ISOLATION, STRUCTURE ELUCIDATION AND SYNTHESIS OF A NEW PRENYLATED FLAVONOL, MAACKIAFLAVONOL, FROM MAACKIA TENUIFOLIA

A new prenylated flavonol, maackiaflavonol, was isolated from the ethanol extract of the roots of Maackia tenuifolia. Its structure was elucidated as 7-hydrox-8-prenylflavonol by means of spectroscopic analysis (UV, IR, MS, NMR and 1H-1H COSY) and confirmed by total synthesis.

Synthesis, Biological Evaluation, and SAR Studies of Varyingly Substituted 4-Thioflavonols

A series of 4-thioflavonols compounds were synthesized by treating flavonols with lawsons reagent with variable substituent groups at A, B, and AB rings. All the synthesized compounds were checked for antibacterial and antifungal activity. We report that many compounds were found active against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus, bacterial strains and, C. albicans, C. parapsilosisstrains and C. krusei fungal strains. Most of the synthesized 4-thioflavonols compounds were found to show enhanced antimicrobial activity than respective flavonol compounds.

A New Isoprenylated flavonol from the Leaves of Broussonetia kazinoki

A new isoprenylated flavonol, named broussonol A (1) was isolated from the leaves of Broussonetia kazinoki Sieb. The structure of broussonol A was characterized by chemical and spectral methods.

A New Antimicrobial Flavonol Glycoside from Alchornea davidii

A new flavonol glycoside, isorhamnetin-3-O-b-D-xyloside, was isolated from the extract of leaves and twigs of Alchornea davidii (Euphorbiaceae). Its structure was established on the basis of the spectral analysis and chemical degradation. Antimicrobial assay showed that it moderately inhibited the growth of test bacteria (Staphylococcus aureus, Bacillus subtilis and Pseudomonas fluorescens) and fungi (Candida albicans, Aspergillus niger and Trichophyton rubrum) with MICs at 50 g/mL.

A Flavonol Glycoside from Smilax glabra

A new flavonol glycoside, named neosmitilbin was isolated form the rhizome of Smilax glabra. Its structure and absolute configuration were elucidated on the basis of spectroscopic studies.

Chemical Components of Helicia nilagirica Beed.I.Structure of Three New Flavonol Glycosides

Three new flavonol glycosides were isolated from the leaves of Helicia nilagirica Beed.. The structures were elucidated as kaempferol-3-O-b-D-xylopyranosyl-(16)-b-D-glyco- pyranosyl-(12)-a-L-rhamnopyranoside, quercetin-3-O-b-D-xylopyranosyl-(16)-b-D-glycopy- ranosyl-(12)-[-b-D-xylopyranosyl-(14)]-a-L-rhamnopyranoside, and quercetin-3-O-b-D- xylopyranosyl-(16)-b-D-glycopyranosyl-(12)-a-L-rhamnopyranoside, named as Helicianeoside A、B and C, respectively.

Persimmon Leaf Flavonols Enhance the Anti-Cancer Effect of Heavy Ion Radiotherapy on Murine Xenograft Tumors

The cell cycle checkpoint system play a pivotal role in the cellular DNA damage response, and the discovery of checkpoint inhibitors is expected to sensitize current cancer therapies. Checkpoint signaling cascades are critically modulated by ATM (ataxia telangiectasia-mutated) and its related molecules. Generally, ATM primarily responds to ionizing irradiation-induced DNA double-strand breaks. Heavy ions from an accelerated carbon ion beam have been used to cure cancer because they are more effective than ionizing irradiation such as X-ray and γ-radiation in terms of biological damage. In a previous study, we demonstrated that a persimmon leaf flavonol (PLF) promoted the cytotoxic effect of chemotherapeutic agents on cancer cells through inhibition of checkpoint activities, especially in the ATM dependent pathway. The present study investigated whether PLF inhibits checkpoint activity during the DNA damage response induced by heavy ion irradiation. Treatment with PLF significantly increased the cytotoxicity of heavy ion irradiation in A549 adenocarcinoma cells. The phosphorylation of checkpoint proteins such as p53, SMC1, and Chk1 was increased by heavy ions. PLF reduced the phosphorylation of checkpoint proteins. Pre-treatment with PLF significantly prevented the decrease of mitotic cells in heavy ion-exposed cells. We further evaluated tumor volume in SCID mice inoculated with human lung adenocarcinoma A549 cells. The combination treatment of PLF and heavy ion resulted in a decrease of tumor volume compared with controls, although PLF itself did not exhibit any effect. These results indicate that PLF inhibits tumor growth through modulation of the DNA damage response. PLF may be useful for clinical application in combination with heavy ion radiotherapy.

