B. Košíková

Investigation of the Lignin-Saccharidic Complex by Electron Microscopy

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Reduction of carcinogenesis by bio-based lignin derivatives

Abstract The potential medicinal application of lignin component of biomass derived from chemical treatment of wood for paper production was examined with regard to its ability to bind N -nitrosoamines and bile acids. Correlation between adsorption affinity of lignins towards N -nitrosodiethylamine and their cross-linking density was revealed. In contrast to lignin, all the tested carbohydrate preparations were poor adsorbents. It was revealed that the most effective lignin adsorbents—modified kraft and prehydrolysis lignins inhibit mutagenicity and SOS response induced by 4-nitroquinoline- N -oxide. Moreover, these lignin preparations exhibited a protective effect on deoxyribonucleic acid (DNA) in hamster V79 cells and in human VH10 and Caco-2 colon carcinoma cells exposed to hydrogen peroxide (H 2 O 2 ) treatment due to their antioxidant nature. In the case of N -methyl- N ′-nitro- N -nitrosoguanidine—treatment lignins reduced alkylation of DNA due to their high affinity for adsorption of mutagenic N -nitroso compounds. This dual ability of lignin tested to decrease genotoxic activity of chemicals seems to be very promising for their application as natural antimutagenic and anticarcinogenic agents.

Effect of blending lignin biopolymer on the biodegradability of polyolefin plastics

The ability of the lignin-degrading microorganism Phanerochaete chrysosporium to attack polyethylene and polypropylene was investigated using a series of polymer blends containing 10, 20 and 30% lignin obtained from the waste product of pulp and paper industry. In the cultivation medium, lignin peroxidase and Mn(II)peroxidase activities were detected. Degradation was verified by quantitative u.v. spectrophotometric analysis of the cultivation medium and by liberation of CO2 from the blends. Measurement of the tensile strength after 30-days cultivation showed that the mechanical properties of the polymer blends were decreased during the biodegradation process. The isolation of oligomer fractions by tetrahydrofuran (THF) extraction of biodegraded polymers and their characterization by gel permeation chromatography (GPC), u.v. and Fourier transmission infrared (FTIR) spectroscopy indicates that biotransformation of the lignin component during the cultivation process initiates partial biodegradation of the synthetic polymer matrix.

Lignin antioxidants for preventing oxidation damage of DNA and for stabilizing polymeric composites

Abstract The antioxidative behavior of various lignin preparations derived from chemical wood treatment for paper production was examined. All lignin samples exhibited higher antioxidant activity than Trolox. The protective effect of lignin antioxidants against H2O2-induced oxidative damage of DNA in human carcinoma cells and male rats was evaluated. Moreover, lignin was tested as a stabilizer in the processing of polypropylene composites, as well as in thermo-oxidative aging of styrene-butadiene vulcanizates. The results indicate that the lignin preparations show great potential as antioxidants in human diets and polymer blends. Lignin has the potential to protect living organisms against cancer diseases and contributes to the protection of polymers against degradation.

Modulation of mutagenicity of various mutagens by lignin derivatives

The effect of lignin on cytotoxicity, mutagenicity and SOS response induced by 4-nitroquinoline-N-oxide (4NQO), 3-(5-nitro-2-furyl)acrylic acid (5NFAA), 2-nitrofluorene (2NF) as well as hydrogen peroxide was investigated in bacterial assay systems, i.e. the Ames test with Salmonella typhimurium TA98, TA100, TA102 and the SOS chromotest with Escherichia coli PQ37. Lignin preparations obtained from beech wood significantly decreased the mutagenicity induced by 4NQO, 2NF and H(2)O(2). In the case of mutagenicity induced by 5NFAA the effect was lower. Antimutagenic properties of lignin samples tested were shown also by SOS chromotest where lignin inhibited the ability of both 4NQO and H(2)O(2) to induce the SOS response. Derivatives of lignin including those from soft and hard wood, as well as from annual plants differ in their efficiency to inhibit the induction of the SOS response. The modified lignins isolated from beech and spruce wood exhibit a high level of protection. Lignins from annual plants-corn cobs and straw-only marginally evoked an antimutagenic response, but their effect was increased by hydrothermic treatment of both annual plants. The results obtained indicate the prospective utilization of lignin preparations as additive in chemo-prevention. The antimutagenic effect of lignin samples varies with the method of isolation and modification, as well as with the genetic origin of the lignin.

Biodegradability of lignin—Polypropylene composite films

Biological degradation of composite lignin-polypropylene films containing 4% organocell lignin was confirmed by treatment with lignin-degrading enzymes produced by the white-rot fungusPhanerochœte chrysosporium. The kinetics ofP. chrysosporium culture in the presence of lignin-containing and lignin-free polypropylene films show that the fungus produced lignin-degrading enzymes into the liquid medium during incubation with the lignin-polypropylene film. The degree of biodegradation of both types of film was followed by monitoring their mechanical properties. Correlation was found between the decrease of elongation at break and the amount of released lignin fragments into the extracellular fluid in the course of microbial treatment. The incorporation of lignin into polyolefins represents a new way of using wastes from pulp and paper industry to reduce the environmental impact factor of waste plastics.

Biotransformation of lignin polymers derived from beech wood pulping by Sporobolomyces roseus isolated from leafy material

The ability of the yeast, Sporobolomyces roseus, isolated from leafy material, to modify lignin derived from beechwood pulping was examined by FTIR and 13C NMR spectroscopy, which revealed oxidative cleavage of the Cα-Cβ linkages between lignin units. Using veratryl alcohol as a model substrate confirmed that Sp. roseus could oxidize veratryl alcohol into veratric acid. This yeast might be suitable for the pretreatment of lignocellulosic materials and/or for biotransformation of technical lignins.

Effect of Soda-Additive Pulping on Molecular Characteristics of Residual Pulp Lignin

ABSTRACT The soda-additive pulps of pine wood were compared to corresponding soda and kraft pulps in respect to the macromolecular properties of the residual pulp lignins. Results of measurements of number and weight—average molecular weights as well as branching parameters show that the presence of additives such as anthraquinone, methanol and O2—pretreatment significantly causes the breaking of cross-links in the pulp lignin. On the other hand, ethylenediamine and hydroeulfide ion contribute mainly to extensive lignin degradation. The influence of used additives on the condensation reactions of the residual lignin has also been studied.

Anti-u.v. activity of lignin biopolymers on Euglena gracilis

Sulphur-free lignin biopolymer and its oxidized and reduced derivatives have been prepared and their inhibitory activity against u.v.-induced mutagenesis in Euglena gracilis was evaluated. The structure- and dose-dependent anti-u.v. activity of lignins was observed at concentrations higher than 250 μg ml−1. The oxidized lignin showed the most antimutagenic activity, followed by the reduced lignin and the unmodified lignin had the least antimutagenic activity.

Changes of Molecular Characteristics of Residual Pulp Lignin in Two-Step Soda-Oxygen Pulping

ABSTRACT In order to explain the behavior of soda pulp in the following next oxygen stage, the molecular characteristics of the residual lignins isolated from spruce and pine wood pulps cooked to yieldB between 71.8 and 49.8% in the soda pretreatment step were examined. The revealed differences in the cross-linking density and degree of condensation correlated with the effectiveness of lignin removal from soda pulps in the oxygen stage.