Five new pyrazin-2(1H)-one derivatives, ochramides A-D (1-4) and ochralate A (5), as well as three known analogues (6-8) were isolated from the fermentation broth of the marine coral-derived halotolerant Aspergillus ochraceus LCJ11-102 in a nutrient-limited medium containing 10% NaI. Their chemical structures were determined by analyzing NMR and X-ray diffraction data. Compounds 2, 5 and 6 showed antimicrobial activities against Enterobacter aerogenes with the MIC values of 40.0, 18.9, and 20.1 μM, respectively.
Keywords: Aluminum chelates; Antibacterial activity; Aspergillus ochraceus; Coral; Halotolerant fungus.