Two New Flavonol Glycosides from Bridelia tomentosa

Two new flavonol glycosides, tamarixetin 3-O-β-D-xylopyranosyl-（1-2）-α-L-ribopyranoside （1） and tamarixetin 3-O-α-L-ribopyranoside （2） were isolated from the leaves of Bridelia tomentosa. Their structures were elucidated by 1D and 2D NMR analysis, as well as MS and IR spectra.

New Acetylated Flavonol Glycosides from Knoxia corymbosa

Two new diacetylated flavonol glycosides, kampferol-3-O--3? 6?diacetylglucopyrano- side and quercetin-3-O--3? 6?diacetylglucopyranoside were isolated from knoxia corymbosa. Their structures were elucidated by spectroscopic evidents.

A new benzofuranolignan and a new flavonol derivative from the stem of Morus australis

A new benzofuranolignan austrafuran A （1） and a new flavonol derivative 5,7,2′,4′-tetrahydroxy-3-methoxyflavone （2） were isolated from the stem of Morus australis. Their structures were determined on the basis of spectroscopic evidences.

A New Flavonol Oligosaccharide from the Seeds of Aesculus chinensis

A new flavonol oligosaccharide, quercetin-3-O-[b-D-xylopyranosyl-(12)- a-L-rhamnopyranosyl-(16)]-b-D-glucopyranoside-3-O-b-D-glucopyranoside, named aescuflavoside was isolated from Aesculus chinensis. Its structure was elucidated by spectra FAB-MS, 1D NMR and 2D NMR including 1H NMR, 13C NMR, HMQC and HMBC techniques.

Microwave Assisted-extraction of Flavonols from Acanthopanax Senticosus Harms and High-performance Liquid Chromatography Analysis

Flavonols were extracted from Acanthopanax Senticosus Harms by Soxhlet extraction（SE）,atmospheric pressure microwave-assisted extraction（AMAE） and pressurized microwave-assisted extraction（PMAE）.The influences of experimental conditions,such as concentration of ethanol in the eluent,microwave irradiation time,etc.on the extraction yield were studied.Four flavonols（hyperin,rutin,quercitrin and quercetin） in the extracts were determined quantitatively by HPLC method.The experimental results demonstrate the advantages of PMAE and AMAE over those of conventional SE,that is the extraction time is dramatically reduced,and the yields of flavonols are effective improved.Although the yield of flavonols is higher and the extraction time is shorter by PMAE than those of AMAE,flavonols are easy to be decomposed over a certain time.

New Prenylated flavonol from Hypericum japonicum

One new prenylated flavonol, 7,8-(2'',2'' -dimethylpyrano)-5,3',4'-trihydroxy-3-methoxyflavone was isolated from Hypericum japonicum. The chemical structure was determined by spectroscopic methods.

Two New Flavonol Glycosides from Knoxia corymbosa

Two new flavonol glycosides (1 and 2) together with two known flavonoides (3 and 4), were isolated from the whole plant of Knoxia corymbosa willd. The structures of 1 and 2 were elucidated as kaempferol-7-O-α-L-arabinosyl-3-O-β-D-6'-acetylglucopyranoside and kaempferol -7-O-α-L-arabinosyl-3-O-β-D-3',6'-diacetylglucopyranoside respectively.

