Antimicrobial anthraquinones from cultures of the ant pathogenic fungus Cordyceps morakotii BCC 56811.

Five new anthraquinones, morakotins A-E (1-5), together with seven known compounds, lunatin (6), rheoemodin (7), YM187781 (8), bislunatin (9), 6-(1-hydroxypentyl)-4-methoxypyran-2-one, 9,11-dehydoergrosterol peroxide, and cerevisterol, were isolated from the insect pathogenic fungus Cordyceps morakotii BCC 56811. The morakotin structures were elucidated from NMR spectroscopic and mass spectrometric data. The absolute configurations of bianthraquinone compounds, morakotins C-E (3-5), were determined by application of the exciton chirality method. Compounds 3, 7, 8, and 9 showed weak to moderate antimycobacterial and antifungal activities. Compounds 4 and 8 exhibited antibacterial activity against both Bacillus cereus and Staphylococcus aureus (MIC 3.13-25 µg ml-1 ), whereas compounds 3 and 9 were active against B. cereus (MIC 12.5 and 3.13 µg ml-1 , respectively), and compound 7 was active against Acinetobacter baumannii (MIC 12.5 µg ml-1 ).