HSQC–TOCSY Fingerprinting for Prioritization of Polyketide- and Peptide-Producing Microbial Isolates

Microbial products are a promising source for drug leads as a result of their unique structural diversity. However, reisolation of already known natural products significantly hampers the discovery process, and it is therefore important to incorporate effective microbial isolate selection and dereplication protocols early in microbial natural product studies. We have developed a systematic approach for prioritization of microbial isolates for natural product discovery based on heteronuclear single-quantum correlation–total correlation spectroscopy (HSQC–TOCSY) nuclear magnetic resonance profiles in combination with antiplasmodial activity of extracts. The HSQC–TOCSY experiments allowed for unfractionated microbial extracts containing polyketide and peptidic natural products to be rapidly identified. Here, we highlight how this approach was used to prioritize extracts derived from a library of 119 ascidian-associated actinomycetes that possess a higher potential to produce bioactive polyketides and peptides.