Lack of chemical factors in host-plant resistance of alfalfa towards alfalfa weevil: Ovicidal activity of some coumarin derivatives

A resistant line of alfalfa was studied in an attempt to identify possible chemical factors responsible for alfalfa weevil (Hypera brunneipennis) resistance. Bioassays were developed to measure ovicidal, larval development, pupation, and adult development rates. Serial alfalfa extracts of a weevil-resistant line showed no effect in the bioassays when compared to those of a weevil-susceptible line. It was concluded that resistance substances are not present but that resistant lines are simply more tolerant to weevil attack. Alfalfa constitutents and synthetic analogs were also screened in the egg hatch bioassay. Among these were a series of 3-acyl-4-hydroxycoumarins. 3-Acyl-4-hydroxycoumarins with short-chain acyl groups showed good ovicidal rates, but activity decreased with increasing length of the acyl group.     

Potential allelochemicals fromRuta graveolens L. and their action on radish seeds

An aqueous extract ofRuta graveolens L. (250 g/liter) was tested for its allelopathic activity in vitro on radish germination and radicle growth in light and darkness. It caused a delay in the onset and a decrease in the rate of germination (40%) in the light. The photoinhibition of germination was accompanied by an inhibition of water uptake into the seed. Furthermore, the inhibition of radicle growth was slightly higher in the light than in darkness. Three potential allelochemicals, biologically active in the light, were isolated from the extract: 5-methoxypsoralen (5-MOP), 8-methoxypsoralen (8-MOP), and 4-hydroxy-coumarin at concentrations of 10^–4 M, 2×10^–4 M, and 0.4 ×10^–5 M respectively. At a concentration of 2×10^–4 M, 5-MOP was the most potent inhibitor, decreasing radish germination to 32% and radicle growth to 17% with respect to control. Microscopic observations of radish seeds treated with 5-MOP suggest that this substance changes the swelling of the seed coat and aleurone layer, which precedes radicle protrusion.     

Comparative Antiseizure Analysis of Diverse Natural Coumarin Derivatives in Zebrafish

Coumarins are a well-known group of plant secondary metabolites with various pharmacological activities, including antiseizure activity. In the search for new antiseizure drugs (ASDs) to treat epilepsy, it is yet unclear which types of coumarins are particularly interesting as a systematic analysis has not been reported. The current study performed behavioral antiseizure activity screening of 18 different coumarin derivatives in the larval zebrafish pentylenetetrazole (PTZ) model using locomotor measurements. Activity was confirmed for seven compounds, which lowered seizure-like behavior as follows: oxypeucedanin 38%, oxypeucedanin hydrate 74%, notopterol 54%, nodakenetin 29%, hyuganin C 35%, daphnoretin 65%, and pimpinellin 60%. These coumarins, together with nodakenin, underwent further antiepileptiform analysis by local field potential recordings from the zebrafish opticum tectum (midbrain). All of them, except for nodakenetin, showed pronounced antiepileptiform activity, decreasing PTZ-induced elevation in power spectral density (PSD) by 83–89% for oxypeucedanin, oxypeucedanin hydrate, and notopterol, 77% for nodakenin, 26% for nodakenetin, 65% for hyuganin C, 88% for daphnoretin, and 81% for pimpinellin. These data demonstrate the potential of diverse coumarin scaffolds for ASD discovery. Finally, the structural differences between active and inactive coumarins were investigated in silico for oxypeucedanin hydrate and byacangelicin for their interaction with GABA-transaminase, a hypothetical target.     

Cytotoxicity of new Ho(Ⅲ) and Pr(Ⅲ) complexes

New complexes of coumarin-3-carboxylic acid(HCCA) with Ho(Ⅲ) and Pr(Ⅲ) were synthesized and their structures and spectral properties were investigated by elemental analysis,IR,Raman and NMR measurements.According to the experimental data the complexes’ formula and geometries were suggested.Vibrational frequencies,IR intensities and Raman activities as well as 1H NMR chemical shifts of HCCA and its Ho(Ⅲ) and Pr(Ⅲ) complexes were presented.The comparative experimental vibrational and NMR analyses of both the ligand and the Ln(Ⅲ) complexes predicted the bidentate binding to Ho(Ⅲ) and Pr(Ⅲ) through the deprotonated carboxylic oxygen and the carbonylic oxygen of the ligand.The cytotoxic/cytostatic properties of the ligand and the newly synthesized complexes of coumarin-3-carboxylic acid with Ho(Ⅲ) and Pr(Ⅲ) were tested by MTT reduction assay against two mouse tumor cell lines:melanoma B16 and fibrosarcoma L929.They were also tested for cytotoxicity against normal mouse peritoneal macrophages.The proliferation inhibitory effect of the complexes compared to that of the ligand proved their cytotoxic/cytostatic properties against both the tumor cell lines.In addition,the complexes were less cytotoxic against normal mouse macrophages and were able to modulate NO release by activated macrophages.The obtained results were in accordance with our previously published data concerning the activity of lanthanide(Ⅲ) complexes with other coumarin derivatives.     

