Mianhua Chen

Antifungal activity of volatile organic compounds from Streptomyces alboflavus TD‐1

Streptomyces sp. TD-1 was identified as Streptomyces alboflavus based on its morphological characteristics, physiological properties, and 16S rDNA gene sequence analysis. The antifungal activity of the volatile-producing S. alboflavus TD-1 was investigated. Results showed that volatiles generated by S. alboflavus TD-1 inhibited storage fungi Fusarium moniliforme Sheldon, Aspergillus flavus, Aspergillus ochraceus, Aspergillus niger, and Penicillum citrinum in vitro. GC/MS analysis revealed that 27 kinds of volatile organic compounds were identified from the volatiles of S. alboflavus TD-1 mycelia, among which the most abundant compound was 2-methylisoborneol. Dimethyl disulfide was proved to have antifungal activity against F. moniliforme by fumigation in vitro.

Primary Virtual and in vitro Bioassay Screening of Natural Inhibitors from Flavonoids against COX-2

Abstract In this study, we reported the screening of 9 compounds of flavonoids from the ZINC and PubChem databases (containing 2 092 flavonoids) using the iGEMDOCK software tool against the COX-2 3D protein structures. Each compound was also evaluated by an in vitro bioassay testing the inhibition of COX-2. Centaureidin and luteolin were found to be the potential inhibitors of COX-2 as demonstrated by IC 50 : 45 and 36.6 μmol·L −1 , respectively. In addition, structure activity relationships and other important factors of the flavonoids binding to the active site of COX-2 were discussed, which is expected for further rational drug design.

Effects of blue light on pigment biosynthesis of Monascus.

The influence of different illumination levels of blue light on the growth and intracellular pigment yields of Monascus strain M9 was investigated. Compared with darkness, constant exposure to blue light of 100 lux reduced the yields of six pigments, namely, rubropunctatamine (RUM), monascorubramine (MOM), rubropunctatin (RUN), monascorubrin (MON), monascin (MS), and ankaflavin (AK). However, exposure to varying levels of blue light had different effects on pigment production. Exposure to 100 lux of blue light once for 30 min/day and to 100 lux of blue light once and twice for 15 min/day could enhance RUM, MOM, MS, and AK production and reduce RUN and MON compared with non-exposure. Exposure to 100 lux twice for 30 min/day and to 200 lux once for 45 min/day decreased the RUM, MOM, MS, and AK yields and increased the RUN and MON. Meanwhile, the expression levels of pigment biosynthetic genes were analyzed by real-time quantitative PCR. Results indicated that gene MpPKS5, mppR1, mppA, mppB, mmpC, mppD, MpFasA, MpFasB, and mppF were positively correlated with the yields of RUN and MON, whereas mppE and mppR2 were associated with RUM, MOM, MS, and AK production.

Pleurotus nebrodensis polysaccharide induces apoptosis in human non-small cell lung cancer A549 cells

Polysaccharides derived from edible fungi inhibit the proliferation of tumor cells. In this study, we investigated the effects of a polysaccharide (PN50G) from Pleurotus nebrodensis on A549 cell proliferation and apoptosis. MTT assay showed that PN50G induced apoptosis in the A549 cells in a dose-dependent. However, PN50G did not affect the proliferation viability of human fetal lung fibroblast cells MRC-5. Scanning electro microscopy (SEM) results indicate that PN50G induced a typical apoptotic morphological feature in A549. DNA accumulation and fragmentation were determined by acridine orange/ethidium bromide (AO/EB) staining. Flow cytometric analysis demonstrated that PN50G caused A549 cell apoptosis via cell arrest at the S phase. PN50G also extended the comet tail length in single-cell gel electrophoresis and disrupted the mitochondrial membrane potential as determined by Rdamine-123 staining. Further analysis by qRT-PCR showed that the expression of caspase-3 and caspase-9 mRNA increased. These findings suggest that PN50G can inhibit A549 cell proliferation and induce apoptosis mainly by activating the intrinsic mitochondrial pathway.

Fumigant Activity of Volatiles from Streptomyces alboflavus TD-1 against Fusarium moniliforme Sheldon

The fumigant activity of volatiles generated by Streptomyces alboflavus TD-1 against Fusarium moniliforme Sheldon was investigated. The results showed that the mycelial growth, sporulation, and spore germination of F. moniliforme were significantly suppressed, and that membrane permeability was disrupted in the presence of the volatiles. Gas chromatography-mass Spectrometry analysis revealed 31 kinds of volatile organic compound from the volatiles. Among them, two earthy-smelling substances, namely, 2-methylisoborneol (50.97%) and trans-1,10-dimethyl-trans-9-decalinol (3.10%) were found. The most abundant compound, 2-methylisoborneol, exhibited inhibitory activity against F. moniliforme by fumigation. All these results suggested that S. alboflavus TD-1 can be a promising starter for the inhibition of F. moniliforme through fumigant action.

