Research Information System
SAKARYA UNIVERSITY JOURNAL OF SCIENCE, vol.27, no.5, pp.991-1001, 2023 (Peer-Reviewed Journal)
In recent years, dramatically rising multidrug-resistant bacteria (MDR) and side effects of
antibiotics lead ethnopharmacology to discover novel antimicrobials derived from plants for
bacterial infections. Traditionally, decoction or infusion of the species of Sideritis has been used
for the treatment of diseases such as cough, stomach, gastrointestinal, and kidney disorders. In
this study, we aimed to investigate the antioxidant and antibacterial activity of the ethanolic
extract of Sideritis trojana (S.trojana) and its synergistic potential with antibiotics against
human pathogens. Gas chromatography-mass spectrometry (GC-MS), Folin- Ciocalteu, 1-
diphenyl-2-picrylhydrazyl radical (DPPH), disc diffusion, and minimum inhibitory
concentration (MIC) assays were used for identifying phytochemicals, total phenolic content
(TPC), antioxidant, and antibacterial activity of ethanolic extract of S.trojana alone and binary
combination with selected antibiotics against Gram-positive and Gram-negative bacterial
strains, respectively. Furthermore, the combined effects of the extract with classical antibiotics
were evaluated by measuring the inhibition zone diameter (IZD). The S.trojana extract showed
moderate antibacterial activity with the MIC ranging between 15.625 to 500 µg/mL against
human pathogens and the synergistic effect was detected in a dual combination of extract and
antibiotics. The extract exhibited high antioxidant activity with a low IC50 value (0.138±0.010
mg/mL). The TPC value was 47.95±0.24 (mg GAE/g extract). After measurements of
cytotoxicity were performed, S.trojana can be used alone or combined with antibiotics as an
alternative therapy to eliminate pathogens and can be preferred as an antioxidant agent in the
pharmaceutical industry.