Chemical Composition of Essential Oil and Evaluation of Antimicrobial and Antidiabetic Activities of Teucrium kotschyanum Poech (Lamiaceae)

The genus Teucrium L., member of Lamiaceae, is represented by approximately 36 species in Türkiye. In this study, the essential oil composition of the aerial parts of Teucrium kotschyanum Poech collected from İzmir (Ödemiş) was investigated by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The major compounds were identified as germacrene D (20.0 %), α-cadinol (6.9 %), β-bourbonene (6.6 %), hexadecanoic acid (6.6 %), δ-cadinene (5.9 %) and manool (4.1 %). The antibacterial and antifungal activities of the essential oil were studied against six bacteria and six fungi using the microdilution broth method. The essential oil showed moderate to weak inhibitory effects. The minimum inhibitory concentration (MIC) ranged from 125 to 2000 μg/mL for all tested microorganisms. The present study was also designed to evaluate the antidiabetic effects of the essential oil and extracts of the root and aerial parts of Teucrium kotschyanum via their potential inhibition of the related key enzymes. Essential oil showed significantly higher activity with an IC50 value of 100.25 mg/mL, than the positive control, with an IC50 value of 122.03 mg/mL. Among the extracts, the best activity was observed in the petroleum ether and ethyl acetate extracts of root parts, with the inhibition value of 94.79%, 55.49%, respectively.