Armenin and isoarmenin--two prenylated coumarins from the aerial parts of Artemisia armeniaca.

The reversed-phase (RP) preparative HPLC analyses of the MeOH extract of the aerial parts of Artemisia armeniaca yielded four prenylated coumarins, 7-hydroxy-8-(4-hydroxy-3-methylbutoxy)coumarin (named armenin), 8-hydroxy-7-(4-hydroxy-3-methylbutoxy)coumarin (named isoarmenin), lacarol, and deoxylacarol, together with five other compounds, including three flavonoid glycosides, quercetin 3-O-ß-D-glucopyranoside, rutin, and kaempferol 3-O-ß-D-glucopyranoside, and chlorogenic acid, and tryptophan. (10E,12Z)-9-Hydroxyoctadeca-10,12-dienoic acid (ß-dimorphecolic acid) was isolated from the CH(2)Cl(2) extract. Armenin and isoarmenin were new coumarins. Structures of all compounds were determined by spectroscopic means, including UV, MS, 1D- and 2D-NMR. The in vitro free-radical-scavenging property of the extracts and isolated compounds was evaluated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay.

Coumarins from the aerial parts of Prangos uloptera (Apiaceae) / Cumarinas das partes aéreas de Prangos uloptera (Apiaceae)

Phytochemical studies on the aerial parts of Prangos uloptera, an endemic Iranian species of the genus Prangos, yielded five coumarins, xanthotoxin (1), prangenin (2), scopoletin (3), deltoin (4) and prangolarin (5). The structures of these coumarins were elucidated by spectroscopic means, and the antioxidant potential of 1-5 was evaluated by the DPPH assay. The chemotaxonomic significance of 1-5 is also discussed.

Os estudos fitoquímicos das partes aéreas de Prangos uloptera, uma espécie do gênero Prangos endêmica do Irã, forneceram cinco cumarinas, xantotoxina (1), prangenina (2), escopoletina (3), deltoína (4) e prangolarina (5). As estruturas destas cumarinas foram elucidas através de métodos espectroscópicos e o potencial antioxidante de 1-5 foi avaliado pelo ensaio de DPPH. O significado quimiotaxonômico de 1-5 também é discutido.

Microtitre plate-based antibacterial assay incorporating resazurin as an indicator of cell growth, and its application in the in vitro antibacterial screening of phytochemicals.

The resazurin assay utilising microtitre-plate, described by Drummond and Waigh in 2000, has been modified to achieve more accuracy in the determination of the minimum inhibitory concentration (MIC) values of natural products, including crude extracts, chromatographic fractions or purified compounds against various bacterial strains. This modified resazurin method is simple, sensitive, rapid, robust and reliable, and could be used successfully to assess antibacterial properties of natural products.

Screening seeds of some Scottish plants for free radical scavenging activity.

From a consideration of ethnobotanical and taxonomic information, seeds of 45 Scottish plant species encompassing 23 different families were obtained from authentic seed suppliers. The n-hexane, dichloromethane (DCM) and methanol (MeOH) extracts were assessed, both qualitatively and quantitatively, for free radical scavenging activity in the DPPH assay. The MeOH extracts of 37 species exhibited low to high levels of free radical scavenging activity (RC50 values ranging from 2.00 to 4.7 x 10(-4) mg/mL), and Alliaria petiolata, Prunus padus and Prunus spinosa were the most potent antioxidant extracts. The DCM extracts of 17 species showed similar levels of activity, and among those, Prunus padus and Prunus spinosa extracts were the most active with RC50 values of 2.5 x 10(-4) and 5.0 x 10(-4) mg/mL, respectively. The n-hexane extracts were much less active than the MeOH and DCM extracts, and 17 species, with the exception of Glechoma hederacea (RC50 = 1.94 x 10(-4)) displayed low to moderate levels of free radical scavenging property (RC50 values ranging from 2.00 to 8.7 x 10(-3) mg/mL).

Americanin, a bioactive dibenzylbutyrolactone lignan, from the seeds of Centaurea americana.

The reversed-phase preparative HPLC analysis of the methanol (MeOH) extract of the seeds of Centaurea americana afforded a dibenzylbutyrolactone lignan, 3''-O-caffeoyl arctiin (named americanin), together with five known lignans, arctiin, arctigenin, matairesinol, matairesinoside and lappaol A, and two known phytoecdysteroids, 20-hydroxyecdysone and makisterone A. While the structures of the known compounds were determined by direct comparison of the spectral data with published data, the structure of americanin was elucidated by UV, MS and a combination of 1D and 2D NMR spectral analyses. The antioxidant properties and toxicity of the extracts and the isolated compounds were determined by the DPPH and the brine shrimp lethality assays, respectively.

