Burnettramic acid A and its aglycone are members of a new class of antibiotics from an Australian fungus Aspergillus burnettii. The rare bolaamphiphilic scaffold consists of β-d-mannose linked to a pyrrolizidinedione unit via a 26-carbon chain. Burnettramic acid A is active against the Gram positive bacteria, B. subtilis and S. aureus, with IC50 2.3 and 5.9 µg/mL, respectively. Burnettramic acid A is a potent antifungal agent (IC50 0.5 µg/mL and 0.2 µg/mL against C. albicans and S. cerevisiae, respectively). Burnettramic acid A is also active against murine myeloma NS-1 cell line (IC50 13.8 µg/mL). Removal of the glycosyl group negates antibiotic and antifungal activity, but not activity against murine myeloma cell line (IC50 8.5 µg/mL for the aglycone).
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Hang et al (2019) Discovery and heterologous biosynthesis of the burnettramic acids: Rare PKS-NRPS-Derived bolaamphiphilic pyrrolizidinediones from an Australian Fungus, Aspergillus burnettii. Org Lett 21:1287