Phytochemical analysis of essential oils and the extracts of an ethnomedicinal plant, Teucrium multicaule collected from two different locations with focus on their important biological activities.

• Teucrium species have been among the most commonly used traditional medicinal plants. • Teucrium multicaule is renowned for being an important medicinal and aromatic plant. • The samples collected from two different locations were compared to each other. • The essential oils and the extracts were found to be highly rich in terms of particular phytochemicals. • The extracts exhibit significant antioxidant, enzyme inhibition, and antimicrobial activity. Teucrium species have been among the most commonly used traditional medicinal plants and they are known to have extensive therapeutic applications. The main focus of this study, Teucrium multicaule is also renowned for being an important medicinal and aromatic plant in Turkiye. Volatile profiling of the essential oils was conducted by GC–MS, phytochemical profiling of the ethanol extracts was carried out by LC HRMS, antioxidant, anticholinesterase, antityrosinase, antiurease, antidiabetic, anticancer, and antimicrobial activities were revealed by different assays. Germacrene D was the most abundant compound in the essential oils from Diyarbakir (TmuD) with 45.4%, and Batman (TmuB) with 54.7%. All extracts were found to be quite rich in phytochemicals by LC HRMS, and herniarin, caffeic acid, naringenin, luteolin, scutellarein, hispidulin, rhamnocitrin, penduletin, eupatilin, (-)-epigallocatechin gallate, hederagenin, and verbascoside were found to be present in all extracts. T. multicaule roots extract from Diyarbakir (TmuRD) demonstrated the highest radical scavenging, α-amylase inhibitory (59.82±0.36%), and antibutyrylcholinesterase activity (61.96±1.72%), whereas T. multicaule aerial parts extract from Batman (TmuHB) exhibited the strongest antityrosinase (66.17±0.92%), antiurease (67.85±0.69%), and cytotoxic (54.76 ± 1.57 μg/mL) activities. TmuRD also showed significant antimicrobial activity against S. epidermidis with 156.2 μg/mL MIC value. As revealed by this first detailed report on T. multicaule , the plant demonstrates various important biological activities attributed to its rich phytochemicals, which also justifies its use in ethnomedicine. [ABSTRACT FROM AUTHOR]