A new lanostane-type triterpenoid, ascosteroside D, was isolated from a fungus, Aspergillus sp. FKI-6682. It inhibited insect ADP/ATP carrier protein (AAC)-expressing Saccharomyces cerevisiae in glycerol-containing medium, but did not inhibit Δaac S. cerevisiae in glucose-containing medium. It is hypothesized that ascosteroside D inhibits ATP production in mitochondria.
The study was supported by the Programme for Promotion of Basic and Applied Researches for Innovations in Bio-oriented Industry and the Science and Technology Research Promotion Program for Agriculture, Forestry, Fisheries and Food Industry (26021A). We are grateful to Dr Kenichiro Nagai and Ms Noriko Sato, School of Pharmacy, Kitasato University, for help in obtaining NMR and MS data, and are grateful to Dr Rokuro Masuma for suggestions concerning the experiments.
Supplementary Information accompanies the paper on The Journal of Antibiotics website (http://www.nature.com/ja)