Essential oils from Colombian Croton spp. exhibit antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and ampicillin- and streptomycin-resistant Escherichia coli

Bacterial resistance, a global public health concern prioritized by the World Health Organization, is particularly alarming in Staphylococcus aureus and Escherichia coli. Urgently addressing this, the search for new antibiotics has turned to plant essential oils. Our study focused essential oils derived from Colombian plants Croton killipianus, Croton smithianus, Croton leptostachyus, Croton hondensis, and Croton gossypiifolius. We performed antimicrobial susceptibility tests targeting Staphylococcus aureus, methicillin-resistant Staphylococus aureus, sensitive Escherichia coli, and ampicillin- and streptomycin-resistant Escherichia coli. Simultaneosly, citotoxic assays and chemical analysis were carried out. The essential oil derived from C. hondensis demonstrated superior inhibitory efficacy, effectively targeting methicillin-resistant S. aureus, susceptible S. aureus, and both sensitive and ampicillin- and streptomycin-resistant strains of E. coli. Furthermore, it exhibited notable potential for protective activity in Chinese hamster ovary cells. C. killipianus manifested inhibitory effects against MRSA and susceptible S. aureus, whereas C. smithianus specifically affected susceptible strains of S. aureus. Chemical analysis of the essential oils revealed rich content in phenolic compounds, flavonoids, tannins, and steroids. Gas-coupled mass spectrometry identified key compounds like γ-muurolene, α-humulene, (E)-caryophyllene, α-copaene, curcumene, and (E)-nerolidol. These findings underscore C. hondensis, C. killipianus, and C. smithianus as potential natural sources for antibacterial agent development.