Characterization of Thitsiol Dimer Structures fromMelanorrhoea usitatawith Laccase Catalyst by NMR Spectroscopy

Polysaccharide metabolism in Anacardiaceae (Asian lacquer) cross-linked polymers elucidated using in situ trimethylsilylation pyrolysis-gas chromatography-mass spectrometry

Carbohydrates from polysaccharides in natural thermoset Anacardiaceae polymers of Gluta usitata, Toxicodendron succedaneum and Toxicodendron vernicifluum were identified using pyrolysis-gas chromatography-mass spectrometry with in situ trimethylsilylation. Pyrolysates resulting from the pyrolytic intermolecular chain scission of the polysaccharides were used to elucidate monomeric units. Polysaccharides, dispersed in the phenolic lacasse catalysed cross-linked macromolecules, showed to be metabolised through various catabolic and anabolic routes. Galactose functionalities, abundantly present in the polysaccharides were determined to be enzymatically converted to glucose-6-phosphate, followed by conversion via glycolysis and pentose phosphate pathways. Determination of specific routes of carbohydrate modification via glycolysis and pentose phosphate pathways facilitated differentiating G. usitata, T. succedaneum and T. vernicifluum polymers, based on the carbohydrate content. It was also found that uronic type acids, present as end groups of the branched polysaccharide structure, were biochemically converted to aldonic acids. Following the pentose phosphate and glycolysis routes, carbohydrates in G. usitata and T. vernicifluum polymers showed to be further modified via shikimate and cinnamate pathways to produce phenylpropanoid compounds. Parent molecules and pyrolysis products thereof were verified using analytical standards of high purity. The mass spectra and Kovats retention indices were compiled in an AMDIS library, which can be made available on request.

Analysis of Fresh Sap Collected from Ryukyu Lacquer Tree

The chemical structure of fresh lacquer sap collected from a lacquer tree growing in Nago City of Okinawa, Japan, was analyzed by gas chromatography/mass-spectrometry (GC/MS) and nuclear magnetic resonance (NMR). The results showed that Nago lacquer is laccol lacquer and its major components are 3-(heptadeca-10Z,13E,15E-trienyl)catechol, 3-(heptadeca-10Z,13E-dienyl)catechol, 3-(heptadeca-14Z-enyl)catechol, and 3-(heptadeca-12Z-enyl)catechol, which are similar to the components of Vietnamese lacquer. It showed higher laccase activity at pH 5 - 8 and better low temperature adaptability than Vietnamese lacquer. The Nago lacquer reached a dust free dry (DF) condition after 6 h, but Vietnamese lacquer did not. However, both were able to achieve harden dry (HD) in 24 h at 25°C, 80% relative humidity. In order to identify the lacquer provenance, the strontium isotope ratio was analyzed. The strontium isotope ratio (⁸⁷Sr/⁸⁶Sr) of Nago lacquer was 0.7110, which is different from the 0.7450 of Vietnamese lacquer.