Betaine (BET) is a native compound widely studied as an antioxidant in agriculture and human health. However, the antioxidant mechanism of BET remains unclear. In this research, radical scavenging assays showed that BET had little free radical scavenging activity. However, the antioxidant activity of BET was confirmed by cellular antioxidant activity (CAA) and erythrocyte hemolysis assays. The results of quantitative PCR (qPCR) and enzyme activity determination kits showed that the antioxidant activity of BET was not due to the gene expression and activity of antioxidases. High-pressure liquid chromatography (HPLC) assessment of the effect of BET on sulfur-containing amino acid metabolism showed that BET increased the levels of nonenzymatic antioxidants,S-adenosylmethionine (SAM) and methionine (p < 0.05), via the regulation of the methionine-omocysteine cycle. Additionally, the three methyl groups of BET were found to play a key role in its antioxidant activity. The possible reason was that because of the hydrophobicity of the three methyl groups and hydrophilicity of the carboxyl of BET, a tight protective membrane was formed around cells to prevent oxidative stress inducer from inducing ROS generation and cell damage. In conclusion, the antioxidant mechanism of BET was found to enhance nonenzymatic antioxidant defenses via the methionine-homocysteine cycle and form a protective membrane around cells.

In our previous study, three novel polysaccharides, named MC-1, MC-2, and MC-3, were separated from the roots of maca (Lepidium meyenii), which is a food source from the Andes region. The structural information and immunomodulatory activity of MC-1 were then investigated. The structure and activity of MC-2 are still unknown. In this study, structural characterization revealed that MC-2 has an average molecular weight of 9.83 kDa and is composed of arabinose (20.9%), mannose (4.5%), glucose (71.9%), and galactose (2.7%). The main linkage types of MC-2 were proven to be (1→5)-α-l-Ara, (1→3)-α-l-Man, (1→)-α-d-Glc, (1→4)-α-d-Glc, (1→6)-α-d-Glc, and (1→6)-β-d-Gal by methylation and NMR analyses. Congo red assay showed that MC-2 possesses a triple-helix conformation. Immunostimulating assays indicated that MC-2 could induce M1 polarization of original macrophages and convert M2 macrophages into M1 phenotype. Although MC-2 could not shift M1 macrophages into M2, it could still inhibit inflammatory reactions induced by lipopolysaccharide. Furthermore, Toll-like receptor 2, tTll-like receptor 4, complement receptor 3, and mannose receptor were confirmed as the membrane receptors for MC-2 on macrophages. These results indicate that MC-2 could potentially be used toward hypoimmunity and tumor therapies.

A bacterium (designated SM04) which can rapidly grow on zearalenone (ZEN) as sole carbon and energy source was isolated from agricultural soil. On the basis of 16S rDNA sequencing analysis, strain SM04 was classified as a bacterium belonging to the Acinetobacter genus. In this study, the biodegradation of ZEN by the extracellular extracts of strain SM04 liquid cultures in M1 medium and Nutrient Broth medium was examined using HPLC analysis, APCI-MS analysis, and MTT (tetrazolium salt) cell proliferation assay. Results showed no ZEN and other equally estrogenic metabolites were found after 12 h when ZEN was treated with the extracellular extracts of M1 cultures, but no significant (P < 0.01) reduction of ZEN was observed over the 12-h incubation period in the extracellular extracts of Nutrient Broth cultures. Results also indicated that some proteins in the extracellular extracts of M1 cultures were essential to ZEN degradation. The proteins in the extracellular extracts of M1 cultures and Nutrient Broth cultures were analyzed with SDS-PAGE, bands showing different intensities among the two extracellular extracts were processed for protein identification by MALDI-TOF/TOF/MS, and nine proteins from M1 cultures matched the database for Acinetobacter genus with great confidence. Furthermore, the function of some proteins identified is unknown or unconfirmed because of the lack of well-annotated genomic sequence data and protein data for Acinetobacter genus on the public database, but in further studies these data of proteins identified will be useful for screening the genes related to ZEN degradation.

No abstract

Zearalenone (ZEN) is a Fusarium mycotoxin, which has been associated with hyperestrogenism and other reproductive disorders in farm animals. ZEN-contaminated grains as well as its by-products had engendered numerous economic losses to farm animals' production, so the detoxification of ZEN-contaminated grains and its by-products would be necessary and beneficial. In this study, a peroxiredoxin (Prx) gene from Acinetobacter sp. SM04 was cloned, and over-expressed in Escherichia coli BL21 (DE3). The Prx gene of Acinetobacter sp. SM04 encodes a protein of 187 amino acids residues and NCBI BLAST program analysis of deduced amino acids shows high identity with 2-Cys Prx family. Interestingly, recombinant Prx show efficient ability to degrade ZEN using H(2)O(2). Results of MCF-7 cell proliferation assay also found ZEN were oxidized into little estrogenic metabolites by purified recombinant Prx plus H(2)O(2). Further, model experiments on decontamination of ZEN-contaminated corn using recombinant Prx were performed, and results found nearly 90% of ZEN was degraded when crushed ZEN-contaminated corn samples (nearly 1,000 μg ZEN per kg grain) were treated with purified recombinant Prx plus 0.09% (m/m) H(2)O(2) for 6h at 30°C. In addition, the optimum pH and temperature of purified recombinant Prx for ZEN degradation were 9.0 and 70°C respectively.