In Vitro Antibacterial Activity of Plant Ethanolic Extracts against Fish Pathogens

Fifteen commercial ethanolic extracts from medicinal plants were in vitro screened for antibacterial activity against Listonella anguillarum (serotypes O1 and O2), Yersinia ruckeri, Photobacterium damselae subsp. piscicida, and Lactococcus garvieae. Their antimicrobial potential was assessed by the disc diffusion assay, then minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were established by the broth microdilution method. The extracts of lavender, Lavandula officinalis; lemon balm, Melissa officinalis; basil, Ocimum basilicum; oregano, Origanum vulgare; rosemary, Rosmarinus officinalis; common sage, Salvia officinalis; and red bilberry, Vaccinium vitis‐idaea, showed a broad spectrum of inhibitory effects. The extracts of yarrow, Achillea millefolium; arnica, Arnica montana; marigold, Calendula officinalis; Icelandic lichen, Cetraria islandica; horsetail, Equisetum arvense; grindelia, Grindelia robusta; java tea, Orthosiphon stamineus; and thyme, Thymus vulgaris, were less or not active. P. damselae subsp. piscicida was the most susceptible bacterial strain, while Y. ruckeri was the most resistant. These results can be considered for further investigations aimed to identify novel natural antimicrobial compounds that could be used in aquaculture for the control of bacterial infections.     

Synthesis and antifungal action of new tricyclazole analogues

Melanins are very important pigments for the survival and longevity of fungi, so their biosynthesis inhibition is a new biochemical target aiming at the discovery of selective fungicides. In this work is described the synthesis of new pyrazolo-thiazolo-triazole compounds, analogues of tricyclazole (a commercial antifungal product that acts by inhibiting melanin synthesis), and their biological activity was studied on some dermatophytes and phytopathogens. The compounds poorly inhibited the growth and pigmentation of fungi tested and were less efficient than tricyclazole. Electron microscopy on Botrytis cinerea showed that treatment with the most active compound caused abnormally thickened and stratified walls in fungi, whose ultrastructure was, in contrast, generally normal. The fungus treated with tricyclazole, on the other hand, appeared to be drastically altered, so as to become completely disorganized. These results suggest that the new azole compounds employ an action mechanism similar to that of other azoles, but dissimilar to that of tricyclazole.     

Determination of selenium content in different types of seed oils by cathodic stripping potentiometry (CSP)

Seed oils are consumed worldwide; moreover, they are used in the alimentary, cosmetic, pharmaceutical, and chemical industries. Due to their diffusion, it is interesting to investigate the presence of important micronutrients such as selenium in seed oils. The aim of this work was to develop a rapid, precise, and sensitive cathodic stripping potentiometry (CSP) method to determine the concentration of selenium in different types of seed oils. Selenium was extracted from the oily matrix by concentrated hydrochloric acid treatment at 90 degrees C. The analysis was executed by applying an electrolysis potential of -150 mV for 60 s and a constant current of -30 microA. Under these conditions, detection limits of <0.5 ng g(-1) were obtained. The method reproducibility (expressed as total RSD %) spanned from 0.2 to 0.8%. Recoveries ranged from 92.1 to 97.5%, providing evidence that selenium quantification remained unaffected by the extraction procedure described. The results obtained with the proposed method were compared with those obtained via graphite furnace atomic absorption spectroscopy (GFAAS), a common method for determining selenium. The results of the two methods agreed within 93.5-107.7%. The mean amounts of selenium found were 313.0 +/- 2.0, 458.3 +/- 1.3, 224.6 +/- 0.9, 99.5 +/- 0.8, 332.2 +/- 0.5, 144.0 +/- 0.7, and 295.5 +/- 1.2 ng g(-1), respectively, in peanut, soybean, sunflower, rice, corn, grapestone, and seed oils.     

Minor components of olive oil modulate proatherogenic adhesion molecules involved in endothelial activation

The Mediterranean diet reduces the risk of coronary artery disease as a consequence of its high content of antioxidants, namely, hydroxytyrosol (HT) and oleuropein aglycone (OleA), typical of virgin olive oil. Because intercellular and vascular cell adhesion molecules (ICAM-1 and VCAM-1) and E-selectin are crucial for endothelial activation, the role of the phenolic extract from extra virgin olive oil (OPE), OleA, HT, and homovanillyl alcohol (HVA) on cell surface and mRNA expression in human umbilical vascular endothelial cells (HUVEC) was evaluated. OPE strongly reduced cell surface expression of ICAM-1 and VCAM-1 at concentrations physiologically relevant (IC50 < 1 microM), linked to a reduction in mRNA levels. OleA and HT were the main components responsible for these effects. HVA inhibited cell surface expression of all the adhesion molecules, whereas the effect on mRNA expression was weaker. These results supply new insights on the protective role of olive oil against vascular risk through the down-regulation of adhesion molecules involved in early atherogenesis.     

