Eriodictyol and naringenin inhibit the formation of AGEs: An in vitro and molecular interaction study.

Maillard reaction occurs between the carbonyl group of reducing sugars and the free amino groups of protein, which eventually results in the formation and accumulation of advanced glycation end products (AGEs) irreversibly. Excessive production of AGEs is associated with many diseases, such as Alzheimer disease, neuropathy, retinopathy, and nephropathy. In this study, the effects of eriodictyol and naringenin on the inhibition of AGEs were studied with bovine serum albumin (BSA)-methylglyoxal (MGO) model by spectroscopic techniques and molecular docking methods. The fluorescence spectroscopy results suggested that eriodictyol and naringenin could inhibit the formation of AGEs. Circular dichroism (CD) studies indicated that eriodictyol and naringenin could stabilize the structure of BSA and inhibit the formation of AGEs. The molecular docking results demonstrated that eriodictyol formed two hydrogen bonds with Lys 350 and Leu 480 and the main forces were hydrogen bonding and hydrophobic interactions. However, naringenin interacted with Arg 484 of BSA, and the main force was hydrophobic interaction. It can be concluded that eriodictyol and naringenin can inhibit the formation of AGEs and eriodictyol has stronger inhibitory activity of AGEs than that of naringenin, which is probably due to the additional hydroxyl group in the position C-3' of B ring of eriodictyol.

Cadmium induced BEAS-2B cells apoptosis and mitochondria damage via MAPK signaling pathway.

Cadmium, a heavy metal pollutant in industrial production, is found in air, water and soil, which is harmful to human health and can lead to diseases, such as asthma, lung cancer, and emphysema. In this study, the toxicity of cadmium on human bronchial epithelial cells (BEAS-2B) was investigated. Cell viability, mitochondrial membrane potential, reactive oxygen species (ROS) level, apoptosis and the related signaling pathways were detected with MTT assay, Rhodamine staining, DCFH-DA staining, Hoechst33258 staining and Western blot methods respectively. The results showed that the cell viability decreased, the mitochondrial membrane potential declined, ROS was accumulated and apoptotic rate raised in BEAS-2B cells. Meanwhile, the expression of B-cell lymphoma-2 (Bcl-2) was downregulated, while the expression of Bcl-2-associated X protein (Bax) and the cleaved caspase-3 was upregulated, which indicated mitochondria-mediated intrinsic apoptosis pathway was activated. Furthermore, the phosphorylation of JNK, ERK and p38 was enhanced respectively, which manifested that MAPK signaling pathways were activated. Therefore, it could be concluded that cadmium could increase intracellular ROS, result in cellular oxidative stress, activate JNK, ERK and p38 MAPK pathways and ultimately lead to apoptosis of BEAS-2B cells by activating mitochondria-mediated intrinsic apoptosis pathway. This study provided useful information to elucidate the toxicity of cadmium and revealed the possible mechanism for the occurrence of lung disease induced by cadmium.

Antitumor activity of polysaccharide extracted from Pleurotus ostreatus mycelia against gastric cancer in vitro and in vivo.

The present study aimed to determine the antitumor effects of polysaccharides extracted from Pleurotus ostreatus mycelium on gastric cancer in vitro and in vivo. Polysaccharides were extracted from Pleurotus ostreatus mycelium and an antitumor component, known as Pleurotus ostreatus mycelium polysaccharides 2 (POMP2), with a relative molecular weight of 29 kDa, was then sequentially purified using Sephadex G200 size-exclusion chromatography and diethylaminoethyl-52 cellulose ion-exchange chromatography. The MTT method was used to determine the proliferation of BGC-823 cells treated with POMP2; cell migration assay, colony formation assay and in vivo antitumor tests were used to assess the effect of POMP2 on migration, cell survival and the in vivo tumor formation of BGH-823 cells. Results of the MTT assay indicated that POMP2 had a marked inhibitory effect on the BGC-823 human gastric cancer cell line; when administered at a concentration of 400 mg/l for 72 h, the rate of inhibition was 35.6%. In addition, the colony forming capacity of the BGC-823 cells was significantly reduced following treatment with POMP2. A migration assay indicated that the invasive capabilities of the BGC-823 cells were also significantly inhibited by POMP2. Furthermore, in vivo tests of mice engrafted with BGC-823 cancer cells demonstrated that both tumor weight and volume were markedly reduced following two weeks of treatment with POMP2. The results of the present study suggested that the polysaccharide POMP2 may have a potential application as a natural antitumor treatment for gastric cancer.

Effective microbial calcite precipitation by a new mutant and precipitating regulation of extracellular urease.

Microbial calcite precipitation is a promising and environmental friendly biological technology in remediation of the surface and subsurface of porous media, especially for in situ soil remediation. The present study isolate a urea-degrading strain LH1 from soil on soybean root, identified as Bacillus niabensis strain (99% similarity) by 16S rRNA gene sequencing analysis. Then, using ultraviolet mutagenesis method, a mutant LHUM107 with outstanding urease-producing ability was further obtained to study its effects on calcite precipitation. The mutant LHUM107 had good genome stability and exhibited 92.2% urea-degrading efficiency till 21st generation. Response surface methodology (RSM) noted that the urea degradation was more dependent on initial urea addition, and brought forward the optimal conditions. Adapting to these optimal conditions, calcite precipitation by mutant LHUM107 and extracellular urease was respectively further investigated. It was shown that extracellular urease excreted from mutant LHUM107 was more effective and more targeted for CaCO3 precipitation.

[Prokaryotic expression of Drosophila selenoprotein D-SelK and preparation of polyclonal antibody to D-SelK].

AIM: To clone and encode Drosophila selenoprotein D-SelK structure gene, express it in E.coli efficiently, and after purification, to generate its antibody in rabbits. METHODS: D-SelK gene segment amplified from pGM-T-D-SelK plasmid by PCR was inserted into pGEX-6p-1 to construct recombinant plasmid pGEX-6p-1-D-SelK. The recombinant plasmid was transfected into E.coli BL21(DE3) to express the recombinant protein D-SelK in E.coli under IPTG induction. The protein was purified by denaturation and electrophoresis, and then identified by SDS-PAGE and Western blotting. Polyclonal antibody to D-SelK was obtained by immunizing rabbits with the protein. Quality and quantity of the antibody was examined. RESULTS: D-SelK gene segment was successfully inserted into pGEX-6p-1 and the positive clones of the recombinant plasmid was identified by PCR screening and restriction endonuclease analysis. The target protein was effectively expressed in E.coli by the IPTG induction. Through immunizing rabbits with the purified target protein, we obtained the specific antibodies to D-SelK, the titer of which was more than 1:51 200. The polyclonal antibody had a good specificity to D-SelK. CONCLUSION: D-SelK recombinant protein and rabbit anti-D-SelK polyclonal antibody with high specificity were obtained, which provides good tools for further research on the functional characterization of D-SelK.