[Show abstract][Hide abstract] ABSTRACT: An EtOAc extract from the roots of Sophora flavescens (Kushen) potentiated γ-aminobutyric acid (GABA)-induced chloride influx in Xenopus oocytes transiently expressing GABAA receptors with subunit composition, α
2S. HPLC-based activity profiling of the extract led to the identification of 8-lavandulyl flavonoids, kushenol I, sophoraflavanone G, (−)-kurarinone, and kuraridine as GABAA receptor modulators. In addition, a series of inactive structurally related flavonoids were characterized. Among these, kushenol Y (4) was identified as a new natural product. The 8-lavandulyl flavonoids are first representatives of a novel scaffold for the target.
Full-text · Article · May 2011 · Molecular Diversity
[Show abstract][Hide abstract] ABSTRACT: Two new saponins, 3-O-[β-D-xylopyranosyl-(13)-β-D-galactopyranosyl-(13)-β-glucuronopyranosyl]oleanolic acid 28-O-β-D-glucopyranosyl ester (1) and the corresponding monodesmoside, 3-O-[β-D-xylopyranosyl-(13)-β-D-galactopyranosyl-(13)-β-glucuronopyranosyl]oleanolic acid (2), have been isolated from the leaves of Guapira graciliflora (Nyctaginaceae), together with two further oleanane saponins, 3 and 4, daucosterol (5), and two known glycerogalactolipids, 6 and 7. The structures of the new compounds were established by extensive NMR and MS experiments, in conjunction with acid hydrolysis and sugar analysis. This is the first report on the phytochemistry of plants of the genus Guapira.
Full-text · Article · Jun 2010 · Helvetica Chimica Acta
[Show abstract][Hide abstract] ABSTRACT: In a screen of 880 extracts from plants and fungi for antiplasmodial, antitrypanosomal, and leishmanicidal activity, an ethyl acetate extract of the mushroom Ganoderma lucidum showed antiplasmodial activity with 79% inhibition at 4.9 microg/mL. HPLC-based activity profiling and subsequent isolation of the antiplasmodial compounds yielded seven lanostanes (1-7), of which three (2, 3, and 7) were new. A new benzofuran derivative (8) of the farnesyl hydroquinone ganomycin B was also identified. The structures and relative configurations of the new compounds were elucidated by comprehensive spectroscopic analysis and by comparison of their NMR data with those of related compounds. The lanostanes exhibited in vitro antiplasmodial activity with IC(50) values from 6 to greater than 20 microM.
[Show abstract][Hide abstract] ABSTRACT: A new dihydroisocoumarin was isolated from a dichloromethane extract of Haloxylon scoparium with the aid of a functional assay with Xenopus oocytes transiently expressing GABA(A) receptors of defined subunit composition (alpha(1)beta(2)gamma(2S)). Compound 1 induced a maximum potentiation of the chloride currents by 144.6 +/- 35.3% with an EC(50) of 140.2 +/- 51.2 muM.
No preview · Article · Mar 2010 · Journal of Natural Products
[Show abstract][Hide abstract] ABSTRACT: In the course of a medium throughput screen of 640 plant extracts for antimalarial activity an ethyl acetate extract of Pistacia atlantica DC. (Anacardiaceae) was found to be active. With analytical scale time-based HPLC separation and testing for antiplasmodial activity in combination with hyphenated methods (HPLC-PDA, -MSn, HR-MS, off line microprobe NMR) the active substance was identified. Subsequent isolation and structure elucidation yielded flavone 3-methoxycarpachromene. It had an IC50 of 3.4 mu M towards Plasmodium falciparum K1 strain.
Full-text · Article · Nov 2009 · Phytochemistry Letters
[Show abstract][Hide abstract] ABSTRACT: Two gamma-Proteobacteria strains, that is, HP1 and HP9, which both produce a diffusible deep blue pigment, were isolated from the German Wadden Sea and from the Øresund, Denmark, respectively. Both strains affiliate with the genus Rheinheimera. Small amounts of the pigment could be extracted from HP1 grown in a 50 L fermenter and were purified chromatographically. Chemical analysis of the pigment including NMR and mass spectrometry led to a molecular formula of C(34)H(56)N(4)O(4) (m.w. 584.85) which has not yet been reported in literature. The molecule is highly symmetrically and consists of two heterocyclic halves to which aliphatic side chains are attached. The pigment has been named glaukothalin due to its blue color and its marine origin (glaukos, gr. = blue, thalatta, gr. = sea). Production of glaukothalin on MB2216 agar plates by our Rheinheimera strains is affected in the presence of other bacterial strains either increasing or decreasing pigment production. The addition of a single amino acid, arginine (5 gl(-1)), greatly increases pigment production by our Rheinheimera strains. Even though the production of glaukothalin leads to inhibitory activity against three bacterial strains from marine particles, our Rheinheimera isolates are inhibited by various bacteria of different phylogenetic groups. The ecological role of glaukothalin production by Rheinheimera strains, however, remains largely unknown.
Full-text · Article · Jun 2009 · International Journal of Microbiology
[Show abstract][Hide abstract] ABSTRACT: A broad-based characterisation of a pharmacologically active dichloromethane extract from Isatis tinctoria leaves was carried out. For a comprehensive picture we also included the polar constituents of I. tinctoria (MeOH extract) and for comparative purposes, the taxonomically closely related plant I. indigotica. Diode array detector, evaporative light scattering detector, atmospheric pressure chemical ionisation and electrospray ionisation mass spectrometry, and electrospray ionisation time-of-flight mass spectrometry detectors were used in parallel to ensure a wide coverage of secondary metabolites with highly diverging analytical properties. Off-line microprobe nuclear magnetic resonance spectroscopy after peak purification by semi-preparative high-pressure liquid chromatography served for structure elucidation of some minor constituents. More than 65 compounds belonging to various structural classes such as alkaloids, flavonoids, fatty acids, porphyrins, lignans, carotenoids, glucosinolates and cyclohexenones were unambiguously identified, and tentative structures were proposed for additional compounds. Numerous compounds were identified for the first time in the genus Isatis, and an indolic alkaloid was discovered.
[Show abstract][Hide abstract] ABSTRACT: A proposal for a European Pharmacopoeia monograph concerning Indigo naturalis has recently been published, whereby the indigo (1) and indirubin (2) content should be determined by HPLC-UV. This method was tested, but problems were seen with the dosage of indigo due to poor solubility. A quantitative assay for indigo based on (1)H-NMR was developed as an alternative. The HPLC and qNMR assays were compared with eight Indigo naturalis samples. The HPLC assay consistently gave much lower indigo concentrations because solubility was the limiting factor in sample preparation. In one sample, sucrose was identified by (1)H-NMR as an organic additive. Simple wet chemistry assays for undeclared additives such as sugars and starch were tested with artificially spiked Indigo naturalis samples to establish their limits of detection, and sulfate ash determinations were carried out in view of a better assessment of Indigo naturalis in a future European monograph.
[Show abstract][Hide abstract] ABSTRACT: A racemic mixture of a new bicyclononane aldehyde, (1 RS,5 SR,6 RS)-5-hydroxybicyclo[4.3.0]non-2-ene-2-carbaldehyde (1) was isolated from the fruits of Amomum tsao-ko, together with 12 known compounds (2-13). The structure of 1 was determined on the basis of extensive spectroscopic analysis, including 1D and 2D NMR data. The antiproliferative activity of compounds 1-13 was assessed in the murine neuroblastoma cell line N2a.