Constituents from Clausena excavata

Three new coumarins containing a C(10) terpenoid side chain, clauslactones R - T (1 - 3), together with 14 known coumarins (4 - 17) and 11 known carbazole alkaloids (18 - 28), were isolated from the leaves and stems of Clausena excavata. Their structures were established by detailed spectroscopic analyses. Furthermore, the stereochemistry of 1 was confirmed by single-crystal X-ray diffraction analysis, which was the first example among coumarins with a C(10) terpenoid side chain. Additionally, compounds 22 and 27 were found to show moderate topoisomerase II inhibitory effects at 50 microM.     

Interaction of coumarin derivatives with human serum albumin: investigation by fluorescence spectroscopic technique and modeling studies

Interactions of several 7-aminocoumarins with human serum albumin (HSA) were studied by using fluorescence spectroscopic technique and modeling studies. There is a large change in fluorescence spectral parameters like intensity, emission maxima and anisotropy for all aminocoumarins. There were two binding sites for cou-1, 311 and a single binding site for other coumarins. The binding constant(s) are large for all coumarins reflective of a strong binding. These spectral studies show that structural variants at the third, fourth and seventh position affects binding. The probable location of these coumarins in domain II has been predicted based on modeling. The effect of structural modification on the efficiency of binding was obtained for various other coumarins, using modeling.     

Chemical constituents of Micromelum minutum. Isolation and structural elucidation of new coumarins

The chemical constituents of an acetone extract of the stems of Micromelum minutum Wight et Arn (Rutaceae), collected at Nakorn-Rachasima province in Thailand, were studied. Six new coumarins, named micromarin-A (1), -B (2), -C (3), -F (4), -G (5), and -H (6), were isolated along with six known coumarins, and their structures were elucidated by chemical and spectroscopic methods.     

New monoterpenoid coumarins from Clausena anisum-olens

Two new monoterpenoid coumarins: anisucumarin A (1) and B (2), a pair of epimers, were isolated from Clausena anisum-olens. Their structures were established based on extensive spectroscopic analyses.     

Two new coumarins from Micromelum falcatum with cytotoxicity and brine shrimp larvae toxicity

Two new coumarins, 7-methoxy-8-(2-hydroxmethyl-1-O-isovaleryl-4-butenyl)-coumarin (1) and 7-methoxy-8-(1-hydroxy-2-O-β-glucopyranosyl-3-methyl-4-butene-1-yl)coumarin (2), and twelve known coumarins 3-14 were isolated from the stem bark of Micromelum falcatum. The structures of compounds 1-14 were elucidated by extensive spectroscopic data analyses. The toxicity of compounds 1-14 was tested using a brine shrimp assay and in vitro antiproliferative assay against mammary cancer (F10) and lung cancer (HvEvc) cell lines by the MTT method. Some compounds had moderate activities. All compounds were also tested against the microorganisms Bacillus subtilis, Bacillus thuringiensis and Escherichia coli, but no activity was observed.     

Recyclization of 2-iminocoumarins using nucleophilic reagents. 6. Reaction of 2-iminocoumarin-3-carboxamides with 2-aminobenzophenones

It has been shown that the reaction of 2-iminocoumarin-3-carboxamides with substituted 2-aminobenzophenones occurs in accordance with recyclization mechanism to form substituted 3-(4-phenylquinazolin-2-yl)coumarins. The structure of the compounds obtained was confirmed by spectroscopic data and by X-ray analysis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1533–1542, October, 2004.     

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.     

Kallisteine A and B, two new coumarins from the roots of Peucedanum paniculatum L, a species endemic to Corsica

From the dichloromethane extract of the roots of Peucedanum paniculatum L., two new coumarins, a species endemic to Corsica, have been isolated. Their structures were elucidated, on the basis of spectroscopic studies, particularly 1D and 2D NMR spectroscopy, as 6-(7'-beta-cyclolavandulyl)-7-hydroxycoumarin 1 and a spirodihydrofurano-coumarin 2 (Kallisteine A and B).     

