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Abstract: Monascus products have been widely used as food additives and pharmaceuticals. Citrinin is a toxic metabolite produced during the Monascus fermentation. In this work, a quick extraction method with ultrasonic treatment was studied for a complete extraction of citrinin from the fungi cells. Furthermore, the proposed HPLC method has the advantage of the simultaneous determination of Monascus pigments and citrinin without sample pretreatment. Under the optimized HPLC conditions, a baseline resolution of pigments, citrinin and other catabolites was achieved. The detection limit of citrinin reached 0.5ngmL−1 (S/N >3/1) with a fluorescence detector (FD). Eight Monascus pigments were detected, with photodiode array detector (PAD), two of which not yet described. The HPLC fingerprint profile of the eight Monascus pigments and citrinin appears significant for the quality control of the Monascus product. [Copyright &y& Elsevier]

Impaired endothelial functions are closely associated with many chronic vascular-related diseases. Maslinic acid (MA), a natural pentacyclic triterpene compound, has received more and more attentions in recent years due to a variety of bioactivities. In the present study, we investigated the effect of MA on impaired endothelial functions in human aortic endothelial cells (HAEC) induced by high glucose treatment and discussed its possible mechanism. We showed that MA decreased the ROS level, inhibited the inflammatory cytokines expression, facilitated insulin-mediated IRS-1/PI3K/Akt/eNOS signaling and suppressed the cellular apoptosis ratio induced by high glucose. The molecular docking results showed that MA may regulate multiple targets to improve the endothelial dysfunction in HAECs exposed to high glucose. These results revealed potential application of MA in improving endothelia dysfunction. [ABSTRACT FROM AUTHOR]

Abstract: The determination of citrinin (CIT) by a microsphere-based flow cytometric immunoassay (MFCI) has been developed. In the method, the carboxyl-modified microspheres were conjugated with CIT-Ovalbumin (OVA) antigen. CIT competed with the CIT-OVA antigen on the surface of the microspheres for the anti-CIT McAb. Under the optimised conditions, IC50 value was 1.0ng/mL and the limit of detection reached 0.005ng/mL. The cross-reactivity was less than 0.01% against each of the four mycotoxins such as aflatoxin B1 (AFB1), ochratoxin A (OTA), zearalenone (ZEA), deoxynilvalenol (DON). In the work, the MFCI could accurately determine CIT in the real red yeast rice. The systematic error was low with the coefficient of variation (CV) from 5.24% to 8.16% by the MFCI. The mean recovery of CIT from artificially contaminated red yeast rice was from 89% to 94%, with CV from 7.2% to 8.7%. The experimental data showed that the precision, sensitivity and specificity of the developed MFCI method for the determination of CIT were satisfactory. [Copyright &y& Elsevier]

Abstract: Context: Pregnane X receptor (PXR) is an important transcriptional regulator that plays important roles in the cell metabolism and cell growth by regulating the transcriptional of a sort of metabolizing enzymes. Objective: To investigate whether rifampicin effected HepG2 cells growth and the inhibition was due to the G0/G1 phase arrest. Methods: PXR-knockdown experiments using RNAi showed that the cell cycle phase arrest mediated by rifampicin based on activation of PXR. The results also indicated that cell phase arrest by rifampicin could protect cells form UVB-induced DNA damage. Retinoid X receptor alpha (RXRα) expression level in cells is another key factor for cell cycle phase arrest mediated by rifampicin. Both over expression and lacking expression of RXRα in cell reduced the cell arrest efficiency mediated by rifampicin. In the study, we found that rifampicin inhibited HepG2 cells growth and demonstrated that the inhibition is due to the G0/G1 phase arrest through flow cytometry analysis. Conclusion: The results showed that RXRα promote cell cycle phase transition rate of HepG2. Competitive bind of rifampicin-activated PXR with RXRα is one main reason to arrest cell cycle phase through inhibiting combination of RXRα with other partners. Rifampicin could promote cell growth rate when RXRα expressed more excessively than PXR in cells. [Copyright &y& Elsevier]

Abstract: Natural 2-phenylethanol (PEA) could be produced on a large scale by way of bioconversion with yeast from l-phenylalanine. In this work the synergistic inhibition effect of the target product PEA and the byproduct ethanol on the bioconversion rate by Saccharomyces cerevisiae R-UV3 was systematically studied and a new kinetic model with an item representing the synergistic effect was proposed. Optimization strategies to repress the inhibition effect of PEA and ethanol were carried out in the mode of fed-batch culture with ISPR. The glucose concentration was regulated at the level of 0.2±0.1g/L by controlling a suitable respiratory quotient on line, which could limit the accumulation of the ethanol lower than 10g/L. In the presence of resin FD0816 with a weight of 10% of the medium, PEA was removed from the broth and the overall PEA concentration and the space-time yield reached 13.7g/L and 0.39g L−1 h−1 respectively. The semi-continuous process with ISPR was performed, in which the replacement of the resin was operated repeatedly when the aqueous PEA was over 2.7g/L and bioconversion continued until the bioactivity of the yeast cells declined, consequently achieving a final overall PEA concentration of 32.5g/L and a space-time yield of 0.45g L−1 h−1. [Copyright &y& Elsevier]

Abstract: Natural 2-phenylethanol is a high value aroma chemical and can be produced from l-phenylalanine via Ehrlich pathway by yeasts. Due to serious product inhibition, the space–time yield is usually low. A continuous approach using macroporous resin as in situ adsorbent made it possible that the quantity and viability of the cells were improved simultaneously. With Saccharomyces cerevisiae sp. strain R-UV3, the highest space–time yield of 0.90gL−1 h−1 reported so far was obtained. [Copyright &y& Elsevier]

Abstract: The efforts were focused on exploring alternative pneumococcal vaccine strategies, aimed at addressing the shortcomings of existing formulations, without compromising efficacy. We generated a stable Escherichia coli construct expressing functional recombinant PsaA and prepared CPS–rPsaA conjugate. The distribution of anti-CPS antibody response was almost completely of IgG2a subclass followed by IgG3 and low level of IgG1 subclass, which was opposite to the distribution of anti-PsaA IgG subclass antibodies. Though rPsaA was not detectable on the surface of the pneumococcal strain, the CPS–rPsaA conjugate possessed more accessibility to the surface of the strain. Mice immunized with conjugate exhibited rapid bacterial clearance from blood for the first 23h and afterward provided the best protection against challenge with pneumococcal 23F strain. [Copyright &y& Elsevier]

Abstract: Use of microorganisms for bioleaching processes is commonly limited by low tolerance of extreme culture conditions such as temperature, pH, and pulp density. Adaptation to extreme conditions is the main approach for strain improvement. Traditional methods for breeding strains with tolerance of extreme condition are difficult to apply without genetic tools because of many of such strains are not readily purely cultivated in liquid or agar medium. Here, we developed a method using ultraviolet (UV) irradiation for mutation in a continuous stirred tank reactor (CSTR) for screening to improve the bioleaching performance of a poorly characterized strain of Acidianus brierleyi (A. brierleyi). An improved strain developed with our method exhibited a good tolerance to Cu2+ and a high bioleaching rate of chalcopyrite, which was four-fold better than that of a strain selected by traditional adaptation method. We also designed a countercurrent bioleaching process in stirred tanks in series, and copper recovery in 7–8 days at a 15% chalcopyrite pulp density was more than 90% in a two stage countercurrent reactor. [Copyright &y& Elsevier]