Validation of a Spectroscopic Screening Method for Secondary Metabolites from New Zealand Extremophilic Microbes

<p>The existing protocol for the screening of natural products from marine invertebrates and macroalgae has been demonstrated successfully at VUW on multiple occasions. This study describes the evaluation of an adapted version of the protocol to screen liquid microbial cultures. The adapted protocol was carried out using an NMR-guided approach and was used to screen 10 New Zealand extremophilic microbes. Investigation of the bacteria Anoxybacillus flavithermus led to the isolation of the known compound 1-acetyl-β-carboline (25), which was briefly evaluated for its biological activity. A detailed investigation on the marine bacteria Shewanella sp. resulted in the isolation of indole-3-carboxaldehyde (93) and 14 known 2,5-diketopiperazines (36, 38, 41–44, 53, 54, 94–99). Three of the isolated 2,5-DKPs were tested against Saccharomyces cerevisiae to evaluate their antifungal activity, the results of which are also described. Overall, the use of the adapted screening method proved successful to guide the isolation of secondary metabolites from microbial cultures.</p>