*Article* **Structural Identification of Antibacterial Lipids from Amazonian Palm Tree Endophytes through the Molecular Network Approach**

**Morgane Barthélemy 1, Nicolas Elie 1, Léonie Pellissier 2, Jean-Luc Wolfender 2, Didier Stien 3, David Touboul 1,\* and Véronique Eparvier 1,\***


Received: 31 March 2019; Accepted: 17 April 2019; Published: 24 April 2019

**Abstract:** A library of 197 endophytic fungi and bacteria isolated from the Amazonian palm tree *Astrocaryum sciophilum* was extracted and screened for antibacterial activity against methicillin-resistant *Staphylococcus aureus* (MRSA). Four out of five antibacterial ethyl acetate extracts were also cytotoxic for the MRC-5 cells line. Liquid chromatography coupled to tandem mass spectrometry (UPHLC-HRMS/MS) analyses combined with molecular networking data processing were carried out to allow the identification of depsipeptides and cyclopeptides responsible for the cytotoxicity in the dataset. Specific ion clusters from the active *Luteibacter* sp. extract were also highlighted using an MRSA activity filter. A chemical study of *Luteibacter* sp. was conducted leading to the structural characterization of eight fatty acid exhibiting antimicrobial activity against MRSA in the tens of μg/mL range.

**Keywords:** *Astrocaryum sciophilum*; endophytes; molecular networking; antibacterial; cytotoxicity; fatty acids
