The B-ring substitution pattern of flavonols is a significant structural feature for their function as free radical scavengers and antioxidants. In this paper, four differently substituted B-ring hydroxylation flavonols (galangin, kaempferol, quercetin, and myricetin) and a flavonol glycoside (quercitrin) were studied for their ability to bind BSA by quenching the protein intrinsic fluorescence. From the spectra obtained, the biomolecular quenching constants, the apparent static binding constants, and the binding site values were calculated. The B-ring hydroxylation of flavonols significantly affected the binding/quenching process; in general, the binding affinity increased with the number of hydroxyl groups on the B-ring. The binding constants ( Ka) were determined as myricetin (4.90 x 10(8) L/mol) > quercetin (3.65 x 10(7) L/mol) > kaempferol (2.57 x 10(6) L/mol) > galangin (6.43 x 10(5) L/mol). The glycoside substitute at the C-ring position decreased the binding affinity. The chromatographic retention factor ( K') and logarithms of apparent partition coefficient (log Kow) were linear to the logarithms of apparent binding constants (log Ka) for flavonols with increasing hydroxyl groups on the B-ring. These results showed that the hydrogen bond force play an important role in binding flavonols to BSA. These results are also in agreement with the generally accepted structure-dependent free radical scavenger and antioxidant abilities of flavonols.

BackgroundHepatocellular carcinoma (HCC) is one of the most common malignancies worldwide with poor prognosis due to resistance to conventional chemotherapy and limited efficacy of radiotherapy. There is an urgent need to develop novel biomarkers for early diagnosis, as well as to identify new drug targets for therapeutic interventions.Patients and methods54 paired HCC samples and 21 normal liver tissues were obtained from West China Hospital of Sichuan University. Informed consent was obtained from all the patients or their relatives prior to analysis, and the project was approved by the Institutional Ethics Committee of Sichuan University. Stable Isotope Labeling with Amino Acids in Cell Culture (SILAC)-based proteomics was employed to profile the differentially expressed proteins between a HepG2 human hepatoma cell line and an immortal hepatic cell line L02. Validation of PGAM1 expression was performed by semi-quantitative RT-PCR, immunoblot and immunohistochemistry using clinical samples. shRNA expressing plasmids specifically targeting PGAM1 were designed and constructed by GenePharma Corporation (Shanghai, China), and were utilized to silence expression of PGAM1 in vitro and in vivo. Cell proliferation was measured by a combination of colony formation assay and Ki67 staining. Apoptosis was examined by flow cytometry and TUNEL assay.ResultsA total of 63 dysregulated proteins were identified, including 51 up-regulated proteins, and 12 down-regulated proteins (over 2-fold, p < 0.01). Phosphoglycerate mutase 1 (PGAM1) was found markedly upregulated. Clinico-pathological analysis indicated that overexpression of PGAM1 was associated with 66.7% HCC, and strongly correlated with poor differentiation and decreased survival rates (p < 0.01). shRNAs-mediated repression of PGAM1 expression resulted in significant inhibition in liver cancer cell growth both in vitro and in vivo.ConclusionOur studies suggested that PGAM1 plays an important role in hepatocarcinogenesis, and should be a potential diagnostic biomarker, as well as an attractive therapeutic target for hepatocellular carcinoma.

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A new type of grafting chitosan (CTS) was synthesized using 2-hydroxyethyl- trimethyl ammonium chloride (HGCTS). The adsorption of Cr(VI) on HGCTS was studied. The effect factors on adsorption and the adsorption mechanism were considered. The results indicated that the HGCTS could concentrate and separate Cr(VI) at pH 4.0; the adsorption equilibrium time was 80 min; the maximum adsorption capacity was 205 mg/g. The adsorption isotherm and kinetics were investigated, equilibrium data agreed very well with the Langmuir model and the pseudo second-order model could describe the adsorption process better than the pseudo first-order model. A novel method for speciation of Cr(VI) and Cr(III) in environmental water samples has been developed using HGCTS as adsorbent and FAAS as determination means. The detection limit of this method was 20 ng/L, the relatively standard deviation was 1.2% and the recovery was 99%~105%.