香豆素酰胺荧光探针的合成及金属离子识别性能研究

以间氨基酚为原料,通过五步反应合成了两个香豆素酰胺荧光探针：N-（2-羟乙基）-2-（（4-甲基-2-氧代-2H-苯并吡喃-7-基）氨基）乙酰胺（C1）和Ⅳ-（3-羟丙基）-2-（（4-甲基-2-氧代-2H-苯并吡喃-7-基）氨基）乙酰胺（C2）,以’HNMR,13CNMR和质谱对所化合物的结构进行表征。在乙腈中,该类探针对Fe^3＋和Cu^2＋有淬灭作用,其中C2对Cu^2＋具有较高的选择性。     

Green Synthesis of Novel Class of Azo Dyes Based on Naphthols,Coumarins, and Phenols with Molybdate Sulfuric Acid

A new series of polycyclic aromatic azo dyes based on naphthols, coumarins, and phenols were efficiently synthesized by the diazotization of 7-amino coumarins in the presence of catalytic amounts of molybdate sulfuric acid (MSA) followed by coupling reactions. The diazotization and subsequent azo-coupling generated the related azo dyes at 0–5°C in short reaction times with a simple experimental procedure.     

Allelochemicals fromPilocarpus goudotianus leaves

The effect on germination, shoot, and root growth by bergapten, xanthotoxin, imperatorin, xanthyletin, xanthoxyletin, luvangetin, donatin and alloxanthoxyletol fromPilocarpus goudotianus leaves, onLactuca sativa var. nigra seedlings has been evaluated. A structure-activity correlation is discussed based on the bioassay results. Furanocoumarins appear to be the most active compounds in comparison with pyrano- and simple coumarins. The presence of an oxygenated function at C-8 decreases the germination effect in furano- and pyranocoumarins, while C-5 substituents do not cause significant changes on the activity.Part 2 in the series:Natural Product Models as Allelochemicals. For Part 1 see: Macíaset al. (1992).     

Regioselective Cleavage of Unstrained C?C Bond and C?H Bond: Palladium–Copper Catalyzed Deacetophenonylative Arylation of Coumarin Derivatives

A C_α C_β bond activation of the carbonyl group in unstrained ketones catalyzed cooperatively by palladium and copper(II) with the departure of the acetophenone has been developed, and the subsequent coupling with a variety of aromatics via the formal C H activation similar to the Friedel–Crafts reaction affords the skeleton‐reconstructed coumarin derivatives with high regioselectivity.     

HPLC-DAD-FLD同时测定柑橘果汁中12种多甲氧基黄酮和香豆素类物质

建立高效液相色谱-串联二极管阵列检测器和荧光检测器(high performance liquid chromatography-diode array detector-fluorescence detector,HPLC-DAD-FLD)同时检测柑橘果汁中12种多甲氧基黄酮、香豆素及呋喃香豆素类物质的方法。以0.01%磷酸、甲醇、乙腈组成三元流动相进行梯度洗脱,12种物质在30 min内实现基线分离。利用DAD和FLD获得各物质的紫外和荧光光谱信息,将柑橘果汁样品组分的光谱与之比对,并结合色谱保留时间,实现样品成分的定性分析。分别以320 nm和450 nm为紫外和荧光的检测波长,研究该方法的定量性能。结果显示:标准曲线线性关系良好;荧光定量限低至μg/L级,可作为紫外定量的重要补充手段;果汁回收率的紫外和荧光检测值分别为95.2%~104.8%和94.5%~103.5%。该方法对样品定性、定量分析准确,适合柑橘多甲氧基黄酮、香豆素等能发射荧光物质的检测。