Monocarbonyl Analogs of Curcumin with Potential to Treat Colorectal Cancer

Curcumin has a plethora of biological properties, making this compound potentially effective in the treatment of several diseases, including cancer. However, curcumin clinical use is compromised by its poor pharmacokinetics, being crucial to find novel analogs with better pharmacokinetic and pharmacological properties. Here, we aimed to evaluate the stability, bioavailability and pharmacokinetic profiles of monocarbonyl analogs of curcumin. A small library of monocarbonyl analogs of curcumin 1a–q was synthesized. Lipophilicity and stability in physiological conditions were both assessed by HPLC-UV, while two different methods assessed the electrophilic character of each compound monitored by NMR and by UV-spectroscopy. The potential therapeutic effect of the analogs 1a–q was evaluated in human colon carcinoma cells and toxicity in immortalized hepatocytes. Our results showed that the curcumin analog 1e is a promising agent against colorectal cancer, with improved stability and efficacy/safety profile.     

Leachate from a Waste Disposal Centre reduces the initiation of arbuscular mycorrhiza,and spread of hyphae in soil

Irrigating arbuscular mycorrhizal plants with leachate from a waste disposal centre was examined in a set of experiments. Application of leachate at half the average concentration found in the field or higher reduced the growth of the host plant, the initiation of mycorrhizal colonisation, and hyphal growth of the mycorrhizal fungus Glomus pellucidum through the soil. Causes of these reductions are complex and interrelated, and associated with the electrical conductivity of the solution, toxicity of specific ions, in particular NH₄ ⁺, NH₃ and HCO₃ ⁻, and changes in the pH causing shifts in the equilibria of the soil solution. This revised version was published online in June 2006 with corrections to the Cover Date.     

Survival of Escherichia coli O157:H7 in farm water: its role as a vector in the transmission of the organism within herds

AIMS: The study aimed to investigate the survival characteristics of Escherichia coli O157:H7 in farm water (FW), and in sterile distilled municipal water (SDW), stored outdoors under field conditions, with or without the addition of faeces (1% w/v), in a farmyard shed and the laboratory at 15 degrees C. METHODS AND RESULTS: Water samples were inoculated with E. coli O157:H7 at 10(3) and 10(6) ml(-1), and sampled over a 31-day period. In FW stored outdoors in a field, E. coli O157:H7 survived for 14 days at temperatures <15 degrees C, at both inoculation levels, while in the laboratory at 15 degrees C, the organism was still detectable at low levels (<1 log10 cfu ml(-1)) after 31 days. The addition of bovine faeces to water outdoors (1% w/v) resulted in survival for 24 days. In SDW inoculated at 10(6) ml(-1) and stored in the laboratory (15 degrees C), only a 2.5 log reduction was observed after 31 days, while the organism could not be detected after 17 days in the field. Preliminary screening of water samples stored outdoors isolated a bacterium which exhibited antimicrobial activity towards E. coli O157:H7. CONCLUSIONS: The survival of E. coli O157:H7 observed in this study illustrates the potential of farm water to act as a vehicle in the transfer of the organism across a herd. SIGNIFICANCE AND IMPACT OF THE STUDY: The difficulty in extrapolating results from controlled laboratory situations to on-farm conditions is also highlighted in this study.     

Metabolism of leukotriene A4 by human erythrocytes. A novel cellular source of leukotriene B4

Human erythrocytes transformed leukotriene A4 into leukotriene B4. Metabolism was proportional to the erythrocyte concentration, even at subphysiological levels (0.08-4 X 10(9) erythrocytes/ml). Comparative metabolic studies excluded the possibility that leukotriene B4 originated from trace amounts of polymorphonuclear leukocytes or platelets present in the purified erythrocyte suspensions. For example, suspensions of isolated platelets (100-500 X 10(6) cells/ml) failed to convert leukotriene A4 into leukotriene B4; and conversion by suspensions of isolated polymorphonuclear neutrophils was insufficient to account for the amounts of leukotriene B4 formed by erythrocytes. Leukotriene B4 formation was maximal within 2 min and substrate concentration dependent. Enzymatic activity originated from a 56 degrees C labile nondialyzable (Mr greater than 30,000) soluble component in the 100,000 X g supernatant obtained from lysed erythrocytes. In contrast to the contemporary view, our results indicate that human erythrocytes are not metabolically inert in terms of eicosanoid biosynthesis. The role of human erythrocytes during inflammatory or pulmonary disorders deserves re-examination in this context.     

