Aspen knots, a rich source of flavonoids

Suvi P. Pietarinen*, Stefan M. Willför, Frank A. Vikström, Bjarne R. Holmbom

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

35 Citations (Scopus)


Hydrophilic extractives in heartwood, sapwood, and knots of three aspen species were analyzed by gas chromatography, gas chromatography-mass spectrometry, and high-performance size-exclusion chromatography. The amounts of flavonoids were considerably higher in the knots relative to the stem wood. Flavonoids identified were dihydrokaempferol, naringenin, kaempferol, catechin, and taxifolin. In addition, glycosides of dihydrokaempferol, naringenin, and kaempferol were identified by mass spectrometry and shown to be glucosides by enzymatic hydrolysis by β-D-glucosidase. Dihydrokaempferol and its glucoside dominated in all knot samples although there were variations in the amounts and composition of the extractives. The total amounts of flavonoids varied between 11 and 43 mg/g in Populus tremula, 12 and 62 mg/g in Populus tremuloides and 47 and 82 mg/g in Populus grandidentata. The aspen knots were found to be a rich source of bioactive flavonoids.

Original languageEnglish
Pages (from-to)245-258
Number of pages14
JournalJournal of Wood Chemistry and Technology
Issue number3
Publication statusPublished - 2006
MoE publication typeA1 Journal article-refereed


  • Aspen
  • Flavonoids
  • Heartwood
  • Hydrophilic extractives
  • Knots
  • Populus grandidentata
  • Populus tremula
  • Populus tremuloides
  • Sapwood


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