Optimization of submerged fermentation medium for citrinin-free monascin production by Monascus

ABSTRACT Microbial fermentation of citrinin-free Monascus pigments is in favor in the development of food industry. This study investigated the influences of carbon source, nitrogen source, and mineral salts on the cell growth, monascin (MS), and citrinin (CT) production in Monascus M9. A culture medium composition was established for maximizing the production of citrinin-free MS in submerged culture, as follows: 50 g/L Japonica rice powder, 20 g/L NH4NO3, 3 g/L NaNO3, 1.5 g/L KH2PO4, 1 g/L MgSO4 · 7H2O, 0.2 g/L MnSO4. Under these conditions, no CT was detectable by high performance liquid chromatography. The yield of MS reached 14.11 mg/g, improving approximately 30% compared with before optimization.

Angiotensin I-Converting Enzyme Inhibitory Effect of Chinese Soypaste Along Fermentation and Ripening: Contribution of Early Soybean Protein Borne Peptides and Late Maillard Reaction Products

Angiotensin I-converting enzyme inhibitory effect of Chinese soypaste was investigated during 4-month fermentation and ripening. This effect increased significantly at early stage and reached a plateau until the end of ripening, with an IC50 value of 0.436 mg/mL for the final product. Peptide and reducing sugar contents increased drastically during early fermentation and declined afterward. Maillard reaction took place continuously as indicated by consistent accumulation of precursor, intermediate, and final Maillard reaction products monitored by fluorescence, ultraviolet-absorbance and absorbance at 420 nm, respectively. During early fermentation, peptides were principal compounds responsible for the angiotensin I-converting enzyme inhibitory effect. During late ripening, angiotensin I-converting enzyme inhibition by Maillard reaction products could compensate for the loss of the effect caused by the utilization of peptides, and enable the total effect to remain at a good and steady level, suggesting an indispensable contribution of Maillard reaction products to angiotensin I-converting enzyme inhibitory effect of soypaste, particularly in products with prolonged maturation.

Pleurotus nebrodensis polysaccharide (PN-S) enhances the immunity of immunosuppressed mice.

In the present study, the effects of Pleurotus nebrodensis polysaccharide (PN-S) on the immune functions of immunosuppressed mice were determined. The immunosuppressed mouse model was established by treating the mice with cyclophosphamide (40 mg/kg/2d, CY) through intraperitoneal injection. The results showed that PN-S administration significantly reversed the CY-induced weight loss, increased the thymic and splenic indices, and promoted proliferation of T lymphocyte, B lymphocyte, and macrophages. PN-S also enhanced the activity of natural killer cells and increased the immunoglobulin M (IgM) and immunoglobulin G (IgG) levels in the serum. In addition, PN-S treatment significantly increased the phagocytic activity of mouse peritoneal macrophages. PN-S also increased the levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), interferon-γ (INF-γ), and nitric oxide (NOS) in splenocytes. qRT-PCR results also indicated that PN-S increased the mRNA expression of IL-6, TNF-α, INF-γ, and nitric oxide synthase (iNOS) in the splenocytes. These results suggest that PN-S treatment enhances the immune function of immunosuppressed mice. This study may provide a basis for the application of this fungus in adjacent immunopotentiating therapy against cancer and in the treatment of chemotherapy-induced immunosuppression.

Germplasm resources research of Toona sinensis with RAPD and isoenzyme analysis

Collected from Chinese mainland, 25 samples of Toona sinensis seed were planted in a standard garden. Three years later, samples were analyzed with random amplified polymorphic DNA (RAPD) and isoenzymes variants of cytochrome oxidase and peroxidases. Results of RAPD and isoenzymes variants were analyzed with software POPGENE32 and SPSS10.0 respectively. Phylogenetic trees were calculated from the clustered result of RAPD and isoenzymes variants. Such additional factors as leaves color, latitude and altitude of original seeds were analyzed at the same time. Our result suggested that a general similarity is concurred with the three analyses as RAPD, isoenzymes variants analysis of peroxidases and cytochrome oxidase. Two clusters can be separated from the sample collected as southern and northern ones. In the evolutionary history, a migrating route in the direction from West-South to East-North and with sequential differentiation in the direction South-North can be decided if only it is true with the argument that Toona sinensis came from tropic Asia, the border of east-north India and Burma.

Effect of pH on Nitrite Reduction of Pickled Chinese Cabbage

The pickled Chinese cabbage is one of the traditional fermented vegetables in China. In this article, the spontaneous and Lactic acid bacteria(LAB) inoculated fermentation methods were compared. The nitrite peak came forth at the middle stage of natural fermentation, but did not appear at the LAB starter fermentation. The pickled Chinese cabbage with natural and inoculated processing was safe, as no nitrite was monitored at the end of the fermentation. The acid milieu was meritorious in eradicating the cumulated nitrite in pickled Chinese cabbage.