ABSTRACT
BACKGROUND: Effective control of postprandial blood glucose (PBG) level is essential for the prevention and treatment of diabetes and its complications. Several flavonoids have attracted much attention due to their significant PBG-lowering effects. However, there is still a certain gap in the in vivo hypoglycemic activity of most flavonoids compared to first-line drugs available on the market, and are still lack of the PBG-lowering effects of 8-hydroxyflavones and their structure-activity relationship. PURPOSE: Evaluate hypoglycemic effects of 8-hydroxyflavones from Rhodiola crenulata in vitro and in vivo, especially comparatively analyze the relationship between hypoglycemic effects and flavonoid configuration and reveal the possible mechanism of 8-hydroxyflavones in lowering hyperglycemia. METHODS: Starch, maltose, sucrose, and glucose tolerance tests in both diabetic and normal mice were used to evaluate and compare the hypoglycemic effects of 8-hydroxyflavones rhodiosin (RHS), rhodionin (RHN), and herbacetin (HBT). Molecular docking, enzyme kinetics, and immunofluorescence analysis were used to research the possible hypoglycemic mechanisms of 8-hydroxyflavones. RESULTS: RHS (5 and 10 mg/kg) could efficiently decrease PBG levels in both normal and diabetes mice. Moreover, RHS, RHN, and HBT all had significant PBG-lowering effects in transgenic diabetes mice, and the effects were equivalent to or stronger than acarbose. Further mechanism research indicated that 8-hydroxyflavones achieved PBG-lowering effects by inhibiting both the activity and production of glycosidase. Notably, we have innovatively discovered that inhibiting the expression of glycosidases rather than just their activities may be a new target for hypoglycemic drugs. CONCLUSION: We have firstly comprehensively and systematically clarified PBG-lowering effects of 8-hydroxyflavones from Rhodiola crenulata, and revealed their structure-activity relationships and hypoglycemic mechanisms. The study demonstrated that the substitution of 8-hydroxy groups in flavonoids could significantly enhance their hypoglycemic effects, which were equivalent to or stronger than commercially available drug acarbose. 8-Hydroxyflavones could be used as therapeutic or health drugs with significant potential to reduce postprandial hyperglycemia.
ABSTRACT
Methicillin-resistant Staphylococcus aureus (MRSA) is a zoonotic antibiotic-resistant pathogen that negatively impacts society from medical, veterinary, and societal standpoints. The search for alternative therapeutic strategies and innovative anti-infective agents is urgently needed. Among the pathogenic mechanisms of Staphylococcus aureus (S. aureus), sortase A is a virulence factor of great concern because it is highly linked with the ability of MRSA to invade the host. In this study, we identified that rhodionin, a natural compound of flavonoid glucosides, effectively inhibited the activity of SrtA without affecting the survival and growth of bacteria, and its half maximal inhibitory concentration (IC50) value was 22.85 µg/mL. In vitro, rhodionin prominently attenuated the virulence-related phenotype of SrtA by reducing the adhesion of S. aureus to fibrinogen, reducing the capacity of protein A (SpA) on the bacterial surface and biofilm formation. Subsequently, fluorescence quenching and molecular docking were performed to verify that rhodionin directly bonded to SrtA molecule with KA value of 6.22 × 105 L/mol. More importantly, rhodionin showed a significant protective effect on mice pneumonia model and improved the survival rate of mice. According to the above findings, rhodionin achieved efficacy in the treatment of MRSA-induced infections, which holds promising potential to be developed into a candidate used for MRSA-related infections.
Subject(s)
Methicillin-Resistant Staphylococcus aureus , Pneumonia, Staphylococcal , Mice , Animals , Staphylococcus aureus , Molecular Docking Simulation , Flavonoids/pharmacologyABSTRACT
Objective To develop and fully validate an UPLC-MS/MS method for simultaneous quantification of six active ingredients in Rhodiola extract including salidroside, rhodiosin, rhodionin, herbacetin, kaempferol and quercetin. Methods The chromatographic separation of the analytes was achieved by using Zorbax Eclipse plus C18 column (2.1 mm×100 mm, 3.5 μm). The mobile phase consisted of 0.2% aqueous formic acid and acetonitrile. Analytes were separated using a linear gradient with a flow rate of 0.4 ml/min. The column temperature was set at 25 °C. The mass spectrometric conditions were electrospray negative ionization (ESI) and the scanning mode was multi reaction monitoring (MRM). Results The calibration curves of the six active ingredients were linear over 1020000, 10-4000, 10-4000, 5-2000, 10-2000, and 5-2000 ng/ml concentration ranges, respectively. The RSD of the instrument precision was within 3.31%. The current assay was stable and reproducible in quantification of all analytes with RSD within 5.07% and 4.05%, respectively. The average recovery of all analytes was in a range from 99.27% to 108.91%, with an acceptable RSD of no more than 4.92%. Conclusion The UPLC-MS/MS method could be successfully applied to simultaneously quantifying six major active ingredients in Rhodiola extract with the acceptable specificity, sensitivity and reproducibility.
