Bioassay-Guided Isolation and Identification of Antibacterial Compounds from Invasive Tree of Heaven Stem and Trunk Bark.

Flash column chromatographic fractionation of tree of heaven () stem and trunk bark extracts, guided by thin-layer chromatography (TLC)- assay and TLC-heated electrospray high-resolution tandem mass spectrometry (HESI-HRMS/MS), lead to the isolation of six known compounds: (9,11)-13-hydroxy-9,11-octadecadienoic acid (13-HODE, ), (10,12)-9-hydroxy-10,12-octadecadienoic acid (9-HODE, ), hexadecanedioic acid (thapsic acid, ), 16-hydroxyhexadecanoic acid (juniperic acid, ), 16-feruloyloxypalmitic acid (alpinagalanate, ), and canthin-6-one (). Their structures were elucidated by HESI-HRMS/MS and one- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy. This is the first study identifying - in tree. Except for , all isolated compounds exhibited antibacterial activity against in microdilution assays. showed the strongest effect with a minimum inhibitory concentration (MIC) value of 8.3 µg/mL. The antibacterial activity of and is newly described.