TLC analysis of the in-vitro reaction of beech (Fagus sylvatica L.) wood enzyme extract with catechins

The factors affecting the economically and sylviculturally disadvantageous formation of red heartwood in beech are only partly understood. It has already been proved that at the color boundary of the red heart the total phenol concentration decreases sharply whereas the activity of oxidative enzymes (POD, PPO) increases substantially. The concentrations of (+)-catechin and (-)-epicatechin fall drastically and the five taxifolin and quercetin glycosides undergo hydrolysis. It is unclear, however, what role the flavonoids present at the boundary ((+)-catechin, (-)-epicatechin, taxifolin, and quercetin) have in the formation of the red chromophores of the heartwood. Understanding the transformation of the precursors and analysis of the products could result an enhanced utilization of red-heartwood timber and better understanding of the physiology of red heartwood formation. In this work the role of catechins has been investigated by in-vitro transformation of (+)-catechin and (-)-epicatechin by extracts of beech wood enzymes. Thin-layer chromatography with scanning densitometry and acquisition of the products' UV-visible reflection spectra proved suitable for monitoring the reactions and analyzing the products. Result have shown that rapid oxidation and oligomerization of the catechins is caused by beech enzyme extract. In-vitro products have also been compared with the chromophores of beech red heartwood. Conclusions have been drawn regarding the physiology of red heartwood formation.