The Experts below are selected from a list of 2547 Experts worldwide ranked by ideXlab platform
Richard A. Dixon - One of the best experts on this subject based on the ideXlab platform.
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Supplementary materials: Regioselective synthesis of plant (iso)Flavone Glycosides in Escherichia coli
2008Co-Authors: Jack W. Blount, Richard A. DixonAbstract:Supplementary materials accompanying an article on regioselective synthesis of plant (iso)Flavone Glycosides in Escherichia coli.
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regioselective synthesis of plant iso Flavone Glycosides in escherichia coli
Applied Microbiology and Biotechnology, 2008Co-Authors: Jack W. Blount, Richard A. DixonAbstract:The flavonoids genistein, biochanin A, luteolin, quercetin, and kaempferol are plant natural products with potentially useful pharmacological and nutraceutical activities. These natural products usually exist in plants as Glycosides, and their glycosylation has a remarkable influence on their pharmacokinetic properties. The glycosyltransferases UGT71G1 and UGT73C8 from Medicago truncatula are excellent reagents for the regioselective glycosylation of (iso)flavonoids in Escherichia coli grown in Terrific broth. Ten to 20 mg/L of either genistein or biochanin A 7-O-glucoside was produced after feeding genistein or biochanin A to E. coli expressing UGT71G1, and similar levels of luteolin 4’-O- and 7-O-glucosides were produced after feeding luteolin to cultures expressing UGT73C8. For the production of kaempferol 3-O-glucoside or quercetin 3-O-glucoside, the Phe148Val or Tyr202Ala mutants of UGT71G1 were employed. Ten to 16 mg/L of either kaempferol 3-O- or quercetin 3-O-glucosides were produced on feeding kaempferol or quercetin to E. coli expressing these enzymes. More than 90% of the glucoside products were released to the medium, facilitating their isolation.
Jack W. Blount - One of the best experts on this subject based on the ideXlab platform.
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Supplementary materials: Regioselective synthesis of plant (iso)Flavone Glycosides in Escherichia coli
2008Co-Authors: Jack W. Blount, Richard A. DixonAbstract:Supplementary materials accompanying an article on regioselective synthesis of plant (iso)Flavone Glycosides in Escherichia coli.
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regioselective synthesis of plant iso Flavone Glycosides in escherichia coli
Applied Microbiology and Biotechnology, 2008Co-Authors: Jack W. Blount, Richard A. DixonAbstract:The flavonoids genistein, biochanin A, luteolin, quercetin, and kaempferol are plant natural products with potentially useful pharmacological and nutraceutical activities. These natural products usually exist in plants as Glycosides, and their glycosylation has a remarkable influence on their pharmacokinetic properties. The glycosyltransferases UGT71G1 and UGT73C8 from Medicago truncatula are excellent reagents for the regioselective glycosylation of (iso)flavonoids in Escherichia coli grown in Terrific broth. Ten to 20 mg/L of either genistein or biochanin A 7-O-glucoside was produced after feeding genistein or biochanin A to E. coli expressing UGT71G1, and similar levels of luteolin 4’-O- and 7-O-glucosides were produced after feeding luteolin to cultures expressing UGT73C8. For the production of kaempferol 3-O-glucoside or quercetin 3-O-glucoside, the Phe148Val or Tyr202Ala mutants of UGT71G1 were employed. Ten to 16 mg/L of either kaempferol 3-O- or quercetin 3-O-glucosides were produced on feeding kaempferol or quercetin to E. coli expressing these enzymes. More than 90% of the glucoside products were released to the medium, facilitating their isolation.
Jingbo Liu - One of the best experts on this subject based on the ideXlab platform.
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the antioxidant and free radical scavenging activities of extract and fractions from corn silk zea mays l and related Flavone Glycosides
Food Chemistry, 2011Co-Authors: Jun Liu, Cuina Wang, Zuozhao Wang, Cheng Zhang, Jingbo LiuAbstract:Abstract This study was designed to evaluate both the antioxidant and free-radical scavenging activities of extract and fractions from corn silk. N -butanol fraction (BF) demonstrated the highest total phenolic content (164.1 ± 9.7 μg GAE/g DCS) and total flavonoids content (69.4 ± 5.1 μg RE/g DCS), accompanied with the highest antioxidant activity compared to other fractions through all antioxidant assays. Two Flavone Glycosides showing potent antioxidant activity were isolated from BF and identified, by comparing spectral data (UV, FAB-MS and NMR) with literature values, to be isoorientin-2″- O - α - l -rhamnoside and 3′-methoxymaysin. The two isolated Flavone Glycosides, particularly isoorientin-2″- O - α - l -rhamnoside, demonstrated significant total antioxidant activity, DPPH radical scavenging activity, reducing power and iron-chelating capacity, with EC 50 values of 14.24 ± 1.49, 22.69 ± 2.33, 6.58 ± 1.07 and 30.25 ± 3.05 μg/ml, respectively. Results obtained indicated that corn silk extracts can be used potentially as a ready accessible and valuable bioactive source of natural antioxidants.
