The antimicrobial activity of ethanolic extracts derived from the fruits of wild and cultivated carrots against clinical isolates of Gram-positive and Gram-negative bacteria

Abstract

In this study, we evaluated the in vitro antimicrobial activity of ethanolic extracts from the fruits of Daucus carota subsp. carota (wild carrot) and Daucus carota subsp. sativus (cultivated carrot) against five clinically significant bacterial strains: Acinetobacter sp. 12/19, Escherichia coli 83, Streptococcus pneumoniae UEV, Staphylococcus aureus MP1989, and Enterococcus faecalis 26. The antimicrobial activity was determined using the serial dilution method, followed by the establishment of the minimum inhibitory concentration (MIC₅₀) that caused 50% inhibition of the growth of the tested cultures. The results demonstrated a pronounced antimicrobial activity of the tested extracts against all tested strains. The ethanolic extract from D. carota subsp. carota fruits showed higher antimicrobial activity compared to the extract from D. carota subsp. sativus. Specifically, against Acinetobacter sp. 12/19, the extract from wild carrot fruits exhibited a bacteriostatic effect at concentrations starting from 2.0 µg/mL. Against E. coli 83, both extracts demonstrated comparable antibacterial activity, with an MIC₅₀ at the level of 2.0 µg/mL (growth inhibition was 59% relative to the control). However, the minimal bactericidal concentration (MBC) for both extracts was determined as 135 µg/mL, indicating a less pronounced bactericidal effect compared to ceftriaxone, which was used as a reference drug. Against S. pneumoniae UEV, both extracts showed comparable levels of growth suppression across the entire range of tested concentrations, with the percentage of inhibition ranging from 86% (at low concentration) to 93% (at high concentration). Against S. aureus MP1989, both extracts demonstrated bacteriostatic activity in the concentration range of 2.0-135 µg/mL, with a percentage of inhibition from 32.8% to 95.7% for the D. carota subsp. carota extract and from 49.9% to 92.8% for the D. carota subsp. sativus extract. Against E. faecalis 26, the tested extracts were inferior in activity to ceftriaxone, but exhibited a pronounced bacteriostatic effect, with a percentage of inhibition from 69.0% to 96% in the concentration range of 8.0-67.0 µg/mL. The obtained results indicate the promise of further study of the phytochemical composition and antimicrobial potential of Daucus carota fruit extracts for the development of new antimicrobial agents.