Exploration of Binding Mechanism of a Potential Streptococcus pneumoniae Neuraminidase Inhibitor from Herbaceous Plants by Molecular Simulation.

Streptococcus pneumoniae can cause diseases such as pneumonia. Broad-spectrum antibiotic therapy for Streptococcus pneumoniae is increasingly limited due to the emergence of drug-resistant strains. The development of novel drugs is still currently of focus. Abundant polyphenols have been demonstrated to have antivirus and antibacterial ability. Chlorogenic acid is one of the representatives that has been proven to have the potential to inhibit both the influenza virus and Streptococcus pneumoniae. However, for such a potential neuraminidase inhibitor, the interaction mechanism studies between chlorogenic acid and Streptococcus pneumoniae neuraminidase are rare. In the current study, the binding mechanism of chlorogenic acid and Streptococcus pneumoniae neuraminidase were investigated by molecular simulation. The results indicated that chlorogenic acid might establish the interaction with Streptococcus pneumoniae neuraminidase via hydrogen bonds, salt bridge, and cation-π. The vital residues involved Arg347, Ile348, Lys440, Asp372, Asp417, and Glu768. The side chain of Arg347 might form a cap-like structure to lock the chlorogenic acid to the active site. The results from binding energy calculation indicated that chlorogenic acid had strong binding potential with neuraminidase. The results predicted a detailed binding mechanism of a potential Streptococcus pneumoniae neuraminidase inhibitor, which will be provide a theoretical basis for the mechanism of new inhibitors.

Optimization of liquid fermentation conditions for biotransformation zein by Cordyceps militaris 202 and characterization of physicochemical and functional properties of fermentative hydrolysates

Abstract Cordyceps militaris 202 is a potential fungus for biotransformation zein, due to its various proteases, high tolerance and viability in nature. In this article, single factor experiment and response surface methodology were applied to optimize the liquid fermentation conditions and improve the ability of biotransformation zein. The optimized fermentation conditions were as follows: inoculum concentration of 19%, volume of liquor of 130 mL/500 mL and pH of 4.7. Under this condition, the degree of hydrolysis (DH) was 27.31%. The zein hydrolysates from fungi fermentation maintained a high thermal stability. Compared to the original zein, the zein hydrolysates were found to have high solubility, which most likely results in improved foaming and emulsifying properties. Overall, this research demonstrates that hydrolysis of zein by C. militaris 202 is a potential method for improving the functional properties of zein, and the zein hydrolysates can be used as functional ingredients with an increased antioxidant effect in both food and non-food applications.

[The anti-tumor mechanisms in long-lived rodents].

Rodents, including the nude mice with congenital aplasia of the thymus, cancer-resistant naked mole rat (Heterocephalus glaber) and blind mole rat (Spalax galili), are important model organisms that are widely used in biomedical research. The aging process is closely related to cancer incidence in mammals and the aging degree is positively correlated with the risk of cancer. Since rodents account for 40% of mammals, study of the unique antitumor mechanism in long-lived rodents is very important. Replicative senescence is anti-tumor mechanism that prevalently exist in rodents, however, unique anti-tumor mechanisms have been found in naked mole-rats and blind mole-rats. The cancer resistance of Spalax galili is mediated by cell-released IFN-ß which activates p53 and Rb signaling pathway and the cells undergoes concerted cell death while that of Heterocephalus glaber is mediated by high molecular weight hyaluronan (HMW-HA) which causes contact inhibition. In addition, highly expressed pro-cell-death and anti-inflammation related genes are found in the genome of both naked mole-rats and blind mole-rats. In this review, we summarize the anti-tumor mechanisms in both Heterocephalus glaber and Spalax galili, which may provide information for related research.