Eremostachiin: a new furanolabdane diterpene glycoside from Eremostachys glabra.

The reversed-phase preparative HPLC analysis of the methanol extract of the rhizomes of Eremostachys glabra (Lamiaceae) led to the isolation of two furanolabdane diterpene glycosides, phlomisoside II, and beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl ester of phlomisoic acid (named eremostachiin), the latter being a novel natural product. The structure of the new compound has been elucidated unambiguously by HRMS and a series of 1D- and 2D-NMR spectroscopic techniques. The free radical scavenging activity of these compounds was assessed using the DPPH assay.

The assessment of biological activities associated with the major constituents of the methanol extract of 'wild carrot' (Daucus carota L) seeds.

Daucus carota L. (Family: Apiaceae alt. Umbelliferae), commonly known as 'wild carrot' or 'Queen Anne's-lace,' is an ecologically invasive erect biennial naturalized to Scotland. The ethnobotanical uses of this species include applications in the treatment of cough, diarrhea, dysentery, cancer, malaria and tumors, and as an antiseptic, abortifacient, aphrodisiac, carminative, stimulant, stomachic and tonic. The major constituents isolated from the methanol extract of D. carota seeds by reversed-phase preparative high performance chromatography were luteolin, luteolin 3'-O-beta-D-glucopyranoside and luteolin 4'-O-beta-D-glucopyranoside, three flavones. The constituents were assessed for their antibacterial and free radical scavenging activities, as well as toxicity towards brine shrimp. Among these three flavones, luteolin showed the highest degree of free radical scavenging activity (RC50 = 4.3 x 10(-4) mg/mL) in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Both luteolin and its 4'-O-glucoside demonstrated bactericidal activity against Staphylococcus aureus and Escherichia coli (Minimum Inhibitory Concentration [MIC] = 5.0 x 10(-2) - 1.0 x 10(-1) mg/mL). Luteolin also demonstrated antibactericidal activity against Bacillus cereus and Citrobacter freundii (MIC = 5.0 x 10(-2) mg/mL). Luteolin 3'-O-glucoside showed bactericidal activity against Bacillus cereus and Lactobacillus plantarum (MIC = 2.5 x 10(-1) mg/mL and 5 x 10(-1) mg/ mL, respectively). In the brine shrimp lethality assay, the LD50 value of luteolin was 5.3 x 10(-2) mg/mL, and that of its 3'-O-glucoside and 4'-O-glucoside were > 1.0 mg/mL.

Iridoid glycosides from Eremostachys glabra.

Reversed-phase preparative HPLC of a methanol extract of the rhizomes of Eremostachys glabra yielded three new iridoid glycosides, namely, 6,9-epi-8-O-acetylshanziside methyl ester, 5,9-epi-penstemoside, and 5,9-epi-7,8-didehydropenstemoside. Their structures were elucidated on the basis of spectroscopic data interpretation. The free-radical scavenging activity of these compounds was assessed using the DPPH assay.

2D NMR spectroscopic analyses of archangelicin from the seeds of Angelica archangelica.

A total of six coumarins, bergapten (1), xanthotoxin (2), imperatorin (3), isoimperatorin (4), phellopterin (5) and archangelicin (6), have been isolated from an n-hexane extract of the seeds of Angelica archangelica. The results of comprehensive 2D NMR analyses of archangelicin are discussed.

A mixed crystal of imperatorin and phellopterin, with C--H...O, C--H...pi and pi-pi interactions.

The crystal structure of 9-(3-methylbut-2-enyloxy)-7H-furo[3,2-g]chromen-7-one-4-methoxy-9-(3-methylbut-2-enyloxy)-7H-furo[3,2-g]chromen-7-one (0.926/0.074), 0.926C(16)H(14)O(4)*- x 0.074C(17)H(16)O(5), is characterized by two independent imperatorin molecules in the asymmetric unit, which exhibit different side-chain conformations. A small amount of phellopterin overlaps with one of the two imperatorin molecules. The supramolecular structure is supported by C--H...O, C--H...pi and pi-pi interactions.

Screening seeds of Scottish plants for antibacterial activity.

Based on ethnopharmacological and taxonomic information, seeds of 21 Scottish plant species from 14 different families were obtained from authentic seed suppliers. Their n-hexane, dichloromethane and methanol extracts were assessed for antibacterial activity against 11 pathogenic bacterial species. Methanol extracts of 11 plant species showed significant antibacterial activity. Malva moschata and Prunus padus were active against five bacterial species, Reseda lutea against four, Centaurium erythraea and Crithmum maritimum against three, Calluna vulgaris against two, and Armeria maritima, Centaurea scabiosa, Daucus carota, Rosa canina and Stellaria holostea against one bacterial species. C. erythraea and P. padus were also active against methicillin resistant Staphylococcus aureus.