented by a homologous series of alkanes, alkenes, related aliphatic alcohols, aldehydes and ketones, as well as fatty acids and terpenoids. Copyright

Simple and rapid physico-chemical methods to examine action of antimalarial drugs with hemin: Its application to Artemisia annua constituents

Malaria is a major health problem in many countries and according to an estimate of the WHO, more than 500 million infections occur per year. Artemisinin, a sesquiterpene from Artemisia annua L., has received considerable attention as a promising and potent antimalarial drug for its stage speciticity, its rather low toxicity, effectiveness against drug-resistant Plasmodium species and activity against cerebral malaria. From recent studies it seems that hemin is primarily involved in the antimalarial activity of the constituents of Artemisia annua L. Thus, the interaction of a compound with hemin may represent a crucial screening test to define its efficacy. In this study the interaction between artemisinin and hemin was investigated by UltraViolet/Visible (UV/Vis) spectrophotometry and High Performance Liquid Chromatography/Diode Array Detector/Mass Spectrometry (HPLC/DAD/MS). In addition, some flavonols isolated from Artemisia annua L. were also tested to investigate their possible role in the interaction between artemisinin and hemin. These two simple physico-chemical methods can be useful as rapid and widespread screening methods for the search of other alkylating antimalarial constituents from natural sources or for the evaluation of the activity of semisynthetic analogues of artemisinin.

Volatile constituents of Centaurea raphanina Sm. subsp. mixta (DC.) Runemark and C. spruneri Boiss. & Heldr. (Asteraceae), growing wild in Greece

The volatile constituents of the aerial parts of Centaurea raphanina subsp. mixta and C. spruneri (Asteraceae) were obtained by steam distillation and analysed by gas chromatography–electron impact mass spectroscopy (GC–MS). Their components were mainly represented by terpenoids and a homologous series of alkanes, alkenes, aliphatic alcohols and related aldehydes, as well as fatty acids and fatty acid methyl esters. Copyright

Antioxidant and antiinflammatory activities of Sideritis perfoliata subsp. perfoliata (Lamiaceae)

Sideritis perfoliata L. subsp. perfoliata is a plant widely used in folk medicine in Greece since antiquity because of its antiinflammatory, antirheumatic, antiulcer, digestive and vasoprotective properties.

Antifungal activity of secondary metabolites of Centaurea raphanina ssp. mixta, Growing Wild in Greece

The present study was carried out on the aerial parts of C. raphanina Sm. ssp. mixta (DC.) Runemark (Asteraceae), which is a commonly edible plant in Greece, on maturation stage. Although the isolation procedure is the appropriate one for the isolation of sesquiterpene lactones, the analysis revealed the presence of only one sesquiterpene lactone, namely cnicin, in small amounts. The main compounds were found to belong to polyphenols. The in vitro antifungal activity of the isolated compounds was tested, using the micro-dilution method. Only cnicin has been proved to be active against all fungi tested with a fungicidal potential higher than miconazole.

Secondary metabolites from Centaurea deusta with antimicrobial activity

The aerial parts of Centaurea deusta Ten. afforded in addition to several known compounds, mainly sesquiterpene lactones, one new eudesmanolide and one new elemane derivative. Structures of the new compounds were elucidated by spectroscopic methods. The in vitro antifungal and antibacterial activities of the isolated compounds was tested, using the microdilution method. All compounds tested showed high antifungal activity.

Essential oils of Marrubium velutinum Sm. and Marrubium peregrinum L., growing wild in Greece

The essential oil of Marrubium velutinum Sm., isolated in 0.02–0.04% yield, contained, as principal components, γ-muurolene, β-caryophyllene and β-caryophyllene oxide. A significant number of sesquiterpenes were present in smaller amounts. The essential oil of Marrubium peregrinum L., obtained in 0.07% yield, contained (Z)- and (E)-β-farnesene as main compounds. Copyright