Wood anatomical characteristics and chemical composition of Prosopis laevigata grown in the Northeast of Mexico

摘要

Structural heartwood characteristics for Prosopis laevigata (Humb. & Bonpl. exWilld.) M.C. Johnst., including a histometrical evaluation, were obtained by light microscopy coupled with a digitised image analysis system. The growth ring boundaries of the semi-ring-porous or diffuse-porous wood are often marked by a marginal parenchyma band. Average fibre length is 975 mu m, the fibres are thick-walled with a single cell wall thickness of 13 mu m on average. Average diameter of the vessels which are arranged in non-specific patterns differs significantly between earlywood (116 mu m) and latewood (44 mu m). The topochemical distribution of lignin and phenolic deposits in the tissue was investigated by means of scanning UV microspectrophotometry (UMSP). Thereby, in heartwood tissue the deposition of extractives in vessels, pit canals, parenchyma cells, fibre lumina and partly also in the S-2 layers of the fibres was detected. Monosaccharides were qualitatively and quantitatively determined by borate complex anion exchange chromatography. Holocellulose content is between 61.5 and 64.7 % and Klason lignin content between 29.8 and 31.4%. Subsequent extraction of the soluble compounds was performed with petrolether, acetone/water and methanol/water by accelerated solvent extraction (ASE). Total extractives content in heartwood ranges between 14 to 16 % on a dry weight basis. Major compounds in acetone/water extracts were identified as (-)-epicatechin, (+)-catechin and taxifolin, and quantitatively determined by liquid chromatography (RP-HPLC-UV).