Structure of Flavones and Flavonols. Part II: Role of Position on the O-H Bond Dissociation Enthalpy

The enthalpies of bond dissociations of the hydroxyl groups, the energy of the highest occupied molecular orbitals and the corresponding radicals spin densities of all possible ten isomeric mono-hydroxyl flavones are calculated by means of 3-parameter Becke, Lee, Yang and Parr functional. The structural factors affecting these descriptors of radical-scavenging activity are outlined. The results obtained show that the hydroxyl groups in ring A and C are more involved in the process of a radical-capturing than recently believed.

Molecular docking simulation analysis of the interaction of dietary flavonols with heat shock protein 90

Hsp90 is a major protein involved in the stabilization of various proteins in cancer cells.The present investigation focused on the molecular docking simulation studies of flavanols as inhibitors of Hsp90 at the high affinity adenosine triphosphate（ATP）binding site and analyzed absorption,distribution,metabolism,excretion and toxicity（ADME-toxicity）.The molecular docking analysis revealed that the flavanols showed competitive inhibition with ATP molecule at the active site and enhanced pharmacological parameters.

A concise total synthesis of natural flavonols

In this study,we designed a convenient method,to total synthesis of fl avonols especially for C-5 substituted ones and derivatives on a large scale.Beginning from the inexpensively available 2,4,6-trihydroxyacetophenone through Aldol condensation reaction,I2/DMSO cyclization reaction,Oxone“one pot”oxidation,kaempferol(1)and derivative(2)was obtained in an overall yield of 35%.The structures of the target compound and key intermediates were verifi ed by MS,IR,1H-NMR and 13C-NMR techniques,and the structure of 5a was further confi rmed by X-ray diff raction analysis.

The gene encoding flavonol synthase contributes to lesion mimic in wheat

Lesion mimic often exhibits leaf disease-like symptoms even in the absence of pathogen infection,and is characterized by a hypersensitive-response(HR)that closely linked to plant disease resistance.Despite this,only a few lesion mimic genes have been identified in wheat.In this investigation,a lesion mimic wheat mutant named je0297 was discovered,showing no alteration in yield components when compared to the wild type(WT).Segregation ratio analysis of the F_(2)individuals resulting from the cross between the WT and the mutant revealed that the lesion mimic was governed by a single recessive gene in je0297.Using Bulked segregant analysis(BSA)and exome capture sequencing,we mapped the lesion mimic gene designated as lm6 to chromosome 6BL.Further gene fine mapping using 3315 F_(2)individuals delimited the lm6 within a 1.18 Mb region.Within this region,we identified 16 high-confidence genes,with only two displaying mutations in je0297.Notably,one of the two genes,responsible for encoding flavonol synthase,exhibited altered expression levels.Subsequent phenotype analysis of TILLING mutants confirmed that the gene encoding flavonol synthase was indeed the causal gene for lm6.Transcriptome sequencing analysis revealed that the DEGs between the WT and mutant were significantly enriched in KEGG pathways related to flavonoid biosynthesis,including flavone and flavonol biosynthesis,isoflavonoid biosynthesis,and flavonoid biosynthesis pathways.Furthermore,more than 30 pathogen infection-related(PR)genes exhibited upregulation in the mutant.Corresponding to this expression pattern,the flavonoid content in je0297 showed a significant decrease in the 4^(th)leaf,accompanied by a notable accumulation of reactive oxygen,which likely contributed to the development of lesion mimic in the mutant.This investigation enhances our comprehension of cell death signaling pathways and provides a valuable gene resource for the breeding of disease-resistant wheat.

