Quercetin-3-O-β-D-glucuronide Inhibits Mitochondria Pathway-mediated Platelet Apoptosis via the Phosphatidylinositol-3-kinase/AKT Pathway in Immunological Bone Marrow Failure

Objective: Quercetin-3-O-β-D-glucuronide(QG) can alleviate immunological bone marrow failure(BMF) by increasing platelet counts. However, the principal mechanism is less known. This study aimed at deciphering the possible underlying mechanism of QG that is indicated in thrombocytopenic purpura. Methods: In vitro and in vivo experiments were carried out for investigating the mechanism behind QG-facilitated inhibition of mitochondrial pathway-mediated excessive apoptosis of platelets through the phosphatidylinositol-3-kinase(PI3K)/AKT pathway. Results: Our results revealed that QG, the main effective ingredient of Herba Sarcandrae, increases the number of platelets and decreases the expression of Bax, Bad, Bid, and caspase-9 in immunological BMF, indicating the inhibition of mitochondrial pathway-mediated apoptosis. Moreover, we found that the protein and m RNA expressions, as well as the phosphorylated levels of PI3K and AKT, were increased significantly by QG, suggesting the activation of the PI3K/AKT pathway. Furthermore, the inhibition of the PI3K/AKT pathway by LY294002 antagonizes the effects of QG on platelet counts and mitochondrial pathway-mediated apoptosis. Conclusion: We demonstrate that QG inhibits the mitochondria pathway-mediated platelet apoptosis via the PI3K/AKT pathway in immunological BMF. This study thus sheds light on exploring the possible regulatory mechanism of traditional Chinese medicine in the treatment of thrombocytopenia induced by BMF.

Quercetin-3-O-β-D-glucopyranosyl-(4→1)-α-L-rhamnoside metabolites in the rat using UPLC-Q-TOF/MS

Ultraperformance liquid chromatography/quadrupole-time-of-flight mass spectrometry(UPLC-Q-TOF/MS) and the MetabolynxTM software, combined with mass defect filtering, were applied to identity the metabolites of quercetin-3-O-β-D-glucopyranosyl-(4→1)-α-L-rhamnoside(QGR) in rats after intravenous administration. MSE was used for simultaneous acquisition of precursor ion information and fragment ion data at high and low collision energy in one analytical run, which facilitated the rapid structural characterization of eight metabolites in rat plasma, urine and bile. The results indicated that methylation and glucuronidation were the major metabolic pathways of QGR in vivo. The present study provided important information about the metabolism of QGR which will be useful for fully understanding the mechanism of action of this compound. Furthermore, this work demonstrated the potential of the UPLC-Q-TOF/MS approach using Metabolynx for rapid and automated research of the metabolites of natural products.

Preparation of Glycyrrhetinic Acid Monoglucuronide by Selective Hydrolysis of Glycyrrhizic Acid via Biotransformation

Objective To search for the microorganisms which have the high selectivity of hydrolyzing glycyrrhizic acid(GL) into 18β-glycyrrhetinic acid-3-O-β-D-glucuronide(GAMG) without glycyrrhetinic acid(GA) byproduct.Methods GL was biotransformed by Aspergillus sp.,the products were separated by chromatography on reverse phase C18 column and semi-preparative HPLC,and their structures were elucidated on the basis of HR-ESI-MS,1D NMR(1H-NMR,13C-NMR,and NOESY) and 2D NMR(1H-1H COSY,HSQC,and HMBC) spectral analyses.Results Aspergillus sp.could partially hydrolyze GL into GAMG(3),along with two minor byproducts,3-O-β-D-glucuronopyranosyl-18β-liquiritic acid(1) and 3-O-β-D-glucuronopyranosyl-24-hydroxy-18β-glycyrrhetinic acid(2).Conclusion Aspergillus sp.has the high selectivity of hydrolyzing GL into GAMG without GA byproduct and the yield of GAMG is about 60%.The complete assignments of 1H-NMR and 13C-NMR data for compounds 1 and 2 are reported for the first time.