Two new dimeric coumarins isolated from Murraya exotica

Bismurrangatin and murramarin A, two new coumarins, were isolated from the vegetative branches of Murraya exotica. Murramarin A is a rare type of bicoumarin that connects two coumarin moieties by orthoester structure. The structures were elucidated based on spectroscopic methods, especially by 2D-NMR experiments.     

Synthesis and structural revision of naturally occurring ayapin derivatives

The synthesis of three highly oxygenated naturally occurring coumarins, 8-methoxy-6,7-methylenedioxycoumarin, 5-methoxy-6,7-methylenedioxycoumarin and 5,8-dimethoxy-6,7-methylenedioxycoumarin is described for the first time, together with a new method for the preparation of ayapin (6,7-methylenedioxycoumarin). Comparison of the spectroscopic data of the synthetic tetraoxygenated coumarin 5,8-dimethoxy-6,7-methylenedioxycoumarin with literature reports resulted in the structural revision of several natural coumarins. Two coumarins, both identified as 5,8-dimethoxy-6,7-methylenedioxycoumarin must have other structures, while the structure of another coumarin, described as the isomeric 7,8-dimethoxy-5,6-methylenedioxycoumarin has to be revised to 5,8-dimethoxy-6,7-methylenedioxycoumarin.     

Synthesis of the reported structure of crassiflorone, a naturally occurring quinone isolated from the African ebony Diospyros crassiflora, and regioisomeric pentacyclic furocoumarin naphthoquinones

A synthesis of the structure reported for the natural product crassiflorone, a furocoumarin naphthoquinone, is described. The key steps are a Diels-Alder reaction to form 2-bromo-8-hydroxy-6-methylnaphthoquinone, followed by O-protection and copper(II) mediated coupling to 4-hydroxy-5-methylcoumarin to establish the pentacyclic framework whose structure was unambiguously confirmed by X-ray crystallography. Since the spectroscopic data of the synthetic material did not match those reported for the natural product, three further regioisomeric furocoumarin naphthoquinones were prepared by copper(II) mediated coupling of 4-hydroxy-5- or 8-methyl coumarins with 5-benzyloxy-2-bromo-7-methyl- or 8-benzyloxy-2-bromo-6-methyl-1,4-naphthoquinone. Again the spectroscopic data did not match those of the natural material and therefore the true structure of crassiflorone remains unknown.     

Phebaclavin I, a novel 3-prenylated coumarin, and trichoclin acetate, a new natural furocoumarin, from the aerial parts of Phebalium aff. tuberculosum (Rutaceae)

Phebaclavin I, a novel 3-prenylated coumarin, was isolated from the aerial parts of Phebalium aff. tuberculosum (Rutaceae) together with five known related compounds, Phebaclavin A, B, D, G, H. The structure of phebaclavin I was established by spectroscopic methods. Several other known coumarins were obtained, including trichoclin acetate, a furocoumarin isolated for the first time from a natural source, but previously described from acetylation of trichoclin.     

Furanocoumarins and Sesquiterpene Ketone from Clausena Lansium Skeels

Three known furanocoumarins, imperatorin (1), wampetin (dehydroindicolactone) (2) and 8-geranoxypsoralen (3) and a new sesquiterpene ketone, (+)-oplopanone (4), were isolated from Clausena lansium Skeels. The stereochemistry of the last two coumarins was determined by NOESY experiments. The idendity of (+)-oplopanone was established by comparison of its physical constants and spectroscopic data with those reported for its enantiomer as well as a comparison of its' TLC behavior with that of an authentic sample.     

Constituents of Gardenia volkensii: their brine shrimp lethality and DPPH radical scavenging properties

The seeds and the pulp of Gardenia volkensii yielded one new iridiod, namely 4-(2N-gardenamide)n-butanoic acid, together with the known iridoids genipin and genipin gentiobioside, the pterocarpin medicarpin, coumarins, phenylpropanoids, benzenoids and triterpenes. The structures of these were determined on the basis of spectroscopic data and by comparison of obtained data with those from literature. The fruit extracts of this plant exhibited moderate radical scavenging activity against DPPH radical and moderate lethality against brine shrimps (Artemia salina).     

