Antibacterial activity against drug-resistant microbial pathogens of cytochalasan alkaloids from the arthropod-associated fungus Chaetomium globosum TW1-1 |
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Affiliation: | 1. College of Materials and Energy, South China Agricultural University, Guangzhou 510642, China;2. School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275, China |
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Abstract: | By feeding 1-methyl-l-tryptophan (1-MT) into cultures of the arthropod-associated fungus Chaetomium globosum TW1-1, three novel cytochalasan alkaloids, termed as armochaetoglosins A–C (1–3), together with five known analogues, namely prochaetoglobosin I (4), chaetoglobosin T (5), chaetoglobosin C (6), armochaetoglobin Y (7), and chaetoglobosin Vb (8), were isolated and characterized. Their structures including absolute configurations were elucidated by means of NMR spectroscopy, single-crystal X-ray crystallography, and comparison of the experimental electronic circular dichroism (ECD) spectra. Structurally, compounds 1–3 represented the first examples of 1′-N-methyl-chaetoglobosins, which were possibly biosynthesized from the additive 1-MT rather than tryptophan. Additionally, compound 3 showed the highest antibacterial activity against K. pneumoniae and ESBL-E. coli with MIC values of 4.0 μg/mL and 16.0 μg/mL, respectively, wherein the inhibitory effect of 3 against K. pneumoniae was stronger than that of the clinically used antibiotic meropenem, with an MIC value of 8 μg/mL. Our findings may provide new chemical templates for the development of new antibacterial agents against drug-resistant microbial pathogens. |
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Keywords: | Feeding experiment Cytochalasan alkaloids Antibacterial activity |
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