Composition, phenolic content, antioxidant and antimicrobial activity of Pistacia atlantica subsp. kurdica hulls' essential oil

Chemical compounds, total phenolic content, antioxidant and antimicrobial activity of Pistacia atlantica subsp. kurdica hulls' essential oil (EO) was investigated. The EO was extracted using hydrodistillation and its GC-MS analysis showed 95 compounds, the most important of which were alpha-pinene (10.8%), beta-citral (7.0%), carvone hydrate (4.4%), myristic acid (4.9%), p-acetyltoluene (3.5%), pinocarveol (3.3%) and palustrol (3.3%). Total phenolic compounds in the EO was 178 mg GAE/100 g dry weight (dw). Antioxidant activity of the EO was measured using two methods: The FRAP (ferric reducing antioxidant power) assay and the DPPH free radical scavenging activity. The FRAP value was 6.24 mg/g, and the IC50 value using the DPPH method was 25.2 mg/mL. In addition, using broth microdilution and disc diffusion techniques, the antimicrobial activity of the EO against Escherichia coli, Pseudomonas aeruginosa, Salmonella Typhimurium, Streptococcus faecalis, Bacillus cereus, Staphylococcus aureus and Candida albicans was investigated. The minimum inhibitory concentration of the EO was between 0.13 mg/mL (C. albicans) and 0.42 mg/mL (E. coli). Moreover, the lowest minimum microbicidal concentration of the EO (0.16 mg/mL) was with C. albicans and the highest of 0.52 mg/mL was with E. coli. Furthermore, the highest inhibition zone of 24.2 mm was with C. albicans and the lowest inhibition zone of 20.8 mm was with E. coli.