蓝星睡莲花瓣类黄酮分析及花色形成关键基因鉴定

为明确蓝星睡莲(Nymphaea colorata)蓝色、白色两种花色花瓣在不同发育时期的类黄酮物质含量、成分及其代谢途径中的关键基因,本研究采用高效液相色谱法(HPLC)和超高效液相色谱-串联四极杆飞行时间高分辨质谱(UPLC-Triple TOF-MS/MS)技术,分析了蓝星睡莲5个发育时期花瓣的花青苷和黄酮醇苷含量和成分.结果表明,蓝、白花瓣中类黄酮含量差异明显,白花花瓣花青苷和黄酮醇苷含量均保持在较低水平,尤其是在S4,S5时期与蓝花达到了显著性差异,可能是造成蓝白花色差异的物质成因.在蓝星睡莲花瓣中,两种花色花瓣类黄酮成分相同,共鉴定出3种花青苷和11种黄酮醇苷.花青苷为飞燕草素-3-O-β-半乳糖苷、飞燕草素-3-O-(2″-O-没食子酰-6″-O-乙酰-β-半乳糖苷)和飞燕草素-3′-O-(2″-O-没食子酰-6″-O-乙酰-β-半乳糖苷);黄酮醇苷主要有槲皮素3-O-半乳糖苷、杨梅素3-O-α-L-(3″-O-丙二酰)-鼠李糖苷、杨梅素3-O-α-L-鼠李糖甘、杨梅素3-O-α-L-(3″-O-乙酰)-鼠李糖苷、槲皮素3-O-α-L-(3″-O-丙二酰)-鼠李糖苷等.通过实时荧光定量PCR(RT-qPCR)技术进一步分析了类黄酮代谢途径相关基因在两种花色花瓣中的转录表达情况,结果表明,在蓝花花瓣5个发育时期,类黄酮3′5′-羟化酶基因(F3′5′H)、黄酮醇合成酶基因(FLS)、二氢黄酮醇4-还原酶基因(DFR)的转录表达变化与花青苷积累趋势一致,推测其可能是蓝色花瓣花青苷积累的关键结构基因;F3′5′H和糖基转移酶基因(GT)在蓝花中的表达量均明显高于白花,推测其是造成蓝白花色差异的重要基因.本研究为进一步解析蓝星睡莲花色形成分子机理提供了新的证据,为睡莲蓝色花分子育种提供了参考.

银杏雌、雄植株叶片药用成分含量及转录组差异分析

【目的】探究雌、雄银杏叶片中萜内酯和黄酮醇苷及其主要组分的含量差异及基因在转录水平上的差异。【方法】选取雌、雄银杏各10株,以叶片为试验材料,运用液相色谱-质谱联用技术(LC-MS)、高效液相色谱-紫外检测法(HPLC-UV),分别测定萜内酯、黄酮醇苷含量,并选取萜内酯和黄酮醇苷含量具有代表性的3个雌株和3个雄株进行转录组测序。【结果】雌株中萜内酯及其主要组分含量均略高于雄株,但差异不显著;黄酮醇苷及其主要组分含量均高于雄株,但各组分中仅槲皮素含量差异显著(P=0.045)。转录组测序共得到288 023 696条Raw reads,257 059 884条Clean reads,Q30≥91.24%,GC含量≥45.95%,唯一比对率≥85.04%。共鉴定(P <0.05且|log2FC|≥1)出676个差异表达基因,与雌株相比,雄株有340个差异表达基因上调表达,336个差异表达基因下调表达。GO富集分析显示有372个差异表达基因显著富集到氧化还原过程、碳水化合物代谢过程、解毒、催化活性等163个GO条目中。KEGG富集分析表明差异表达基因主要与植物激素信号转导、植物-病原互作、其他聚糖降解、类固醇生物合成等代谢通路有关。银杏萜内酯和黄酮醇合成通路上相关结构基因的表达在雌株中均高于雄株,与雌株中萜内酯、黄酮醇苷含量高于雄株的趋势相一致。【结论】不同性别银杏叶片中萜内酯和黄酮醇苷含量及生物合成途径相关基因的表达量均有差异,雌株略高于雄株。研究为基于不同性别的叶用银杏优良种质的筛选和培育提供了一定的理论基础。