Chemical composition and biological capacity of essential oils and ethanol extracts from endemic <i>Nepeta</i> species in the Armenian flora

The chemical composition and biological activities of Nepeta species growing in Armenia were investigated. The essential oil composition was analysed using gas chromatography–mass spectrometry, which revealed the presence of key sesquiterpenes such as copaene (12.59%) and β-elemene (3.77%) across all samples. Antioxidant activity of the ethanolic extracts was evaluated <i>via</i> the DPPH radical scavenging assay, and total flavonoid content was determined, with <i>N. sulphurea</i> from Mantash showing the highest total flavonoid content (1.17 ± 0.23 mg RE/g DW). The essential oil and ethanolic extract of <i>Nepeta sulphurea</i> demonstrated the highest antibacterial and antifungal activity. The lowest MIC values (0.025–0.05 mg/mL) and the largest inhibition zones (30 mm) were recorded against <i>Enterococcus faecalis</i>. Notably, both the essential oils and ethanolic extracts from all Nepeta samples exhibited significant antimicrobial and antioxidant activities. This study contributes to the discovery and utilisation of herbs of Nepeta as a valuable source of biologically active compounds with therapeutic potential. Although Nepeta mussinii and Nepeta sulphurea growing in Armenia do not belong to any of the three established chemotype categories, further the results of their pharmacognostic and phytochemical screening can be used for the standardisation of different chemotypes of Nepeta.