sinapyl-alcohol and coniferaldehyde

This study was carried out to better understand the characteristic modification mechanisms of monolignols by enzyme system of Abortiporus biennis and to induce the degradation of monolignols. Degradation and polymerization of monolignols were simultaneously induced by A. biennis. Whole cells of A. biennis degraded coniferyl alcohol to vanillin and coniferyl aldehyde, and degraded sinapyl alcohol to 2,6-dimethoxybenzene- 1,4-diol, with the production of dimers. The molecular weight of monolignols treated with A. biennis increased drastically. The activities of lignin degrading enzymes were monitored for 24 h to determine whether there was any correlation between monolignol biomodification and ligninolytic enzymes. We concluded that complex enzyme systems were involved in the degradation and polymerization of monolignols. To degrade monolignols, ascorbic acid was added to the culture medium as a reducing agent. In the presence of ascorbic acid, the molecular weight was less increased in the case of coniferyl alcohol, while that of sinapyl alcohol was similar to that of the control. Furthermore, the addition of ascorbic acid led to the production of various degraded compounds: syringaldehyde and acid compounds. Accordingly, these results demonstrated that ascorbic acid prevented the rapid polymerization of monolignols, thus stabilizing radicals generated by enzymes of A. biennis. Thereafter, A. biennis catalyzed the oxidation of stable monolignols. As a result, ascorbic acid facilitated predominantly monolignols degradation by A. biennis through the stabilization of radicals. These findings showed outstanding ability of A. biennis to modify the lignin compounds rapidly and usefully.

Topics: Acrolein; Ascorbic Acid; Basidiomycota; Benzaldehydes; Culture Media; Lignin; Molecular Structure; Molecular Weight; Phenols; Phenylpropionates; Polymerization; Reducing Agents

Coniferyl and sinapyl alcohols were prepared from commercially available coniferaldehyde and sinapaldehyde using borohydride exchange resin in methanol. This reduction is highly regioselective and exceptionally simple, making these valuable monolignols readily available to researchers lacking synthetic chemistry expertise.

Topics: Acrolein; Borohydrides; Phenols; Phenylpropionates

The thermochemolytic behavior of 4-O-etherified cinnamyl alcohols and aldehydes in lignin was investigated in the presence of tetramethylammonium hydroxide (TMAH) (315 degrees C/4 s), using veratrylglycol-beta-(coniferyl alcohol) ether (1a), veratrylglycol-beta-(sinapyl alcohol) ether (1b), and veratrylglycol-beta-(coniferyl aldehyde) ether (2). The methylated products were monitored with gas chromatography-mass spectrometry. Dimers 1a and 1b provided the coniferyl and sinapyl alcohol dimethyl ethers consisting of three isomers, respectively. Coniferyl alcohol dimethyl ether isomers were also observed in the TMAH thermochemolysis pyrolysates of a bulk dehydrogenation polymer of coniferyl alcohol and a Japanese cedar (Cryptomeria japonica) wood. Coniferyl aldehyde methyl ether was not provided from TMAH thermochemolyses of coniferyl aldehyde, 2, a dehydrogenation polymer of coniferyl aldehyde, and the cedar wood. The former three provided veratryl aldehyde in a large abundance, instead of coniferyl aldehyde methyl ether. Sinapyl aldehyde provided 3,4,5-trimethoxybenzaldehyde in a large abundance and sinapyl aldehyde methyl ether in a trace abundance. The results showed that TMAH thermochemolysis is an effective tool to obtain information on cinnamyl alcohol end groups, but is not applicable to analysis of cinnamyl aldehyde end groups.

Topics: Acrolein; Aldehydes; Dimerization; Ethers; Gas Chromatography-Mass Spectrometry; Lignin; Methylation; Phenols; Phenylpropionates; Propanols; Quaternary Ammonium Compounds; Tracheophyta; Wood