Xueguang Shao - One of the best experts on this subject based on the ideXlab platform.
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preparation of 4 butylaniline bonded silica gel for the solid phase extraction of Flavone Glycosides
IEEE Journal of Solid-state Circuits, 2015Co-Authors: Ganghui Chu, Wensheng Cai, Xueguang ShaoAbstract:To extract Flavone Glycosides efficiently, a new extraction material based on 4-butylaniline-bonded silica gel was prepared using a two-step grafting method including a ring-opening reaction and synchronous hydrolysis. Preparation of the silica-based material was easily achieved under mild conditions, and the material was characterized by Fourier transform infrared spectroscopy, elemental analysis, and scanning electron microscopy. The material was used in solid-phase extraction, and the extraction can be performed in neutral conditions without regard to ionic strength. Selectivity tests of 14 compounds on the extraction cartridge showed that the material has a high affinity to Flavone Glycosides in contrast to octadecyl silica, and the extraction yields for four Flavone Glycosides were found to be >93%. Selectivity tests further reveal that the adsorption on its surface is likely attributed to multiple interactions, including hydrophobic interactions, π-π interactions, and hydrogen bonding. To explore the applicability of 4-butylaniline-bonded silica gel, naringin and hesperidin from Simotang oral liquid were extracted, and the extraction yields were >90%, which is distinguished from <28% on octadecyl silica cartridge.
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Preparation of 4-butylaniline-bonded silica gel for the solid-phase extraction of Flavone Glycosides
Journal of separation science, 2015Co-Authors: Ganghui Chu, Wensheng Cai, Xueguang ShaoAbstract:To extract Flavone Glycosides efficiently, a new extraction material based on 4-butylaniline-bonded silica gel was prepared using a two-step grafting method including a ring-opening reaction and synchronous hydrolysis. Preparation of the silica-based material was easily achieved under mild conditions, and the material was characterized by Fourier transform infrared spectroscopy, elemental analysis, and scanning electron microscopy. The material was used in solid-phase extraction, and the extraction can be performed in neutral conditions without regard to ionic strength. Selectivity tests of 14 compounds on the extraction cartridge showed that the material has a high affinity to Flavone Glycosides in contrast to octadecyl silica, and the extraction yields for four Flavone Glycosides were found to be >93%. Selectivity tests further reveal that the adsorption on its surface is likely attributed to multiple interactions, including hydrophobic interactions, π-π interactions, and hydrogen bonding. To explore the applicability of 4-butylaniline-bonded silica gel, naringin and hesperidin from Simotang oral liquid were extracted, and the extraction yields were >90%, which is distinguished from
Mariechristine Poelman - One of the best experts on this subject based on the ideXlab platform.
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in vivo and in vitro assessment of the free radical scavenger activity of ginkgo Flavone Glycosides at high concentration
Journal of Pharmacy and Pharmacology, 1999Co-Authors: Jalila Hibatallah, Charlotte Carduner, Mariechristine PoelmanAbstract:Free radicals are involved in numerous skin diseases, especially inflammatory reactions and photosenescence. To identify possible free-radical scavenging by an original terpenefree Ginkgo biloba extract containing 33% Ginkgo Flavone Glycosides, mostly quercetin and kaempferol derivatives, we studied its activity by means of in-vitro and in-vivo experiments, using superoxide dismutase (SOD) as a positive control. By means of an in-vitro electron-spin resonance (ESR) assay we compared the activity of the Ginkgo extract with that of its two aglycones, quercetin and kaempferol. Quercetin and Ginkgo extract had significant antioxidant properties without pro-oxidant effect. In contrast, kaempferol, above an optimum antioxidant concentration, behaved as a pro-oxidant. The in-vivo experiments were conducted on an anti-inflammatory model. The cutaneous blood flux which reflects the skin inflammatory level was recorded by means of a laser Doppler perfusion imager. The data confirmed the free-radical-scavenging property of both Ginkgo extract and SOD. The Ginkgo extract significantly inhibited (37%) cutaneous blood flux to the same extent as SOD. These data confirmed the antioxidant property of Ginkgo extract. A complementary spin-trapping technique would enable identification of the free radicals involved. This Ginkgo extract should be useful for protection of the skin against free radicals.