Plant pressure sensitive adhesives: similar chemical properties in distantly related plant lineages

Main conclusion

A mixture of resins based on aliphatic esters and carboxylic acids occurs in distantly related genera Peperomia and Roridula , serving different functions as adhesion in seed dispersal and prey capture. According to mechanical characteristics, adhesive secretions on both leaves of the carnivorous flypaper Roridula gorgonias and epizoochorous fruits of Peperomia polystachya were expected to be similar. The chemical analysis of these adhesives turned out to be challenging because of the limited available mass for analysis. Size exclusion chromatography and Fourier transform infrared spectroscopy were suitable methods for the identification of a mixture of compounds, most appropriately containing natural resins based on aliphatic esters and carboxylic acids. The IR spectra of the Peperomia and Roridula adhesive resemble each other; they correspond to that of a synthetic ethylene–vinyl acetate copolymer, but slightly differ from that of natural tree resins. Thus, the pressure sensitive adhesive properties of the plant adhesives are chemically proved. Such adhesives seem to appear independently in distantly related plant lineages, habitats, life forms, as well as plant organs, and serve different functions such as prey capture in Roridula and fruit dispersal in Peperomia. However, more detailed chemical analyses still remain challenging because of the small available volume of plant adhesive.

     

Mitochondrial dysfunction in neocortex and hippocampus of olfactory bulbectomized mice,a model of Alzheimer’s disease

Structural and functional impairments of mitochondria in brain tissues in the pathogenesis of Alzheimer’s disease (AD) cause energy deficiency, increased generation of reactive oxygen species (ROS), and premature neuronal death. However, the causal relations between accumulation of beta-amyloid (Aβ) peptide in mitochondria and mitochondrial dysfunction, as well as molecular mechanisms underlying deleterious effects of both these factors in sporadic AD, the most common form in humans, remain unknown. Here we used olfactory bulbectomized (OBX) mice of NMRI strain as a model for sporadic AD. Five weeks after surgery, the OBX mice developed major behavioral and biochemical features of AD neurodegeneration, including spatial memory loss, increased brain levels of Aβ, and energy deficiency. Mitochondria isolated from the neocortex and hippocampus of OBX mice displayed severe functional impairments, such as low NADH oxidation rate, reduced transmembrane potential, and decreased cytochrome c oxidase (complex IV) activity that correlated with high levels of soluble Aβ1-40. Mitochondria from OBX mice showed increased contents of lipid peroxidation products, indicative of the development of oxidative stress. We found that neurodegeneration caused by olfactory bulbectomy is accompanied by energy metabolism disturbances and oxidative stress in brain mitochondria similar to those occurring in transgenic animals–familial AD models and patients with sporadic AD. Therefore, OBX mice can serve as a valid AD model for investigating the mechanisms of AD neurodegeneration, drug testing, and development of therapeutic strategies for AD treatment.     

Synthesis,molecular modeling and NAD(P)H:quinone oxidoreductase 1 inducer activity of novel 2-phenylquinazolin-4-amine derivatives

Reactive oxygen species (ROS) play an integral role in the pathogenesis of most diseases. This work presents the design and synthesis of novel 2-phenylquinazolin-4-amine derivatives (2–12) and evaluation of their NAD(P)H:quinone oxidoreductase 1 (NQO1) inducer activity in murine cells. Also, molecular docking of all the new compounds was performed to assess their ability to inhibit Keap1–Nrf2 protein–protein interaction through occupying the Keap1–Nrf2-binding domain which biologically leads to a consequent Nrf2 accumulation and enhanced gene expression of NQO1. Docking results showed that all compounds have the ability to interact with Keap1; however compound 7, the most active compound in this study, showed more interactions with key amino acids.     

Synthesis and biological properties of α-thymidine 5′-aryl phosphonates

Diethyl(N-arylaminocarbonyl)methyl phosphonates have been obtained by the reaction of diethylphosphonoacetic acid imidazolides with methyl-4-aminobenzoate or 3,5-bis(trifluoromethyl)phenylamine. Their treatment with Me₃SiBr in DMF led to a mixture of the corresponding (N-arylaminocarbonylmethyl)phosphonic acids and their monoethyl esters. After separation, they were condensed with 3′-O-acetyl-α-thymidine, which, after the removal of the acetyl protecting group, gave (α-D-thymidine-5′-yl)-[4-aminocarbonyl-, methoxycarbonyl-, or carboxy)phenylaminocarbonyl]methyl phosphonates and (α-D-thymidine-5′-yl)-[3,5-bis(trifluoromethyl)phenylaminocarbonyl]methyl phosphonate and their ethyl esters. It was shown that the compounds are stable under different conditions, low toxic (in Vero and K-562 cell cultures), and capable of penetrating into K-562 cells. Only ethyl (α-D-thymidine-5′-yl)-[4-(methoxycarbonyl)phenylaminocarbonyl]methyl phosphonate at a high concentration (200 μg/mL) inhibited in vitro the growth of the laboratory strain M. tuberculosis H37Rv.     

Are nociceptin(1‐13)NH2 and its structural analogue [ORN9]nociceptin(1‐13)NH2 able to affect brain antioxidant status in control and kainic acid‐treated rats?