ABSTRACT
Objective: To establish a determination method for the contents of ternatumoside II, rhodiosin, rhodionin, herbacetin, kaempferol, and rhodiolin in Rhodiolae Crenulatae Radix et Rhizoma and to compare the content differences of the six flavonid compounds in Rhodiolae Crenulatae Radix et Rhizoma from different sources. Methods: Using HPLC-DAD method and Kromasil C18 column (250 mm × 4.6 mm, 5 μm), with acetonitrile and water as mobile phase, gradient elution at flow rate of 1.0 mL/min and column temperature of 35℃. The detection wavelength was 382 nm. Results: Ternatumoside II, rhodiosin, rhodionin, herbacetin, kaempferol, and rhodiolin had good linearity in the ranges of 0.015 08-0.301 6, 0.123 2-2.464, 0.109 5-2.190 8, 0.007 8-0.156, 0.021 46-0.429 2, and 0.006 48-0.129 6 μg, respectively. The average recoveries of the six constituents were 98.17%-100.52% and RSD values were 1.64%-1.98%. Conclusion: The method is simple and accutate. It provides the reference for comprehensive quality control of Rhodiolae Crenulatae Radix et Rhizoma.
ABSTRACT
Objective To develop and fully validate an UPLC-MS/MS method for simultaneous quantification of six active in?gredients in Rhodiola extract including salidroside,rhodiosin,rhodionin,herbacetin,kaempferol and quercetin. Methods The chro?matographic separation of the analytes was achieved by using Zorbax Eclipse plus C18 column(2.1 mm×100 mm,3.5μm). The mobile phase consisted of 0.2%aqueous formic acid and acetonitrile. Analytes were separated using a linear gradient with a flow rate of 0.4 ml/min. The column temperature was set at 25℃. The mass spectrometric conditions were electrospray negative ionization(ESI)and the scan?ning mode was multi reaction monitoring(MRM). Results The calibration curves of the six active ingredients were linear over 10-20000,10-4000,10-4000,5-2000,10-2000,and 5-2000 ng/ml concentration ranges,respectively. The RSD of the instrument precision was within 3.31%. The current assay was stable and reproducible in quantification of all analytes with RSD within 5.07%and 4.05%,respectively. The average recovery of all analytes was in a range from 99.27%to 108.91%,with an acceptable RSD of no more than 4.92%. Conclusion The UPLC-MS/MS method could be successfully applied to simultaneously quantifying six major active in?gredients in Rhodiola extract with the acceptable specificity,sensitivity and reproducibility.
ABSTRACT
A novel on-line three-dimensional liquid chromatography method was developed to separate four main flavonoids from Rhodiola rosea. Ethyl acetate/0.5 mol/L ionic liquid 1-butyl-3-methylimidazolium chloride aqueous solution was selected as the solvent system. In the first-dimension separation, the target flavonoids were entrapped and subsequently desorbed into the second-dimension high-speed countercurrent chromatographic column for separation. In the third-dimension chromatography, the residual ionic liquid in the four separated flavonoids was removed and the used ionic liquid was recovered. As a result, 35.1 mg of compound 1, 20.4 mg of compound 2, 8.5 mg of compound 3, and 10.6 mg of compound 4 were obtained from 1.53 g R. rosea extract. They were identified as rhodiosin, rhodionin, herbacetin, and kaempferol, respectively. The recovery of ionic liquid reached 99.1% of the initial amount. The results showed that this method is a powerful technology for the separation of R. rosea flavonoids and that the ionic-liquid-based solvent system has advantages over traditional solvent systems in renewable and environmentally friendly properties.
