Enhancing the yield of alkyl lactate from sugars is in great demand but challengeable to accomplish. Here we report a facile but efficient route to make this by employing a hierarchical and Sn-containing Beta zeolite (Sn-Beta-H). The hierarporosity in the Sn-Beta-H facilitates the conversion of sugars into important intermediates for producing alkyl lactate in the competition with undesirable side reactions, thus outperforming the conventional Sn-zeolite catalysts in yielding alkyl lactate from a wide scope of sugars. Particularly, the yield of alkyl lactate could reach as high as 72.1% from sucrose. Importantly, the Sn-Beta-H is stable and can be easily recycled for five times with constant catalytic performances.
Saponins are a class of glycosides whose aglycones can be either triterpenes or helical spirostanes. It is commonly recognized that these active ingredients are widely found in various kinds of advanced plants. Rare saponins, a special type of the saponins class, are able to enhance bidirectional immune regulation and memory, and have anti-lipid oxidation, anticancer, and antifatigue capabilities, but they are infrequent in nature. Moreover, the in vivo absorption rate of saponins is exceedingly low, which restricts their functions. Under such circumstances, the biotransformation of these ingredients from normal saponins—which are not be easily adsorbed by human bodies—is preferred nowadays. This process has multiple advantages, including strong specificity, mild conditions, and fewer byproducts. In this paper, the biotransformation of natural saponins—such as ginsenoside, gypenoside, glycyrrhizin, saikosaponin, dioscin, timosaponin, astragaloside and ardipusilloside—through microorganisms (Aspergillus sp., lactic acid bacteria, bacilli, and intestinal microbes) will be reviewed and prospected.
Alliinase is a homodimeric glycoprotein found most often in genus Allium plants. In this study, alliinase was purified from fresh garlic by using ammonium sulfate precipitation and gel filtration on a Sephacryl S-200 column. Homogeneity of the purified protein with a molecular weight of 54,000 Da was confirmed by SDS-PAGE. The effect of ultrasound on the alliinase activity was further studied. The optimal parameters for stimulating the alliinase activity were as follows: ultrasonic intensity, 0.5 W/cm(2) and ultrasonic frequency, 40 kHz. Under the optimal conditions, ultrasonic irradiation did not affect the enzyme's optimal temperature and pH, and improved its thermal stability. The low frequency and mild intensity ultrasound could increase the alliinase activity about 47.1%. Under ultrasound, the alliinase activity was inhibited by exogenous pyridoxal 5'-phosphate (PLP) and K(+), and obviously enhanced by Fe(2+). However, PLP and both of the metal ions showed opposite effects in the absence of ultrasound. Ultrasound could retard or slow down the inhibitory effect of l-cysteine on the alliinase activity. These results indicated that the activity of alliinase from fresh garlic might be enhanced by the low frequency and mild intensity ultrasound.
The objective of this study was to investigate the molecular interaction and complex stability of four major cow's milk (CM) proteins (α-LA, β-LG, α s1-CA, and β-CA) with cyanidin-3-O-glucoside (C3G) using computational methods. The results of molecular docking analysis revealed that hydrogen bond and hydrophobic interaction were the main binding forces to maintain the stability of the C3G-CM protein complexes. Molecular dynamics simulation results showed that all complexes except for C3Gα s1-CA were found to reach equilibrium within 50 ns of simulation. α s1-CA and β-CA switched to a more compact conformation after binding with C3G. Additionally, the radius of gyration, number of hydrogen bond, radial distribution function, and interaction energy showed that β-CA is the best C3G carrier protein among the four CM proteins. This study can provide valuable information for CM proteins to serve as C3G delivery carriers. Practical applications Anthocyanins (ACNs) are flavonoid-based pigments that play an important functional role in regulating human's health. Cow's milk (CM) proteins are the most representative protein-based carriers that can improve the short-term bioavailability and stability of ACNs. Thus, it is important to study the interactions between ACNs and CM proteins at the molecular level for the development of effective ACNs delivery carriers. Our study showed that caseins (α s1-CA and β-CA) had more hydrophobic and hydrogen-bonding sites with cyanidin-3-O-glucoside (C3G) than whey proteins using computational methods. Among the four CM proteins, β-CA was the best C3G carrier protein showing the best interaction stability with C3G. Thus, it is helpful for us to screen effective ACNs carriers from multiple protein sources by computational methods.
Metabolic syndrome is a serious health problem worldwide. Increasing evidence indicates that flavonoid-rich foods exert beneficial effects. However, the function of flavonoids in metabolic syndrome is controversial. Here, we focus on the structural effects of flavonoids by comparing the effect of five purified subclasses of flavonoids on high-fat and high-fructose diet (HFFD) induced metabolic syndrome in vivo. Sprague−Dawley (SD) rats were fed with (i) basal diet (3.21 kcal/g) (ii) HFFD (25% lard and 25% fructose, 4.70 kcal/g), and (iii) HFFD with flavonoids representing different subclasses (2.6 mmol/kg diet): apigenin (flavones), quercetin (flavonols), genistein (isoflavones), naringenin (flavanones), and epigallocatechin gallate (flavanols) for 13 weeks. Our results showed that structurally different flavonoid subclasses prevented the HFFD-induced metabolic syndrome. Apigenin significantly decreased adipose fat and leptin levels and increased adiponectin levels. Epigallocatechin gallate and naringenin were both effective on dyslipidemia and hepatic lipid accumulations. The proinflammatory cytokines TNF-α and IL-6 were alleviated by quercetin, genistein, and naringenin. All the flavonoids exerted significant functions on improving insulin resistance and fasting glucose. In conclusion, flavonoid subclasses structurally exert antihyperlipidemic, antidiabetic, and anti-inflammatory functions by attenuating the lipid metabolism, glucose metabolism, and inflammation of metabolic syndrome.
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