Antifungal and new metabolites of Myrothecium sp. Z16, a fungus associated with white croaker Argyrosomus argentatus

Abstract

Aims: Fungal infection is still a life-threatening risk for the immunocompromised population such as AIDS patients and those who receive treatments with immunosuppressors and/or frequent administrations of wide-spectrum antibiotics, which inevitably lead to the drug resistance and unbalanced microflora populations. The present work was accordingly performed to characterize more potent antifungal metabolites from various cultures of marine fungi residing in white croaker Argyrosomus argentatus. Methods and Results: The three most common opportunistic human pathogens Candida albicans (CCCCM ID 00148), Aspergillus niger (CCCCM ACCC 30005) and Trichophyton rubrum (CCCCM ID 00001) were selected as test fungi. A total of 16 cultivable fungal strains were isolated from the variant tissues of Ar. argentatus collected from the Yellow Sea, followed by preliminary antifungal screenings of the EtOAc extracts of the corresponding cultures. As a result, the inhibition of the three target fungi, plus being allergic to isolators' skin, were discerned with the EtOAc extract of the fungus under the isolation number Z16 that was identified subsequently as Myrothecium sp. by a combination of morphological and 18S rDNA finger-typing characteristics. A followup bioassay fractionation of the EtOAc extract, in conjunction with spectral analyses [MS, 1 H-NMR, 13 C-NMR, distortionless enhancement by polarization transfer (DEPT), heteronuclear multiple quantum coherence (HMQC) and heteronuclear multiple bond resonance (HMBC)] wherever required, afforded eventually the characterization of a new acid (compound 1: 4,5-ditridecyl-octanedioic acid), three macrocyclic trichothecenes including roridin A (compound 2), verrucarin A (compound 3) and 8b-acetoxy-roridin H (compound 4), (22E,24R)-cerevisterol (compound 5) and N-phenyl-b-amino-naphthalene (compound 6). In vitro antifungal tests showed that the three trichothecenes were active against A. niger, T. rubrum and C. albicans with MICs of 31AE25, 62AE5 and 125 lg ml )1 for compound 2, 250, 125 and 31AE25 lg ml )1 for compound 3 as well as 125, 62AE5 and 125 lg ml )1 for compound 4 respectively.The MICs of ketoconazole (co-assayed herewith as a positive reference) against A. niger, T. rubrum and C. albicans were 31AE25, 250, 31AE25 lg ml )1 respectively.A preliminary structure-activity relationship of the antifungal trichothecenes was highlighted in brief.Conclusions: The present investigation demonstrated that marine fungus Myrothecium sp. Z16 associated with white croaker (Ar. argentatus), was an efficient producer of a new acid and antifungal trichothecenes, the latter presumably being also the allergic substances in the culture.

Biocontrol of Sclerotinia sclerotiorum and white mold of soybean using saprobic fungi from semi-arid areas of Northeastern Brazil

“…Liu et al (18) studied the effect of metabolites produced by Myrothecium sp. on Candida albicans, Aspergillus niger and Trichophyton rubrum.…”

Biological Activities and Identification of Bioactive Metabolite from Endophytic Aspergillus flavus L7 Isolated from Aegle marmelos

“…Similarly, various medicinal plants have been reported for the presence of endophytic fungi with antimicrobial activities. For example, Xu et al [41] studied antibacterial potential of fungal endophytes isolated from Dioscorea zingiberensis, whereas Liu et al [19] identified fungal endophytes from the different aerial tissues of Argyrosomus argentatus with antimicrobial activity. Similarly, as many as 25 fungal strains were isolated and identified from Coffea Arabica and Coffea robusta [32] and 32 endophytic fungi from the medicinal herb Cynodon dactylon with varying antimicrobial activities [18].…”

Absolute Configuration of New Cytotoxic and Other Bioactive Trichothecene Macrolides

“…In our continuous characterization of chemically novel and/or biologically potent metabolites produced by fungi harboring in healthy plant tissues [10] or normal animal organs, [11] the presence of trichothecene metabolites was ascertained, prior to the detailed fractionation procedure, by 1 H NMR spectral analysis of extracts derived from a solidsubstrate culture of Myrothecium roridum IFB-E009 and a liquid culture of Myrothecium roridum IFB-E012, which are endophytic fungi residing in two traditional Chinese medicinal plants, Trachelospermum jasminoides (Apocynaceae) and Artemisia annua (Asteraceae), respectively. Subsequent 1 H NMR monitored fractionation of the extracts led to the isolation of three new 10,13-cyclotrichothecane-based macrolides 1-3 in coexistence with the known analogues roridin E (4) and mytoxin B (5).…”