Antibacterial sesquiterpenes from the stems and roots of Thuja sutchuenensis.

• Thuja sutchuenensis , an endangered China native plant, has been systematically investigated focusing on secondary metabolites. • Eight novel sesquiterpenes (1 – 8) with diverse skeletons were isolated from the stems and roots of T. sutchuenensis. • Compounds 5 (thujasutchin J) and 9 exhibited considerable antibacterial activities with MIC ranging from 6.25 to 25 μg/mL. Eight new sesquiterpenes with diverse skeletons involving four cuparenes, denominated thujasutchins F-I (1 – 4), one eudesmane and one cedrol, named thujasutchin J (5) and thujasutchin K (6), as well as two thujopsenes thujasutchins L-M (7 – 8) together with three known congener compounds (9 – 11) were isolated from EtOAc soluble fraction of ethanolic extract of the stems and roots of Thuja sutchuenensis. Their structures including absolute configurations were unambiguously established by extensive interpretation of the NMR and mass spectroscopic data, X-ray diffractions, and ECD measurements powered by molecular calculations. The biological assays disclosed that 5 and 9 displayed potent inhibitory effect against Staphylococcus. aureus (CMCC 26003), methicillin-resistant Staphylococcus aureus (JCSC 4744), Bacillus cereus (ATCC 10876), and Staphylococcus epidermidis (ATCC 12228) with MICs ranging from 6.25 to 25 μg/mL. [ABSTRACT FROM AUTHOR]