In‐vivo effects of nociceptin (N/OFQ(1‐13)NH₂) on the levels of lipid peroxidation and cell enzyme (superoxide dismutase, glutathione peroxidase and glutathione reductase) and non‐enzyme (glutathione) antioxidants in brain of control and kainic acid‐treated rats were studied. N/OFQ(1‐13)NH₂ effects were compared with those of its structural analogue [Orn⁹]N/OFQ(1‐13)NH₂. Kainic acid (25 µg, i.c.v) increased the lipid peroxidation (4 and 24 h after kainic acid treatment) and decreased the glutathione level (1 h after kainic acid injection). We failed to find, any changes in antioxidant enzyme activities, independently of the time of kainic acid treatment. At the background of kainic acid‐effects, N/OFQ(1‐13)NH₂ and [Orn⁹] N/OFQ(1‐13)NH₂, injected 30 min before kainic acid, had no effects on all parameters, tested in brain. In addition, the neuropeptides did not change the antioxidant status in brain of control animals. It might be concluded that N/OFQ(1‐13)NH₂ and [Orn⁹]N/OFQ(1‐13)NH₂ have neither pro‐ nor anti‐oxidant activity. Copyright © 2009 John Wiley & Sons, Ltd.     

Involvement of protein HMG1 in DNA replication

Antibodies against HMG1 inhibit the incorporation of [3H]thymidine in Ehrlich ascites cell nuclei. By the use of specific inhibitors it is shown that HMG1 is needed for the action of the replicative DNA polymerase and not for the reparative one. This is supported by the fact that the addition of exogenous HMG1 to the nuclei enhances the replication process.     

A new approach for analysis of chemiluminescent kinetics of activated phagocytes in blood

Luminol chemiluminescence (LCL) is a simple, sensitive and time-saving tool to elucidate the oxidative activity of polymorphonuclear leukocytes (PMNL). In this study, a new approach for analysing the LCL kinetics, recorded from stimulated PMNL, and for a more accurate elucidation of their functional state, is proposed. This approach is based on the proposal that the LCL kinetics of stimulated PMNL is a result of time-probabilistic nature of the processes, leading to light emission. On this basis the LCL response was described by the parameters of a Poisson-type distribution. Relationships between these parameters and some factors influencing LCL kinetics (number of PMNL and erythrocytes, temperature, stirring) were investigated. Their development in time was different. It was suggested, that the two phases of the model LCL response were connected with extracellular and intracellular LCL. The terms and the advantages of this approach for analysis of phagocyte oxidative capacity are discussed.     

Membrane microdomains: Role of ceramides in the maintenance of their structure and functions

Free-standing giant unilamellar vesicles were used to visualize the complex lateral heterogeneity, induced by ceramide in the membrane bilayer at micron scale using C₁₂-NBD-PC probe partitioning under the fluorescence microscope. Ceramide gel domains exist as leaf-like structures in glycerophospholipid/ceramide mixtures. Cholesterol readily increases ceramide miscibility with glycerophospholipids but cholesterol-ceramide interactions are not involved in the organization of the liquid-ordered phase as exemplified by sphingomyelin/cholesterol mixtures. Sphingomyelin stabilizes the gel phase and thus decreases ceramide miscibility in the presence of cholesterol. Gel/liquid-ordered/liquid-disordered phase coexistence was visualized in quaternary phosphatidylcholine/sphingomyelin/ceramide/cholesterol mixtures as occurrence of dark leaf-like and circular domains within a bright liquid phase. Sphingomyelin initiates specific ceramide-sphingomyelin interactions to form a highly ordered gel phase appearing at temperatures higher than pure ceramide gel phase in phosphatidylcholine/ceramide mixtures. Less sphingomyelin is engaged in formation of liquid-ordered phase leading to a shift in its formation to lower temperatures. Sphingomyelinase activity on substrate vesicles destroys micron L_o domains but induces the formation of a gel-like phase. The activation of phospholipase A₂ by ceramide on heterogeneous membranes was visualized. Changes in the phase state of the membrane bilayer initiates such morphological processes as membrane fragmentation, budding in and budding out was demonstrated.     

Influence of surfactant protein C on the interfacial behavior of phosphatidylethanolamine monolayers

In the current work we study with monolayer tensiometry and Brewster angle microscopy (BAM) the surface properties of Dipalmitoleoylphosphatidylethanolamine (DPoPE) films at the air/water interface in presence and absence of specific surfactant protein C (SP-C). DPoPE is used, as it readily forms both lamellar (L_α) and non-lamellar inverted hexagonal (H_II) phases and appears as a suitable model phospholipid for probing the interfacial properties of distinct lipid phases. At pure air/water interface L_α shows faster adsorption and better surface disintegration than H_II phase. The interaction of DPoPE molecules with SP-C (predeposited at the interface) results in equalizing of the interfacial disintegration of the both phases (reaching approximately the same equilibrium surface tension) although the adsorption kinetics of the lamellar phase remains much faster. Monolayer compression/decompression cycling revealed that the effect of SP-C on dynamic surface tensions (γ _max and γ _min) of mixed films is remarkably different for the two phases. If γ _max for L_α decreased from the first to the third cycle, the opposite effect is registered for H_II where γ _max increases during cycling. Also the significant decrease of γ _min for L_α in SP-C presence is not observed for H_II phase. BAM studies reveal the formation of more uniform and homogeneously packed DPoPE monolayers in the presence of SP-C.