A concise total synthesis of biologically active frutinones via tributylphosphine-catalyzed tandem acyl transfer-cyclization

A concise and step-economical total synthesis of biologically active frutinones has been achieved. Tributylphosphine (PBu₃) efficiently induced the tandem acyl transfer-cyclization of carbonates 5 to afford 3-methoxycarbonylflavone derivatives 4 in excellent yields. Finally, concomitant deprotection and lactonization under acidic conditions furnished the desired frutinones A (1a), B (1b), and the proposed structure of frutinone C (1c).     

Microwave-assisted synthesis of functionalized flavones and chromones

A facile microwave synthesis of functionalized flavones and chromones via the cyclization of 1-(2-hydroxyaryl)-3-aryl-1,3-propanedione is described.     

Four new constituents from Taraxacum mongolicum

Two new flavone glycosides,isoetin-7-O-β-D-glucopyranosyl-2′-O-α-L-arabinopyranoside (1) and isoetin-7-O-β-D-glucopyr- anosyl-2′-O-α-D-glucopyranoside (2),a new lignan,mongolicumin A (3),and a new guaianolide,mongolicumin B (4) were isolated from the aerial part of Taraxacum mongolicum.Their structures were elucidated mainly by spectral analyses.     

Novel nonaqueous capillary electrophoresis separation and determination of bioactive flavone derivatives in Chinese herbs

Nonaqueous CE (NACE) coupled to UV detection is described for the separation and determination of bioactive flavone derivatives in Chinese herbs extraction. After optimization of electrophoresis parameters, including the electrolyte nature and the organic solvent composition, a reliable separation of the analytes in an ACN/methanol (60:40, v/v) mixture containing 80 mM Tris and 10 mM sodium cholate was performed. The detection was performed at 254 nm. Method performances, including migration time and peak area reproducibility, linearity, sensitivity, and accuracy, were evaluated. The method was applied to determine bioactive flavone derivatives in seven Chinese herbs.     

Flavone Glycosides from Strobilanthes Formosanus

Two new flavone glycosides, 3′‐hydroxy‐5,7‐dimethoxyflavone 4′‐O‐β‐D‐apiofuranoside ( 1 ), and 5,7‐dimethoxyflavone 4′‐O‐[β‐D‐apiofuranosyl(1→5)‐ β‐D‐glucopyranoside] ( 2 ) along with four known compounds, 4′‐hydroxy‐5,7‐dimethoxyflavone ( 3 ), 2,6‐dimethoxy‐1,4‐benzoquinone ( 4 ), lupeol ( 5 ) and betulin ( 6 ) were isolated from the stem and roots of Strobilanthes formosanus. Their structures were elucidated on the basis of their spectroscopic evidence.     

Syntheses of Novel Flavones Containing Schiff Base Moiety

Introduction Flavones and their derivatives existing in naturae are commonly contained in plants. The members of the flavone class show a wide variety of biological activities, such as anti-inflammatory[1], antimicrobial[2] and antitumor activities[3]. Schiff bases have been intensively investigated due to their antibacterial activity and antitumor property[4,5].     

Further constituents from Rhododendron lepidotum L.

<正>A unusual flavone glycoside named Shamimarin(1) and a new compound Acetoxy-8-methyl-chromen-2H-one(2) were isolated from aerial parts of Rhododendron lepidotum L.along with four known coumarins daphnin(3),daphnetin 8-O-β-D-glucopyrano-side (4),daphnetin(5) and umbelliferone(6).The structural elucidations were based on analyses of chemical and spectroscopic data by including ID and 2D NMR analyses.     

山楂总黄酮提取及其抗氧化作用

用微波提取法提取山楂总黄酮,探讨最佳提取条件及其抗氧化活性.研究表明最佳提取工艺条件为乙醇浓度50％、提取时间20min、微波功率300W、料液比1∶30（g/mL）,总黄酮提取率可达13.4％;并以过氧化值（POV）为指标,研究了山楂总黄酮对猪油的抗氧化性能,其抗氧化效果明显.     

Colorimetric and ratiometric sensors derivated from natural building blocks for fluoride ion detection

Three novel colorimetric and ratiometric probes (SH-1~3) for fluoride ion detection were designed and synthesized from nature small molecules. Obvious yellow-to-orange color change of these probes in the THF was achieved only in presence of F^? among the eight anions (F^?, Cl^?, Br^?, I^?, H₂PO₄^?, HSO₄^?, CH₃COO^–, ClO₄^?), along with the emission shifting from green to orange red. These three probes are 1:1 complexed with fluoride ions, with complexation constant of around 0.1 × 10⁴ M^?1. The detection limit of probes SH-1~3 reached as low as around 1 μM. ¹H NMR titration study suggested that the fluoride ion induced deprotonation of the probe through hydrogen bonding interaction between amino group of probe and fluoride ion.     

Preparation of 4‐butylaniline‐bonded silica gel for the solid‐phase extraction of flavone glycosides

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.