Changes of isoflavones during the growth cycle of Lupinus albus

The objective of this study was to monitor the changes in isoflavone content in different plant organs (leaves, stems, roots) during the crop growth stage of three cultivars of Lupinus albus (white lupin) under field conditions, taking into account sowing time effects (autumn and early spring) and cultivar effects. Three sampling dates (from late vegetative to late grain growth stages) were evaluated. Seven isoflavones and four flavonoids were identified by LC-ESI-MS analysis. The isoflavone content was higher in leaves than in stems, and it was highest before flowering, whereas it decreased during maturity. Autumn-sown plants showed higher isoflavone content than early spring-sown plants, especially in late vegetative and early reproductive stages. Genistein 7- O-glucoside was the main isoflavone of leaves and stems in the late vegetative stages of early spring sowing, whereas genistein was the main isoflavone under autumn sowing. Variation among cultivars affected only marginally the total isoflavone content. No isoflavones were detected in seeds.     

Medicinal plant extracts modulate respiratory burst and proliferation activity of rainbow trout (<Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>) leukocytes

The present study was designed to investigate the immunomodulatory effects of Aloe vera, Curcuma longa, Echinacea purpurea, Lavandula officinalis, Origanum vulgare, Panax ginseng, and Rheum officinale extracts on leukocytes purified from rainbow trout (Oncorhynchus mykiss) head kidney. The cells were cultured in a medium containing increasing doses of extracts; afterwards, they were tested for reactive oxygen species production after stimulation with phorbol myristate acetate (PMA) and proliferation in the presence or absence of phytohemagglutinin from Phaseolus vulgaris (PHA-P). After a 2-h exposure, the extracts of L. officinalis, O. vulgare, and R. officinale strongly reduced the oxidative burst activity of PMA-stimulated leukocytes, in a dose-dependent manner (P ≤ 0.05). A. vera, C. longa, E. purpurea, and P. ginseng extracts reduced this response with lower efficacy and especially at lower concentrations. On the contrary, the highest concentration of ginseng extract stimulated the respiratory burst of leukocytes compared to untreated control cells. After a 72-h exposure, the extracts of L. officinalis, R. officinale, C. longa, E. purpurea, and P. ginseng had a clear dose-dependent stimulatory effect on leukocyte proliferation (P ≤ 0.05). The results suggest that these medicinal plants can be considered as reliable sources of new antioxidants or immunostimulants to be used in aquaculture.     

In vivo morphological and antigenic characteristics of Photobacterium damselae subsp. piscicida

The present study was conducted to examine the morphology and antigenicity of Photobacterium damselae subsp. piscicida by culturing the bacterium in vivo in the peritoneal cavity of sea bass (Dicentrarchus labrax) within dialysis bags with either a low molecular weight (LMW) cut-off of 25 kDa or a high molecular weight (HMW) cut-off of 300 kDa. Differences were observed in the growth rate between the bacteria cultured in vivo or in vitro. Bacteria cultured in vivo were smaller and produced a capsular layer, which was more prominent in bacteria cultured in the HMW bag. Antigenicity was examined by Western blot analysis using sera from sea bass injected with live Ph. d. subsp. piscicida. The sera recognised bands at 45 and 20 kDa in bacteria cultured in vivo in the LMW bag. Bacteria cultured in vivo in the HMW bag did not express the 45 kDa band when whole cell extracts were examined, although the antigen was present in their extracellular products. In addition, these bacteria had a band at 18 kDa rather than 20 kDa. Differences in glycoprotein were also evident between bacteria cultured in vitro and in vivo. Bacteria cultured in vitro in LMW and HMW bags displayed a single 26 kDa band. Bacteria cultured in the LMW bag in vivo displayed bands at 26 and 27 kDa, while bacteria cultured in vivo in the HMW bag possessed only the 27 kDa band. These bands may represent sialic acid. The significance of the changes observed in the bacterium''s structure and antigenicity when cultured in vivo is discussed.     

Genetic characterization of central Mediterranean stocks of the loggerhead turtle (Caretta caretta) using mitochondrial and nuclear markers,and conservation implications

1. that the north Adriatic, the Tunisian continental shelf, the waters around Malta and the Italian Ionian Sea represent important areas for the conservation of rookeries in Greece, Libya and Turkey, respectively;
2. that waters off the Italian peninsula and the islands of Lampedusa and Malta are mainly inhabited by individuals of Mediterranean origin, with a major contribution from the nearest and largest colonies, while Atlantic turtles are restricted to the western areas;
3. that specific migratory routes exist from rookeries to foraging grounds;
4. a poor bi‐parental genetic structuring, which suggests a high male‐mediated gene flow in the Mediterranean;
5. mixing of small turtles in waters distant from natal rookeries, and recovery of structuring for large‐sized individuals; and
6. that uncommon mtDNA haplotypes are more powerful markers than microsatellite alleles in assessing an individual's origin, owing to their higher geographic specificity.

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