Determination of contents of total phenols in sapwood and red heart of beach by UV/VIS spectrophotometry

Preiskovali smo 2 bukvi (Fagus sylvatica L.), požagani v urbanem gozdu na pobočju Rožnika, Ljubljana. Namen naše preiskave je bil ugotoviti vsebnost celokupnih fenolov in delež ekstraktibilnih snovi v beljavi, rdečem srcu in reakcijskih conah na različnih višinah vzdolž drevesa. Drevesa smo razžagali, odvzeli vzorčne kolute, jih skrbno pregledali, označili vzorce, jih izžagali, zmleli in posušili. Lesni prah smo nato ekstrahirali v hladni vodni raztopini 80 % metanola s pomočjo magnetnega mešala. Delež celokupnih fenolov smo določili spektrofotometrično po Folin-Ciocalteau metodi. Ugotovili smo, da je vsebnost celokupnih fenolov v drevesu št. 1 večja v beljavi in reakcijski coni, rdeče srce pa ima nižjo povprečno vsebnost celokupnih fenolov kot rdeče srce v drevesu 2. Najvišja povprečna vsebnost celokupnih fenolov je v lesu reakcijske cone (drevo št. 1). Drevo 2 ima največjo povprečno vsebnost celokupnih fenolov v lesu beljave, sledi ji reakcijska conanajmanjši povprečni delež celokupnih fenolov pa je v lesu rdečega srca. Rdeče srce bukve je tkivo, ki vsebuje najmanj ekstraktibilnih snovi in najmanj fenolnih. Porazdelitev fenolnih snovi v drevesu odraža fiziološko funkcijo, ki jo imajo ta tkiva v drevesu.2 beech trees (Fagus sylvatica L.), cut down in urban forest of Rožnik in Ljubljana, were investigated. The aim of our work was examination of content of total phenols and content of total extractable substances in sapwood, red heart and reaction zones at different heights along the trees. The trees were dissected and discs removed. They were carefully examined macroscopicallythe samples were marked, dissected, milled and dried. Then wood powder was extracted in cold 80 % aqueous solution of methanol by aid of magnetic stirrer. Contents of total phenols were determined spectrophotometrically according to Folin-Ciocalteau method. We found out that the content of total phenols was higher in sapwood and reaction zone in the tree No. 1 than in the tree No. 2. Red heart in tree No. 1 had lower content of total phenols then the red hart in tree No. 2. The highest average content of total phenols was in reaction zones in tree No. 1. The tree No. 2 had the highest content of total phenols in sapwood, following by reaction zone, whereas the least phenolic compounds were found in red heart in both trees. Distribution of phenolic compounds in the tree reflects its physiological function of tissues in the living tree