Xanalteric Acids I and II and Related Phenolic Compounds from an Endophytic Alternaria sp Isolated from the Mangrove Plant Sonneratia alba

Institut für Pharmazeutische Biologie und Biotechnologie, Heinrich-Heine-Universität Düsseldorf, Universitätsstrasse 1, Geb. 26.23, 40225 Düsseldorf, Germany.
Journal of Natural Products (Impact Factor: 3.8). 10/2009; 72(11):2053-7. DOI: 10.1021/np900417g
Source: PubMed


Two new 10-oxo-10H-phenaleno[1,2,3-de]chromene-2-carboxylic acids, xanalteric acids I (1) and II (2), and 11 known secondary metabolites were obtained from extracts of the endophytic fungus Alternaria sp., isolated from the mangrove plant Sonneratia alba collected in China. The metabolites were confirmed to be of fungal origin, and the structures of the new natural products were unambiguously elucidated on the basis of extensive one- and two-dimensional NMR spectroscopic studies and mass spectrometric analysis. The two new compounds 1 and 2 exhibited weak antibiotic activity against multidrug-resistant Staphylococcus aureus. Altenusin (3) displayed broad antimicrobial activity against several additional multidrug-resistant bacterial and fungal strains.

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    • "The production of stemphyperylenol (1) has been reported in Alternaria genus (Gao et al. 2009; Hradil et al. 1989; Kjer et al. 2009) as well in Stemphylium botryosum (Arnone et al. 1986; Andersen et al. 1995), Pleospora herbarum (Krohn et al. 1999a), Monodictys fluctuate (Krohn et al. 1999b), and Talaromyces sp. (Liu et al. 2010). "
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    ABSTRACT: Secondary metabolites produced by endophytic microorganisms can provide benefits to host plants, such as stimulating growth and enhancing the plant's resistance toward biotic and abiotic factors. During its life, a host plant may be inhabited by many species of endophytes within a restrictive environment. This condition can stimulate secondary metabolite production that improves microbial competition and may consequently affect both the neighboring microorganisms and the host plant. The interactions between the endophytes that co-habit the same host plant have been studied. However, the effect of these interactions on the host plant has remained neglected. When using mixed microbial cultures, we found that the endophytic fungus Alternaria tenuissima significantly increased the production of some polyketides, including antifungal stemphyperylenol in response to the endophytic Nigrospora sphaerica. Biological activity assays revealed that stemphyperylenol can cause cytotoxic effects against N. sphaerica, although no phytotoxicity was observed in the host plant Smallanthus sonchifolius, even at concentrations much higher than those toxic to the fungus. The polyketides produced by A. tenuissima may be important for the ecological relationships between endophyte-endophyte and endophytes-host plants in the natural environment.
    Journal of Chemical Ecology 10/2013; 39(10). DOI:10.1007/s10886-013-0351-7 · 2.75 Impact Factor
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    • "This plant is known as Mangrove Apple, an edible salt-tolerant plant eaten by humans and camels in Africa and the Pacific, but also used as a traditional herb against skin or intestinal parasites. These compounds exhibited weak antibiotic activity against S. aureus (Kjer et al., 2009). "
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    ABSTRACT: Endophytes are microbes that inhabit host plants without causing disease and are reported to be reservoirs of metabolites that combat microbes and other pathogens. Here we review diverse classes of secondary metabolites, focusing on anti-microbial compounds, synthesized by fungal endophytes including terpenoids, alkaloids, phenylpropanoids, aliphatic compounds, polyketides, and peptides from the interdisciplinary perspectives of biochemistry, genetics, fungal biology, host plant biology, human and plant pathology. Several trends were apparent. First, host plants are often investigated for endophytes when there is prior indigenous knowledge concerning human medicinal uses (e.g., Chinese herbs). However, within their native ecosystems, and where investigated, endophytes were shown to produce compounds that target pathogens of the host plant. In a few examples, both fungal endophytes and their hosts were reported to produce the same compounds. Terpenoids and polyketides are the most purified anti-microbial secondary metabolites from endophytes, while flavonoids and lignans are rare. Examples are provided where fungal genes encoding anti-microbial compounds are clustered on chromosomes. As different genera of fungi can produce the same metabolite, genetic clustering may facilitate sharing of anti-microbial secondary metabolites between fungi. We discuss gaps in the literature and how more interdisciplinary research may lead to new opportunities to develop bio-based commercial products to combat global crop and human pathogens.
    Frontiers in Microbiology 03/2013; 4:65. DOI:10.3389/fmicb.2013.00065 · 3.99 Impact Factor
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    • "The identification and structure elucidation of the most potent metabolite is essential in the development of a new antibiotic that would potentially be used in therapy. Two new 10-oxo-10H-phenaleno[1,2,3-de]chromene-2- carboxylic acids, xanalteric acids I and II (Fig. 1), and 11 known secondary metabolites were obtained from extracts of the endophytic fungus Alternaria sp., isolated from the mangrove plant Sonneratia alba collected in China (Kjer et al. 2009). The two new compounds xanalteric acids I and II showed weak antibacterial activity against Staphylococcus aureus with MIC values of 250 and125 ␮g/ml, respectively. "
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    ABSTRACT: Over more than 20 years, the endophytic fungi have been explored as "biofactories" of novel bioactive substances, and they have not disappointed. Among the extracts and pure substances obtained from the culture broths or fungal biomass, some have exerted antibacterial activity ranging from moderate to powerful when tested on the bacterial strains resistant to the antibiotics currently in use. In this article we review the accumulated data on endophytic fungi isolated from plants that produce metabolites with antibacterial activity against human pathogenic bacteria.
    Phytomedicine: international journal of phytotherapy and phytopharmacology 10/2012; 19(14). DOI:10.1016/j.phymed.2012.09.007 · 3.13 Impact Factor
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