Anthony L. J. Cole

Evolving Trends in the Dereplication of Natural Product Extracts: New Methodology for Rapid, Small-Scale Investigation of Natural Product Extracts

The use of an HPLC bioactivity profiling/microtiter plate technique in conjunction with capillary probe NMR instrumentation and access to appropriate databases effectively short-circuits conventional dereplication procedures, necessarily based on multimilligram extracts, to a single, more rapid submilligram operation. This approach to dereplication is illustrated using fungal or bacterial extracts that contain known compounds. In each case the dereplication steps were carried out on microgram quantities of extract and demonstrate the discriminating power of (1)H NMR spectroscopy as a definitive dereplication tool.

A model system for examining involvement of bacteria in basidiome initiation of Agaricus bisporus

A model system/bioassay for studying involvement of bacteria in basidiome initiation of Agaricus bisporus is described. Central to this model, is a novel strain of A. bitorquis , W19, which produces primordia in association with basidiome stimulatory bacteria in Petri dish culture.

Cytotoxic and antibacterial activities of endophytic fungi isolated from plants at the National Park, Pahang, Malaysia

BackgroundEndophytes, microorganisms which reside in plant tissues, have potential in producing novel metabolites for exploitation in medicine. Cytotoxic and antibacterial activities of a total of 300 endophytic fungi were investigated.MethodsEndophytic fungi were isolated from various parts of 43 plants from the National Park Pahang, Malaysia. Extracts from solid state culture were tested for cytotoxicity against a number of cancer cell lines using the MTT assay. Antibacterial activity was determined using the disc diffusion method.ResultsA total of 300 endophytes were isolated from various parts of plants from the National Park, Pahang. 3.3% of extracts showed potent (IC50 < 0.01 μg/ml) cytotoxic activity against the murine leukemic P388 cell line and 1.7% against a human chronic myeloid leukemic cell line K562. Sporothrix sp. (KK29FL1) isolated from Costus speciosus showed strong cytotoxicity against colorectal carcinoma (HCT116) and human breast adenocarcinoma (MCF7) cell lines with IC50 values of 0.05 μg/ml and 0.02 μg/ml, respectively. Antibacterial activity was demonstrated for 8% of the extracts.ConclusionResults indicate the potential for production of bioactive agents from endophytes of the tropical rainforest flora.

Evolving Trends in the Dereplication of Natural Product Extracts. 2. The Isolation of Chrysaibol, an Antibiotic Peptaibol from a New Zealand Sample of the Mycoparasitic Fungus Sepedonium chrysospermum

By the application of an HPLC bioactivity profiling/microtiter technique in conjunction with capillary NMR instrumentation and access to the AntiMarin database the conventional evaluation/isolation dereplication/characterization procedures can be dramatically truncated. This approach is illustrated using the isolation of a new peptaibol, chrysaibol (1), from a New Zealand isolate of the mycoparasitic fungus Sepedonium chrysospermum. The unique nature of chrysaibol was recognized by bioactivity-guided fractionation using HPLC bioactivity profiling/microtiter plate analysis in conjunction with capillary NMR instrumentation and the AntiMarin database. 2D NMR techniques, in combination with MS fragmentation experiments, determined the planar structure of chrysaibol (1), while the absolute configurations of the amino acid residues were defined by Marfeys method. Chrysaibol (1) was cytotoxic against the P388 murine leukemia cell line (IC50 6.61 microM) and showed notable activity against Bacillus subtilis (IC50 1.54 microM).

Isolation of 2-pyridone alkaloids from a New Zealand marine-derived penicillium species.

Fermentation of a Penicillium sp. isolated from a surface-sterilized thallus segment of the brown alga Xiphophora gladiata, collected from Macrocarpa Point, Otago, New Zealand, in half-strength potato dextrose broth led to the isolation and characterization of three alkaloids: the known N-hydroxy-2-pyridone, PF1140 (1), and two new 2-pyridones, 2 and 3.

