External leaf flavonoids of Thymus species from Macedonia

Abstract

External flavonoids of 40 Macedonian species and infraspecific taxa of Thymus, belonging to sections Marginati, Pseudothymbra and Serpyllum, were studied by HPLC combined with diode array detection and atmospheric pressure chemical ionisation mass spectrometry. Nineteen different flavones were identified and the most common and abundant compound was 5,6-dihydroxy-7, 3′,4′-trimethoxyflavone. Most species also produce surface flavanones, including eriodictyol, naringenin and isosakuranetin. The external flavonoid profiles found in species of Thymus provide useful additional taxonomic characters at various different levels of classification. © 2003 Elsevier Science Ltd. All rights reserved.