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Albrecht Berg

Publications and source records attributed to Albrecht Berg.

16 recordsLinked to original sources
PubMed2006

Peptaibiomics: Screening for polypeptide antibiotics (peptaibiotics) from plant-protective Trichoderma species.

Eight strains of Trichoderma species (T. strigosum, T. erinaceus, T. pubescens, T. stromaticum, and T. spirale as well as T. cf. strigosum, T. cf. pubescens) were selected because of their antagonistic potential against Eutypa dieback and Esca which are fungal diseases of grapevine trunks. These isolates were screened for the production of a group of polypeptide antibiotics named peptaibiotics, including its subgroups peptaibols and lipopeptaibols. Fully-grown fungal cultures on potato-dextrose agar were extracted with CH(2)Cl(2)/MeOH, and these extracts were subjected to SPE using C(18) cartridges. The methanolic eluates were analyzed by on-line LC/ESI-MS(n) coupling--a method which is referred to as 'peptaibiomics'. New seven-, ten-, and eleven-residue lipopeptaibols, with N-terminal alkanoyl, and C-terminal leucinol or isoleucinol residues were found and named lipostrigocins and lipopubescins. Furthermore, new 18-residue peptaibols named trichostromaticins and 19-residue peptaibols named trichostrigocins were discovered. One peptaibiotic carrying a free C-terminal valine (or isovaline) named trichocompactin XII was also sequenced. These results corroborate the hypothesis that peptaibiotics might contribute to the plant-protective action of their fungal producers. The data also point out that comparison of peptaibiotic sequences is of limited relevance in order to establish chemotaxonomic relationships among species of the genus Trichoderma.

Anti-Bacterial Agents↗
PubMed2006

Influence of ELF sinusoidal electromagnetic fields on proliferation and metabolite yield of fungi.

The response of mycelium proliferation in 12 strains of fungi were tested by sinusoidal ELF 50 Hz electromagnetic field treatment in the range B = 0.6-10 mT over 10 days. The ratio of experiment/control indicated three types of proliferation changes: a) no significant change, b) a strong decrease down to E/C = 0.2, c) a maximization of mycelium diameter by treatment at 5-7 mT. According to these results, effects can be produced noninvasively by varying either magnetic intensities or time of treatment. As yet, systematic bioelectromagnetic research using sinusoidal electromagnetic fields (SEMF)-on fermentation of fungi is still in its initial stages.

Cell Division↗
PubMed2006

Transcriptional response to the neuroleptic-like compound Ampullosporin A in the rat ketamine model.

Psychotic disorders affecting up to 1% of the human population represent pathological changes to the metabolic homeostasis of the brain. Increasing evidence in the literature suggests complex biochemical and/or transcriptional alterations accompanying schizophrenia-like phenomena. Sub-chronic treatment with sub-anaesthetic doses of ketamine induces schizophrenia-related psychotic alterations that can be used as an animal model in the study of this disorder. Ampullosporin A belongs to a specific group of pore-forming fungal peptides, peptaibols. We focused on the analysis of molecular events occurring in the brain of ketamine-pre-treated rats after administration of Ampullosporin A with neuroleptic-like activity. The complex experimental approach allowed us to correlate the use of low molecular weight substances with a transcriptome fingerprint in the prefrontal cortex. We found 63 genes to be up-regulated and 22 genes suppressed, with transthyretin, syndecan-1 and NeuroD1 showing the highest degree of up-regulation. Our results suggest the possibility that Ampullosporin A belongs to the group of neuroleptic-like compounds, inducing massive changes in neurotransmitter receptor composition, calcium signalling cascades and second messenger systems, and leading to the plastic reorganization of brain tissue, metabolic pathways and synapses.

Animals↗
PubMed2004

Lignoren, a new sesquiterpenoid metabolite from Trichoderma lignorum HKI 0257.

The new compound lignoren (1) was isolated from Trichoderma lignorum HKI 0257 by chromatographic methods. This metabolite has a santalane-like structure, which was elucidated by mass spectrometric and NMR spectroscopic investigations. Lignoren (1) shows a moderate narrow-spectrum of antibacterial and antifungal activity.

