Antioxidant properties and essential oil composition of Calamintha grandiflora L.

Essential oil was isolated from the leaves of Calamintha grandiflora L. by hydrodistillation and analysed by gas chromatography–mass spectrometry (GC–MS). The most abundant compounds in C. grandiflora essential oil were isomenthone, neo-isomenthol, pulegone and isomenthol, constituting 34.07%, 7.65%, 19.83% and 19.54%, respectively. The residues obtained after hydrodistillation were separated into the solid and liquid fractions, the former one was extracted with acetone, methanol and ethanol, while the latter one was sprayed or freeze dried. Antioxidant potential of extracts was evaluated by DPPH (batch and HPLC-on-line) and ABTS+ radical scavenging, ferric ion reduction (FRAP) assays and by the effect on oil peroxidation in Oxipres apparatus. The content of total phenolic compounds, flavonoids and flavonols was determined spectrophotometrically. Rosmarinic and salvianolic C acids were identified as the main antioxidants in C. grandiflora.