Antimicrobial and cytotoxic activities of Malaysian endophytes

Endophytes, which are receiving increasing attention, have been found to be potential sources of bioactive metabolites following the discovery of paclitaxel producing endophytic fungi. In the present study, a total of 348 endophytes were isolated from different parts of 24 Malaysian medicinal plants. Three selected endophytes (HAB10R12, HAB11R3 and HAB21F25) were investigated for their antimicrobial and cytotoxic activities. For antimicrobial activity, HAB10R12 and HAB11R3 were found to be most active against bacteria and fungi, respectively. Their antimicrobial effects were comparable to, if not better than, a number of current commercial antibacterial and antifungal agents. Both HAB10R12 and HAB21F25 were found to be potential anticancer drug candidates, having potent activity against MCF‐7 and HCT116 cell lines and warrant further investigation. Copyright

Investigation of the New Zealand basidiomycete Favolaschia calocera: Revision of the structures of 9-methoxystrobilurins K and L, strobilurin D, and hydroxystrobilurin D

Abstract 9-Methoxystrobilurin K has been obtained from Favolaschia calocera . The previously proposed epoxyprenyl structure for 9-methoxystrobilurin K 2c and dioxan structure for 9-methoxystrobilurin L 3 have both been revised to the prenyldioxepin structure 1a . The epoxyprenyl structures of strobilurin D 2a and hydroxystrobilurin D 2c should also be revised.

Inhibition of frog antimicrobial peptides by extracellular products of the bacterial pathogen Aeromonas hydrophila

Aims:  To determine whether the extracellular products (ECPs) from Aeromonas hydrophila, a frog bacterial pathogen that is resistant to skin antimicrobial peptides of three different frog species Xenopus laevis, Litoria aurea and Litoria raniformis, can modulate the activity of these peptides.

SAPROPHYTIC GROWTH IN SOIL OF A STRAIN OF TRICHODERMA KONINGII

Abstract A soil‐sandwich bioassay was used to determine the influence of temperature, moisture, form of nitrogen, and the soil microflora on the saprophytic growth through soil of an isolate of Trichoderma koningii. Incubation temperature affected the saprophytic growth of the fungus in soil over the range tested. Saprophytic growth of the isolate in sterile soil increased with incubation temperature from 5°C to the optimum temperature 25°C; there was no saprophytic growth at 30°C. Saprophytic growth also increased with soil moisture content in sterile soil, with a growth optimum at 70% soil water holding capacity (WHC). There was little saprophytic growth at soil moisture contents below 20% WHC. Nitrogen added as ammonium sulphate (NH+4‐N) increased the saprophytic growth of T. koningii in sterile soil whereas nitrogen added as nitrate (NO−3‐N) suppressed growth of T. koningii. Saprophytic growth of T. koningii was markedly reduced in the presence of a natural soil microflora, and enhanced in soil steril...

Skin peptides of different life stages of Ewing's tree frog.

In frogs, an important mechanism of skin innate immunity against invading microbial pathogens is secretion of antimicrobial peptides from the specialized granular glands. Since these glands develop fully in skin dermis after completion of metamorphosis, they are small and immature in skin of larvae (tadpoles). Skin secretions vary among different life stages. Antimicrobial activity and peptide composition of natural mixture of skin peptides of three different life stages of New Zealand Ewings Tree Frog (Litoria ewingii), tadpoles, metamorphs and adults were analyzed. The peptide mixtures were collected from skin secretions and analyzed for activity against the standard reference bacterium, Escherichia coli (ATCC 25922). Their peptide components were analyzed using liquid chromatography mass spectrometry (LC-MS). The peptide mixture from adults and metamorphs contained the species-specific antimicrobial peptide uperin 7.1 and inhibited the growth of E. coli (ATCC 25922). In contrast, the peptide mixture of tadpoles did not inhibit the growth of E. coli (ATCC 25922). This peptide mixture did not contain uperin 7.1 but had peptides whose molecular masses did not correspond to molecular masses of any known frog antimicrobial peptides.