Lignin-Stimulated Reduction of Oxidative DNA Lesions in Testicular Cells and Lymphocytes of Sprague-Dawley Rats In Vitro and Ex Vivo

Abstract

Lignin biopolymers constitute 30% of plant biomass and belong to the most abundant organic polymers on earth. We showed previously that this important component of dietary fiber exhibited a protective effect against the overall DNA damage induced by H2O2 or N-methyl-N'-nitro-N-nitrosoguanidine in hamster lung cells and human foreskin cells cultured in vitro. The objective of the present work was to examine DNA-protective effects of lignin in rat testicular cells and rat peripheral blood lymphocytes using in vitro and ex vivo experiments. H2O2 and visible light-excited methylene blue (MB) were used as DNA-damaging agents. Testicular cells were chosen because the germinal epithelium of testes is one of the most proliferately active tissues potentially susceptible to DNA-damaging effects. As a second target peripheral blood lymphocytes were chosen because dietary lignin or its metabolites circulate in the animal organism probably through the blood system. For the in vitro experiments, isolated cells were preincubated with lignin for 2 h before treatment with one of the oxidative agents. In ex vivo experiments, the cells were exposed to H2O2 or visible light-excited MB after isolation from rats fed either a common diet or a lignin-supplemented diet. The water-soluble, sulfur-free lignin used in experiments was obtained by fractionation of hardwood hydrolysate. The level of direct single-strand DNA breaks in H2O2-treated cells was measured by the classical comet assay, and the level of oxidative DNA lesions in visible light-treated cells was measured by a modified comet assay. We found that lignin reduced DNA lesions induced by H2O2 or visible light-excited MB both in vitro and ex vivo. The major conclusion of our study is that lignin polymer obtained by fractionation of hardwood hydrolysate manifested a specific type of antimutagenic effect.

Ex vivo assessment of protective effects of carvacrol against DNA lesions induced in primary rat cells by visible light excited methylene blue (VL+MB)

“…Our assumption that carvacrol given to rats in drinking water reaches different rat organs including testes is supported by several findings, e.g. that Origanum majorana L. oil containing carvacrol minimizes hazard effects of ethanol toxicity on male fertility as well as toxic effects of ethanol on liver and brain tissues [25] or that huge molecules of lignin biopolymer could be found by FTIR (fourier-transformed infrared) spectroscopy in lyophylized blood lymphocytes and testicular cells isolated from rats fed lignin enriched food [26].…”

In vitro simulation studies of silica deposition induced by lignin from rice

“…Once lignin dissolves, it rapidly decomposed (Sun et al, 2000;Lewis and Yamamoto, 1990). In DMSO, lignin was decomposed into its components and failed to deposit (Labaj et al, 2004), it might not form coordinate bond with silica to co-precipitate. These results indicated that macro lignin could induce silica deposition, but the lignin residue did not have this function.…”

New hypotheses for the health-protective mechanisms of whole-grain cereals: what is beyond fibre?

“…Their adsorptive ability would increase with increased methylation of the hydroxyl moieties on the phenyl-propane units ( 107 , 108 ) . Lignins also reduce DNA lesions in rat testicular cells and lymphocytes both in vitro and ex vivo ( 109 ) . Se inhibits the occurrence of neoplasia in rats and mice, suggesting that an Se-poor diet is associated with an increased prevalence of neoplasia in specific human populations ( 110 ) .…”