Determination of nine nucleosides in Rhizoma Paridis by quantitative analysis of multi-components via a single marker method.

In this work, a new quantitative analysis method of multi-components analysis via a single marker strategy coupled with high-performance liquid chromatography (HPLC) analysis, was proposed to analyze nine nucleosides (cytidine, uridine, 2'-deoxyuridine, inosine, guanosine, 2'-deoxyguanosine, thymidine, adenosine, and 2'-deoxyadenosine) as quality control markers in Rhizoma Paridis. Guanosine was set as the internal reference substance, whose content in Rhizoma Paridis was determined using conventional external standard method. Then, relative correction factors between guanosine and the other eight nucleosides were measured respectively. The amounts of the other eight components were calculated according to the relative correction factors by the quantitative analysis of multi-components via a single marker method. Finally, the result of vector angle cosine analysis showed that there was no significant difference of the contents between the external standard method and the quantitative analysis of multi-components via a single marker method, indicating that the quantitative analysis of multi-components via a single marker method can be applied for the quality control of Rhizoma Paridis. As far as we know, this is also the first report to analyze nucleosides by the quantitative analysis of multi-components via a single marker method, providing an efficient and promising quality assessment method for other traditional Chinese medicine containing nucleosides.

Role of simulated in vitro gastrointestinal digestion on biotransformation and bioactivity of astragalosides from Radix Astragali.

Radix Astragali (RA) is commonly used in Asian herbal therapy or food supply, and astragalosides and flavonoids are its major components with diverse pharmaceutical effects. To provide new information on the potential cardiovascular benefits of RA administered orally, the bioaccessibility of these compounds with relevant in vitro digestion parameters was determined for four digestion phases (oral, gastric, small and large intestines) by ultrahigh-performance liquid chromatography quadrupole time-of-flight-mass spectrometry (UPLC-Q-TOF/MS). Meanwhile, we compared the effects of digestion products on advanced glycation end products (AGEs)-induced intracellular reactive oxygen species (ROS) levels in a human arterial endothelial cells (HAECs) model, and studied the potential of RA against oxidative stress-related cardiovascular disease. The changes of saponins and flavonoids composition and antioxidant activity after digestion in intestines were mainly due to the astragaloside IV (AS-IV) biosynthesis involving saponins acetyl isomerization and deacetylation, and the flavonoid glycosides converted to aglycone by deglycosylation processes. All these results suggest that acetyl biotransformation of RA in small intestine directly influenced the response to oxidative stress, and might provide a reference for elucidation of the multi-component action after oral RA in cardiovascular health care.

Elucidation of the binding mechanism of astragaloside IV derivative with human serum albumin and its cardiotoxicity in zebrafish embryos.

LS-102 is a new derivative of astragaloside IV (AGS IV) that has been shown to possess potentially significant cardioprotective effects. However, there are no reports concerning its interaction with human serum albumin (HSA) and toxicology in vertebrates. The present investigation was undertaken to characterize the interaction of AGS IV and LS-102 with HSA using equilibrium dialysis and UHPLC-MS/MS methods, along with computational methods. Notably, the effects of AGS IV and LS-102 were studied in vivo using the zebrafish embryo model. Markers related to embryonic cardiotoxicity and thrombosis were evaluated. We showed that the plasma protein binding rate of AGS IV (94.04%-97.42%) was significantly higher than that of LS-102 (66.90%-69.35%). Through site marker competitive experiments and molecular docking, we found that AGS IV and LS-102 were located at the interface of subdomains IIA and IIIA, but the site I might be the primary binding site. Molecular dynamics revealed that AGS IV showed a higher binding free energy mainly due to the stronger hydrophobic and hydrogen bonding interactions. Moreover, the secondary structure implied no obvious effect on the protein structure and conformation during the binding of LS-102. LS-102 significantly ameliorated the astramizole-induced heart rate slowing, increased SV-BA spacing, and prevented arachidonic acid-induced thrombosis in zebrafish. To our knowledge, we are the first to reveal that LS-102 binds to HSA with reversible and moderate affinity, indicating its easy diffusion from the circulatory system to the target tissue, thereby providing significant insights into its pharmacokinetic and pharmacodynamic properties when spread in the human body. Our results also provide a reference for the rational clinical application of LS-102 in the cardiovascular field.

A feasible image-based colorimetric assay using a smartphone RGB camera for point-of-care monitoring of diabetes.

Urinary glucose determination using a glucose test strip is simple and convenient in daily self-monitoring of diabetes. However, diabetic patients exhibit acquired impaired color vision (ICV), which results in the inability to discriminate between hues. Even with the assistance of a color chart, it is still not easy for these patients to read the urinary glucose results with the naked eye. In this study, a smartphone camera using an image-based colorimetric detection method was successfully developed for quantitative analysis of urine glucose. A horseradish peroxidase-hydrogen peroxide-3,3'5,5'-tetramethylbenzidine (HRP-H2O2-TMB) system was optimized for a reliable and gradual color fading process via a glucose oxidase (GOD) catalyzed oxidation reaction. The color changes of the peroxidase-H2O2 enzymatic reactions in the 96-well microplate were captured by a smartphone RGB camera with subsequent detection of red, green, and blue (RGB) intensities decreasing at each image pixel. The highly quantitative relationships between the glucose concentrations and the color characteristic values of the blue channel of the captured images were successfully established. The high accuracy of this method was demonstrated in urine glucose measurements with a linear response over the 0.039 mg mL-1 to 10.000 mg mL-1 glucose concentration range and a 0.009 mg mL-1 detection limit. The method has great potential as a point-of-need platform for diabetic patients with defective color vision and features high accuracy and low cost.