Ekstraktivi v lesu debel, grč in vej bele jelke ter njihov fungicidni potencial

Keržič, Eli (author), Vek, Viljem (mentor)

Analizirali smo kemijsko sestavo ekstraktivov v beljavi, jedrovini, grčah in vejah bele jelke (Abies alba Mill.) ter preučili njihove fungistatične, antimikrobne in antioksidativne lastnosti. Preiskali smo variabilnost v vsebnosti ekstraktivov v centripetalni smeri, torej od perifernega dela debla proti strženu, ter v longitudinalni smeri. Izolirali smo vzorce lesa debla, grč in vej. Jelovino smo ekstrahirali pri povišani temperaturi in tlaku s cikloheksanom in acetonom. Vsebnosti ekstraktivov in celokupnih fenolov smo določili z gravimetrično in s spektrofotometrično metodo. Fenolne ekstraktive smo identificirali s tankoplastno kromatografijo in s tekočinsko kromatografijo visoke ločljivosti. Fungistatične, antimikrobne in antioksidativne lastnosti ekstraktivov smo ocenili z difuznim testom in z metodo lovljenja difenilpikrilhidrazilnega radikala. Ugotovili smo, da največ hidrofilnih ekstraktivov vsebuje les grč in vej, manj jedrovina, najmanj pa beljava. Med identificiranimi spojinami so lignani, fenolne kisline in flavonoidi. V živih grčah in vejah je bilo največ sekoizolaricirezinola, v jedrovini pa matairezinola. Največ fenolnih spojin smo ekstrahirali iz delov grč, ki so vključene v beljavo ter delov vej tik ob deblu. Jedrovina je vsebovala več lignanov v njenih starejših delih. Značilne variabilnosti v vsebnosti ekstraktivov v longitudinalni smeri debla nismo ugotovili. Hidrofilni ekstrakti grč in vej so inhibirali razvoj gliv razkrojevalk lesa ter plesni, vendar pa inhibicija ni bila močna. Ekstrakti grč in vej so izkazali dobre antioksidativne lastnosti. Ugotovili smo, da so ekstrakti grč in vej boljši lovilci prostih radikalov kot ekstrakti jedrovine. Rezultati pričujoče raziskave opisujejo les grč in vej kot najbogatejši vir fenolnih ekstraktivov in lignanov v drevesu bele jelke. Rezultati testov bioloških aktivnosti kažejo na to, da lahko zaščitno funkcijo fenolnih ekstraktivov v lesu bele jelke pojasnimo tudi z njihovimi antioskidativnimi lastnostmi.

• Language: Slovenian
• Keywords: grče, bela jelka, ekstraktivi, variabilnost, kromatografija, naravni antioksidanti
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Publisher: [E. Keržič]
• Year: 2019
• PID: 20.500.12556/RUL-109790
• UDC: 630*813..2
• COBISS.SI-ID: 3110025
• Publication date in RUL: 08.09.2019

Secondary language

• Language: English
• Title: Extractives in wood of stems, knots and branches in silver fir and their fungicidal potential

Abstract

We analysed the chemical composition of extracts in the sapwood, heartwood, knots and branches of silver fir (Abies alba Mill.) and examined their fungistatic, antimicrobial and antioxidative properties. We investigated the variability in extract content in the centripetal direction, that is, from the periphery of the trunk towards the pith, and in the longitudinal direction. We isolated wood samples from the trunk, knots and branches. The wood was extracted at an elevated temperature and pressure. Cyclohexane and acetone were used as solvents. Extract and total phenol content were determined by the gravimetric and spectrophotometric methods. Phenolic extracts were identified using thin-layer chromotography and high-resolution liquid chromatography. Fungistatic, antimicrobial and antioxidative properties of the extracts were assessed with a diffusion test and the diphenylpicrylhydrazyl radical scavenging method. We found that knot and branch wood contains the highest amount of hydrophilic extracts, heartwood less so and sapwood the least. Among the identified compounds are lignans, phenolic acids and flavonoids. Secoisolariciresinol was predominent in live knots and branches, while matairesinol was prevalent in heartwood. The largest amount of phenolic compounds was extraced from sections of knots included in the sapwood and from parts of branches closest to the trunk. Heartwood contained more lignans in its older sections. A characteristic variability in extract content in the longitudinal direction of the trunk was not found. Hydrophilic extracts from knots and branches inhibited the growth of wood-decay fungi and molds, but the inhibition was not strong. Knot and branch extracts exhibited good antioxidative properties. We found that knot and branch extracts are better free radical scavengers than heartwood extracts. The results of this study describe knot and branch wood as the richest sources of phenolic extracts and lignans in a silver fir tree. Results of biological activity tests indicate that the protective function of phenolic extracts in silver fir wood can also be explained by their antioxidative properties.

• Keywords: knots, silver fir, extractives, variability, chromatography, natural antioxidants