Dihydroquercetin [(2,3-trans)-3,3',4',5,7-pentahydroxyflavanonol]
was shown to be the precursor to the phenolic
stains that often develop in Douglas-fir [Pseudotsuga
menziesii (Mirb.) Franco] sapwood. Douglas-fir sapwood was
extracted with methanol and the methanol solubles were
fractionated by solvent partition, thin-layer chromatography,
silica-gel column chromatography, and Sephadex gelpermeation
chromatography. Tyrosinase, a commercially
available...
