Phytochemical Screening and Antimicrobial Activity Evaluation of Armenian Chaerophyllum bulbosum L

This study is the first report on the chemical composition and antimicrobial activity of Chaerophyllum bulbosum L. sampled from the Armenian flora. Essential oil (EO) and hydrosol were obtained from the aerial parts by hydrodistillation, and their chemical compositions were determined by GC-MS, identifying a total of 48 volatiles. The EO was composed of 60.42% monoterpenes and their oxygenated derivatives and 18.75% sesquiterpenes and their oxygenated derivatives, while the hydrosol was composed of 75% oxygenated monoterpenes, with the remaining 20% and 5% being monoterpenes and sesquiterpenoids respectively. Pulegone (21.55%) was identified as the major constituent. With regard to the non-volatile fraction, the methanolic extract displayed a total phenolic content of 1.17 ± 0.03 mg GAE/g dry weight and a total flavonoid content of 0.62 ± 0.02 mg QE/g, as well as significant antioxidant capacity, with IC₅₀ values of 2.87 ± 0.06 μg Trolox/g dried plant sample for the DPPH^• assay and 46.87 ± 1.2 μmol Fe²⁺/g dried plant sample for the FRAP assay. The evaluation of EO and hydrosol antimicrobial properties revealed notable antibacterial activity against Gram-positive bacteria, with inhibition zones ranging from 13.5 to 20 mm. The respective minimum inhibitory concentration (MIC) values ranged from 0.4 to 6.0 mg/mL for the EO and from 62.5 to 400 μL/mL for hydrosol, while the minimum bactericidal concentration (MBC) values ranged from 0.8 to 10.0 mg/mL and from 125 to 800 μL/mL, respectively. Streptococcus mutans was the most susceptible microorganism (MIC = 0.4 mg/mL), whereas Pseudomonas aeruginosa was the most resistant (MIC = 6.0 mg/mL). Both the EO and hydrosol exhibited antifungal activity against Candida albicans, with inhibition zones of 13.0 ± 1.2 mm and 11.0 ± 0.8 mm, respectively. The MIC and MBC values were 1.0 and 2.0 mg/mL for the EO, while the respective values for the hydrosol were 400 and 800 μL/mL. These findings highlight the C. bulbosum plant as a promising source of bioactive compounds with significant activity against Gram-positive bacteria and moderate antifungal effects that may be associated with the high content of pulegone, a monoterpene known for its membrane-disruptive properties.