Recent advances in chemistry,therapeutic properties and sources of polydatin

Polydatin (PLD), the 3-O-β-glucopyranoside of the well-known stilbenoid compound resveratrol, is a major compound of Fallopia japonica (Houtt.) R. Decr. (Japanese knotweed), which is widely used in traditional Chinese medicine to treat infection, inflammatory diseases and circulatory problems. It has shown a wide range of biological activities including anti-inflammatory, anti-oxidant, anti-cancer, neuroprotective, hepatoprotective, nephroprotective and immunostimulatory effects. Although resveratrol has similar beneficial effects, its low bioavailability has remained a problem. Glycosylation increases solubility of resveratrol in an aqueous environment, thus improving its bioavailability. This has led to a growing interest in PLD. Promising results obtained from bioactivity studies have boosted an intense research on this compound. The aim of this review is to give a comprehensive overview of the botanical sources, pharmacology, biosynthesis, biotechnological production, and bioactivities of PLD, and to discuss clinical studies on this compound.     

Stereoselective synthesis of new rac-quercitols containing hydroxymethyl groups as glucosidase inhibitors

Stereoselective and efficient synthesis of hydroxymethyl-substituted rac-quercitols (13–15) was achieved, starting from cis-furan (Kobayashi, 2008) with photooxygenation reaction, which is readily available by the reduction of cis-phtalic anhydride. α- and β-Glucosidase enzyme activity of the target molecules was evaluated and good inhibitor activity was seen. One- and two-dimensional NMR spectroscopy, IR spectroscopy and X-ray crystallography were utilized in the structure characterization of products.     

Effects of salt and osmotic shocks on unadapted and adapted callus lines of tobacco

Growth, viability and proline content of adapted and unadapted calluses of Nicotiana tabacum L. var. Jayasri, affected due to osmotic stresses and particularly to stress-shocks treated with different osmotica like NaCl (ionic-penetrating), mannitol (non-ionic-penetrating) and polyethylene glycol, (PEG) (non-ionic-non penetrating) were studied to evaluate the physiological differences of stress effects. The tissues adapted to a low concentration of NaCl (85 mM) showed low growth with high proline content compared to the tissues adapted to a low concentration of mannitol (165 mM). Proline content was similar in tissues adapted to high concentrations of NaCl (171 mM) and mannitol (329 mM) but growth in the latter case was relatively low. Growth and viability were subsequently correlated with the pattern of retention in or diffusion of proline out of the tissues after shock-treatments. The loss of tissue viability of the adapted calluses was comparatively less than the unadapted callus even after shock-treatments with 1282 mM NaCl and 823 mM mannitol. The former calluses retained the capability of regrowth though at a slow rate. Such adapted tissues also retained more proline. The mannitol-adapted tissues, when shocked with PEG (200 g l-1), showed low viability with more diffusion and a very little retention of proline while, in the unadapted tissue, all the proline was leached out. The results indicated that the effects of different osmotica on plant tissue varied depending upon the physico-chemical nature of the compounds used as stress-inducing-agents, and retention and diffusion of proline was altered when the tissues were shocked with high concentrations of all these compounds. This revised version was published online in June 2006 with corrections to the Cover Date.     

Evaluation of the interactions between strains of S. aureus and peripheral blood phagocytic cells

The aim of this study was to investigate the interactions occurring between peripheral blood phagocytes and strains of S. aureus isolated from different clinical specimens (blood, respiratory tract, pus). To evaluate the sensitivity of microorganisms to bactericidal activity of phagocytes, monocytes and granulocytes separated from peripheral blood by standard density gradient and by counter-current centrifugal evaluation these cells were incubated with suspensions of opsonized bacteria. In parallel, the viability of phagocytes was examined by flow cytometry, and the ability of bacteria to trigger reactive oxygen intermediates (ROI) production was evaluated by chemiluminescence measurement. To investigate the efficiency of phagocytosis, bacteria were labelled with fluorescein isothiocynate (FITC) and the percentage of cells containing FITC-labelled bacteria were analysed by flow cytometry. The data obtained show the strains of S. aureus derived from different clinical specimens, differ in their sensitivity to bactericidal activity of phagocytes--strains isolated from the blood show the highest, but strains isolated from the respiratory tract have the lowest sensitivity to killing. These strains differ too in their ability to trigger monocyte CL response. On the contrary, there was no difference in toxicity of bacteria against phagocytes. Strains isolated from peripheral blood showed a significant negative correlation between the ability to trigger CL response and toxicity against phagocytes.     

Physical study of prophage excision and curing of lambda prophage from lysogenic Escherichia coli

A sex factor, F′450(λ), which can be isolated as a covalent circle of DNA, has been examined by alkaline sucrose gradient centrifugation of lysates of induced cells in order to study λ prophage excision. Thermal derepression of the prophage results in loss of F′450(λ) covalent circles, which is mediated by systems involved in excision and initiation of replication. When protocols known to result in prophage curing are used, the F′450(λ) is converted to an F′450 and a λ covalent circle; in normal excision leading to phage development, F′450 covalent circles are not found. We have shown that: (1) excision usually occurs later than initiation of DNA replication of the prophage so that the excised prophage is usually already replicated or in the act of replication; (2) the DNA growing points of the prophage leave the prophage and enter the bacterial DNA; (3) the int and xis genes are involved in the earliest detectable stage of the excision process, i.e. breakage of the DNA at the attachment region; (4) the xis gene product is involved in a weak non-specific nuclease activity in addition to its highly specific activity in excision; and (5) the excision system fails to attack a single attachment site.     

Invasive round goby Neogobius melanostomus has sex‐dependent locomotor activity and is under‐represented in catches from passive fishing gear compared with seine catches

The higher proportion of males of the invasive round goby Neogobius melanostomus in samples from two activity selective passive fishing gears compared with one activity non‐selective fishing gear in three Dutch lakes is related to higher male locomotory activity and is a sex‐dependent trait. This difference in activity reflects the different ecology of male and female N. melanostomus.