Evaluation of wood chemical constituents of Hevea brasiliensis and Cupressus decomposed by Gloeophyllum striatum using CP/MAS 13C NMR and HPLC techniques
2010
Cruz, C. L. da S. C. | Resck, I. S. | Santos, P. H. O. | Okino, E. Y. A. | Santana, M. A. E. | Falcomer, V. A. S.
The aim of this study was to evaluate chemical changes in wood constituents of six rubberwood Hevea brasiliensis clones and two cypress Cupressus glauca and Cupressus spp., exposed to brown-rot fungus Gloeophyllum striatum. Wood constituents were analysed before and after deterioration by HPLC and CP/MAS 13C NMR. Extractive contents increased, on average, 1.3 and 1.7 times in attacked rubberwood and cypress respectively. Ash content increased 12.5% in attacked rubberwood. Fungus in rubberwood relatively decreased cellulose as much as 8.9% and an increase of 16% in total lignin. However, there was no clear trend in hemicelluloses. Cypress showed a relative decrease of 3.6% in cellulose, 15.1% in hemicelluloses and an increase of 14.6% in total lignin. Mannan was removed faster than xylan, and both faster than glucan. Cypress showed higher content of xylan than mannan. Nevertheless, rubberwood showed higher acetyl groups than cypress. Gloeophyllm striatum corroborated the biodeterioration pattern where more carbohydrate was removed than lignin. Spectroscopic and chromatographic techniques are shown to be complementary tools in assessing chemical changes in wood. HPLC is time consuming in sample preparation but the results are quantitative and accurate. On the other hand, CP/MAS uses non-destructive samples, demands high end machine and the results are qualitative but suitable for monitoring structural organic changes.
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