Anti-Bacterial Agents↗
PubMed2004

New communesin derivatives from the fungus Penicillium sp. derived from the Mediterranean sponge Axinella verrucosa.

The ethyl acetate extract of Penicillium sp., derived from the Mediterranean sponge Axinella verrucosa, yielded the known compound communesin B (1) and its new congeners communesins C (2) and D (3), as well as the known compounds griseofulvin, dechlorogriseofulvin, and oxaline. All structures were unambiguously established by 1D and 2D NMR and MS data. In several bioassays performed on different leukemia cell lines, the communesins exhibited moderate antiproliferative activity.

Animals↗
PubMed2004

New imidazole alkaloids from the Indonesian sponge Leucetta chagosensis.

Chemical investigation of the sponge Leucetta chagosensis collected in Indonesia afforded five new imidazole alkaloids, naamine F (2), naamine G (3), kealiinine A (6), kealiinine B (7), and kealiinine C (8), in addition to the known compound naamine A (1). Naamine G (3) exhibited strong antifungal activity against the phytopathogenic fungus Cladosporium herbarum and also showed mild cytotoxicity against mouse lymphoma (L5178Y) and human cervix carcinoma (HeLa) cell lines. In the brine shrimp assay, kealiinine A (6) was more active than naamine G (3). The structures of the new compounds were unambiguously established by 1D and 2D NMR and MS data.

Alkaloids↗
PubMed2003

Novel chromone derivatives from the fungus Aspergillus versicolor isolated from the marine sponge Xestospongia exigua.

From the marine sponge Xestospongia exigua collected in Indonesia the fungus Aspergillus versicolor was isolated. Following cultivation in a seawater-based medium seven new angular tricyclic chromone derivatives (1-7) were obtained from the mycelia and culture filtrate. Compounds 2-7 contain an additional dihydropyran ring system which is replaced by a pyridine ring in 1. The structures of the new natural products were established on the basis of extensive one- and two-dimensional NMR spectroscopic studies (1H, 13C, COSY, HMQC, HMBC, NOE difference spectra) as well as on mass spectral analysis.

Animals↗
PubMed2003

Eudistomins W and X, two new beta-carbolines from the micronesian tunicate Eudistoma sp.

Chemical investigation of the Micronesian ascidian Eudistoma sp. afforded two new eudistomin congeners, which were designated eudistomins W (1) and X (2). The structures of the new compounds were unambiguously established on the basis of NMR spectroscopic ((1)H, (13)C, COSY, (1)H detected direct, and long-range (13)C-(1)H correlations) and mass spectrometric (EI and ESIMS) data. Compound 2 exhibited antibiotic activity toward Bacillus subtilis, Staphyloccocus aureus, and Escherichia coli and was also found to be fungicidal against Candida albicans in an agar diffusion assay. Compound 1 was selectively active against C. albicans but showed no antibacterial activity.

Animals↗
PubMed2002

Highly antibacterial active aminoacyl penicillin conjugates with acylated bis-catecholate siderophores based on secondary diamino acids and related compounds.

New acylated bis-catecholates and 1,3-benzoxazine-2,4-dione derivatives based on secondary diamino acids (N-(aminoalkyl)glycines, N-aminopropyl-alanine, and N-aminopropyl-4-aminovaleric acid), on N-(aminoalkyl)aminomethyl benzoic acids, on N-(aminoalkyl)aminomethyl phenoxyacetic acids, or on 3,5-diaminobenzoic acid were synthesized as artificial siderophores. The corresponding diamino acids were obtained from the diamines and oxocarboxylic acids by catalytic hydrogenation. The acylated bis-catecholates and 1,3-benzoxazine-2,4-diones were coupled with ampicillin or amoxicillin to new siderophore aminoacylpenicillin conjugates. These conjugates exhibited very strong antibacterial activity in vitro against Gram-negative bacterial pathogens including Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Escherichia coli, Klebsiella pneumoniae, and Serratia marcescens. The ampicillin derivative 7b (HKI 9924154) and the corresponding amoxicillin derivative 8 (HKI 9924155) represent the most active compounds. The conjugates can use bacterial iron siderophore uptake routes to penetrate the Gram-negative outer membrane permeability barrier. This was demonstrated by assays with mutants deficient in components of the iron transport systems. New siderophore penicillin V conjugates with the siderophore component attached to the phenyl ring of penicillin V are inactive against these Gram-negative bacteria.

