Noonindoles A–F: Rare Indole Diterpene Amino Acid Conjugates from a Marine-Derived Fungus, <i>Aspergillus noonimiae</i> CMB-M0339

Abstract

Analytical scale chemical/cultivation profiling prioritized the Australian marine-derived fungus Aspergillus noonimiae CMB-M0339. Subsequent investigation permitted isolation of noonindoles A–F (5–10) and detection of eight minor analogues (i–viii) as new examples of a rare class of indole diterpene (IDT) amino acid conjugate, indicative of an acyl amino acid transferase capable of incorporating a diverse range of amino acid residues. Structures for 5–10 were assigned by detailed spectroscopic and X-ray crystallographic analysis. The metabolites 5–14 exhibited no antibacterial properties against G-ve and G+ve bacteria or the fungus Candida albicans, with the exception of 5 which exhibited moderate antifungal activity.

Keywords

• indole diterpene
• noonindole
• marine-derived fungus
• <i>Aspergillus noonimiae</i>
• antifungal
• Australia