A novel homosesquiterpenoid from the stems of Cinnamomum burmanii

A novel homosesquiterpenoid, burmanol (1), along with 16 known compounds, including one triterpenoid, one quinol, two chlorophylls, two coumarins, two steroids, three lignans and five benzenoids were obtained from the stems of Cinnamomum burmanii (Lauraceae). The structures of these compounds were determined on the basis of spectroscopic analysis.     

Sesquiterpene coumarins from the roots of Ferula sinkiangensis and Ferula teterrima

Three new natural sesquiterpene coumarins, isofeterin (1), lehmannolol (3), sinkianone (4), and one known compound, lehmannolone (2), were isolated from the roots of Ferula teterrima and Ferula sinkiangensis. Their chemical structures were established on the basis of spectroscopic analysis, including X-ray crystallography and CD spectrum measurements for determining the absolute configuration of compound 2.     

Effective staining of tumor cells by coumarin-6 depends on the stoichiometry of cyclodextrin complex formation

In a comprehensive picture of inclusion complex formation of the highly fluorescent dye coumarin-6 (C6) and betacyclodextrin (beta-CD), which was obtained using various fluorescence spectroscopic methods, it was demonstrated that up to three beta-CD rings can thread on the rod like dye molecule. Interaction of coumarins and modified coumarins with cellular organelles or proteins has been reported in several publications. Especially 7-amino-coumarins are characterized by unique properties like high fluorescence quantum yield and are thus already used successfully in different areas, like staining of fluorescent nanoparticles. We could show that Coumarin-6 made soluble by complexation with beta-cyclodextrin is able to stain eukaryotic cells specifically dependent on their origin and cellular behaviour. The staining reaction is independent from pH, is photo stable, and shows no cross talk with proteins in the cytoplasm and other staining procedures or erythrocytes. Staining with coumarin 6/cyclodextrin complexes can thus be used for fast discrimination of different cell types. Importantly, it could be shown that the ideal staining reaction is dependent on the stoichiometry of the complex-formation.     

New Coumarins and Triterpenes from Calophyllum inophyllum

Four new coumarins, 1 – 4 , and two new triterpenes, 5 and 6 , along with nine known compounds have been identified from the leaves of Calophyllum inophyllum on the basis of spectroscopic analyses and chemical methods. The structure of apetalolide ( 7 ), previously reported from C. apetalum, was revised by means of 2D‐NMR, and the absolute configuration of the known compound inophyllum D ( 8 ) was established by a modified Mosher's method.     

A novel neolignan, mansoxetane, and two new sesquiterpenes, mansonones R and S, from Mansonia gagei

Three new compounds, mansoxetane; 4′-(3-hydroxy-1,2-oxetanyl)-2′,2-dihydroxy-4-(2-formyl-1-ethyl)-6′,6-dimethoxy biphenyl, and mansonones R and S, together with two previously reported coumarins, mansorins A and C, and four known mansonones, mansonones C, E, G and H, were obtained from the methanolic extract of the heartwood from Mansonia gagei Drumm. Their structures were established by spectroscopic methods.     

Constituents from the leaves of Phellodendron amurense and their antioxidant activity

Three new coumarins, phellodenols F-H (1-3) and a new glutaric acid derivative, phellodendric acid-A (4) were isolated from the leaves of Phellodendron amurense together with twenty-nine known compounds. Extensive 1D and 2D NMR experiments and other spectroscopic studies were employed to determine the structures of 1-4. The isolated compounds were screened for their antioxidant activity through DPPH (alpha,alpha-diphenyl-beta-picrylhydrazyl) radical scavenging assay. Compounds quercetin, quercetin-3-O-beta-D-glucoside, quercetin-3-O-beta-D-galactoside and kaempferol-3-O-beta-D-glucoside demonstrated significant radical scavenging activity comparable to vitamin E.