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  • Author or Editor: Xuefeng Guo x
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Flavonoids are the main functional compounds in a bamboo leaf extract. Because of their activity flavonoids are widely used in many of health products, cosmetics, and food supplements. A simple high-performance thin-layer chromatographic (HPTLC) method has been established for simultaneous quantification of vitexin, isovitexin, orientin, and isoorientin in the leaves of three different bamboo species: Phyllostachys pubescens Mazel ex H. de Lehaie, Phyllostachys glauca McClure, and Pleioblastus yixingensis S. L. Chen et S. Y. Chen. The method was validated for precision (expressed as the coefficient of variation, CV [%]), accuracy, sensitivity, and selectivity. Instrumental precision was found to be 0.37, 0.52, 0.39, 0.13, and 0.84% and the repeatability of the method 0.98, 0.91, 1.02, 1.04 and 0.87% for isovitexin, rutin, orientin, isoorientin, and vitexin, respectively. The accuracy of the method was determined by measurement of recovery at three different concentrations. Average recovery was 99.54% for isovitexin, 99.31% for orientin, and 100.55% for isoorientin from P. pubescens; 98.97% for orientin, 99.00% for isovitexin, and 99.58% for vitexin from P. glauca ; and 98.86% for orientin, 100.04% for isoorientin, and 99.63% for vitexin in P. yixingensis . In the fraction extracted from bamboo leaves known as Flavone Gruff the flavonoid content was 6.44% ( w/w ) for orientin, 3.45% for isovitexin, and 6.58% for isoorientin in P. pubescens ; 7.82% for orientin, 2.82% for isovitexin, and 13.7% for vitexin in P. glauca ; and 4.92% for orientin, 3.50% for isoorientin, and 22.5% for vitexin in P. yixingensis . Although the presence of rutin was confirmed in the bamboo leaves investigated, it could not be quantified because of its low concentration. The proposed HPTLC method was found to be simple, precise, selective, sensitive, and accurate for routine quality control of the leaves of different bamboo species and formulations containing bamboo-leaf flavonoids.

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Abstract  

U(VI) sorption on kaolinite was studied as functions of contact time, pH, U(VI) concentration, solid-to-liquid ratio (m/V) by using a batch experimental method. The effects of sulfate and phosphate on U(VI) sorption were also investigated. It was found that the sorption kinetics of U(VI) can be described by a pseudo-second-order model. Potentiometric titrations at variable ionic strengths indicated that the titration curves of kaolinite were not sensitive to ionic strength, and that the pH of the zero net proton charge (pHPZNPC) was at 6.9. The sorption of U(VI) on kaolinite increased with pH up to 6.5 and reached a plateau at pH >6.5. The presence of phosphate strongly increased U(VI) sorption especially at pH <5.5, which may be due to formation of ternary surface complexes involving phosphate. In contrast, the presence of sulfate did not cause any apparent effect on U(VI) sorption. A double layer model was used to interpret both results of potentiometric titrations and U(VI) sorption on kaolinite.

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Abstract

Bamboo leaves extract (BLE) has a variety of physiological functions such as antitumour, anti-inflammatory, antioxidant and blood fat reduction activities and the flavonoids of bamboo leaves are the major active constituents. To profile the flavonoids in the complex BLE, a rapid and sensitive analytical method based on ultra-high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UPLC-ESI-Q-TOF-MS/MS) was developed for the structural identification of the flavonoids in Bambusa chungii leaves extract using accurate mass measurements and characteristic fragmentation patterns. After separation on an Agilent SB-C18 Rapid Resolution High Definition (RRHD) column (2.1 mm × 150 mm, 1.8 μm) by gradient elution with 0.1% formic acid aqueous solution and acetonitrile as the mobile phase, the sample was analysed by ESI-QTOF-MS/MS in the negative mode. A total of 22 flavonoids were detected, and eight of these were identified by comparison with reference standards, while the other fourteen were tentatively identified according to their MS/MS data. The main fragmentation pathways of flavonoid C-glycosides (compounds 1, 5 and 10), flavonoid di-C,O-glycosides (compound 4), flavonoid di-C-glycosides (compound 7) and flavonoid C,O-di-glycosides (compounds 2 and 14) are shown in this article. This is the first report on the analysis of the flavonoids in the extract of B. chungii leaves. The present work demonstrates that UPLC-ESI-Q-TOF-MS/MS is an efficient technique for identifying multiple flavonoids of BLE.

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