**Sustainable Low-Volume Analysis of Environmental Samples by Semi-Automated Prioritization of Extracts for Natural Product Research (SeaPEPR)**

**Riyanti 1,2,3,**†**, Michael Marner 3,**†**, Christoph Hartwig 3, Maria A. Patras 3, Stevy I. M. Wodi 4, Frets J. Rieuwpassa 4, Frans G. Ijong 4,5, Walter Balansa 4,\* and Till F. Schäberle 1,3,6,\***

	- Christoph.Hartwig@ime.fraunhofer.de (C.H.); Maria.Patras@ime.fraunhofer.de (M.A.P.)

Received: 23 October 2020; Accepted: 11 December 2020; Published: 17 December 2020

**Abstract:** The discovery of novel natural products (NPs) that will serve as lead structures has to be an ongoing effort to fill the respective development pipelines. However, identification of NPs, which possess a potential for application in e.g., the pharma or agro sector, must be as cost effective and fast as possible. Furthermore, the amount of sample available for initial testing is usually very limited, not least because of the fact that the impact on the environment, i.e., the sampled biosystem, should be kept minimal. Here, our pipeline SeaPEPR is described, in which a primary bioactivity screening of crude extracts is combined with the analysis of their metabolic fingerprint. This enabled prioritization of samples for subsequent microfractionation and dereplication of the active compounds early in the workflow. As a case study, 76 marine sponge-derived extracts were screened against a microbial screening panel. Thereunder, human pathogenic bacteria (*Escherichia coli* ATCC35218 and *Staphylococcus aureus* ATCC33592) and yeast (*Candida albicans* FH2173), as well as the phytopathogenic fungus *Septoria tritici* MUCL45407. Overall, nine extracts revealed activity against at least one test organism. Metabolic fingerprinting enabled assigning four active extracts into one metabolic group; therefore, one representative was selected for subsequent microfractionation. Dereplication of the active fractions showed a new dibrominated aplysinopsin and a hypothetical chromazonarol stereoisomer derivative. Furthermore, inhibitory activity against the common plant pest *Septoria tritici* was discovered for NPs of marine origin.

**Keywords:** natural products; dereplication; antibiotics; marine sponges; plant pathogen