Neonatal exposure to UVR alters skin immune system development, and suppresses immunity in adulthood

Neonates have a developing immune response, with a predisposition towards induction of tolerance. As the immune system develops, immunity rather than tolerance is induced, with this development of immunity occurring in response to external factors such as the environment. As ultraviolet radiation (UVR) suppresses immunity, it is likely that the effect of UVR on the neonatal immune system would be augmentation of the suppressive response. In support, childhood exposure to UVR has been linked with an increased incidence of melanoma; consistent with an increase in suppression. To address this, phenotypic and functional immune system studies were undertaken at 8 weeks after one single exposure of solar-simulated UVR to mice, when mice had reached adulthood. Subtle changes were observed in cell populations resident in the skin-draining lymph nodes (LNs) and there also appeared to be a subtle, but not statistically significant, increase in the production of interleukin-10 and interferon-γ. Importantly, these changes also corresponded with significant suppression of the contact hypersensitivity response in irradiated mice compared with their control counterparts. This suppression was apparent when antigen sensitisation occurred during the neonatal or adult period, and thus did not appear to be analogous to UVR-induced suppression in adults. Although the percentage of T regulatory cells was increased in the skin-draining LNs, they were induced in a different manner to those induced following adult UVR exposure, with no increase in function on a per-cell basis. It therefore appears that one single neonatal exposure to UVR alters development of the immune system, leading to long-term implications for induction of immunity.     

Carbohydrate side chains of Rauscher leukemia virus envelope glycoproteins are not required to elicit a neutralizing antibody response.

Antisera raised against Rauscher leukemia virus (R-MuLV) contain a preponderance of antibodies against glycoprotein gp70 that are dependent on the presence of carbohydrate side chains for reactivity, as judged by immunoprecipitation or Western blotting. However, the majority of neutralizing antibodies were not dependent on the presence of carbohydrate, as indicated by (i) the ability of deglycosylated R-MuLV to adsorb neutralizing antibody from sera as efficiently as glycosylated R-MuLV and (ii) the ability of deglycosylated R-MuLV to induce neutralizing antibody responses when injected into rabbits. Moreover, a faster response was obtained with deglycosylated R-MuLV than with untreated control virus in the latter experiments. The results indicate that the neutralizing antibodies are a discrete subpopulation of the total antibody response. Furthermore, the carbohydrate moieties appear to afford protection to the virion during infection, rather than serve as a target for neutralization.     

Effects of Prolonged Depolarization on the Nicotinic Acetylcholine Receptors of PC12 Cells

To determine whether prolonged depolarization and/or changes in intracellular Ca2+ concentrations stimulate adaptive responses of neuronal nicotinic acetylcholine receptors, PC12 pheochromocytoma cells were grown in medium containing various concentrations of K+. Nicotinic receptor function was determined as carbachol-stimulated uptake of 86Rb+. Cells were exposed to 50 mM K+ for up to 4 days and then allowed to repolarize for 60 min. Under these conditions, no changes in basal or carbachol-stimulated uptake of 86Rb+ were observed. Furthermore, neither the time course of carbachol-stimulated uptake or the carbachol concentration dependence of 86Rb+ uptake was altered. Finally, concurrent depolarization did not affect the functional down-regulation produced by chronic exposure of the cells to carbachol. Thus, neuronal nicotinic acetylcholine receptors on PC12 cells do not appear to be regulated by depolarization or prolonged elevation of the intracellular Ca2+ level.     

Fragment-based discovery of hepatitis C virus NS5b RNA polymerase inhibitors

Non-nucleoside inhibitors of HCV NS5b RNA polymerase were discovered by a fragment-based lead discovery approach, beginning with crystallographic fragment screening. The NS5b binding affinity and biochemical activity of fragment hits and inhibitors was determined by surface plasmon resonance (Biacore) and an enzyme inhibition assay, respectively. Crystallographic fragment screening hits with 1–10 mM binding affinity (K_D) were iteratively optimized to give leads with 200 nM biochemical activity and low μM cellular activity in a Replicon assay.