Isolation of an antioxidant from Penicillium roquefortii IFO 5956

Fungal Diversity in Intertidal Mudflats and Abandoned Solar Salterns as a Source for Biological Resources

Intertidal zones are unique environments that are known to be ecological hot spots. In this study, sediments were collected from mudflats and decommissioned salterns on three islands in the Yellow Sea of South Korea. The diversity analysis targeted both isolates and unculturable fungi via Illumina sequencing, and the natural recovery of the abandoned salterns was assessed. The phylogeny and bioactivities of the fungal isolates were investigated. The community analysis showed that the abandoned saltern in Yongyudo has not recovered to a mudflat, while the other salterns have almost recovered. The results suggested that a period of more than 35 years may be required to return abandoned salterns to mudflats via natural restoration. Gigasporales sp. and Umbelopsis sp. were selected as the indicators of mudflats. Among the 53 isolates, 18 appeared to be candidate novel species, and 28 exhibited bioactivity. Phoma sp., Cladosporium sphaerospermum, Penicillium sp. and Pseudeurotium bakeri, and Aspergillus urmiensis showed antioxidant, tyrosinase inhibition, antifungal, and quorum-sensing inhibition activities, respectively, which has not been reported previously. This study provides reliable fungal diversity information for mudflats and abandoned salterns and shows that they are highly valuable for bioprospecting not only for novel microorganisms but also for novel bioactive compounds.

Mass spectrometry-based chemotaxonomic classification of Penicillium species (P. echinulatum, P. expansum, P. solitum, and P. oxalicum) and its correlation with antioxidant activity

In this study, 4 Penicillium species (17 strains) were classified on the basis of metabolite profile (chemotaxonomy) by using liquid chromatography-electrospray ionization ion trap-mass spectrometry (LC-ESI-MS), gas chromatography-ion trap-mass spectrometry (GC-IT-MS) and multivariate statistical analysis. The LC-ESI-MS-based dendrogram was similar to the internal transcribed spacer (ITS)-based dendrogram, in that Penicillium oxalicum was separated from the other 3 species. Moreover, vermiculidiol, meleagrin, oxaline, glandicolin A and B, and secalonic acid D were identified as metabolites that enable discrimination of Penicillium species by partial least squares discriminant analysis (PLS-DA). Evaluation of the species-specific metabolites produced by P. expansum, P. echinulatum, and P. solitum revealed that the 3 species differed from each other. On the other hand, GC-IT-MS-based dendrogram revealed that P. expansum was clearly classified separately from the other 3 species, and this result correlated with the antioxidant activity of the 4 species: P. expansum had a higher radical scavenging activity than the other 3 species. The metabolites produced in higher amounts in P. expansum were gluconic acid (12, 29, 33); andrastin A (16), B (15), and C (17); chaetoglobosin C (14), a class of sugar (31, 32); and salicylic acid (28). The results of this study demonstrated that metabolite-based chemotaxonomy could be used not only as a classification method but also as a tool for evaluation of species-specific activities.

New potent DPPH radical scavengers from a marine-derived actinomycete strain USF-TC31

Six compounds were isolated as radical scavengers from the culture broth of a marine-derived actinomycete strain USF-TC31. The structures of two novel compounds were determined to be those of N-carbamoyl-2,3-dihydroxybenzamide (5) and 2-acetamido-3-(2,3-dihydroxybenzoylthio)propanoic acid (6), and four known compounds were identified to be anthranilic acid (1), 2,3-dihydroxybenzoic acid (2), 2,3-dihydroxybenzamide (3) and benadrostin (4) on the basis of spectroscopic data. Compound 6 was characterized as a racemate by its specific rotation. Each of the obtained compounds was evaluated for DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity, and compounds 2, 3, 5 and 6 each exhibited potent activity in comparison with the butylhydroxytoluene (BHT) positive control.

Synthesis and free radical scavenging activity of a novel metabolite from the fungus Colletotrichum gloeosporioides

A novel metabolite (-)-1 was isolated as its peracetylated derivative, (-)-2-(3',4'-diacetoxyphenyl)-3,4-diacetoxytetrahydrofuran (2), from a strain of the phytopathogenic fungus Colletotrichum gloeosporioides CECT 20122. The synthesis of (-)-1 was carried out by ring-closing metathesis of diene 6 and stereoselective dihydroxylation of a dihydrofuran derivative 7 as key steps. The tetraol (-)-1 showed free radical scavenging activity comparable to that of BHT, caffeic acid or protocatechuic acid.

Screening for metabolites from Penicillium novae-zeelandiae displaying radical-scavenging activity and oxidative mutagenicity: isolation of gentisyl alcohol

In the search for new natural products with anti-oxidant activity, we have combined the cell-free assay based on the scavenging of the stable radical 2,2-diphenyl-1-picrylhydrazyl (DPPH), with a bioassay that detects oxidative mutagens. This bioassay uses a new Escherichia coli tester strain, IC203, specifically sensitive to oxidative stress due to a deficiency in the OxyR function. OxyR is a redox-sensitive transcriptional activator of genes encoding anti-oxidant enzymes such as catalase and peroxiredoxin alkyl hydroperoxide reductase. The positive response observed in E. coli IC203 with several known anti-oxidants, including cysteine, catechol and ascorbic acid, suggested to us the usefulness of the mutagenicity assay for a rapid screening of anti-oxidant compounds. The extract from Penicillium novae-zeelandiae was found to scavenge the DPPH radical. Subsequently, guided by the DPPH-scavenging assay and the oxidative mutagenesis assay, we isolated and identified three compounds in fractions from that active extract: patulin (1). 3-hydroxybenzyl alcohol (2). and gentisyl alcohol (2,5-dihydroxybenzyl alcohol) (3). Of these, gentisyl alcohol showed both DPPH-scavenging activity and oxidative mutagenicity. This compound also gave rise to intracellular formation of superoxide, evaluated by monitoring the oxidation of dihydroethidium, and was able to inhibit mutagenesis induced by the model oxidant t-butyl hydroperoxide (t-BuOOH).