Essential oils and hydrophilic extracts from the leaves and flowers of Succisa pratensis Moench. and their biological activity.

OBJECTIVES: This study was undertaken to evaluate the antioxidant activity of methanol and water extracts from Succisa pratensis Moench (Dipsacaceae) leaves and flowers as well as the chemical composition of the essential oils found in them and the antimicrobial activity of the oils and extracts thereof.

METHODS: The essential oils from S. pratensis leaves and flowers were analysed by the GC-MS. The total phenolic content was determined with Folin-Ciocalteu, that of flavonoids with aluminium chloride and that of phenolic acids with Arnov's reagent. The antioxidant activity was investigated by the DPPH radical scavenging assay. Antimicrobial activity was studied in vitro against G-positive and G-negative bacteria, and fungi using disc diffusion and broth microdilution methods.

KEY FINDINGS: Eighty-six components of the leaf essential oil and 50 of the flower essential oil were identified. The main components of the leaf essential oil were 2-hexyl-1-octanol (5.76%) and heptacosane (5.53%), whereas hexadecanoic acid (16.10%), 8-octadecen-1-ol acetate (9.86%), methyl linolenate (8.58%), pentacosane (6.63%) and heptacosane (5.50%) were found in the flower essential oil. The essential oils exerted high antimicrobial activity (range: 0.11 to >3.44mg/ml) against the following bacteria: Pseudomonas aeruginosa, Staphylococcus aureus and fungi: Trichophyton mentagrophytes, Candida albicans, whereas the methanol and water extracts showed moderate or weak activity. The strongest antioxidant activity was shown by methanol extracts from S. pratensis leaves, IC50 = 0.09 mg/ml. There was a positive correlation between the total phenolic content and the antimicrobial activity, while for the antioxidant effect, it was not observed.

CONCLUSIONS: The results suggest great antibacterial activity of the oils and high antioxidant activity of the methanol extract and may justify the application in treating infections.