Intra-specific biodiversity of Italian myrtle (Myrtus communis) through chemical markers profile and biological activities of leaf methanolic extracts.

Methanolic extracts of Myrtus communis leaves from two Italian regions (Calabria and Sardinia) were processed to determine the content of myrtenol, linalool and eucalyptol. Among the Calabrian and Sardinian myrtle samples, linalool and eucalyptol chemotypes were prevalent. The extracts were also tested for antioxidant, antibacterial and antifungal activities. Myrtle leaves samples were dried and extracted through maceration. Partition chromatography was adopted to separate myrtenol, linalool and eucalyptol fractions. Analyses were performed through GC and GC-MS. Some of the samples showed a good scavenger activity evidenced by DPPH radical scavenging assay and beta-carotene bleaching test. Antibacterial and antifungal activities were generally weak. The phytochemical and biological characterization of all the extracts were determined with an aim to characterize the intra-specific biodiversity of myrtle populations.

Influence of environmental factors on composition of volatile constituents and biological activity of Helichrysum italicum (Roth) Don (Asteraceae).

The biovariability of Helichrysum italicum (Roth) Don grown wild in Calabria and Sardinia (Italy) was reported. This species has been characterized through the detection, isolation and quantitative evaluation of chemical markers (alpha-terpinolene, trans-cariophyllene and neryl acetate) by GC and GC-MS. Antioxidant activity of the methanolic H. italicum extracts using DPPH and beta-carotene bleaching test showed that the Calabrian samples were more active than those from Sardinia. The antibacterial activity of all extracts evidenced the best performance on the Gram positive bacteria particularly on Micrococcus luteus. Moreover, antifungal activity of all extracts was also tested evidencing important results particularly on the phytopathogene fungus Pythium ultimum. In general, as regards the antifungal activity, the extracts from Sardinia were more active than those from Calabria. The phytochemical analysis and the biological activity data suggested a possible use of these plant matrices in alimentary, cosmetic and pharmaceutical fields.

Comparative chemical composition and variability of biological activity of methanolic extracts from Hypericum perforatum L.

The biovariability of Hypericum perforatum L. (St. John's Wort) grown wild in Calabria and Sardinia (Italy) was reported with the aim to characterize the species through the isolation, detection, and quantitative evaluations of chemical markers (hypericin, quercetin, rutin) by HPLC analysis. Antioxidant activity of the methanolic H. perforatum extracts showed that the Calabrian samples were more active than those from Sardinia. The antibacterial activity evidenced the best performance on the gram positive bacteria with a MIC value of 50 microg/mL. Moreover, antifungal activity of all the extracts was also tested which showed interesting results particularly on the phytopathogene fungus P. ultimum. The variability shown by the samples could be attributed to environmental factors such as chemical-physical properties, composition of the soil, geographical coordinate, altitude, and solar exposure. The phytochemical analysis and the biological activity data suggested a possible use of H. perforatum extracts in the alimentary, cosmetic, and pharmaceutical fields.

Analysis of protein profiles of genetically modified potato tubers by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Traceability of genetically modified (GM) foods demands the development of appropriate reliable techniques in order to identify and quantify peptide or nucleic acid residues in GM plants and food products through the food chain. In this study the applicability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) was demonstrated for the characterization of proteins of transformed and untransformed potato (Solanum Tuberosum L.) tubers. In GM tubers the expression level of the G1-1 gene, which regulates transition from dormancy to sprouting tubers, was inhibited by antisense technology. The analysis of antisense transformed lines showed that several of them exhibited a significant delay in sprouting relative to the control lines, in accordance with a decrease in the transcript level. Preliminary attempts to compare the protein patterns obtained from transformed and control lines using traditional electrophoresis were not able to reveal differences in the low-kDa range. Instead, MALDI-TOFMS applied to total peptide extract without any purification was able to distinguish spectral patterns of transformed and untransformed lines. In particular, several characteristic peaks from m/z 4373 to 4932 were detected only in the mass spectra of GM tuber samples.

Regulation of the CYB2 gene expression: transcriptional co-ordination by the Hap1p, Hap2/3/4/5p and Adr1p transcription factors.

Expression of the Saccharomyces cerevisiae nuclear gene CYB2 encoding the mitochondrial enzyme L-(+)-lactate-cytochrome c oxidoreductase (EC 1.2.2.3) is subject to several strict metabolic controls at the transcriptional level: repression due to glucose fermentation, derepression by ethanol, induction by lactate and inhibition under anaerobic conditions or in response to deficiency of haem biosynthesis. In this respect, the data obtained from the transcriptional analysis of the CYB2 gene contribute to a better understanding of the control of mitochondrial biogenesis. In this study, we show that Hap1p is the main transcriptional activator involved in the control of CYB2 transcription. We found that Hap1p activity, known to be oxygen dependent, is effected by DNA-protein interaction with two binding sites present in the CYB2 promoter. Control is moreover dependent on carbon sources. This regulation by the carbon substrates is subordinate to the activity of the complex Hap2/3/4/5p, which counteracts the negative effect of the URS1 element. Finally, our results suggest that the Adr1p transcriptional activator is also required in CYB2 transcription control. This work provides new data which allows a better understanding of the molecular mechanisms implicated in the co-regulation at the transcriptional level of the genes encoding proteins involved in various aspects of oxidative metabolism.

Evidence for an interaction between the CYP1(HAP1) activator and a cellular factor during heme-dependent transcriptional regulation in the yeast Saccharomyces cerevisiae.

Previously, it was shown that the CYP1(HAP1) gene product mediates the transcription of several oxygen-regulated genes through a metabolic co-effector, heme, in the yeast Saccharomyces cerevisiae. This study investigates the overproduction of the CYP1 protein when the CYP1(HAP1) gene is placed under the control of the GAL10-CYC1 hybrid promoter (either at the locus of the CYP1(HAP1) gene or cloned in a high-copy-number plasmid). In these conditions, the CYP1 protein is detected by Western blot analysis and has a molecular mass in agreement with the open reading frame sequence. Band-shift experiments show that the CYP1(HAP1) protein is able to interact specifically with its target sequences in vitro without addition of hemin, and forms a large complex with one or several unidentified factors denoted as X. Addition of hemin allows the formation of a new complex which has a lower molecular mass. The internal deletion of the seven repeated amino acid sequences containing the KCPVDH motif in the CYP1(HAP1) protein modifies the heme responsiveness phenomenon observed in vitro in the band-shift experiments and in vivo in the transcription of the CYB2, CYC1, CYP3(CYC7) and ERG11 genes. On the basis of these data, we propose a new model for heme-induced activation of the CYP1 protein.