Chemical composition and biological activity of Peucedanum dhana A. Ham essential oil

The essential oil was extracted from Peucedanum dhana A. Ham, which grows in Thailand, using a Clevenger apparatus, resulting in an oil yield of 0.76% w/w. Forty-two compounds were identified using gas chromatography-mass spectrometry. The major compounds were trans-piperitol (51.23%), β-pinene (11.72%), o-cymene (11.12%), γ-terpinene (9.21%), and limonene (4.91%). The antimicrobial activity of the P. dhana essential oil was investigated by measuring the inhibition zone diameter, minimum inhibitory concentration (MIC), and minimum microbicidal concentration (MMC). The inhibition zone diameters of P. dhana essential oil (1000 µg/mL) against tested pathogens ranged from 10.70 to 40.80 mm. Significant antimicrobial activity against tested pathogens was obtained, with MIC and MMC values of 62.50-250 µg/mL and 250-1000 µg/mL, respectively. Escherichia coli, Pseudomonas aeruginosa, and Enterobacter aerogenes exposed to P. dhana essential oil at the MIC were analysed by flow cytometry using propidium iodide (PI) and SYTO9 to assess membrane integrity compared to trans-piperitol and β-pinene. After 24 h, treatments with trans-piperitol resulted in the most significant cell membrane alteration and depolarization followed by P. dhana essential oil and β-pinene, respectively. It was demonstrated that the P. dhana essential oil presented antibacterial action against E. coli, P. aeruginosa, and E. aerogenes. The antioxidant activity of P. dhana essential oil was measured using 2,2-diphenyl-2-picrylhydrazyl (DPPH) and 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium (ABTS) scavenging activity assays. The IC₅₀ values obtained from the DPPH and ABTS methods were 9.13 and 9.36 mg/mL, respectively. The cytotoxic effect of P. dhana oil was tested against human colonic adenocarcinoma (SW480), human lung adenocarcinoma (A549), cervical cancer (Hela), and murine fibroblast (3T3L1) cells using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The essential oil had cytotoxicity against all cancer cells, with significant cytotoxicity towards SW480 cells. As a control experiment, two pure compounds-trans-piperitol and β-pinene, were also tested for their antimicrobial, antioxidant, and cytotoxic activity. Both compounds showed varied activity in all assays. The results indicate that P. dhana essential oil could be used as a source of functional ingredients in food and pharmaceutical applications.