Phytochemical Characterization of the Aerial Parts of Teucrium nuchense K. Koch: An Endemic Species of Caucasian Flora

Background: The genus Teucrium L. is frequently employed in traditional medicine, primarily for addressing disorders of the digestive and respiratory systems. Biological investigations focused on essential oils have substantiated their antibacterial, antioxidant, anti-tumor, anti-diabetic, and anti-rheumatic properties. Objective: The aim of the study was to assess the chemical composition and biological activities of the aerial parts of the endemic species Teucrium nuchense K. Koch. Methods: The chemical composition of the essential oil was analyzed using gas chromatography-mass spectrometry (GC-MS). The antioxidant activity was evaluated through the Oxygen Radical Absorbance Capacity (ORAC) assay and tested on normal skin fibroblasts (WS-1). Additionally, the antiinflammatory efficacy was assessed by monitoring nitric oxide production. The total phenolic content in the aqueous, methanolic, and chloroformic extracts was quantified using the Folin-Ciocalteu reagent. Individual compounds were isolated using preparative high-performance liquid chromatography. Their identification was accomplished using high-resolution mass spectrometry (HRMS) with an ESI-Q-TOF detector in conjunction with nuclear magnetic resonance (NMR) spectroscopy. Results: The essential oil yield was 0.32 ml/kg. Caryophyllene oxide, constituting 15.19 %, and 1- octen-3-ol, constituting 8.75%, emerged as the primary components in the essential oil. Oxygenated sesquiterpenes dominated the terpenic compounds, representing 25.1 % of the essential oil. The aqueous and methanolic extracts displayed a notable phenolic content, with percentages of 27 ± 2 % and 35 ± 0.1 %, respectively. Both the aqueous and methanolic extracts demonstrated robust antioxidant activity in the ORAC test and in vitro assessments using WS-1 cells. The methanolic extract, at a concentration of 160 μg/ml, inhibited NO formation by 90 %, without toxicity in RAW 264.7. Individual compounds, teucrioside from the phenylethanoid glycoside class, two neo-clerodane diterpenes, teucrin A, and 6-alpha-hydroxyteuscordine, were isolated. Conclusion: The essential oil extracted from the aerial parts of Teucrium nuchense is characterized by the presence of caryophyllene oxide and 1-octen-3-ol. The methanolic extract exhibits notable antioxidant as well as anti-inflammatory properties, whereas the aqueous extract demonstrates high antioxidant activity. Additionally, three compounds of teucrioside, teucrin A, and 6-α- hydroxyteuscordine have been isolated and characterized.