Flash column chromatographic fractionation of tree of heaven (Ailanthus altissima)
stem and trunk bark extracts, guided by thin-layer chromatography (TLC)–Bacillus subtilis
assay and TLC–heated electrospray high-resolution tandem mass spectrometry (HESI-HRMS/MS),
lead to the isolation of six known compounds: (9Z,11E)-13-hydroxy-9,11-octadecadienoic
acid (13-HODE, A1), (10E,12Z)-9-hydroxy-10,12-octadecadienoic acid (9-HODE, A2), hexadecanedioic
acid (thapsic acid, A3), 16-hydroxyhexadecanoic acid (juniperic acid, A4), 16-feruloyloxypalmitic
acid (alpinagalanate, A5), and canthin-6-one (A6). Their structures were elucidated
by HESI-HRMS/MS and one- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy.
This is the first study identifying A1–A5 in A. altissima tree. Except for A5, all
isolated compounds exhibited antibacterial activity against B. subtilis in microdilution
assays. A6 showed the strongest effect with a minimum inhibitory concentration (MIC)
value of 8.3 µg/mL. The antibacterial activity of A3 and A4 is newly described.
