Sung Phil Mun

Characterization of proanthocyanidin in hot water extract isolated from Pinus radiata bark

Proanthocyanidins (PAs) in the hot water extract prepared from Pinus radiata bark were isolated by a Sephadex LH-20 chromatography. The PAs were characterized using UV/Visible, FT-IR and 13C nuclear magnetic resonance (NMR) spectroscopic techniques, matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry (MS), and gel permeation chromatography (GPC) analysis. Bate-Smith acidic alcoholysis and FT-IR spectrum of the PAs indicated the predominant presence of the procyanidin (PC) structure. The 13C NMR spectrum revealed that the PAs comprise PC (94%) together with a small amount of prodelphinidin (PD, 6%), and also that they contain the higher trans configuration rather than the cis configuration of C2–C3. The MALDI-TOF MS results obviously proved the presence of PD units, but the maximum degree of polymerization (DP) was limited to octamer. The average molar mass (Mw, Mn), polydispersity (Mw/Mn), and DP of the pine bark PAs were 3,800 (Mw), 1,200 (Mn), 3.2, and 13, respectively.

Effect of tree age on the cellulose structure of Nalita wood (Trema orientalis)

The change of crystalline structure of Nalita cellulose with tree age has been studied using X-ray diffraction and FT-IR spectroscopy. The proportion of crystallinity and crystal size were increased with tree age. FT-IR spectroscopy showed that the Nalita cellulose was a monoclinic unit cell structure (Iβ). The proportion of crystallinity and crystal size of the 30-month-old Nalita wood was higher as compared to aspen wood. The degree of polymerization (DP) of Nalita cellulose of different ages has also been studied. The DP of cellulose increased with tree age. The DP of Nalita cellulose was lower than that of aspen cellulose. The percentage of glucose in Nalita wood increased with tree age.

Characteristics of Dioxane Lignins Isolated at Different Ages of Nalita Wood (Trema orientalis)

Abstract Nalita (Trema orientalis) is one of the fastest growing trees in the tropical countries. The structural characteristics of lignin isolated at different ages of Nalita wood (Trema orientalis) by acidolytic dioxane method were examined by UV, FTIR, 1H‐NMR and 13C‐NMR spectroscopy, alkaline nitrobenzene oxidation, molecular weight determination, elemental and methoxyl analysis. The data were compared with aspen lignin. The structural analysis revealed that Nalita wood lignin is syringyl‐guaiacyl type. The methoxyl content in Nalita wood lignin was lower than aspen lignin. The C9 formulas for 30‐months‐old Nalita was C9H9.31O3.13(OCH3)1.27, whereas that of aspen was C9H8.94O3.15(OCH3)1.47. The weight average molecular weight of Nalita wood lignin was decreased from 36,500 to 25,500 with increasing tree age from 12 to 30 months, whereas weight average molecular weight of aspen was 20,000. Both alcoholic and phenolic hydroxyl group in Nalita wood lignin is lower than aspen lignin.

Chemical characterization of six mangrove species in Bangladesh

Lack of data especially pertaining to the chemistry of mangrove wood species makes it difficult to prepare successful plans for their conservation and to use mangroves as a source of wood fiber. In this paper, chemical characterizations of the six main mangrove species of Bangladesh [namely Keora (Sonneratia apetala), Geoa (Excoecaria agallocha), Bine (Avicennia alba), Sundari (Heritiera fomes) Pashur (Xyloccarpous mekongests), and Kakra (Bruguiera gymnorhiza)] were investigated. The chemical results revealed that these species contain high percentages of dichloromethane followed by methanol extractives. Methanol extracts in Pashur, Sundari, and Bine were higher than 10%, which indicates high percentage of tannin material. The total lignin content in these species was higher than 25%, except for Gewa (23.6%) and Pashur (21.3%), which is higher than that of the normal range of hardwood. The pentosan content in these six species was within the range of 19.4–22.8%. The α-cellulose content in Keora and Gewa was acceptable for pulp production, but the others were lower than the normal range of hardwood. Alkaline nitrobenzene oxidation showed that all these species had a very high syringaldehyde to vanillin (2.6–5.0) ratio except Keora (1.6). Surprisingly, rhamnose is the main constituent with xylose of hemicelluloses of these six mangrove species. The ash content in these six mangrove wood species was also higher than that in normal hardwood.