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Extracts of aromatic plants of Greek origin were examined as potential sources of phenolic compounds. RP-HPLC with UV detection was employed for the identification and quantification of the phenolic antioxidants, present in methanolic extracts. The most abundant phenolic acids were ferulic acid (1.1-280 mg/100 g of dry sample) and caffeic acid (1.2-60 mg/100 g of dry sample). (+)-Catechin and quercetin were the most abundant flavonoids. Apigenin and luteolin were detected in high amounts in Menta pulegium and Thymus vulgaris, respectively. The antioxidant capacity was determined, in dried ground plants and in their methanol extracts, with the Rancimat test using sunflower oil as substrate. Both pulverized plants and extracts showed antioxidant capacity. Total phenolic content in the extracts was determined spectrometrically according to the Folin-Ciocalteu assay and ranged from 1 to 21 mg of gallic acid/100 g of dry sample. Antimicrobial activity of the extracts against selected microbes was also conducted in this study.

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Financial support: The present work was partially financed by the international cooperation project in industrial research activities of development in precompetitive stage-2005 (ΟΔΣΒΕΠΡΟ-69) entitled "Exploitation of the natural microflora of the olive fruit for the production of virgin oil of high quality" (General Secretariat of Research and Development of the Greek Ministry of Development -E.U.).

Aims: To study patterns of reserve lipid biosynthesis and turnover (degradation) in two oleaginous Zygomycetes, namely Cunninghamella echinulata and Mortierella isabellina under various growth conditions. Fatty acid composition of the reserve lipid of both strains was also studied in all growth steps. Methods and Results: Cunninghamella echinulata and Mortierella isabellina were grown in carbon-excess batch cultures. In the investigated strains, accumulation of reserve lipid occurred only when the activity of both NAD + -isocitrate dehydrogenase (ICDH) and NADP + -ICDH were not detectable in the cell-free extract. Specifically, in C. echinulata, NAD + -ICDH activity was detected even after depletion of ammonium nitrogen in the medium, resulting in a delay of the initiation of lipid accumulation period. On the contrary, in M. isabellina, lipid accumulation occurred simultaneously with ammonium nitrogen exhaustion in the growth medium, as the activity of both NAD + -and NADP + -ICDH were not detectable after nitrogen depletion. In C. echinulata reserve lipid was not degraded after glucose had been exhausted. Supplementations of the medium with Fe 3+ , yeast extract or Mg 2+ induced, however, reserve lipid breakdown and formation of lipid-free material. In M. isabellina after glucose exhaustion, notable lipid degradation occurred, accompanied by a significant lipid-free material biosynthesis. Nevertheless, in multiple-limited media, in which Mg 2+ or yeast extract, besides carbon and nitrogen, were limiting nutrients, reserve lipid breakdown was repressed. In both strains, the quantity of c-linolenic acid (GLA) in the reserve lipids [varying between 9 and 16% (w/w) in C. echinulata and 1AE5-4AE5% (w/w) in M. isabellina] was proportional to lipidfree biomass. Conclusions: Lipid accumulation period in Zygomycetes is initiated by the attenuation of ICDH activity in the mycelium while the regulation of ICDH from ammonium nitrogen is strain specific. While a single nitrogen limitation was enough to induce lipid accumulation, however, multiple limitations were needed in order to repress lipid turnover in oleaginous Zygomycetes. As for GLA, its biosynthesis in the mycelium seemed proportional to lipid-free biomass synthesis. Significance and Impact of the Study: Several nutrients are indispensable for functioning the mechanisms involved in the mobilization of reserve lipid in oleaginous moulds. Therefore, reserve lipid turnover in oleaginous moulds could be repressed in multiple-limited media.