Unveiling multifaceted antimicrobial effect of epicatechin: from bacteria to filamentous fungi and beyond.

This study evaluated the biological properties of epicatechin, a polyphenolic compound widely distributed in green tea, grapes, various berry species, and other dietary matrices, examining its effects on bacteria, filamentous fungi, and the in vivo model Galleria mellonella. Epicatechin proved inhibitory activity against both model bacterial strains and clinical or environmental isolates. Specifically, it was effective against Staphylococcus strains by inhibiting their growth, and against Gram-negative bacteria by preventing biofilm formation. Furthermore, epicatechin increased the susceptibility of MRSA (methicillin-resistant Staphylococcus aureus) to several antibiotics, including cefoxitin, gentamicin, and tetracycline. The in vivo experiments using Galleria mellonella larvae infected with MRSA and treated with high doses of epicatechin displayed an increase in larval survival during the initial 24 h post-infection. Epicatechin exhibited no inhibitory activity against pathogenic yeasts and most of tested filamentous fungi. However, its effect was well pronounced in Neurospora crassa. In this specific case, epicatechin enhanced the efficacy of echinocandins and azoles. The safety profile of epicatechin was confirmed by the Ames test and in vivo toxicity assessments using Galleria mellonella, both indicating that epicatechin is non-mutagenic and non-toxic. These findings highlight the potential of epicatechin, particularly in antimicrobial and antifungal applications.