Amino Acids↗
PubMed2002

Online analysis of xestodecalactones A-C, novel bioactive metabolites from the fungus Penicillium cf. montanense and their subsequent isolation from the sponge Xestospongia exigua.

Fungal isolates of Penicillium cf. montanense were obtained from the marine sponge Xestospongia exiguacollected from the Bali Sea, Indonesia. Culture filtrates of the fungi yielded three novel decalactone metabolites, xestodecalactones A, B, and C (1, 2a, and 2b), consisting of 10-membered macrolides with a fused 1,3-dihydroxybenzene ring. Online HPLC-NMR, ESI-MS/MS, and -CD spectra were acquired, and the structures of the new compounds were established and confirmed on the basis of offline NMR spectroscopic ((1)H, (13)C, COSY, ROESY, (1)H-detected direct and long-range (13)C-(1)H correlations) and mass spectrometric (EIMS) data. Quantum chemical calculations of the CD spectra proved to be difficult because of the conformational flexibility of the xestodecalactones. These compounds, of which 2a and 2b, due to the additional stereocenter at C-9, are diastereomeric compounds, are structurally related to a number of biologically active metabolites found in terrestrial fungal strains. Compound 2a was found to be active against the yeast Candida albicans.

Animals↗
PubMedDate not supplied

The occurrence of peptaibols and structurally related peptaibiotics in fungi and their mass spectrometric identification via diagnostic fragment ions.

Peptaibols and related peptide antibiotics (peptaibiotics) display diagnostically useful fragmentation patterns during mass spectrometry (FAB-MS, ESI-CID-MS/MS and CID-MSn]. The paper compiles fragmentation data of pseudo-molecular ions reported in the literature as a guide to the rational identification of recurrently isolated and new peptaibols and peptaibiotics. Taxonomic and ecological aspects of microorganisms producing peptaibols and peptaibiotics are discussed.

Amino Acids↗
PubMedDate not supplied

Isolation, structure elucidation and biological activities of trichofumins A, B, C and D, new 11 and 13mer peptaibols from Trichoderma sp. HKI 0276W.

Trichofumins A-D were isolated from cultures of Trichoderma sp. HKI 0276 as new 11 and 13mer peptaibols. Similar to 15mer peptaibols they promote morphogenesis of the fungus Phoma destructiva and cause hypothermia in mice as a characteristic of neuroleptic activity. Membrane measurements using a synthetic BLM model showed that A, B, C and D increased membrane permeability for cations in a similar manner as was shown for larger peptaibols but with comparably lower efficiency.

Animals↗
PubMedDate not supplied

Differences in membrane pore formation by peptaibols.

The efficiencies of membrane pore formation by 14 naturally occurring peptaibols and two structurally modified ampullosporins were compared using an artificial bilayer membrane model. Major differences were found in the dependence on peptide sequences and the constituting amino acids. Alamethicin F-30, chrysospermins C/D, paracelsin and texenomycin A displayed higher activity by several orders of magnitude in comparison with smaller peptaibols containing < 17 amino acids such as ampullosporins, trichofumins. bergofungins and cephaibols. Biological activities such as the induction of pigment formation by the fungus Phoma destructiva and long acting hypothermia and depression of locomotor activity in mice were correlated with moderate membrane permeabilization. No or weak membrane activities corresponded with biological inactivity. Highly membrane-active structures such as alamethicin F-30, chrysospermin C, texenomycin A and paracelsin A displayed antibiotic effects against the fungus and toxicity in mice.

Animals↗