1. Indole Alkaloids from Chaetomium globosum
- Author
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Guo-Bo Xu, Tao Yang, Guo-You Li, Lin-Wei Wu, Guolin Zhang, Huan-Huan Bai, and Gu He
- Subjects
Stereochemistry ,DPPH ,Pharmaceutical Science ,chemistry.chemical_element ,Microbial Sensitivity Tests ,Chaetomium ,High-performance liquid chromatography ,Piperazines ,Analytical Chemistry ,Indole Alkaloids ,chemistry.chemical_compound ,Picrates ,Drug Discovery ,Escherichia coli ,Benzothiazoles ,Nuclear Magnetic Resonance, Biomolecular ,Pharmacology ,Indole test ,ABTS ,Chaetomium globosum ,biology ,Molecular Structure ,Superoxide ,Organic Chemistry ,Aspergillus niger ,Biphenyl Compounds ,Oryza ,biology.organism_classification ,Sulfur ,Anti-Bacterial Agents ,Complementary and alternative medicine ,chemistry ,Molecular Medicine ,Sulfonic Acids ,Nuclear chemistry ,Bacillus subtilis - Abstract
Two new indole alkaloids chaetocochin J (1) and chaetoglobinol A (8), along with chetomin (2), chetoseminudin A (3), cochliodinol (9), and semicochliodinol (10), were isolated from the rice culture of the fungus Chaetomium globosum. Their structures were elucidated by spectral analysis. Three new epipolythiodioxopiperazines, chaetocochins G-I (5-7), were identified by the combination of UPLC and mass spectrometric analysis. Chaetocochin I contained two sulfur bridges, one formed by three sulfur atoms between C-3 and C-11a, and the other formed by four sulfur atoms between C-3' and C-6'. Chaetocochin I was readily transformed into chetomin (2), chetoseminudin A (3), chaetocochin D (4), chaetocochin G (5), and chaetocochin H (6) by losing sulfur atoms. Compounds 1-3, and 8 exhibited antibacterial activities against Bacillus subtilis with MICs of 25, 0.78, 0.78, and 50 μg/mL, respectively, but not against Gram-negative bacterium (Escherichia coli). Compounds 2 and 8 were inactive against Candida albicans, Fusarium graminearum, Fusarium vasinfectum, Saccharomyces cerevisiae, and Aspergillus niger even at the high concentrations of 200 and 100 μg/mL, respectively. Compound 8 showed free radical scavenging capacity against the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radical (ABTS(+•)), with IC50 values of 143.6 and 45.2 μM, respectively. The free radical scavenging capacity rates of compounds 1-3 on the DPPH and ABTS(+•) were less than 20% at the test concentrations (89.9-108.3 μM). The superoxide anion radical scavenging assay indicated that compounds 1-3, and 8 showed 14.8% (90.9 μM), 18.1% (90.9 μM), 51.5% (88.3 μM), and 30.4% (61.3 μM) superoxide anion radical scavenging capacity, respectively. more...
- Published
- 2015