Antioxidant flavonoids from knotwood of Jack pine and European aspen

Flavonoids have recently been found in large amounts in knotwood and stemwood of several tree species. Six flavonoids, two flavonoid glucosides, and one cinnamic acid derivative were isolated from Jack pine and European aspen knotwood and structurally characterised using GC-MS, HR-MS, and NMR spectroscopic analyses. Isolated compounds were further assessed on basis of their potency to inhibit lipid peroxidation and scavenge peroxyl radicals. All tested compounds possessed antioxidant properties close to that of the reference compound Trolox.