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Publikation
Pyrofomins A-D, four polyoxygenated sesquiterpenoids have been isolated from the methanolic extract of the fruit bodies of Pyrofomes demidoffii. Their structures are elucidated by IR, HR-FTICR-MS, and 2D NMR spectroscopy. Furthermore, the cedrane carbon skeleton of pyrofomin A (1) is confirmed by X-ray crystallographic analysis. The sesquiterpenoids 1–4 show neither cytotoxicity against KB cells nor antimicrobial activity.
Publikation
Pseudohygrophorones A(12) (1) and B(12) (2), the first naturally occurring alkyl cyclohexenones from a fungal source, and the recently reported hygrophorone B(12) (3) have been isolated from fruiting bodies of the basidiomycete Hygrophorus abieticola Krieglst. ex Gröger & Bresinsky. Their structures were assigned on the basis of extensive one- and two-dimensional NMR spectroscopic analysis as well as ESI-HRMS measurements. The absolute configuration of the three stereogenic centers in the diastereomeric compounds 1 and 2 was established with the aid of (3)JH,H and (4)JH,H coupling constants, NOE interactions, and conformational analysis in conjunction with quantum chemical CD calculations. It was concluded that pseudohygrophorone A(12) (1) is 4S,5S,6S configured, while pseudohygrophorone B(12) (2) was identified as the C-6 epimer of 1, corresponding to the absolute configuration 4S,5S,6R. In addition, the mass spectrometric fragmentation behavior of 1-3 obtained by the higher energy collisional dissociation method allows a clear distinction between the pseudohygrophorones (1 and 2) and hygrophorone B(12) (3). The isolated compounds 1-3 exhibited pronounced activity against phytopathogenic organisms.
Publikation
The Chilean Sepedonium aff. chalcipori strain KSH 883, isolated from the endemic Boletus loyo Philippi, was studied in a polythetic approach based on chemical, molecular, and biological data. A taxonomic study of the strain using molecular data of the ITS, EF1-α, and RPB2 barcoding genes confirmed the position of the isolated strain within the S. chalcipori clade, but also suggested the separation of this clade into three different species. Two new linear 15-residue peptaibols, named chilenopeptins A (1) and B (2), together with the known peptaibols tylopeptins A (3) and B (4) were isolated from the semisolid culture of strain KSH 883. The structures of 1 and 2 were elucidated on the basis of HRESIMS(n) experiments in conjunction with comprehensive 1D and 2D NMR analysis. Thus, the sequence of chilenopeptin A (1) was identified as Ac-Aib(1)-Ser(2)-Trp(3)-Aib(4)-Pro(5)-Leu(6)-Aib(7)-Aib(8)-Gln(9)-Aib(10)-Aib(11)-Gln(12)-Aib(13)-Leu(14)-Pheol(15), while chilenopeptin B (2) differs from 1 by the replacement of Trp(3) by Phe(3). Additionally, the total synthesis of 1 and 2 was accomplished by a solid-phase approach, confirming the absolute configuration of all chiral amino acids as l. Both the chilenopeptins (1 and 2) and tylopeptins (3 and 4) were evaluated for their potential to inhibit the growth of phytopathogenic organisms.
Publikation
The aim of the RADAR (Research Data Repository) project is to set up and establish an infrastructure that facilitates research data management: the infrastructure will allow researchers to store, manage, annotate, cite, curate, search and find scientific data in a digital platform available at any time that can be used by multiple (specialized) disciplines. While appropriate and innovative preservation strategies and systems are in place for the big data communities (e.g., environmental sciences, space, and climate), the stewardship for many other disciplines, often called the “long tail research domains”, is uncertain. Funded by the German Research Foundation (DFG), the RADAR collaboration project develops a service oriented infrastructure for the preservation, publication and traceability of (independent) research data. The key aspect of RADAR is the implementation of a two-stage business model for data preservation and publication: clients may preserve research results for up to 15 years and assign well-graded access rights, or to publish data with a DOI assignment for an unlimited period of time. Potential clients include libraries, research institutions, publishers and open platforms that desire an adaptable digital infrastructure to archive and publish data according to their institutional requirements and workflows.
Publikation
The goal of RADAR is to simplify and establish inter-disciplinary research data management for university libraries and projects. In summer 2016‚ ‘RADAR – Research Data Repository‘ starts as a service that offers researchers, institutions of different disciplines and publishers a generic infrastructure for archiving and publishing their research data. Among others, services are long-term data availability with Handle or Digital Object Identifier (DOI), an adaptable role and access rights management, an optional peer review function and access statistics. The business model encourages researchers to integrate arising charges for using the repository into applications for Third-Party funding and data management plans. Published data are available as Open Data to be used by Data Mining, metadata harvesting or linking with search portals. This interlinking enables a sustainable research data management and the establishment of data infrastructures like RADAR.
