Resin from ant nest (Formica rufa) used in Austrian folk medicine provides a new antimicrobial compound

The escalating threat of antimicrobial resistance (AMR) represents a critical global health challenge, necessitating innovative strategies such as natural product-based drug discovery. This study explores "Waldrauch", a resin derived from wood ant (Formica rufa) nests, traditionally used in Austrian folk medicine for treating infections. A combination of thin-layer chromatography (TLC), gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance spectroscopy (NMR) was employed to identify novel compounds unique to "Waldrauch". Antimicrobial activity was assessed using microdilution assays. The compound 4-(4-isopropylcyclohexyl)acetophenone was identified as a novel constituent exclusive to ant nest resin. A fraction purified via preparative TLC, containing this bioactive compound, demonstrated significantly greater antimicrobial efficacy than coniferous resins (Picea abies and Abies alba), with a minimum inhibitory concentration (MIC) of 20 μg/mL against resistant pathogens, including methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum beta-lactamase (ESBL)-producing Enterobacter species. These findings highlight the bioactive potential of "Waldrauch" and its significance in traditional medicine. Further studies are warranted to isolate and characterize its therapeutic applications, potentially offering a novel strategy for combating antibiotic-resistant infections.