Publikation
Phytochemical investigation of the ethyl acetate extract of the fruiting bodies from the basidiomycete Piptoporus betulinus led to the isolation of a new bioactive lanostane triterpene identified as 3 b -acetoxy-16-hydroxy-24-oxo-5α-lanosta-8- ene-21-oic acid (1). In addition, ten known triterpenes, polyporenic acid A (5), polyporenic acid C (4), three derivatives of polyporenic acid A (8, 10, 11), betulinic acid (3), betulin (2), ergosterol peroxide (6), 9,11-dehydroergosterol peroxide (7), and fomefficinic acid (9), were also isolated from the fungus. All isolated compounds were tested for antimicrobial activity against some Gram-positive and Gram-negative bacteria as well as against a fungal strain. The new triterpene and some of the other compounds showed antimicrobial activity against Gram-positive bacteria.
Publikation
The chemical composition of the hydrodistilled leaf essential oil from Chenopodium ambrosioides L. growing wild in Yemen was determined by GC-MS analysis, and its cytotoxic, and general antioxidant potential were evaluated. Major compounds of C. ambrosioides oil were ascaridole (54.2%), isoascaridole (27.7%) and p-cymene (8.1%). At concentrations of 50 and 25 μg/mL, the essential oil showed cytotoxic activity against HT29 (human colon adenocarcinoma cells), with growth inhibition of 100 and 56% (± 3). The free radical scavenging ability of the oil was assessed by the DPPH assay to show antiradical activity with IC50 of 10.4 μg/mL. TLC-bioautographic assay was used to identify the acetylcholinesterase inhibitory effect, and ascaridole was isolated and characterized (ESIMS, 1H NMR, 13C NMR and HMBC) as the responsible constituent for anticholinesterase activity.
Publikation
Trigonelline (3-carboxy-1-methyl pyridinium) was identified as a relevant bioactivity and taste imparting component in Balanites aegyptiaca fruit, using 1H NMR of crude extracts without any fractionation or isolation step. The structural integrity of trigonelline was established within the extract matrix via1H NMR, 1H–1H COSY, HMQC and HMBC and by comparison with authentic standard. A quantitative 1H NMR method (qHNMR) was used to determine trigonelline concentrations in the peel and pulp of B. aegyptiaca fruit of 8 and 13 mg g−1, respectively. Trigonelline so far has not been reported from B. aegyptiaca or its genus as it easily escapes LC–MS based detection. Its discovery provides novel insight into the balanite fruits antidiabetic properties as the compound is known for a pronounced hypoglycemic effect. In addition, it is likely to impart the perceptible bitter taste portion to balanites sweet bitter taste. UPLC–MS of the crude extract additionally revealed the fruit flavonoid pattern showing quercetin/isorhamnetin flavonol conjugates in addition to epicatechin, the latter being present at much lower levels.
Publikation
Glycyrrhiza glabra, commonly known as licorice, is a popular herbal supplement used for the treatment of chronic inflammatory conditions and as sweetener in the food industry. This species contains a myriad of phytochemicals including the major saponin glycoside glycyrrhizin (G) of Glycyrrhetinic acid (GA) aglycone. In this study, 2D-ROESY NMR technique was successfully applied for distinguishing 18α and 18β glycyrrhetinic acid (GA). ROESY spectra acquired from G. glabra, Glycyrrhiza uralensis and Glycyrrhiza inflata crude extracts revealed the presence of G in its β-form. Anti-inflammatory activity of four Glycyrrhiza species, G, glabra, G. uralensis, G. inflata, and G. echinata roots was assessed against COX-1 inhibition revealing that phenolics rather than glycyrrhizin are biologically active in this assay. G. inflata exhibits a strong cytotoxic effect against PC3 and HT29 cells lines, whereas other species are inactive. This study presents an effective NMR method for G isomer assignment in licorice extracts that does not require any preliminary chromatography or any other purification step.
Publikation
Bacterial wilts of potato, tomato, pepper, and or eggplant caused by Ralstonia solanacearum are among the most serious plant diseases worldwide. In this study, the issue of developing bactericidal agents from natural sources against R. solanacearum derived from plant extracts was addressed. Extracts prepared from 25 plant species with antiseptic relevance in Egyptian folk medicine were screened for their antimicrobial properties against the potato pathogen R. solancearum by using the disc‐zone inhibition assay and microtitre plate dilution method. Plants exhibiting notable antimicrobial activities against the tested pathogen include extracts from Acacia arabica and Punica granatum. Bioactivity‐guided fractionation of A. arabica and P. granatum resulted in the isolation of bioactive compounds 3,5‐dihydroxy‐4‐methoxybenzoic acid and gallic acid, in addition to epicatechin. All isolates displayed significant antimicrobial activities against R. solanacearum (MIC values 0.5–9 mg/ml), with 3,5‐dihydroxy‐4‐methoxybenzoic acid being the most effective one with a MIC value of 0.47 mg/ml. We further performed a structure–activity relationship (SAR) study for the inhibition of R. solanacearum growth by ten natural, structurally related benzoic acids.
Diese Seite wurde zuletzt am 06 Jun 2012 06 Jun 2012 geändert.